10-Mesityl-1,8-diphenylanthracene Dimer: Synthesis, Structure, and

Article pubs.acs.org/joc

Cite This: J. Org. Chem. 2018, 83, 3857−3863

10-Mesityl-1,8-diphenylanthracene Dimer: Synthesis, Structure, and Properties Atsumi Shirai,† Hiroto Sano,† Yuki Nakamura,† Masataka Takashika,† Hiroyuki Otani,*,† Masashi Hasegawa,‡ Shin-ichiro Kato,§ and Masahiko Iyoda*,∥ †

Graduate School of Environment and Information Sciences, Yokohama National University, Hodogaya-ku, Yokohama, Kanagawa 240-8501, Japan ‡ School of Science, Kitasato University, Sagamihara, Kanagawa 252-0373, Japan § Department of Materials Science, School of Engineering, The University of Shiga Prefecture, 2500 Hassaka-cho, Hikone, Shiga 522-8533, Japan ∥ Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan S Supporting Information *

ABSTRACT: Macrocyclic 10-mesityl-1,8-diphenylanthracene dimer 4 was synthesized by using the electron-transfer oxidation of Lipshutz cuprate derived from 1,8-bis(4bromophenyl)-10-mesityl-anthracene 7 in moderate yield. This dimer 4 is a considerably fluorescent molecule (ΦF 0.40) with high thermal, photo, and air stability. The X-ray analysis of 4 revealed a unique structure with a small inner cavity which can incorporate a small molecule or atom. 1H NMR spectra in solution and emission spectra of 4 in the solid state showed that copper(I) ion was incorporated to form a 1:1 complex 4·CuOTf, whereas silver(I) ion only weakly interacted with 4 under similar conditions.

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INTRODUCTION A variety of photonic materials have been recently reported along with important scientific discoveries of new nanostructures.1 One of the most important requirements for photonic materials is stability against light and atmospheric oxygen, although many functional π-systems are light- and air-sensitive by nature. Cyclophanes and cyclic oligophenylenes have attracted considerable attention because of their thermal, light, and air stability, shape-persistent structures, intramolecular and intermolecular π−π interactions, molecular strain, and aromaticity, and as substrates for host−guest chemistry.2−7 Dibenzo[2.2]paracyclophane 1 was synthesized by Wong et al. in 1985,5a and its strained 1,4-phenylene units behaved as a π-donor. Cyclic oligophenylene 2 having a [3.3]biphenylophane frame also showed bent 4,4′-biphenylylene chains with a fairly strong intramolecular π−π interaction and strong fluorescence in solution and the solid state.8 Since 2 possesses a strained, rigid π-frame with a high thermal stability, we planned to synthesize less strained analogues 3 and 4 with 4,4′-biphenylylene chains and splayed anthracene rings (Figure 1). Our preliminary experiments have shown that 3 was highly insoluble, and we only characterized 3 as its silver complex, although the silver complex also scarcely soluble and could be determined by MS and UV−vis spectra.9 Therefore, we introduced bulky mesityl group at 10-position of the anthracene © 2018 American Chemical Society

Figure 1. Dibenzo[2.2]paracyclophane 1, cyclic oligophenylene 2 with [3.3]biphenylophane frame, and cyclic oligophenylenes 3 and 4 with [5.5]biphenylophane frame.

unit, because the mesityl group can be expected to increase the solubility of the cyclic oligophenylene frame by hindering the aggregation of the anthracene units in solution.10 For the synthesis of 2, we employed the Cu(NO3)2-mediated coupling of 1,8-bis(4-tributylstannylphenyl)naphthalene.8 For the synthesis of 4, however, we adopted electron-transfer oxidation of Lipshutz cuprates derived from 1,8-bis(4-lithiophenyl)Received: January 23, 2018 Published: March 2, 2018 3857

DOI: 10.1021/acs.joc.8b00200 J. Org. Chem. 2018, 83, 3857−3863

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The Journal of Organic Chemistry anthracene because the electron-transfer oxidation of Lipshutz cuprates proceeds smoothly to produce the coupling products with less amounts of side products as compared to the Cu(NO3)2-mediated coupling.11−13 Here we report that the electron-transfer oxidation of the above-mentioned Lipshutz cuprate in THF produced 4 in good yield, and the crystal structures of 4 revealed unique structures with a small inner cavity which incorporated a copper(I) ion.

