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Cite This: J. Org. Chem. 2019, 84, 8886−8898

Ion-Pairing Assemblies Comprising Anion Complexes of π‑Extended Anion-Responsive Molecules Shinya Sugiura,† Wakana Matsuda,‡ Wanying Zhang,‡ Shu Seki,‡ Nobuhiro Yasuda,§ and Hiromitsu Maeda*,† †

Department of Applied Chemistry, College of Life Sciences, Ritsumeikan University, Kusatsu 525-8577, Japan Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan § Research and Utilization Division, Japan Synchrotron Radiation Research Institute, Sayo 679-5198, Japan Downloaded via KEAN UNIV on July 19, 2019 at 12:33:30 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.

‡

S Supporting Information *

ABSTRACT: Anion-responsive molecules comprising phenanthropyrrole rings were synthesized by oxidative coupling. Spectroscopic and theoretical examinations revealed the effects of the π-extended structures. In the solid state as ion-pairing assemblies, Cl− complexes of π-extended derivatives formed stacked structures composed of Cl− complexes themselves and those formed with countercations using extended π-moieties. Aliphatic anion-responsive molecules and their Cl− complexes, as ion pairs with the triazatriangulenium cation, provided hexagonal columnar structures with liquid-crystalline mesophases.

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INTRODUCTION Charged π-electronic systems have attracted significantly increasing attention as potential building units of the assemblies for the formation of electronic materials with ferroelectric and electric conductive properties.1,2 The properties of ion-pairing assemblies and materials can be modulated by controlling the locations of the charged building units and their electronic states. Arrangement of the charged building units would provide the assemblies with the contributions of two representative modes, charge-by-charge and charge-segregated assemblies with alternately and independently stacked oppositely charged species, respectively (Figure 1a).3 One of the issues in the construction of ion-pairing assemblies is the limited availability of charged π-electronic systems to be used as building units. Some π-electronic ions are difficult to synthesize and are also reactive due to electron-deficient (cation) and electron-rich (anion) states and thus are easily converted to other undesired species. One method to efficiently synthesize charged πelectronic systems is the complexation of cations and anions with appropriately designed ion-responsive π-electronic molecules (Figure 1b).4 Thus, various ion complexes can be fabricated as pseudo-π-electronic ions that behave as building units in ion-pairing assemblies. A well-designed system to form planar anion complexes includes a series of dipyrrolyldiketone boron complexes (e.g., 1a,b, Figure 2a), which effectively bind anions with high affinities.4,5 Anion complexes of anion-responsive molecules have produced various ion-pairing assemblies as single crystals, supramolecular gels, and thermotropic liquid crystals.5 Their © 2019 American Chemical Society

Figure 1. (a) Ion-pairing assemblies comprising charged π-electronic systems: charge-by-charge (left) and charge-segregated (right) assemblies and their contributing assembly (center); (b) formation of the building units of the assemblies as ion complexes by ion binding of metal-coordinating and anion-responsive molecules. The charged building units are also available as genuine π-electronic ions, rather than as ion complexes.

assembling modes, with the contributions of charge-by-charge and charge-segregated assemblies, were controlled by the geometries and substituents of the constituent anion receptor molecules. A feature of the anion-complexation strategy is the Received: March 17, 2019 Published: June 13, 2019 8886

DOI: 10.1021/acs.joc.9b00754 J. Org. Chem. 2019, 84, 8886−8898

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The Journal of Organic Chemistry

starting material for π-extended derivatives after several synthetic examinations. Following the reported procedures,5a 2 was prepared in 14% yield by the reaction of 2-(2bromophenyl)pyrrole and malonyl chloride and subsequent treatment with BF3·OEt2. Next, biphenyl-substituted 3a was synthesized in 67% yield by Suzuki coupling of 2 with phenylboronic acid pinacol ester in the presence of tetrabutylammonium chloride (TBACl). Similarly, biaryl-substituted 3b−f were synthesized in 32−63% yields from the corresponding arylboronic acid pinacol esters. The aliphatic chains in 3d−f were introduced for the formation of dimension-controlled assemblies, including low-dimension crystals, supramolecular gels, and liquid crystals. In the absence of TBACl, the BF2 unit in 2 was removed, leading to transformation into diketone 2′, which did not react with arylboronic acid pinacol ester. Another possible route to obtain 3a, using 2-(2-phenyl)phenylpyrrole derivatives as diketone precursors, was less efficient due to low yields and low ability to form a variety of derivatives. The synthesis of the desired π-extended derivatives 4a−f was attempted via the Scholl reaction of 3a−f.8 After numerous examinations, 4a−f were obtained using MoCl5 with increased yields upon the addition of BF3·OEt2 as a Lewis acid. In contrast, the reactions from 3a using FeCl3 and AlCl3 did not provide 4a, and the reaction using 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) resulted in several unidentified products. πExtension of N-unsubstituted pyrrole derivatives by the Scholl reaction has been difficult probably due to the high reactivity of the pyrrole NH site, as this reaction is mainly applied to Nprotected pyrrole derivatives.9,10 The chemical identification of 3a−f and 4a−f was conducted by 1H and 13C NMR and matrixassisted laser desorption/ionization (MALDI)- and electrospray ionisation (ESI)-time-of-flight mass spectrometry (TOF-MS). 4a−f, possessing fused aromatic rings, exhibited downfieldshifted 1H NMR signals compared to 3a−f because of the expanding ring current effect, as seen in the pyrrole NH signals of 3b and 4b at 7.21 and 8.83 ppm, respectively (Figure 4a). The signal shifts were correlated with the nucleus-independent

Figure 2. (a) Anion-binding behavior of dipyrrolyldiketone boron complexes 1a,b and (b) anion complexes of π-extended derivatives as building units of ion-pairing assemblies in combination with cations.

preparation of sof t anions whose negative charge, originally located on the guest anion, is partially delocalized in the host πelectronic systems. Therefore, the introduction of appropriately extended π-electronic moieties would result in soft anions, ideally with the more delocalized negative charge (Figure 2b), for the modulation of ion-pairing assemblies. In this study, more π-extended anion-responsive molecules were synthesized as precursors of soft anions (receptor−anion complexes) for the formation of their ion-pairing assemblies.

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RESULTS AND DISCUSSION Synthesis and Characterization. A promising small unit for π-extension is triphenylene, which is often used as a core unit of liquid crystals6 and is comparable to more extended πelectronic systems, such as perylene, coronene, and hexabenzocoronene, which form assemblies with high charge-transporting abilities.7 To introduce phenanthrene moieties, especially those fused with pyrrole rings, into dipyrrolyldiketone boron complexes, the BF2 complex of 1,3-di(5-(2-bromophenyl)pyrrol-2-yl)-1,3-propanedione 2 (Figure 3) was focused on as a

Figure 3. Synthesis of π-extended anion-responsive molecules 4a−f via biphenyl derivatives 3a−f. 8887


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Figure 4. (a) 1H NMR spectra of (i) 3b and (ii) 4b in DMSO-d6; (b) UV/vis absorption spectra of (i) 3a and (ii) 4a in CH2Cl2 (0.01 mM) and the corresponding theoretical absorption stick spectra, with the molecular orbitals contributing to the transitions at the main absorptions, based on the TD-DFT calculations at B3LYP/6-31+G(d,p), and photographs of the samples under visible and UV (365 nm) light (inset).

Figure 5. Single-crystal X-ray structures (top and side views) of (a) 3a, (b) 3b, and (c) 4a. Atom color code: brown, pink, yellow, blue, red, and green refer to carbon, hydrogen, boron, nitrogen, oxygen, and fluorine, respectively.

chemical shift (NICS)11 value in the phenanthropyrrole unit (Figure S43): −9.13, −4.23, and −10.19 ppm for the three phenyl rings and −11.45 ppm for the pyrrole ring (center for each). The NICS value of the core benzene ring (−4.23 ppm) is larger than the center of triphenylene (−2.84 ppm)12 due to the double bond character of the pyrrole-fused part. In contrast to 3a showing a UV/vis absorption band at 495 nm in CH2Cl2, πextended 4a exhibited red-shifted absorption (λmax = 533 nm) along with an absorption appearing at around 250 nm, which were correlated with the theoretical spectra calculated by timedependent (TD)-density functional theory (DFT) (Figures 4b, S41, S42, S46, S48, and S49).12 UV/vis absorption spectra of 3b−f and 4b−f exhibited the maxima in the ranges 498−500 and 544−553 nm, respectively, which were red-shifted upon the introduction of alkoxy substituents. Considering the contributing molecular orbitals for excitation, the absorptions of 4a−f are

derived from the intramolecular charge transfer from the fused rings to the core unit in the extended π-systems. Similar to the absorption spectra, the fluorescence emission, with excitation at λmax, exhibited red-shifted emissions as seen in the maximum at 565 nm (4a) compared to 531 nm (3a). Fluorescence quantum yields (ΦFL) of 3a and 4a in CH2Cl2 were comparable with the values of 0.88 and 0.85, respectively. The exact geometries and packing structures of 3a,b and 4a in the solid state were revealed by single-crystal X-ray analysis (Figures 5, S25−S27, and S33−S35).13 In 3a,b, large pyrrole− phenyl dihedral angles of 41.60 and 36.42/36.08°, respectively, were observed. Intermolecular interactions were observed for 3a,b with N(−H)···F distances of 3.079 and 2.990/3.223 Å, respectively, although π−π interactions were not observed due to large steric hindrance. On the other hand, 4a had smaller pyrrole−phenyl dihedral angles of 1.64/1.44° and exhibited a 8888


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Table 1. Anion-Binding Constants (Ka, M−1) of 3a,b and 4a,b along with 1b as a Reference5a in CH2Cl2 (1.0 × 10−5 M) at 20 °C Cl− Br− CH3CO2−

3a

3b

4a

4b

1b

810 ± 40 93 ± 5 28 000 ± 2000

750 ± 60 97 ± 4 35 000 ± 3000

420 000 ± 39 000 55 000 ± 4200 140 000 ± 25 000

150 000 ± 5900 15 000 ± 1000 490 000 ± 60 000

30 000 ± 1300 2800 ± 140 210 000 ± 25 000

Figure 6. (a) Optimized structures and (b) electrostatic potential (ESP), mapped onto the electron density isosurface (δ = 0.01), of (i) 1b·Cl−, (ii) 3a· Cl−, and (iii) 4a·Cl− (top and side views) calculated at B3LYP/6-31+G(d,p).

Figure 7. Energy diagrams of 3a (left) and 4a (right) for pyrrole-inverted preorganization calculated at PCM-B3LYP/6-31+G(d,p) in CH2Cl2// B3LYP/6-31+G(d,p) and for anion binding derived from Ka values.

tightly stacked π−π interaction with a distance of 3.522 Å based on the core planes (40 atoms). The conformation of 3a in the crystal, influenced by intermolecular interactions, was different from the most stable optimized structure (B3LYP/6-31+G(d,p)), with terminal phenyl moieties orienting to pyrrole NH sites (Figures S41 and S42).12

Anion-Responsive Behavior and Solid-State IonPairing Assemblies. Affinities of 3a,b and 4a,b for anions were estimated based on the changes in the UV/vis absorption spectra in the presence of increasing concentrations of anions (Table 1 and Figures S53−S56). UV/vis absorption spectral changes of 3a,b upon the addition of anions as TBA salts in 8889


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Figure 8. 1H NMR spectra of (a) 3b and (b) 4b upon the addition of Cl− as a TBA salt in CD2Cl2 (0.01 mM) at room temperature (r.t.). As 4b was less soluble in CD2Cl2 even at r.t., the amounts of added TBACl was not estimated by the integral values.

Figure 9. Single-crystal X-ray structures of (a) 3a·Cl−−TBA+, (b) 4a·Cl−−TBA+, and (c) 4b·Cl−−TBA+ as (i) top views showing N/CH···Cl− interactions (red broken lines), (ii) partial structure showing intermolecular interactions (red broken lines), and (iii) packing diagrams. In (i) and (ii), atom color code: brown, pink, yellow, blue, red, green, and green (sphere) refer to carbon, hydrogen, boron, nitrogen, oxygen, fluorine, and chlorine, respectively. In (iii), cyan and magenta represent cations and receptor−anion complexes, respectively.

CH2Cl2 at 20 °C revealed binding constants (Ka) of 810/750, 93/97, and 28 000/35 000 M−1 for Cl−, Br−, and CH3CO2−, respectively. These values were smaller than those of phenylsubstituted 1b (30 000, 2800, and 210 000 M−1)5a due to the large steric hindrance of the biphenyl units. In contrast, the corresponding Ka values of 4a,b were 420 000/150 000, 55 000/ 15 000, and 140 000/>105 M−1, respectively, which were greater than those of 1b for halide anions because of limited steric hindrance and the contribution of phenyl CH units to anion binding as supported from theoretical calculations (Figures 6a, S41, S42, S47, and S51). The fixed cavities of 4a,b resulted in less efficient binding for larger anions such as CH3CO2−. The hypothetical conformations, which are formed by the removal of Cl− from the theoretically optimized Cl− complexes, are less stable, in their Gibbs free energies estimated by single-point calculations at PCM-B3LYP/6-31+G(d,p) in CH2Cl2, by 5.18 (ΔG1‑3a) and 3.35 (ΔG1‑4a) kcal/mol for 3a and 4a, respectively, than their respective most stable conformations,12 suggesting a

less stable preorganized conformation for 3a than 4a (Figure 7). Furthermore, the Gibbs free energies derived from the Ka values for Cl−, −3.92 (ΔG2‑3a) and −7.54 (ΔG2‑4a) kcal/mol, provided the ΔΔG2 value (−(ΔG2‑4a − ΔG2‑3a) = 3.62 kcal/mol), which is greater than the ΔΔG1 value (ΔG1‑3a − ΔG1‑4a = 1.83 kcal/ mol). This result indicated that the anion-binding ability is influenced by the stability of the preorganized structure and can also be significantly controlled by the polarized interaction sites for guest anions and the delocalization of the negative charge of bound anions, seen by comparison of 4a·Cl− with 1b·Cl− and 3a·Cl− in electrostatic potential (ESP) mapping (Figures 6b, S44, and S45). Upon the addition of TBACl to the CD2Cl2 solutions of 3b and 4b, which were used for their good solubilities, 1H NMR signals of pyrrole CH, phenyl CH, and bridged CH in CD2Cl2 shifted downfield for pyrrole NH (9.42 to 12.35 and 10.13 to 13.08 ppm), bridged CH (6.44 to 8.98 and 7.12 to 9.45 ppm), and phenyl CH (7.61 to 8.23 and 8.19 to 9.40 ppm), 8890


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Figure 10. (a) Structure of TATA+; single-crystal X-ray structures of (b) 3a·Cl−−TATA+ and (c) 4a·Cl−−TATA+ as (i) top views showing N/CH··· Cl− interactions (red broken lines), (ii) partial structure showing intermolecular interactions (red broken lines), and (iii) packing diagrams. In (i) and (ii), atom color code: brown, pink, yellow, blue, red, green, and green (sphere) refer to carbon, hydrogen, boron, nitrogen, oxygen, fluorine, and chlorine, respectively. In (iii), cyan and magenta represent cations and receptor−anion complexes, respectively.

charge delocalization via π-extension despite the introduction of electron-donating methoxy units. Geometries and electronic structures of coexisting cations are essential for controlling the assembling modes of ion pairs. Ionpairing assembled structures of the ion pairs of Cl− complexes with the 4,8,12-tripropyl-4,8,12-triazatriangulenium cation (TATA+)14 as a planar cation (Figure 10a), 3a·Cl−−TATA+ and 4c·Cl−−TATA+, were also revealed by single-crystal X-ray analysis (Figures 10b,c, S29, S32, S37, and S40).12 3a·Cl−− TATA+ showed a [1 + 1]-type Cl− complex, whose two pyrrole rings and bridged CH interact with Cl− with N/C(−H)···Cl− distances of 3.457/3.210 and 3.334 Å, respectively. Phenyl oC(−H)···Cl− distances of 3.819/3.919 Å suggested a small affinity of o-CH to Cl− due to large steric hindrance of the biphenyl units. 3a·Cl− and the TATA+ cation alternately stack to form a charge-by-charge assembly with the distances 3.955 and 3.965 Å estimated from the average distances of the mean planes of the dipyrrolyldiketone core unit (16 atoms) of 3a and TATA+ (22 atoms) (Figure 10b). Likewise, 4c·Cl−−TATA+ also formed a [1 + 1]-type Cl− complex, whose two pyrrole rings, bridged CH, and phenyl o-CH showed the interactions with Cl− with N/ C(−H)···Cl− distances of 3.331/3.385, 3.461, and 3.775/3.847 Å, respectively. 4c·Cl− and the TATA+ cation were stacked to form a charge-by-charge assembly with the distances of 3.545 and 3.450 Å estimated from the average distances of the mean planes of the extended pyrrole unit (17 atoms) of 4c and TATA+ (22 atoms) (Figure 10c). 4c·Cl− was partially overlapped with another receptor−anion complex with a distance of 4.586 Å based on the receptor core planes (40 atoms). Dimension-Controlled Assemblies. As the π-electronic systems bearing aliphatic chains often form dimensioncontrolled assembled structures, 3d−f and 4d−f were expected to provide mesophases in the form of anion-free receptors and ion pairs as anion complexes (Table 2). Solid-state samples of 3d−f and 4d−f were prepared by reprecipitation from CH2Cl2/ MeOH. The phase-transition behaviors of 3d−f and 4d−f were examined using differential scanning calorimetry (DSC) (Figure S59). In contrast to 3d,e and 4d exhibiting no mesophases, 3f and 4e,f formed mesophases, as seen in their DSC profiles showing the transition temperatures of 34 and 48/80 °C (3f),

respectively, by the formation of hydrogen bonding (Figures 8, S57, and S58). π-Extended 4b forms the Cl− complex with the interaction of phenyl CH and a planar geometry like 1b,5a in contrast to 3b, which lacks effective interactions by phenyl CH, resulting in the enhanced anion-binding abilities. The shifts by anion binding were correlated with the theoretically optimized structures of Cl− complexes, exhibiting (Cphenyl−)H···Cl− distances of 2.579, 2.742/2.773, and 2.683 Å for 1a, 3a, and 4a, respectively (Figure 6a).12 The (Cphenyl−)H···Cl− distances of 3a and 4a were larger than those of 1a because of the large steric hindrance of the terminal phenyl and pyrrole rings and the rigid structure of the pyrrole units, respectively. Anion complexes of π-electronic systems are the building units of ion-pairing assemblies in combination with cations. Upon single-crystal X-ray analysis of the ion pairs of Cl− complexes with TBA+ as a bulky cation, 3a·Cl−−TBA+ and 4a,b·Cl−−TBA+ revealed the anion-binding geometries and ionpairing assembled structures (Figures 9, S28, S30, S31, S36, S38, and S39).13 3a·Cl−−TBA+ showed a Cl−-binding conformation with a single inverted pyrrole ring. Pyrrole NH and bridged CH showed interactions with Cl− with N/C(−H)···Cl− distances of 3.232 and 3.617 Å, respectively, whereas the other pyrrole NH constructed an intermolecular N−H···F interaction with another BF2 unit with the N(−H)···F distances of 2.957/ 3.159 Å (Figure 9a). In the packing diagram, 3a·Cl− and the TBA cation alternately stack to provide a charge-by-charge assembly. On the other hand, 4a·Cl−−TBA+ afforded a [1 + 1]type Cl− complex, whose two pyrrole rings, bridged CH, and phenyl o-CH showed interactions with Cl− with N/C(−H)··· Cl− distances of 3.200/3.308, 3.382, and 3.728/3.836 Å, respectively (Figure 9b). The Cl− complex 4a·Cl− existed as a dimer through π−π interaction with a π−π distance of 3.306 Å based on the receptor core plane (40 atoms), suggesting that the effects result from π-extension. The TBA+ cations were proximally located with 4a·Cl− as a stacked dimer with a TBA−N···Cl− distance of 4.290 Å, which is smaller than that of 3a·Cl−−TBA+ (7.116 Å). 4b·Cl−−TBA+ also formed a [1 + 1]type Cl− complex, which formed a π−π stacked dimer with a stacking distance of 3.450 Å based on the receptor core planes (40 atoms) (Figure 9c), suggesting the effect of the negative 8891


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1.35 (004), and 1.16 nm (005) derived from a SmA2 phase (Figure 11a-ii). In contrast, the mesophase of 4f at 80 °C upon cooling from Iso showed d spacings of 3.84 (100), 2.22 (110), 2.08 (200), 1.45 (210), 1.28 (300), 1.10 (220), 1.06 (310), and 0.42 nm (001) derived from a hexagonal columnar (Colh) phase of a = 4.43 nm and c = 0.42 nm (Z = 2 for ρ = 0.80) (Figure 11bii). Ion-pairing assemblies of Cl− complexes of 4d−f with TATA+, 4d−f·Cl−−TATA+, were prepared in bulk by mixing of 4d−f with 4,8,12-tripropyl-4,8,12-triazatriangulenium chloride (TATACl)5b (1 equiv) in 1,4-dioxane, whereas mixtures prepared with TBACl (1 equiv) in 1,4-dioxane resulted in the formation of sols, which were difficult to purify. In contrast, the formation of ion pairs was also difficult for 3d−f with TBACl and TATACl because of the low anion-binding abilities and less stable assemblies of the less planar Cl− complexes with cations. The successfully synthesized ion-pairing assemblies 4d−f·Cl−− TATA+ were confirmed by 1H NMR. 4e,f·Cl−−TATA+ formed mesophases, which showed wider temperature ranges than the corresponding anion-responsive molecules, as seen in the transition temperatures of 189/−18 and 194/−13 °C (4e· Cl−−TATA+) and 181/20 and 200/20 °C (4f·Cl−−TATA+) upon cooling and heating, respectively (Figure S59). POM of 4d−f·Cl−−TATA+ exhibited wire-like textures in mesophases (Figures 11c-i and S62). The packing arrangement of 4d−f· Cl−−TATA+ was also examined by synchrotron XRD analysis (SPring-8) at variable temperatures (Figures S69−S75). As an example, the mesophase of 4f·Cl−−TATA+ at 150 °C cooling

Table 2. Summarized Phase-Transition Behaviors of 3f, 4e,f, and 4d−f·Cl−−TATA+a 3f 4e 4f 4d·Cl−−TATA+ 4e·Cl−−TATA+ 4f·Cl−−TATA+

coolingb

heatingb

N 34 Iso Colh 8c Colh 106 Iso Colh 46 Colh 109 Iso Colh 205 Iso Colh −18c Colh 189 Iso Colh 18c Colh 181 Iso

N 48 SmA2 80 Iso Colh 13c Colh 126 Iso Colh 50c Colh 122 Iso Colh 208 Iso Colh −13 Colh 194 Iso Colh 20b Colh 200 Iso

a

Crystalline states are described in italics. bTransition temperatures (°C, the onset of the peak) from DSC 1st cooling and 2nd heating scans (5 °C min−1). cPeak top values due to the broad peaks.