Table 1. Synthesis of Macrocycle 4 Using Electron-Transfer Oxidation of Lipshutz Cuprate Derived from 7 in Ether or THFa

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RESULTS AND DISCUSSION Synthesis. The synthesis of 10-mesityl-1,8-diphenylanthracene dimer 4 was carried out as outlined in Scheme 1. Nickel-

entry

t-BuLi (equiv)

CuCN (equiv)

duroquinone (equiv)

solv.

yield (%)

1 2 3 4

4 4 4 5.2

1.1 1 1.2 1.1

3 3 3 3

ether THF THF THF

5b 29 4 50

Dibromide 7 was reacted with t-BuLi at −78 °C, followed by treatment with CuCN at 0−5 °C to produce Lipshutz cuprate, which was oxidized with duroquinone at 5−25 °C. b10-Mesityl-1,8diphenylantracene 8 was formed as the major product (39%). a

Scheme 1. Synthesis of 10-Mesityl-1,8-diphenylanthracene Dimer 4 and 1,8-Bis(4-biphenylyl)-10-mesitylanthracene 9

10-mesitylanthracene 9 in 64% yield (Scheme 1). 4 has a high thermal, photo, and air stablility: 4 is stable at 300 °C for 1 h in air without decomposition. Furthermore, photoirradiation of 4 with a high-pressure mercury lamp in benzene at room temperature produced no dimer and/or oxidation products. Crystal Structure. Single crystals of 4·(THF)2 suitable for the measurement of X-ray analysis were obtained by recrystallization from benzene/CH2Cl2/THF, and the structure was unambiguously confirmed (R1 = 5.3%). As shown in Figure 2a, 4 has a crystallographic C2-symmetry with a 2-fold axis at

catalyzed cross-coupling of 1,8-dichloro-10-mesitylanthracene 510 with excess amounts of p-trimethylsilylphenylmagnesium bromide produced 6 in 72% yield. The treatment of 6 with 2.5 equiv of NBS in CH2Cl2-acetone afforded dibromide 7 in 79% yield. For the synthesis of 4, we first tried nickel-catalyzed homocoupling of 7 using NiBr2(PPh3)2, Et4NI, and Zn in THF.14 However, this reaction mainly afforded oligomeric products without 4. After trying various copper-mediated coupling reactions of 7,11 electron-transfer oxidation of Lipshutz cuprate derived from 7 was found to produce 4 in moderate yield (Table 1). Although the reaction of Lipshutz cuprate derived from 7 with duroqinone in ether produced 4 in 5% yield together with 10-mesityl-1,8-diphenylantracene 8 (39%) (entry 1), a similar reaction in THF proceeded smoothly to afford 4 in 50% yield (entry 4). It is noteworthy that only a small amount of linear oligomer was formed as the byproduct except for polymer. Therefore, 4 was easily isolated from the reaction mixture. Slightly excess amount of CuCN (1.2 equiv) decreased the yield of 4 because of incomplete formation of Lipshutz cuprate (entry 3). In order to compare optical properties of 4 with those of noncyclic compound, 9 was prepared by the nickel-catalyzed cross-coupling of 7 with phenylmagnesium bromide to produce 1,8-bis(4-biphenylyl)-

Figure 2. (a) ORTEP diagram of 4. Interatomic distances: C1−C8 4.954 Å, C4−C5 4.962 Å, C11−C18′ 5.002 Å, C14−C15′ 5.047 Å, and C9−C9′ 10.217 Å. Dihedral angles: θ1 49°, θ2 70°, θ3 20°, θ4 90°. Thermal ellipsoids are 50% probability, and hydrogen atoms and THF molecules are omitted for clarity. (b) Crystal packing of 4·(THF)2. THF molecules are shown as space-filling model, whereas 4 are shown as wireframe model. (c) Calculated structure of 4 at B3LYP/631G(d,p) level. 3858