106/13 and 16/126 °C (4e), and 109/46 and 50/122 °C (4f) upon cooling and heating, respectively. In contrast to 3f showing monotropic transitions, π-extended 4d,e exhibited enantiotropic transitions with higher transition temperatures. Polarized optical microscopy (POM) of 3f showed a mosaic texture at 30 °C upon cooling from the isotropic liquid (Iso). 3f showed a dark field at 45 °C and a mosaic texture at 70 °C upon heating from 30 °C, exhibiting quasi-isotropic and smectic (Sm) phases (Figures 11a-i and S60). 4e,f showed mosaic textures upon cooling from Iso (Figures 11b-i and S61). The arrangements of the packing structures of 3f and 4e,f were examined by synchrotron X-ray diffraction (XRD) analysis (SPring-8) at variable temperatures (Figures S52 and S63−S68). The solid phase of 3f at 10 °C upon cooling from Iso showed a nematic phase and, upon heating to 70 °C, showed d spacings of 5.36 (001), 2.70 (002), 1.80 (003),

Figure 11. Mesophase behaviors of (a) 3f, (b) 4f, and (c) 4f·Cl−−TATA+ in (i) POM images at 70 °C upon heating and 80 and 180 °C upon cooling, respectively, and (ii) synchrotron XRD at 60 °C upon heating and 100 and 150 °C upon cooling, respectively, and the corresponding packing models. 8892


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The Journal of Organic Chemistry from Iso showed d spacings of 3.96 (100), 2.29 (110), 1.98 (200), 1.50 (210), 1.32 (300), 1.14 (220), 1.10 (310), and 0.34 nm (001) derived from a Colh phase with a = 4.57 nm and c = 0.34 nm (Z = 2 for ρ = 1.14) (Figure 11c-ii). Similar results were observed for 4e·Cl−−TATA+, at 189 °C upon cooling, with a Colh phase (a = 4.15 nm and c = 0.33 nm (Z = 2 for ρ = 1.23)). According to these data, two ion-pairing units formed one disc, providing Colh structures. The diffractions for stacking were derived mainly from the stacked TATA+ cations along with proximally located Cl− complexes, exhibiting the contribution of charge-segregated assemblies. Electric Conductive Properties. The characteristic wirelike textures of 4e,f·Cl−−TATA+ in Colh structures recall us to examine photoconductivity in the materials with one-dimensional (1D) electric conductive pathways stabilized not only by hexagonal columnar stacking but also by complemental ion repulsion. The latter particularly is presumed to facilitate the interplay of thermodynamic stability of the structures and efficient photoinduced free charge carrier generation yields via the shorter Onsager distances in the condensed phase.15 Photoconductivity transients were monitored in mesophases at r.t. to screen the series of compounds. It is evident that ionpairing assemblies gave clear conductivity transients with long enough free charge carrier stability up to 10 μs without significant decays, in spite of negligible conductivity observed for the others with initial rapid recombination of charge carriers. To confirm the 1D electronic conductive pathways along the textures of the ion-pairing assemblies of 4e,f·Cl−−TATA+, the condensed mesophases were sheared, giving the aligned structures in a 1D manner. It should be noted that the photoconductivity transient in 4f·Cl−−TATA+ showed remarkable enhancement after shearing with almost identical decay kinetics (Figures 12 and S76), and the conductivity reached up to 2.6-fold higher value (ϕ∑μ = 3 × 10−5 cm2 V−1 s−1) than that observed in the initial isotropically aligned one. The anisotropic

factor of 1D-alignment relative to three-dimensional random distribution is presumed to be 3 at maximum, thus the shearing of 4f·Cl−−TATA+ is considered to give a well aligned solid film in the present protocol. In sharp contrast, the identical shearing protocol for 4e·Cl−−TATA+ led to almost no significant enhancement in photoconductivity transients. The lower Colh mesophase−crystalline-state transition temperature in 4e·Cl−− TATA+ allows relatively efficient macroscopic structural relaxation to 4f·Cl−−TATA+ at r.t., and this is the case that the anisotropic alignment of 1D structures was not well reflected as anisotropic photoconductivity in 4e·Cl−−TATA+.

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SUMMARY Newly synthesized pyrrole-based π-extended anion-responsive molecules exhibited fascinating anion-binding and assembly behaviors, which differ from those of their less planar precursors. Planar π-extended anion-responsive molecules showed high anion-binding abilities due to the contribution of the phenyl CH moiety to anion binding, small steric hindrance, and delocalization of the negative charge. Observed solid-state ionpairing assemblies include diverse assembling modes, with stacked structures of two Cl− complex units and those of Cl− complexes and cations, according to the geometries and electronic structures of the coexisting cations. Furthermore, dimension-controlled assemblies with liquid-crystalline mesophases were fabricated from aliphatic derivatives in the ionpairing form as revealed by POM and synchrotron XRD. Enhancement of the photoconductivity was observed in an anisotropically aligned mesophase of the ion-pairing assembly. In a variety of states, the assembling modes were modulated by the introduction of π-extended moieties. Further modifications of the π-extended anion-responsive molecules are currently under investigation for future functional materials.

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EXPERIMENTAL SECTION

General Procedures. Starting materials were purchased from FUJIFILM Wako Pure Chemical Corp, Nacalai Tesque Inc., and Sigma-Aldrich Co. and used without further purification unless otherwise stated. NMR spectra used in the characterization of products were recorded on a JEOL ECA-600 600 MHz spectrometer. All NMR spectra were referenced to solvent. UV−visible absorption spectra were recorded on a Hitachi U-3500 spectrometer. Fluorescence spectra and quantum yields were recorded on a Hitachi F-4500 fluorescence spectrometer and a Hamamatsu Quantum Yields Measurements System for Organic LED Materials C9920-02, respectively. Matrixassisted laser desorption ionization time-of-flight mass spectrometries (MALDI-TOF-MS) were recorded on a Shimadzu Axima-CFR plus. High-resolution (HR) electrospray ionization mass spectrometries (ESI-MS) were recorded on a BRUKER microTOF using the ESI-TOF method. Double-focusing electron impact high-resolution mass spectrometries (EI-HRMS) were recorded on a JEOL JMS-700 MStation spectrometer at the Nara Institute of Science and Technology (NAIST). TLC analyses were carried out on aluminum sheets coated with silica gel 60 (Merck 5554). Column chromatography was performed on Wakogel C-300 and Merck silica gel 60. The spectroscopic data of the products are shown in Figures S1−S24. N-Boc-2-(2-bromophenyl)pyrrole, s1. According to the literature procedure,16 a round-bottomed flask placed with N-Boc-pyrrole-2boronic acid17 (2.11 g, 10.0 mmol), 2-bromo-1-iodobenzene (1.25 mL, 10.0 mmol), Pd(PPh3)2Cl2 (105 mg, 0.15 mmol), and K2CO3 (3.45 g, 25.0 mmol) was flushed with N2 and charged with a mixture of degassed dimethoxyethane (DME) (30 mL) and water (4 mL). The mixture was heated at 80 °C using an oil bath for 18 h, cooled, and partitioned between water and CH2Cl2. The combined organic extracts were dried over anhydrous Na2SO4 and evaporated. The residue was then chromatographed over a flash silica gel column (Merck silica gel 60,

Figure 12. Photoconductivity kinetic traces of (a) 4e·Cl−−TATA+ and (b) 4f·Cl−−TATA+ as mesophases at r.t. after shearing (red) with respect to the corresponding initial disordered structures (blue) upon excitation of 355 nm laser pulses at 9.1 × 1015 photons cm−2. The shearing direction of the film was set at parallel to the electric field vector in the microwave cavity. 8893