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from CHCl3−hexane. Two biphenylyl arms connecting to anthracene were disordered owing to their ring flipping even at low temperatures (Figure S7-4). As shown in Figure 3c, the biphenylyl arms slightly spread over, and their interatomic distances were found to be C1−C8 (4.991 Å), C11−C19 (5.151 Å), C14−C22 (5.569 Å), and C18−C26 (5.955 Å) (Figure 3c). As compared with the structure of 4 shown in Figure 2a, the C11− C19, C14−C22, and C18−C26 distances in 9 are much longer than the C11−C18′ and C14−C15′ distances in 4, while the C1−C8 distance in 9 is almost similar to the C1−C8 distance in 4. Optical Properties and Oxidation Potentials. As shown in Figure 4a, dilute (1 × 10−6 M) and concentrated (1 × 10−3

the center of the macroring. The theoretically optimized structure of 4 at B3LYP/6-31G(d,p) level showed a twisted form (Figure 2c), and X-ray structure of 4 (R1 = 9.7%) obtained by recrystallization from CHCl3 exhibited a similar twisted structure (Figure S7-2). The incorporated two THF molecules locate up and down the molecular plane and may force 4 to hold a flat shape in the crystal. The deviation from the plane between the two anthracene rings is only 1.8°. The dihedral angles between the anthracene and biphenyl rings are relatively large, and the angles of θ1 and θ2 are 49 and 70°, respectively. Due to fairly long interatomic distances between the biphenylylene linkages, the intramolecular interaction between the biphenylylene units can be negligible. Interestingly, the interatomic distances between the biphenylylene linkages in the calculated and X-ray analyzed 4 [calculated: C1−C8 4.979 Å, C11−C18′ 5.096 Å, and C14−C15′ 5.352 Å; X-ray: C1−C8 4.954 Å, C11−C18′ 5.002 Å and C14−C15′ 5.047 Å] are fairly shorter than those in the calculated carbon−carbon distances between the biphenylylene units in 3 [C1−C8 4.999 Å, C11− C18′ 5.139 Å, and C14−C15′ 5.405 Å], probably because of the buttressing effect of mesityl group at the C10 position in 4 (C4− C5 distance > C1−C8 distance). This smaller inner cavity may allow 4 to incorporate a smaller molecule or ion as compared with 3. In the crystal packing shown in Figure 2b, THF molecules fill the interspace between the molecules to produce a columnar structure. To compare the cyclic structure of 4 with the acyclic one, Xray analysis of 10-mesityl-1,8-diphenylanthracene 8 and 10mesityl-1,8-bis(4-biphenylyl)anthracene 9 were carried out (Figure 3). Single crystals of 8·acetone were obtained by

Figure 4. Absorption and emission spectra of 4, 8, and 9 in CH2Cl2. (a) Absorption spectra of 4 (1 × 10−3 M solution, red line; 1 × 10−6 M solution, red dotted line), 8 (1 × 10−3 M solution, black line), and 9 (1 × 10−3 M solution, blue line). (b) Emission spectra of 4 (1 × 10−6 M solution, red line; film, gray line), 8 (1 × 10−6 M solution, black line), and 9 (1 × 10−6 M solution, blue line). Figure 3. (a) ORTEP diagram of 8. Interatomic distances: C3−C3′ 4.953 Å, C9−C9′ 4.948 Å, C12−C12′ 4.822 Å. Thermal ellipsoids are 50% probability. Hydrogen atoms are omitted for clarity. (b) Calculated structure of 8 at B3LYP/6-31G(d,p) level. (c) ORTEP diagram of 9. Interatomic distances: C1−C8 4.991 Å, C11−C19, 5.151 Å, C14−C22, 5.569 Å, C18−C26 5.955 Å. Thermal ellipsoids are 50% probability. Hydrogen atoms are omitted for clarity. (d) Calculated structure of 9 at B3LYP/6-31G(d,p) level.