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was flushed with N2 and charged with a mixture of degassed THF (8 mL) and water (4 mL). The mixture was heated at 80 °C using an oil bath for 12 h, cooled, and then partitioned between water and CH2Cl2. The combined organic extracts were dried over anhydrous Na2SO4 and evaporated. The residue was then chromatographed over a silica gel column (Wakogel C-300) to give 3a−f. BF2 Complex of 1,3-Di(5-(2-phenylphenyl)pyrrol-2-yl)-1,3-propanedione, 3a. From 2 (5.61 mg, 10.0 μmol) and 4,4,5,5tetramethyl-2-phenyl-1,3,2-dioxaborolane (9.10 mg, 44.6 μmol). Yield: 3.73 mg (6.7 μmol, 67%), red solid. Rf = 0.61 (1% MeOH/ CH2Cl2). 1H NMR (600 MHz, CDCl3, 20 °C): δ (ppm) 8.92 (s, 2H, NH), 7.63−7.62 (m, 2H, Ar-H), 7.47−7.38 (m, 12H, Ar-H), 7.27−7.25 (m, 4H, A-H), 6.93 (dd, J = 3.6 and 2.4 Hz, 2H, pyrrole-H), 6.20 (s, 1H, CH), 6.19 (t, J = 3.6 Hz, 2H, pyrrole-H). 1H NMR (600 MHz, DMSOd6, 20 °C): δ (ppm) 12.42 (s, 2H), 7.65−7.64 (m, 2H), 7.46 (m, 4H), 7.38−7.37 (m, 2H), 7.32−7.27 (m, 6H), 7.17 (d, J = 6.6 Hz, 4H), 7.08 (s, 2H), 7.05 (s, 1H), 5.77−5.66 (m, 2H). 13C{1H} NMR (151 MHz, CDCl3, 20 °C): δ (ppm) 167.8, 140.7, 140.5, 140.3, 131.3 129.2, 129.0, 128.9, 128.5, 128.3, 128.2, 126.4, 118.3, 113.6, 89.6 (some of the aryl signals were overlapped with other signals). UV/vis (CH2Cl2, λmax [nm] (ε, 105 M−1 cm−1)): 495 (1.08). Fluorescence (CH2Cl2, λem [nm] (λex [nm])): 531 (495). MALDI-TOF-MS: m/z (% intensity): 553.2 (100), 554.2 (33). Calcd for C35H24BF2N2O2 ([M − H]−): 553.20. HRMS (ESI-TOF) m/z: [M − H]− calcd for C35H24BF2N2O2 553.1904; found 553.1912. This compound was further characterized by single-crystal X-ray diffraction analysis. BF2 Complex of 1,3-Bis(5-(2-(3,4,5-trimethoxyphenyl)phenyl)pyrrol-2-yl)-1,3-propanedione, 3b. From 2 (112.6 mg, 0.201 mmol) and 4,4,5,5-tetramethyl-2-(3,4,5-trimethoxyphenyl)-1,3,2-dioxaborolane (173.4 mg, 0.589 mmol). Yield: 91.65 mg (0.125 mmol, 63%), red solid. Rf = 0.26 (2% MeOH/CH2Cl2). 1H NMR (600 MHz, DMSO-d6, 20 °C): δ (ppm) 12.38 (s, 2H), 7.66−7.65 (m, 2H), 7.50− 7.47 (m, 6H), 7.21 (br, 2H), 7.17 (s, 4H), 7.06 (s, 1H), 6.48 (s, 4H), 5.89 (dd, J = 1.8 and 1.8 Hz, 2H), 3.652 (s, 6H), 3.647 (s, 12H). 13 C{1H} NMR (151 MHz, DMSO-d6, 20 °C): δ (ppm) 167.7, 152.5, 141.7, 140.8, 136.8, 136.1, 130.2, 129.9, 128.8, 127.3, 126.1, 119.3, 114.0, 106.7, 89.8, 60.1, 55.8 (one aryl signal was overlapped with other signals). UV/vis (CH2Cl2, λmax [nm] (ε, 105 M−1 cm−1)): 498 (0.93). Fluorescence (CH2Cl2, λem [nm] (λex [nm])): 533 (498). MALDITOF-MS: m/z (% intensity): 733.3 (63), 734.3 (100), 735.3 (40). Calcd for C41H37BF2N2O8 ([M]−): 734.26. HRMS (ESI-TOF) m/z: [M − H]− calcd for C41H36BF2N2O8 733.2538; found 733.2535. This compound was further characterized by single-crystal X-ray diffraction analysis. 4,4,5,5-Tetramethyl-2-(3,4,5-tributoxyphenyl)-1,3,2-dioxaborolane, s4. According to the literature procedure,18 a round-bottomed flask placed with 5-bromo-1,2,3-tributoxybenzene19 (500.2 mg, 1.25 mmol), Pd(PPh3)2Cl2 (29.4 mg, 0.042 mmol), bis(pinacolato)diboron (485.1 mg, 1.89 mmol), and KOAc (370.0 mg, 3.77 mmol) was flushed with N2 and charged with a mixture of degassed dioxane (17 mL). The mixture was heated at 80 °C for 12 h, cooled, and then partitioned between water and CH2Cl2. The combined extracts were dried over anhydrous Na2SO4 and evaporated. The residue was then chromatographed over a flash silica gel column (Merck silica gel 60, eluent: CH2Cl2/n-hexane = 1:3) to give s4 (313.2 mg, 0.70 mmol, 56%) as a colorless solid. Rf = 0.30 (CH2Cl2/n-hexane = 1:2). 1H NMR (600 MHz, CDCl3, 20 °C): δ (ppm) 7.02 (s, 2H), 4.02 (t, J = 6.6 Hz, 4H), 4.00 (t, J = 6.6 Hz, 2H), 1.80 (tt, J = 7.2 and 6.6 Hz, 4H), 1.74 (tt, J = 7.2 and 6.6 Hz, 2H), 1.57−1.50 (m, 6H), 1.36 (s, 12H), 0.99 (t, J = 7.8 Hz, 6H), 0.97 (t, J = 7.2 Hz, 3H). 13C{1H} NMR (151 MHz, CDCl3, 20 °C): δ (ppm) 153.1, 141.2, 112.9, 83.9, 73.1, 68.9, 32.5, 31.7, 25.0, 19.5, 19.4, 14.0. HRMS (EI-TOF) m/z: [M]+ calcd for C24H41BO5 420.3047; found 420.3052. BF2 Complex of 1,3-Bis(5-(2-(3,4,5-tributoxyphenyl)phenyl)pyrrol-2-yl)-1,3-propanedione, 3c. From 2 (58.9 mg, 0.105 mmol) and s4 (133.2 mg, 0.316 mmol). Yield: 44.3 mg (45 μmol, 43%), orange solid. Rf = 0.18 (CH2Cl2). 1H NMR (600 MHz, CDCl3, 20 °C): δ (ppm) 9.24 (s, 2H), 7.60−7.59 (m, 2H), 7.45−7.38 (m, 6H), 6.99− 6.98 (m, 2H), 6.44 (s, 4H), 6.24 (br, 1H), 6.15 (br, 2H), 4.03 (t, J = 6.0 Hz, 4H), 3.88 (t, J = 6.6 Hz, 8H), 1.78−1.70 (m, 12H), 1.58−1.52 (m,

eluent: CH2Cl2/n-hexane = 1:5) to give s1 (2.01 g, 6.23 mmol, 62%) as a colorless oil. Rf = 0.38 (CH2Cl2/n-hexane = 1:5). 1H NMR (600 MHz, DMSO-d6, 20 °C): δ (ppm) 7.63 (dd, J = 7.8 and 1.2 Hz, 1H), 7.40−7.37 (m, 2H), 7.35 (dd, J = 7.8 and 2.4 Hz, 1H), 7.30−7.27 (m, 1H), 6.28 (t, J = 2.4 Hz, 1H), 6.16 (dd, J = 3.6 and 1.8 Hz, 1H), 1.22 (s, 9H). 13C{1H} NMR (151 MHz, DMSO-d6, 20 °C): δ (ppm) 148.3, 135.8, 132.0, 131.7, 131.5, 129.4, 127.1, 124.8, 121.4, 114.2, 110.6, 83.0, 26.8. HRMS (EI-TOF) m/z: [M]+ calcd for C15H16BrNO2 321.0364; found 321.0364. 2-(2-Bromophenyl)pyrrole, s2. A round-bottomed flask placed with s1 (2.01 g, 6.23 mmol) under N2 was heated at 180 °C using an oil bath for 30 min. After cooling, the residue was then chromatographed over a silica gel column (Wakogel C-300; eluent: CH2Cl2/n-hexane = 1:3) to give s2 (1.23 g, 5.54 mmol, 88%) as a colorless oil. Rf = 0.50 (CH2Cl2/nhexane = 1:3). 1H NMR (600 MHz, DMSO-d6, 20 °C): δ (ppm) 11.16 (s, 1H), 7.67 (dd, J = 7.8 and 1.8 Hz, 1H), 7.50 (dd, J = 7.8 and 1.8 Hz, 1H), 7.40 (td, J = 7.2 and 1.8 Hz, 1H), 7.16 (td, J = 7.2 and 1.8 Hz, 1H), 6.89−6.88 (m, 1H), 6.55−6.53 (m, 1H), 6.15−6.14 (m, 1H). 13C{1H} NMR (151 MHz, DMSO-d6, 20 °C): δ (ppm) 133.8, 133.7, 130.0, 128.9, 127.7, 120.3, 119.3, 109.7, 108.4 (one aryl signal was overlapped with other signals). HRMS (EI-TOF) m/z: [M]+ calcd for C10H8BrN: 220.9840; found 220.9840. 1,3-Bis(5-(2-bromophenyl)pyrrol-2-yl)-1,3-propanedione, s3. According to the literature procedure,5a to a solution of s2 (318.2 mg, 1.44 mmol) in CH2Cl2 (28 mL) under N2 was added malonyl chloride (70.0 μL, 0.72 mmol) at 0 °C. The mixture was stirred at 0 °C for 1 h and added to saturated Na2CO3 aq. The suspension was extracted with CH2Cl2 and washed with water. The organic phase was dried over anhydrous Na2SO4 and evaporated. The residue was then chromatographed over a silica gel column (Wakogel C-300, eluent: CH2Cl2) to give s3 (58.0 mg, 0.23 mmol, 16%) as a yellow solid. Rf = 0.22 (CH2Cl2). 1H NMR (600 MHz, DMSO-d6, 20 °C: diketone s3 was obtained as a mixture of keto and enol tautomers in the ratio of 1:0.58): keto form δ (ppm) 12.12 (s, 2H), 7.73 (dd, J = 6.6 and 1.2 Hz, 2H), 7.55 (dd, J = 6.0 and 1.8 Hz, 2H), 7.45 (td, J = 7.8 and 1.2 Hz, 2H), 7.30 (td, J = 7.2 and 1.8 Hz, 2H), 7.21−7.20 (m, 2H), 6.56−6.55 (m, 2H), 4.36 (s, 2H); enol form δ (ppm) 12.01 (s, 2H), 7.75 (dd, J = 7.2 and 1.2 Hz, 2H), 7.59 (dd, J = 6.0 and 1.8 Hz, 2H), 7.48 (td, J = 7.8 and 1.2 Hz, 2H), 7.32 (td, J = 5.4 and 1.8 Hz, 2H), 7.09 (dd, J = 2.4 and 1.8 Hz, 2H), 6.88 (s, 1H), 6.60 (dd, J = 2.4 and 1.8 Hz, 2H). 13C{1H} NMR (151 MHz, DMSO-d6, 20 °C): δ (ppm) 183.5, 175.2, 137.2, 135.9, 133.4, 133.3, 132.8, 132.5, 132.2, 131.7, 131.6, 129.9, 129.7, 129.2, 127.73, 127.67, 121.67, 121.64, 118.5, 114.4, 112.2, 111.9, 90.8, 48.8. MALDI-TOFMS: m/z (% intensity): 509.0 (43), 511.0 (100), 512.0 (46). Calcd for C23H15Br2N2O2 ([M − H]−): 508.95. HRMS (ESI-TOF) m/z: [M − H]− calcd for C23H15Br2N2O2 508.9506; found 508.9508. BF2 Complex of 1,3-Bis(5-(2-bromophenyl)pyrrol-2-yl)-1,3-propanedione, 2. According to the literature procedure,5a to a solution of s3 (25.8 mg, 0.050 mmol) in CH2Cl2 (80 mL) under N2 was added BF3· OEt2 (189 μL, 1.5 mmol) at r.t. The mixture was stirred for 30 min and evaporated. The residue was then chromatographed over a silica gel column (Wakogel C-300; eluent: CH2Cl2) to give 2 (25.7 mg, 0.046 mmol, 92%) as a red solid. Rf = 0.51 (CH2Cl2). 1H NMR (600 MHz, DMSO-d6, 20 °C): δ (ppm) 12.66 (s, 2H), 7.78 (dd, J = 6.6 and 1.8 Hz, 2H), 7.62 (dd, J = 6.0 and 1.8 Hz, 2H), 7.50 (td, J = 6.0 and 1.8 Hz, 2H), 7.47−7.46 (m, 2H), 7.37 (td, J = 7.8 and 1.8 Hz, 2H), 7.29 (s, 1H), 7.30 (dd, J = 3.6 and 2.4 Hz, 2H). 13C{1H} NMR (151 MHz, DMSO-d6, 20 °C): δ (ppm) 168.5, 140.2, 133.3, 132.1, 132.0, 130.5, 127.7, 126.7, 121.9, 119.3, 114.2, 90.4. UV/vis (CH2Cl2, λmax [nm] (ε, 105 M−1 cm−1)): 480 (1.06). Fluorescence (CH2Cl2, λem [nm] (λex [nm])): 518 (480). MALDI-TOF-MS: m/z (% intensity): 558.0 (29), 559.0 (100), 560.0 (31). Calcd for C23H15BBr2F2N2O2 ([M]−): 557.95. HRMS (ESI-TOF) m/z: [M − H]− calcd for C23H14BBr2F2N2O2 556.9489; found 556.9490. General Procedure of BF 2 Complexes of 1,3-Bis(5-(2phenylphenyl)pyrrol-2-yl)-1,3-propanedione Derivatives, 3a−f. A round-bottomed flask placed with 2 (60 mg, 0.107 mmol), 4,4,5,5tetramethyl-2-aryl-1,3,2-dioxaborolane (0.300 mmol), Pd(OAc)2 (9.2 mg, 7.9 μmol), 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (Sphos) (32.4 mg, 31.6 μmol), and K2CO3 (82.9 mg, 0.60 mmol) 8894


Article

The Journal of Organic Chemistry 4H), 1.49−1.42 (m, 8H), 0.97 (t, J = 7.2 Hz, 6H), 0.92 (t, J = 7.2 Hz, 12H). 13C{1H} NMR (151 MHz, CDCl3, 20 °C): δ (ppm) 168.0, 153.7, 141.0, 140.7, 138.6, 135.9, 131.5, 129.3, 129.0, 128.6, 128.3, 126.5, 118.9, 114.1, 108.2, 89.7, 73.7, 69.3, 32.8, 31.7, 19.6, 19.5, 14.3, 14.2. UV/vis (CH2Cl2, λmax [nm] (ε, 105 M−1 cm−1)): 499 (0.98). Fluorescence (CH2Cl2, λem [nm] (λex [nm])): 537 (499). MALDITOF-MS: m/z (% intensity): 985.5 (29), 986.5 (100), 987.5 (69). Calcd for C59H73BF2N2O8 ([M]−): 986.54. HRMS (ESI-TOF) m/z: [M − H]− calcd for C59H72BF2N2O8 985.5355; found 985.5355. BF2 Complex of 1,3-Bis(5-(2-(3,4,5-trioctyloxyphenyl)phenyl)pyrrol-2-yl)-1,3-propanedione, 3d. From 2 (114.4 mg, 0.204 mmol) and 4,4,5,5-tetramethyl-2-(3,4,5-trioctyloxyphenyl)-1,3,2-dioxaborolane (355.3 mg, 0.603 mmol). Yield: 85.6 mg (65 μmol, 32%), red solid. Rf = 0.41 (CH2Cl2). 1H NMR (600 MHz, CDCl3, 20 °C): δ (ppm) 9.28 (s, 2H), 7.59 (dd, J = 7.2 and 1.2 Hz, 2H), 7.45−7.38 (m, 6H), 6.98 (s, 2H), 6.44 (s, 4H), 6.25 (s, 1H), 6.12 (s, 2H), 4.02 (t, J = 6.6 Hz, 4H), 3.88 (t, J = 6.6 Hz, 8H), 1.80−1.72 (m, 12H), 1.54−1.21 (m, 60H), 0.90−0.84 (m, 18H). 13C{1H} NMR (151 MHz, CDCl3, 20 °C): δ (ppm) 167.7, 153.4, 140.9, 140.4, 138.3, 135.7, 131.3, 129.0, 128.7, 128.3, 128.0, 126.3, 118.7, 114.0, 108.0, 89.5, 73.8, 69.4, 32.1, 32.0, 30.6, 29.8, 29.6, 29.52, 29.46, 29.4, 26.3, 26.2, 22.9, 22.8, 14.2 (some of the octyl signals were overlapped with other signals). UV/vis (CH2Cl2, λmax [nm] (ε, 105 M−1 cm−1)): 500 (1.02). Fluorescence (CH2Cl2, λem [nm] (λex [nm])): 536 (500). MALDI-TOF-MS: m/z (% intensity): 1320.8 (27), 1321.8 (32), 1322.8 (100). Calcd for C83H121BF2N2O8 ([M]−): 1322.92. HRMS (ESI-TOF) m/z: [M − H]− calcd for C83H120BF2N2O8 1321.9111; found 1321.9124. BF2 Complex of 1,3-Bis(5-(2-(3,4,5-tridodecyloxyphenyl)phenyl)pyrrol-2-yl)-1,3-propanedione, 3e. From 2 (112.2 mg, 0.200 mmol) and 4,4,5,5-tetramethyl-2-(3,4,5-tridodecyloxyphenyl)-1,3,2-dioxaborolane (454.3 mg, 0.600 mmol). Yield: 222.2 mg (0.13 mmol, 67%), orange solid. Rf = 0.53 (CH2Cl2). 1H NMR (600 MHz, CDCl3, 20 °C): δ (ppm) 9.26 (s, 2H), 7.59 (d, J = 7.8 Hz, 2H), 7.44−7.37 (m, 6H), 6.97 (s, 2H), 6.43 (s, 4H), 6.24 (s, 1H), 6.12 (s, 2H), 4.01 (t, J = 6.6 Hz, 4H), 3.87 (t, J = 6.6 Hz, 8H), 1.79−1.71 (m, 12H), 1.53−1.23 (m, 108H), 0.89−0.85 (m, 18H). 13C{1H} NMR (151 MHz, CDCl3, 20 °C): δ (ppm) 167.5, 153.2, 140.6, 140.2, 138.1, 135.5, 131.1, 128.8, 128.5, 128.1, 127.8, 126.1, 118.5, 113.8, 107.8, 89.3, 73.6, 69.2, 31.86, 30.4, 29.75, 29.66, 29.61, 29.40, 29.32, 29.27, 26.1, 26.0, 22.6, 14.1 (some of the dodecyl signals were overlapped with other signals). UV/vis (CH2Cl2, λmax [nm] (ε, 105 M−1 cm−1)): 500 (0.97). Fluorescence (CH2Cl2, λem [nm] (λex [nm])): 536 (500). MALDI-TOF-MS: m/z (% intensity): 1658.5 (68), 1659.2 (100). HRMS (ESI-TOF) m/z: [M − H]− calcd for C107H168BF2N2O8 1658.2967; found 1658.2968. BF2 Complex of 1,3-Bis(5-(2-(3,4,5-trihexadecyloxyphenyl)phenyl)pyrrol-2-yl)-1,3-propanedione, 3f. From 2 (113.7 mg, 0.203 mmol) and 4,4,5,5-tetramethyl-2-(3,4,5-trihexadecyloxyphenyl)-1,3,2dioxaborolane (443.8 mg, 0.480 mmol). Yield: 173.1 mg (87 μmol, 42%), orange solid. Rf = 0.67 (CH2Cl2). 1H NMR (600 MHz, CDCl3, 20 °C): δ (ppm) 9.27 (s, 2H), 7.59 (d, J = 7.8 Hz, 2H), 7.44−7.37 (m, 6H), 6.97 (s, 2H), 6.43 (s, 4H), 6.23 (s, 1H), 6.12 (s, 2H), 4.01 (t, J = 6.6 Hz, 4H), 3.87 (t, J = 6.6 Hz, 8H), 1.79−1.71 (m, 12H), 1.51−1.23 (m, 168H), 0.88 (t, J = 7.2 Hz, 18H). 13C{1H} NMR (151 MHz, CDCl3, 20 °C): δ (ppm) 167.8, 153.5, 140.8, 140.4, 138.4, 135.7, 131.3, 129.0, 128.7, 128.3, 128.0, 126.3, 118.7, 114.0, 108.0, 89.5, 73.8, 69.5, 32.1, 30.6, 29.98, 29.89, 29.84, 29.6, 29.53, 29.49, 26.3, 26.2, 22.9, 14.3 (some of the hexadecyl signals were overlapped with other signals). UV/vis (CH2Cl2, λmax [nm] (ε, 105 M−1 cm−1)): 500 (1.00). Fluorescence (CH2Cl2, λem [nm] (λex [nm])): 535 (500). MALDITOF-MS: m/z (% intensity): 1993.5 (36), 1994.6 (71), 1995.8 (100). Calcd for C131H217BF2N2O8 ([M]−): 1995.67. HRMS (ESI-TOF) m/ z: [M − H]− calcd for C131H216BF2N2O8 1994.6623; found 1994.6622. General Procedure of BF2 Complexes of 1,3-Bis(phenanthro[9,10b]pyrrol-2-yl)-1,3-propanedione Derivatives, 4a−f. According to the literature procedure,8e to a solution of 3a−f (0.010 mmol) and BF3· OEt2 (0.10 mmol) in dry CH2Cl2 (50 mL) under N2 was added MoCl5 (0.20 mmol) at 0 °C and the reaction mixture was stirred for 3 h. To the mixture was added MeOH/CH2Cl2 (1:1, 40 mL) and CH2Cl2 and water were added for separation. The organic phase was dried over