M) solutions of 4 in CH2Cl2 exhibited almost superimposable spectra (1 × 10−6 M, λabs 370sh, 388, and 409 nm), reflecting no self-assembly in solution. In a dilute solution (1 × 10−6 M) in CH2Cl2, 9 showed similar absorption maxima (1 × 10−6 M, λabs 370, 388, and 409 nm), indicating similar effective conjugation length. In contrast, the absorption maxima of 8 (1 × 10−6 M, λabs 364, 384, and 405 nm) showed a small blue shift, reflecting its slightly smaller π-conjugation. In the emission spectra (Figure 4b) in CH2Cl2, 4 and 9 exhibited similar emission in a 1 × 10−6 M solution (4: λem 431 with a shoulder at 455 nm, ΦF = 0.40; 9: λem 431 with a shoulder at 452 nm, ΦF = 0.33), whereas the emission maxima of 8 showed a small blue shift (λem 424, 446 nm, ΦF = 0.30). In the solid state, a film of 4 on a quartz plate has a similar absorption spectrum (λabs 371, 388, and 409 nm, Figure S2-2) to those in solution, whereas the emission spectrum of the film of 4 (λem 448 nm with shoulders at λem 487 and 535 nm, ΦF = 0.04) exhibited a large red shift, reflecting electronic interactions in

recrystallization from acetone/hexane. As shown in Figure 3a, 8 has a crystallographic C2-symmetry with a 2-fold axis passing through C1, C8, C15, and C18. The crystal structure of 8 is roughly identical to that of 4, but the carbon−carbon distance between C12 and C12′ atoms is much shorter than the distance between C9 and C9′ atoms. Since the calculated interatomic distances between the phenyl groups are normal [C9−C9′ (5.153 Å), and C12−C12′ (5.728 Å)] (Figure 3b), the short C9−C9′ and C12−C12′ distances may be due to the effect of crystal packing in 8. Concerning 9, single crystals were obtained 3859


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the excited state (Figure S2-3). To determine the interaction between the two anthracene units, oxidation potential of 4 was measured by cyclic voltammetry (CV). As shown in Table 2, 4

H NMR spectrum of 4 in the presence of 5 equiv of CuOTf exhibited lower field shifts of Ha, Hb, and 2-mesityl protons by 0.011, 0.006, and 0.003 ppm, respectively. Although the low field shifts of Ha, Hb, and Hc,d and 2-mesityl protons are small, other protons of 4 remain unchanged in the presence of CuOTf. Therefore, 4 forms its Cu(I) complex in benzene at room temperature. In order to determine the structures of copper and silver complexes of 4, 8, and 9, we attempted the preparation of single crystals. However, 4, 8, and 9 only formed crystalline powder with CuOTf and AgOTf. Therefore, we measured absorption and emission spectra of films of 1:1 mixtures of 4, 8, or 9 and CuOTf or AgOTf. The absorption and emission spectra of cast films of 4, a 1:1 mixture of 4 and CuOTf, and a 1:1 mixture of 4 and AgOTf reflect a binding behavior of 4 with Cu+ and Ag+ ion (Figure 6). The absorption maxima of a 1:1

Table 2. Oxidation Potentials of Macrocycle 4, 10-Mesityl1,8-diphenylantracene 8, and 1,8-Bis(4-biphenylyl)-10mesitylanthracene 9a compound

Eox1/2 (V)