anhydrous Na2SO4 and evaporated. The residue was then chromatographed over a silica gel column (Wakogel C-300) to give 4a−f. BF2 Complex of 1,3-Di(phenanthro[9,10-b]pyrrol-2-yl)-1,3-propanedione, 4a. From 3a (11.5 mg, 20.8 μmol). Yield: 1.00 mg (1.82 μmol, 8.6%), dark red solid. Rf = 0.42 (CH2Cl2). 1H NMR (600 MHz, DMSO-d6, 20 °C): δ (ppm) 13.25 (s, 2H, NH), 8.97−8.96 (m, 2H, ArH), 8.85−8.84 (m, 2H, Ar-H), 8.80 (d, J = 8.4 Hz, 2H, Ar-H), 8.56 (s, 2H, pyrrole-H), 8.39 (d, J = 7.8 Hz, 2H, Ar-H), 7.87 (s, 1H, CH), 7.77− 7.72 (m, 6H, Ar-H), 7.65 (dt, J = 7.8 and 1.2 Hz, 2H, Ar-H). 13C{1H} NMR (151 MHz, DMSO-d6, 20 °C): δ (ppm) 169.5, 135.7, 130.3, 129.2, 127.9, 127.8, 127.5, 127.4, 127.3, 125.9, 124.2, 124.1, 123.6, 123.5, 122.6, 122.4, 112.9, 93.2. UV/vis (CH2Cl2, λmax [nm] (ε, 105 M−1 cm−1)): 533 (1.38). Fluorescence (CH2Cl2, λem [nm] (λex [nm])): 565 (533). MALDI-TOF-MS: m/z (% intensity): 549.2 (100), 550.2 (37). HRMS (ESI-TOF) m/z: [M − H]− calcd for C35H20BF2N2O2 549.1591; found 549.1591. This compound was further characterized by single-crystal X-ray diffraction analysis. BF2 Complex of 1,3-Bis(4,5,6,-trimethoxyphenanthro[9,10-b]pyrrol-2-yl)-1,3-propanedione, 4b. From 3b (21.3 mg, 29.0 μmol). Yield: 3.06 mg (4.2 μmol, 14%), dark red solid. Rf = 0.61 (1% MeOH/ CH2Cl2). 1H NMR (600 MHz, DMSO-d6, 20 °C): δ (ppm) 13.09 (s, 2H), 8.94 (d, J = 7.2 Hz, 2H), 8.83 (d, J = 8.4 Hz, 2H), 8.55−8.51 (m, 2H), 8.08 (s, 2H), 7.93 (s, 1H) 7.74−7.70 (m, 6H), 4.15 (s, 6H), 4.07 (s, 6H), 3.97 (s, 6H). 13C{1H} NMR (151 MHz, DMSO-d6, 20 °C): δ (ppm) 169.3, 151.8, 149.7, 142.2, 135.7, 129.9, 129.0, 127.6, 127.1, 124.6, 124.2, 123.6, 122.2, 119.1, 116.2, 115.8, 102.3, 93.0, 60.8, 60.4, 56.2. UV/vis (CH2Cl2, λmax [nm] (ε, 105 M−1 cm−1)): 544 (1.38). Fluorescence (CH2Cl2, λem [nm] (λex [nm])): 580 (544). MALDITOF-MS: m/z (% intensity): 729.2 (97), 730.2 (100), 731.2 (35). Calcd for C41H33BF2N2O8 ([M]−): 730.23. HRMS (ESI-TOF) m/z: [M − H]− calcd for C41H32BF2N2O8 729.2225; found 729.2225. This compound was further characterized by single-crystal X-ray diffraction analysis as a Cl− complex. BF2 Complex of 1,3-Bis(4,5,6-tributoxyphenanthro[9,10-b]pyrrol2-yl)-1,3-propanedione, 4c. From 3c (20.0 mg, 19.3 μmol). Yield: 14.7 mg (14.3 μmol, 74%), dark red solid. Rf = 0.48 (CH2Cl2). 1H NMR (600 MHz, CDCl3, 20 °C): δ (ppm) 9.92 (br, 2H), 8.41−8.39 (m, 2H), 8.28 (m, 2H), 8.03 (m, 2H), 7.70 (m, 2H), 7.61−7.60 (m, 4H), 6.92 (s, 1H), 4.29 (m, 4H), 4.18−4.16 (m, 8H), 1.99−1.92 (m, 8H), 1.89−1.84 (m, 4H), 1.66−1.60 (m, 12H), 1.08−1.04 (m, 18H). 13C{1H} NMR (151 MHz, CDCl3, 20 °C): δ (ppm) 168.2, 151.6, 149.6, 141.8, 134.5, 130.3, 127.8, 127.3, 126.7, 124.2, 123.8, 121.7, 121.4, 120.2, 116.8, 115.1, 101.9, 91.5, 73.5, 73.2, 68.3, 32.6, 32.4, 31.5, 29.6, 19.39, 19.35, 19.28, 14.0, 13.9. UV/vis (CH2Cl2, λmax [nm] (ε, 105 M−1 cm−1)): 552 (1.13). Fluorescence (CH2Cl2, λem [nm] (λex [nm])): 590 (552). MALDI-TOF-MS: m/z (% intensity): 981.5 (26), 982.5 (99), 983.5 (36). Calcd for C59H69BF2N2O8 ([M]−): 982.51. HRMS (ESI-TOF) m/z: [M − H]− calcd for C59H68BF2N2O8 981.5042; found 981.5042. This compound was further characterized by single-crystal X-ray diffraction analysis as a Cl− complex. BF2 Complex of 1,3-Bis(4,5,6-trioctyloxyphenanthro[9,10-b]pyrrol-2-yl)-1,3-propanedione, 4d. From 3d (50.2 mg, 37.9 μmol). Yield: 10.9 mg (8.2 μmol, 22%), dark red solid. Rf = 0.16 (CH2Cl2). 1H NMR (600 MHz, CDCl3, 20 °C): δ (ppm) 10.00 (br, 2H, NH), 8.46 (m, 2H, Ar-H), 8.34 (m, 2H, Ar-H), 8.09 (m, 2H, pyrrole-H), 7.78 (m, 2H, Ar-H), 7.63 (m, 4H, Ar-H), 6.98 (s, 1H, CH), 4.34 (m, 4H, OCH2), 4.20 (t, J = 6.0 Hz, 4H, OCH2), 4.17 (m, 4H, OCH2), 2.03 (m, 4H, OCH2CH2), 1.99−1.94 (m, 4H, OCH2CH2), 1.90−1.88 (m, 4H, OCH2CH2), 1.60−1.17 (m, 60H, O(CH2)2(CH2)5), 0.93−0.90 (m, 12H, O(CH2)7CH3), 0.73 (t, J = 6.6 Hz, 6H, O(CH2)7CH3). 13C{1H} NMR (151 MHz, CDCl3, 20 °C): δ (ppm) 168.4, 151.8, 149.7, 142.0, 134.8, 130.6, 128.1, 127.5, 126.9, 124.5, 124.0, 121.8, 121.6, 120.4, 117.0, 115.5, 102.2, 91.9, 74.1, 73.7, 68.9, 32.1, 32.0, 30.8, 30.7, 29.9, 29.75, 29.67, 29.60, 29.5, 26.5, 26.4, 22.9, 22.8, 14.3, 14.2 (some of the octyl signals were overlapped with other signals). UV/vis (CH2Cl2, λmax [nm] (ε, 105 M−1 cm−1)): 552 (1.32). Fluorescence (CH2Cl2, λem [nm] (λex [nm])): 589 (552). MALDI-TOF-MS: m/z (% intensity): 1317.2 (39), 1318.3 (99), 1319.3 (100). Calcd for C83H117BF2N2O8 ([M]−): 1318.89. HRMS (ESI-TOF) m/z: [M + Cl] − calcd for C83H117BClF2N2O8 1353.8364; found 1353.8364. 8895


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yellow solid. Rf = 0.59 (1% MeOH/CH2Cl2). 1H NMR (600 MHz, CDCl3, 20 °C: diketone 3a′ was obtained as a mixture of keto and enol tautomers in the ratio of 0.38:1): keto form δ (ppm) 8.79 (br, 2H), 7.57−7.56 (m, 2H), 7.29−7.28 (m, 8H), 7.24−7.22 (m, 4H), 6.87 (dd, J = 2.4 and 1.2 Hz, 2H), 6.10 (dd, J = 2.4 and 1.2 Hz, 2H), 3.98 (s, 2H); enol form δ (ppm) 8.62 (s, 2H), 7.61 (dd, J = 7.8 and 0.6 Hz, 2H), 7.43−7.34 (m, 16H), 6.72 (dd, J = 3.6 and 3.0 Hz, 2H), 6.21 (dd, J = 4.2 and 3.0 Hz, 2H), 5.97 (s, 1H). 13C{1H} NMR (151 MHz, CDCl3, 20 °C): δ (ppm) 182.1, 174.5, 141.2, 140.9, 140.3, 139.7, 138.8, 136.5, 131.5, 131.2, 130.0, 129.7, 129.3, 129.0, 128.8, 128.7, 128.6, 128.5, 128.0, 127.94, 127.86, 118.7, 113.6, 111.7, 111.5, 90.2 (some of the aryl signals were overlapped with other signals). MALDI-TOF-MS: m/z (% intensity): 504.2 (48), 505.2 (100). Calcd for C35H25N2O2 ([M − H]−): 505.20. HRMS (ESI-TOF) m/z: [M − H]− calcd for C35H25N2O2 505.1922; found 505.1922. Method for Single-Crystal X-ray Analysis. Crystallographic data are summarized in Table S1. A single crystal of 3a was obtained by vapor diffusion of n-hexane into an EtOAc solution of 3a. The data crystal was a yellow block of approximate dimensions of 0.020 mm × 0.020 mm × 0.010 mm. A single crystal of 3b was also obtained by vapor diffusion of n-hexane into a CHCl3 solution of 3b. The data crystal was an orange prism of approximate dimensions of 0.080 mm × 0.010 mm × 0.005 mm. A single crystal of 4a was obtained by vapor diffusion of nhexane into an acetone solution of 4a. The data crystal was a red plate of approximate dimensions of 0.015 mm × 0.015 mm × 0.002 mm. A single crystal of 3a·Cl−−TBA+ was obtained by vapor diffusion of nhexane into a CH2Cl2 solution of the 1:1 mixture of 3a and TBACl. The data crystal was an orange block of approximate dimensions of 0.030 mm × 0.030 mm × 0.030 mm. A single crystal of 3a·Cl−−TATA+ was obtained by vapor diffusion of n-hexane into a CHCl3 solution of the 1:1 mixture of 3a and TATACl.5b The data crystal was an orange prism of approximate dimensions of 0.070 mm × 0.010 mm × 0.005 mm. A single crystal of 4a·Cl−−TBA+ was obtained by vapor diffusion of nhexane into a CH2Cl2 solution of the 1:1 mixture of 4a and TBACl. The data crystal was a red block of approximate dimensions of 0.100 mm × 0.080 mm × 0.050 mm. A single crystal of 4b·Cl−−TBA+ was obtained by vapor diffusion of n-hexane into a CH2Cl2 solution of the 1:1 mixture of 4b and TBACl. The data crystal was a red block of approximate dimensions of 0.060 mm × 0.060 mm × 0.040 mm. A single crystal of 4c·Cl−−TATA+ was obtained by vapor diffusion of n-hexane into a CHCl3 solution of the 1:1 mixture of 4c and TATACl. The data crystal was an orange prism of approximate dimensions of 0.100 mm × 0.030 mm × 0.010 mm. The data of 3a,b, 4a, 3a·Cl−−TATA+, 4a·Cl−−TBA+, and 4b·Cl−−TBA+ were collected at 100 K on a Rigaku Saturn 724 diffractometer with Si(111) monochromated synchrotron radiation (λ = 0.78238 Å (3a), 0.78192 Å (3b), 0.78228 Å (4a), 0.7829 Å (3a·Cl−− TATA+ and 4a·Cl−−TBA+), and 0.78229 Å (4b·Cl−−TBA+)) at BL40XU (SPring-8), whereas the data of 3a·Cl−−TBA+ and 4c·Cl−− TATA+ were collected at 100 K on a Rigaku Mercury CCD2 diffractometer with Si(311) monochromated synchrotron radiation (λ = 0.7022 Å (3a·Cl−−TBA+) and 0.4307 Å (4c·Cl−−TATA+)) at BL02B1 (SPring-8).13 All of the structures were solved by a dual-space method. The calculations were performed using Yadokari-XG.20 CIF files (CCDC-1900645−1900652) can be obtained free of charge from the Cambridge Crystallographic Data Center via www.ccdc.cam.ac.uk/ data_request/cif. DFT Calculations. DFT calculations were carried out using the Gaussian 09 program.12 Titration Experiments by UV/Vis Absorption Spectra. The titration experiments for the estimation of anion-binding abilities were conducted using UV/vis absorption spectra in CH2Cl2 (spectroscopic grade) at 20 °C. CH2Cl2 solutions (1.0 × 10−5 M) of anion receptors, 3a,b and 4a,b, were prepared, and a 3.00 mL of the receptor solution was transferred to a UV cell (3 mL). As anion sources, CH2Cl2 solutions of Cl−, Br−, and CH3CO2− as TBA salts were prepared. After the measurement of the initial spectrum of the receptor, small portions of the anion solution were added to the solution, and the spectrum was recorded after each addition. Upon the addition of the anion solution, UV/vis absorption spectra were gradually changed. Binding constants (Ka) were determined by nonlinear curve fitting of titration curves,

BF2 Complex of 1,3-Bis(4,5,6-tridodecyloxyphenanthro[9,10-b]pyrrol-2-yl)-1,3-propanedione, 4e. From 3e (50.0 mg, 30.0 μmol). Yield: 12.5 mg (7.52 μmol, 25%), dark red solid. Rf = 0.27 (CH2Cl2). 1H NMR (600 MHz, CDCl3, 20 °C): δ (ppm) 9.89 (s, 2H), 8.35 (m, 2H), 8.24 (m, 2H), 7.97 (m, 2H), 7.65 (m, 2H), 7.58 (m, 4H), 6.91 (s, 1H), 4.31 (m, 4H), 4.14 (m, 8H), 2.04−1.89 (m, 12H), 1.70−1.08 (m, 108H), 0.91−0.88 (m, 12H), 0.80−0.77 (m, 6H). 13C{1H} NMR (151 MHz, CDCl3, 20 °C): δ (ppm) 168.5, 151.8, 149.8, 142.1, 134.8, 130.6, 128.0, 127.5, 126.9, 124.5, 124.0, 121.8, 121.6, 120.5, 117.0, 115.5, 102.2, 91.9, 74.2, 73.7, 68.9, 32.1, 32.0, 30.8, 30.7, 30.1, 30.03, 30.00, 29.92, 29.87, 29.75, 29.67, 29.60, 29.57, 29.50, 26.5, 22.9, 22.8, 14.3, 14.2 (some of the dodecyl signals were overlapped with other signals). UV/vis (CH2Cl2, λmax [nm] (ε, 105 M−1 cm−1)): 553 (1.39). Fluorescence (CH2Cl2, λem [nm] (λex [nm])): 590 (553). MALDITOF-MS: m/z (% intensity): 1654.4 (77), 1655.2 (100). Calcd for C107H165BF2N2O2 ([M]−): 1655.26. HRMS (ESI-TOF) m/z: [M − H]− calcd for C107H164BClF2N2O8 1654.2546; found 1654.2554. BF2 Complex of 1,3-Bis(4,5,6-trihexadecyloxyphenanthro[9,10b]pyrrol-2-yl)-1,3-propanedione, 4f. From 3f (50.0 mg, 25.1 μmol). Yield: 3.14 mg (1.58 μmol, 56%), dark red solid. Rf = 0.37 (CH2Cl2). 1H NMR (600 MHz, CDCl3, 20 °C): δ (ppm) 9.95 (br, 2H), 8.41 (m, 2H), 8.31 (m, 2H), 8.04 (m, 2H), 7.73 (m, 2H), 7.61 (m, 4H), 6.95 (s, 1H), 4.32 (m, 4H), 4.17 (m, 8H), 2.04−1.89 (m, 12H), 1.61−1.05 (m, 156H), 0.89−0.85 (m, 18H). 13C{1H} NMR (151 MHz, CDCl3, 20 °C): δ (ppm) 168.7, 151.9, 149.8, 142.1, 134.8, 130.7, 128.0, 127.7, 127.1, 124.6, 124.1, 121.8, 121.7, 120.5, 117.0, 115.6, 102.3, 91.9, 74.2, 73.7, 69.0, 32.1, 30.9, 30.7, 30.1, 30.0, 29.92, 29.86, 29.73, 29.66, 26.5, 22.9, 14.3 (some of the hexadecyl signals were overlapped with other signals). UV/vis (CH2Cl2, λmax [nm] (ε, 105 M−1 cm−1)): 552 (1.18). Fluorescence (CH2Cl2, λem [nm] (λex [nm])): 587 (552). MALDITOF-MS: m/z (% intensity): 1990.6 (100), 1991.5 (81). Calcd for C131H212BF2N2O8 ([M − H]−): 1990.63. HRMS (ESI-TOF) m/z: [M − H]− calcd for C131H212BF2N2O8 1990.6310; found 1990.6309. N-Boc-2-(2-phenylphenyl)pyrrole, s5. A round-bottomed flask placed with N-Boc-pyrrole-2-boronic acid17 (982 mg, 4.65 mmol), 2bromobiphenyl (0.65 mL, 4.4 mmol), Pd(PPh3)4 (230.8 mg, 0.18 mmol), and Na2CO3 (1.48 g, 4.63 mmol) was flushed with N2 and charged with a mixture of degassed DME (50 mL) and water (4 mL). The mixture was heated at 80 °C for 18 h, cooled, and then partitioned between water and CH2Cl2. The combined organic extracts were dried over anhydrous MgSO4 and evaporated. The residue was then chromatographed over a flash silica gel column (Merck silica gel 60, eluent: CH2Cl2/n-hexane = 1:3) to give s5 (928.5 mg, 2.9 mmol, 65%) as a colorless oil. Rf = 0.60 (CH2Cl2/n-hexane = 1:3). 1H NMR (600 MHz, CDCl3, 20 °C): δ (ppm) 7.43−7.34 (m, 4H), 7.24−7.18 (m, 3H), 7.16−7.14 (m, 3H), 6.15 (td, J = 3.0 and 0.6 Hz, 1H), 6.11−6.10 (m, 1H), 1.22 (s, 9H). 13C{1H} NMR (151 MHz, CDCl3, 20 °C): δ (ppm) 148.7, 141.6, 141.4, 133.7, 133.3, 130.7, 129.6, 128.9, 128.2, 127.9, 126.9, 126.6, 121.5, 115.3, 115.2, 110.5, 83.1, 27.7. HRMS (EITOF) m/z: [M]+ calcd for C21H21NO2 319.1572; found 319.1572. 2-(2-Phenylphenyl)pyrrole, s6. A round-bottomed flask placed with s5 (39.7 mg, 0.124 mmol) flushed with N2 was heated at 180 °C using an oil bath for 30 min. After cooling, the residue was then chromatographed over a silica gel column (Wakogel C-300, eluent: CH2Cl2/n-hexane = 1:1) to give s6 (25.3 mg, 0.12 mmol, 93%) as a white solid. Rf = 0.50 (CH2Cl2/n-hexane = 1:1). 1H NMR (600 MHz, CDCl3, 20 °C): δ (ppm) 7.60 (d, J = 7.8 Hz, 1H), 7.56 (br, 1H), 7.40− 7.33 (m, 4H), 7.32−7.29 (m, 4H), 6.57−6.56 (m, 1H), 6.33−6.32 (m, 1H), 6.17−6.16 (m, 1H). 13C{1H} NMR (151 MHz, CDCl3, 20 °C): δ (ppm) 141.8, 138.5, 131.6, 131.5, 131.1, 129.4, 128.8, 128.6, 127.9, 127.4, 126.7, 118.5, 108.9, 108.3. HRMS (EI-TOF) m/z: [M]+ calcd for C16H13N 219.1048; found 219.1048. 1,3-Bis(5-(2-phenylphenyl)pyrrol-2-yl)-1,3-propanedione, 3a′. According to the literature procedure,5a to a solution of s6 (556 mg, 2.50 mmol) in CH2Cl2 (40 mL) under N2 was added malonyl chloride (182 μL, 1.25 mmol) at 0 °C. The mixture was stirred at 0 °C for 1 h. To the mixture were added water and CH2Cl2 for separation. The organic phase was dried over anhydrous MgSO4 and evaporated. The residue was then chromatographed over a silica gel column (Wakogel C-300, eluent: 1% MeOH/CH2Cl2) to give 3a′ (249 mg, 0.49 mmol, 40%) as a 8896


The Journal of Organic Chemistry plotting the absorbance changes at the maximum absorption wavelengths against the amounts of added anions. The titration curves were fitted to the expression for 1:1 binding as shown below Ka

H + G V HG K a =

A = A free + −

[HG] [H][G]

ΔA max [K a −1 + [H]0 + [G]0 2[H]0

(K a −1 + [H]0 + [G]0 )2 − 4[H]0 [G]0 ]

ACKNOWLEDGMENTS

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REFERENCES

(1) Selected book and review on supramolecular assemblies for functional materials: (a) Supramolecular Soft Matter; Nakanishi, T., Ed.; Wiley, 2011. (b) Supramolecular Materials for Opto-Electronics; Koch, N., Ed.; RSC, 2015. (c) Hoeben, F. J. M.; Jonkheijm, P.; Meijer, E. W.; Schenning, A. P. H. J. About Supramolecular Assemblies of πConjugated Systems. Chem. Rev. 2005, 105, 1491−1546. (2) Selected reviews on ion-pairing assemblies: (a) Binnemans, K. Ionic Liquid Crystals. Chem. Rev. 2005, 105, 4148−4204. (b) Kato, T.; Mizoshita, N.; Kishimoto, K. Functional Liquid-Crystalline Assemblies: Self-Organized Soft Materials. Angew. Chem., Int. Ed. 2006, 45, 38−68. (c) Wang, C.; Wang, Z.; Zhang, X. Amphiphilic Building Blocks for Self-Assembly: From Amphiphiles to Supra-amphiphiles. Acc. Chem. Res. 2012, 45, 608−618. (3) Selected reviews on assemblies based on π-electronic ion pairs: (a) Haketa, Y.; Maeda, H. Dimension-controlled ion-pairing assemblies based on π-electronic charged species. Chem. Commun. 2017, 53, 2894−2909. (b) Haketa, Y.; Maeda, H. Dimension-Controlled πElectronic Ion-Pairing Assemblies. Bull. Chem. Soc. Jpn. 2018, 91, 420− 436. (4) Ion Complexation: Supramolecular Chemistry: From Molecules to Nanomaterials; Gale, P. A., Steed, J. W., Eds.; Jon Wiley & Sons, 2012. (5) (a) Maeda, H.; Haketa, Y.; Nakanishi, T. Aryl-Substituted C3Bridged Oligopyrroles as Anion Receptors for Formation of Supramolecular Organogels. J. Am. Chem. Soc. 2007, 129, 13661−13674. (b) Haketa, Y.; Sasaki, S.; Ohta, N.; Masunaga, H.; Ogawa, H.; Mizuno, N.; Araoka, F.; Takezoe, H.; Maeda, H. Oriented Salts: DimensionControlled Charge-by-Charge Assemblies from Planar Receptor-Anion Complexes. Angew. Chem., Int. Ed. 2010, 49, 10079−10083. (c) Maeda, H.; Naritani, K.; Honsho, Y.; Seki, S. Anion Modules: Building Blocks of Supramolecular Assemblies by Combination with π-Conjugated Anion Receptors. J. Am. Chem. Soc. 2011, 133, 8896−8899. (d) Haketa, Y.; Honsho, Y.; Seki, S.; Maeda, H. Ion Materials Comprising Planar Charged Species. Chem. - Eur. J. 2012, 18, 7016−7020. (e) Dong, B.; Sakurai, T.; Honsho, Y.; Seki, S.; Maeda, H. Cation Modules as Building Blocks Forming Supramolecular Assemblies with Planar ReceptorAnion Complexes. J. Am. Chem. Soc. 2013, 135, 1284−1287. (f) Dong, B.; Sakurai, T.; Bando, Y.; Seki, S.; Takaishi, K.; Uchiyama, M.; Muranaka, A.; Maeda, H. Ion-Based Materials Derived from Positively and Negatively Charged Chloride Complexes of π-Conjugated Molecules. J. Am. Chem. Soc. 2013, 135, 14797−14805. (6) Kumar, S. Recent developments in the chemistry of triphenylenebased discotic liquid crystals. Liq. Cryst. 2004, 31, 1037−1059. (7) (a) Wu, J.; Pisula, W.; Müllen, K. Graphenes as Potential Material for Electronics. Chem. Rev. 2007, 107, 718−747. (b) Wöhrle, T.; Wurzbach, I.; Kirres, J.; Kostidou, A.; Kapernaum, N.; Litterscheidt, J.; Haenle, J. C.; Staffeld, P.; Baro, A.; Giesselmann, F.; Laschat, S. Discotic Liquid Crystals. Chem. Rev. 2016, 116, 1139−1241.