HOMO (eV)b

HOMO (eV)c

4 8 9

0.711 0.731 0.711

−5.51 −5.53 −5.51

−5.02 −5.10 −5.05

Scan rate 0.1 V s−1 in 1,2-dichlorobenzene; V vs Fc/Fc+. bHOMO energy values of 4, 8, and 9 were deduced from the measured Eox1/2. c HOMO levels of 4, 8, and 9 were estimated at the B3LYP/631G(d,p) level. a

shows a reversible one two-electron oxidation, and the oxidation potential of 4 is the same as that of 9. In the case of 8, the oxidation potential is slightly higher than those of 4 and 9, reflecting the lower HOMO level of 8. The calculated HOMO levels are in agreement with the CV data. Complexation of 4 with Copper(I) and Silver(I) Ions. Calculated interatomic distances (5.14−5.40 Å) of 3 between biphenylylene units are enough to incorporate a silver ion in the cavity (Figure S8-2). In contrast, the interatomic distances (5.00−5.05 Å) of 4 between biphenylylene units in Figure 2a seem to be too short to incorporate a silver ion in the cavity. Interestingly, however, this shorter inner cavity of 4 is suitable for incorporating a Cu(I) ion. A number of arene−Ag(I) complexes were synthesized, and their structures were determined by X-ray analysis.15 However, only a limited number of arene−Cu(I) complexes were isolated,16 and their properties were not yet fully characterized. Although 4, 8, and 9 produced no single crystals of their Cu(I) and Ag(I) complexes, we measured 1H NMR spectra of 4, 8, and 9 in the presence of Cu(I) and Ag(I) ions. 1H NMR spectra of 8 and 9 in the presence of Cu(I) and Ag(I) ions showed no spectral change. However, 1H NMR spectrum of a mixture of 4 and CuOTf in benzene-d6 at 25 °C exhibited small low field shifts of Ha, Hb, Hc,d, and mesityl methyl protons. As shown in Figures 5 and S6, 1 H NMR spectrum of 4 in the presence of 2 equiv of CuOTf showed low-field shifts of Ha, Hb, and Hc,d and 2-mesityl H by 0.002, 0.001, 0.001, and 0.001 ppm, respectively. Furthermore,

Figure 6. Absorption and emission spectra of films of 4 and equimolar amount’s mixtures of 4 and copper(I) or silver(I) triflate. The film of copper(I) complex was prepared by casting a solution of a mixture of 4 and CuOTf (1:1) in benzene, and the film of silver(I) complex was prepared by casting a solution of a mixture of 4 and AgOTf (1:1) in benzene.

mixture of 4 and CuOTf in the solid state slightly changed (λabs 370, 389, and 412 nm), whereas the absorption maxima of a 1:1 mixture of 4 and AgOTf in the solid state remained almost unchanged (λabs 371, 389, and 413 nm). In contrast, the emission spectrum of a 1:1 mixture of 4 and CuOTf in the solid state revealed almost different peaks at longer wavelength region (λem 475 and 500sh nm; ΦF = 0.016), and the quantum yield showed 96% decrease. The emission spectrum of a 1:1 mixture of 4 and AgOTf in the solid state exhibited a small change, i.e., a peak at 458 nm with a shoulder at longer wavelength region (ΦF = 0.024). MALDI-TOF-MS spectra of 4 and CuOTf or 4 and AgOTf clearly showed molecular ion peaks of [4·Cu]+ and [4·Ag]+ (Figures S4-2 and S4-3). Since Cu(I) ion coordinates two or three p-orbitals of aromatic systems, we assume that Cu(I) ion coordinates p-orbitals of

Figure 5. 1H NMR spectra of 4 and 4−CuOTf in benzene-d6 at 25 °C: (a) 4 (1.3 mM), (b) 4 (1.3 mM) and CuOTf (2.6 mM), (c) 4 (1.3 mM) and CuOTf (6.5 mM). 3860