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.joc.9b00754. Spectroscopic data, X-ray crystallographic data, theoretical study, anion-binding and assembled behaviors (PDF)

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This work was supported by JSPS KAKENHI Grant Numbers JP26288042 and JP18H01968 for Scientific Research (B) and JP26107007 for Scientific Research on Innovative Areas “Photosynergetics” and Ritsumeikan Global Innovation Research Organization (R-GIRO) project (2017−22). Theoretical calculations were partially performed using the Research Center for Computational Science, Japan (Okazaki). We thank Dr Yohei Haketa, Ritsumeikan University, and Dr Ryohei Yamakado, Yamagata University, for synchrotron radiation single-crystal analyses (SPring-8: 2018A1679 and 2018B1698), Dr Noboru Ohta, JASRI, for synchrotron radiation XRD analyses (SPring-8: 2018B1698), Dr Tsuneaki Sakurai, Kyoto University, for the help of FP-TRMC measurements, Prof. Naoki Aratani, NAIST, for the help of EI-MS measurements, and Prof. Hitoshi Tamiaki, Ritsumeikan University, for various measurements.

wherein A is the absorbance of the UV/vis absorption spectrum observed at each titration point, Afree is the absorbance of the anion-free receptor, ΔAmax is the difference in UV/vis absorbance between the receptor−anion complex and the anion-free receptor, and [H]0 and [G]0 are the initial concentrations of receptor and anion, respectively. Differential Scanning Calorimetry (DSC). The phase transitions were measured on a differential scanning calorimeter (Shimadzu DSC60). Polarizing Optical Microscopy (POM). POM observations were carried out with a Nikon ECLIPSE LV100N-POL polarizing optical microscope equipped with a Mettler-Toledo HS82 hot stage system. Synchrotron X-ray Diffraction Analysis (XRD). High-resolution XRD analysis was carried out using a synchrotron radiation X-ray beam with a wavelength of 1.00 Å on BL40B2 at SPring-8 (Hyogo, Japan). A large Debye−Scherrer camera with camera lengths of 429.0 mm for VTXRD of 3f, 4e,f, and 4d−f·Cl−−TATA+ and 582.0 mm for twodimensional XRD of 4e·Cl−−TATA+, using a quartz capillary, was used with an imaging plate as a detector, where the diffraction patterns were obtained with a 0.01° step in 2θ. The exposure time of the X-ray beam was 10 s. Photoconductivity Assessments. Photoconductivity transients in all of the compounds were monitored by a flash photolysis timeresolved conductivity measurement (FP-TRMC) technique upon excitation at 355 nm laser pulses with 5 ns duration from the Spectra-Physics INDI-HG Nd:YAG laser system as a third harmonic generation. All of the compounds were placed onto quartz substrates, heated up to higher than the phase-transition temperatures into isotropic phases of corresponding compounds, and then cooled down to r.t. Shearing of 4e,f·Cl−−TATA+ was carried out with a sandwiched cell of double quartz plates, followed by subsequent photoconductivity measurements at 20 °C. The conductivity transients were monitored as the product of photocarrier generation yield (ϕ) and the sum of mobilities of positive and negative free carriers (∑μ) and represented as ϕ∑μ.

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Article

Crystallographic data (CCDC-1900645−1900652) (CIF)

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Shu Seki: 0000-0001-7851-4405 Hiromitsu Maeda: 0000-0001-9928-1655 Notes

The authors declare no competing financial interest. 8897


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Liquid Crystalline Crown Ethers. J. Org. Chem. 2014, 79, 10143− 10152. (17) Kelly, T. A.; Fuchs, V. U.; Perry, C. W.; Snow, R. J. The efficient synthesis and simple resolution of a prolineboronate ester suitable for enzyme-inhibition studies. Tetrahedron 1993, 49, 1009−1016. (18) Haketa, Y.; Sakamoto, S.; Chigusa, K.; Nakanishi, T.; Maeda, H. Synthesis, Crystal Structures, and Supramolecular Assemblies of Pyrrole-Based Anion Receptors Bearing Modified Pyrrole β-Substituents. J. Org. Chem. 2011, 76, 5177−5184. (19) Jasiński, M.; Szymańska, K.; Gardias, A.; Pociecha, D.; Monobe, H.; Szczytko, J.; Kaszyński, P. Tuning the Magnetic Properties of Columnar Benzo[e][1,2,4]triazin-4-yls with the Molecular Shape. ChemPhysChem 2019, 20, 636−644. (20) (a) Wakita, K. Yadokari-XG, Software for Crystal Structure Analyses, 2001. (b) Kabuto, C.; Akine, S.; Nemoto, T.; Kwon, E. Release of Software (Yadokari-XG 2009) for Crystal Structure Analyses. J. Crystallogr. Soc. Jpn. 2009, 51, 218−224.

(8) (a) Grzybowski, M.; Skonieczny, K.; Butenschön, H.; Gryko, D. T. Comparison of Oxidative Aromatic Coupling and the Scholl Reaction. Angew. Chem., Int. Ed. 2013, 52, 9900−9930. (b) Fechtenkötter, A.; Saalwächter, K.; Harbison, M. A.; Müllen, K.; Spiess, H. W. Highly Ordered Columnar Structures from Hexa-peri-hexabenzocoronenesSynthesis, X-ray Diffraction, and Solid-State Heteronuclear MultipleQuantum NMR Investigations. Angew. Chem., Int. Ed. 1999, 38, 3039− 3042. (c) Davis, N. K. S.; Thompson, A. L.; Anderson, H. L. A Porphyrin Fused to Four Anthracenes. J. Am. Chem. Soc. 2011, 133, 30−31. (d) Myśliwiec, D.; Bertrand, D.; Piotr, J. C.; Benoît, H.; Marcin, S. Peripherally Fused Porphyrins via the Scholl Reaction: Synthesis, Self-Assembly, and Mesomorphism. J. Am. Chem. Soc. 2012, 134, 4822−4833. (e) Fujikawa, T.; Segawa, Y.; Itami, K. Synthesis and Structural Features of Quadruple Helicenes: Highly Distorted π Systems Enabled by Accumulation of Helical Repulsions. J. Am. Chem. Soc. 2016, 138, 3587−3595. (9) (a) Hayashi, Y.; Obata, N.; Tamaru, M.; Yamaguchi, S.; Matsuo, Y.; Saeki, A.; Seki, S.; Kureishi, Y.; Saito, S.; Yamaguchi, S.; Shinokubo, H. Facile Synthesis of Biphenyl-Fused BODIPY and Its Property. Org. Lett. 2012, 14, 866−869. (b) Oki, K.; Takase, M.; Mori, S.; Shiotari, A.; Sugimoto, Y.; Ohara, K.; Okujima, T.; Uno, H. Synthesis, Structures, and Properties of Core-Expanded Azacoronene Analogue: A Twisted πSystem with Two N-Doped Heptagons. J. Am. Chem. Soc. 2018, 140, 10430−10434. (10) Synthesis of π-extended N-unprotected pyrroles using Scholl reaction: Chen, F.; Tanaka, T.; Mori, T.; Osuka, A. Synthesis, Structures, and Optical Properties of Azahelicene Derivatives and Unexpected Formation of Azahepta[8]circulenes. Chem. - Eur. J. 2018, 24, 7489−7497. (11) Schleyer, P. vR.; Maerker, C.; Dransfeld, A.; Jiao, H.; Hommes, N. vE. Nucleus-Independent Chemical Shifts: A Simple and Efficient Aromaticity Probe. J. Am. Chem. Soc. 1996, 118, 6317−6318. (12) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.; Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Keith, T.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, J. M.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, Ö .; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J.. Gaussian 09, revision D.01; Gaussian, Inc.: Wallingford, CT, 2013. (13) (a) Yasuda, N.; Murayama, H.; Fukuyama, Y.; Kim, J. E.; Kimura, S.; Toriumi, K.; Tanaka, Y.; Moritomo, Y.; Kuroiwa, Y.; Kato, K.; Tanaka, H.; Takata, M. X-ray diffractometry for the structure determination of a submicrometre single powder grain. J. Synchrotron Radiat. 2009, 16, 352−357. (b) Yasuda, N.; Fukuyama, Y.; Toriumi, K.; Kimura, S.; Takata, M. Submicrometer Single Crystal Diffractometry for Highly Accurate Structure Determination. AIP Conf. Proc. 2010, 1234, 147−150. (14) (a) Laursen, B. W.; Krebs, F. C. Synthesis of a Triazatriangulenium Salt. Angew. Chem., Int. Ed. 2000, 39, 3432−3434. (b) Laursen, B. W.; Krebs, F. C. Synthesis, Structure, and Properties of Azatriangulenium Salts. Chem. - Eur. J. 2001, 7, 1773−1783. (15) (a) Onsager, L. Initial Recombination of Ions. Phys. Rev. 1938, 54, 554−557. (b) Sano, H.; Tachiya, M. Partially diffusion-controlled recombination. J. Chem. Phys. 1979, 71, 1276−1282. (c) Falkowski, K.; Stampor, W.; Grygiel, P.; Tomaszewicz, W. Sano−Tachiya− Noolandi−Hong versus Onsager modelling of charge photogeneration in organic solids. Chem. Phys. 2012, 392, 122−129. (16) Wöhrle, T.; Kirres, J.; Kaller, M.; Mansueto, M.; Tussetschlag̈er, S.; Laschat, S. Pushing Steric Bias in the Scholl Reaction to Access 8898


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