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007HF, VariMax-Mo and Rapid II, or Rigaku Pilatus 200 K. DFT calculations were performed at the B3LYP/6-31G(d,p) level. Elemental analyses were performed Elementar Vario EL III. Thin layer chromatography (TLC) was performed with Merck 60 F254 silica gel plates. Column chromatography was performed with Kanto Kagaku Silica gel 60N (spherical neutral). Melting points were determined with MEL-TEMP 1001D-120VAC. The solvents used for synthesis were dried and purified by usual techniques prior to use. 10-Mesityl-1,8-bis(4-trimethylsilylphenyl)anthracene (6). To a solution of 10-mesityl-1,8-dichloroanthracene (5) (4.36 g, 12 mmol), nickel(II) acetylacetonate (727 mg, 2.5 mmol), and triphenylphosphine (1.31 g, 5.0 mmol) in 29 mL of THF was dropwise added a solution of Grignard reagent prepared from 1-bromo-4-trimetylsilylbenzene (11.1 g, 48 mmol) and Mg (1.22 g, 50 mmol) in diethyl ether (22 mL) during 1 h under argon atmosphere. The resulting brown mixture was refluxed for 22 h. The reaction mixture was quenched with aqueous 3 M HCl. The organic layer was separated and the aqueous layer was extracted with dichloromethane. The combined organic layer was dried over MgSO4, and the solvent was evaporated in vacuo to give a crude product. The product was column chromatographed on silica gel using hexane/carbon disulfide (v/v 10/1) as eluent to afford 10-mesityl-1,8-bis(4-trimethylsilylphenyl)anthracene (6) (5.10 g, 72% yield) as pale yellow solid. Mp 274−275 °C. 1H NMR (500 MHz, CDCl3): δ (ppm) 8.90 (s, 1H), 7.62−7.58 (m, 8H), 7.50 (d, J = 7.6 Hz, 2H), 7.39−7.37 (m, 4H), 7.14 (s, 2H), 2.49 (s, 3H), 1.80 (s, 6H), 0.34 (s, 18H). 13C NMR (125 MHz, CDCl3): δ (ppm) 141.3, 140.7, 139.0, 137.6, 137.1, 136.2, 135.2, 133.1, 129.9, 129.7, 129.5, 128.3, 126.6, 125.6, 125.4, 123.4, 21.3, 20.1, 0.9. MS (EI): m/z 592 (M+). HRMS (ESI-TOF) m/z: M+ Calcd for C41H44Si2: 592.2976. Found: 592.2990. 1,8-Bis(4-bromophenyl)-10-mesitylanthracene (7). To a stirred solution of 10-mesityl-1,8-bis(4-trimethylsilylphenyl)anthracene (6) (1.76 g, 3.0 mmol) in acetone (10 mL) and dichloromethane (50 mL) was added N-bromosuccinimide (1.35 mg, 7.5 mmol) in one portion at room temperature, and the resulting mixture was stirred for 43 h. After removing the solvent in vacuo, the residue was column chromatographed on silica gel eluting hexane/ benzene (v/v 10/1) to afford 10-mesityl-1,8-bis(4-bromophenyl)anthracene (7) (1.41 g, 79% yield) as yellow solid. Mp 233−234 °C. 1 H NMR (500 MHz, CDCl3): δ (ppm) 8.43 (s, 1H), 7.58 (d, J = 8.2 Hz, 4H), 7.51 (dd, J = 6.0, 3.8 Hz, 2H), 7.40−7.36 (m, 8H), 7.13 (s, 2H), 2.48 (s, 3H), 1.77 (s, 6H). 13C NMR (125 MHz, CDCl3): δ (ppm) 139.7, 139.7, 137.8, 137.5, 136.6, 134.9, 131.9, 131.5, 130.1, 130.0, 128.6, 126.2, 126.1, 125.7, 123.3, 121.8, 21.5, 20.3. MS (EI): m/ z 604 (M+). Anal. Calcd for C35H26Br2: C, 69.32; H, 4.32. Found: C, 69.23; H, 4.32. Typical Procedure for the Synthesis of 10-Mesityl-1,8diphenylanthracene Dimer (4) Using ET Oxidation of Lipshuts Cuprate. To a solution of 10-mesityl-1,8-bis(4-bromophenyl)anthracene (7) (606 mg, 1.0 mmol) in THF (56 mL) was added tBuLi (3.1 mL, 5.2 mmol, 1.7 M in n-pentane) at −78 °C under argon atmosphere. The mixture was stirred at the same temperature for 3.5 h, and CuCN (101 mg, 1.1 mmol) was added. The reaction mixture was allowed to warm up to 0 °C with vigorous stirring. When all the CuCN was completely dissolved, 2,3,5,6-tetramethyl-1,4-benzoquinone (498 mg, 3.0 mmol) was added in one portion at 0 °C, and the mixture was stirred at room temperature for 5 h to complete the reaction. The reaction mixture was quenched with water. The organic layer was separated and the aqueous layer was extracted with chloroform. The combined organic layer was dried over MgSO4, and the solvent was evaporated in vacuo to give a crude product. The product was column chromatographed on silica gel using hexane/ benzene (v/v 10/1) as eluent to afford 4 (221 mg, 50% yield) as pale yellow solid (mp >370 °C (dec)). 1H NMR (500 MHz, CDCl3): δ (ppm) 8.60 (s, 2H), 7.78 (d, J = 8.2 Hz, 8H), 7.62 (d, J = 8.2 Hz, 8H), 7.54 (d, J = 8.8 Hz, 4H), 7.50 (d, J = 6.5 Hz, 4H), 7.43 (dd, J = 8.8, 6.5 Hz, 4H), 7.16 (s, 4H), 2.51 (s, 6H), 1.84 (s, 12H). 13C NMR (125 MHz, CDCl3): δ (ppm) 140.7, 139.7, 139.2, 137.7, 137.2, 135.9, 134.9, 130.6, 130.3, 129.9, 128.3, 126.3, 125.6, 125.4, 125.3, 124.2, 21.3, 20.2.

two phenyl and one anthracene units. In the case of Ag(I) ion, the change in the absorption and emission spectra is small, but the film of a 1:1 mixture of 4 and AgOTf resulted in 94% decrease of the quantum yield. Therefore, Ag(I) ion may only locate near p-orbitals of phenyl and anthracene rings. In the case of 9, the absorption and emission spectra of 1:1 mixtures of 9 and CuOTf or AgOTf in the solid state were exactly same as the spectra of 9 in the solid state; hence, 9 formed no complex with CuOTf and AgOTf in the solid state (Figures S65−S6-8). On the basis of the 1H NMR data (Figure 5) and absorption and emission spectra (Figure 6), we propose the formation of the complex 4·CuOTf in both solution and the solid state, although the binding constant of 4·CuOTf seems to be very small in solution. Furthermore, fairly low solubility of 4 and CuOTf in organic solvents makes it difficult to determine the binding constant of 4·CuOTf. It is noteworthy that the 1H NMR spectra and absorption and emission spectra of a mixture of 4 and CuOTf exhibited obvious spectral change, and the spectra of a mixture of 8 or 9 with CuOTf remained unaltered. In the case of AgOTF complexes, a film of a mixture of 4 and CuOTf only exhibited a small change depending on the interaction of 4 with AgOTf. As shown in Figure 2a, 4 possesses a narrow cavity, and Cu(I) ion may be incorporated in the hollow created by the C11, C1, C4, C9, C5, C8, and C18′ carbons and 2-mesityl methyl group. The electron-rich anthracene, parallel-arranged biphenylylene carbons, and sticking mesityl methyl group on the anthracene moiety can operate favorably to capture Cu(I) ion.

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CONCLUSIONS In the present study, we revealed that the electron-transfer oxidation of Lipshutz cuprate derived from 1,8-bis(4bromophenyl)-10-mesitylanthracene 7 proceeded smoothly to produce macrocyclic 10-mesityl-1,8-diphenylanthracene dimer 4 in satisfactory yield. The macrocyclic dimer 4 is very stable to light, atmospheric oxygen, and prolonged heating. In the solid state, a film of 4 has a similar absorption spectrum to that in solution, whereas the emission spectrum of the film of 4 exhibited a large Stokes shift, reflecting electronic interactions of the nonplanar macrocycle 4 in the excited state. X-ray analysis of 4 exhibited a rigid, shape-persistent structure, and CuOTf can be incorporated in the hollow constructed by the electron-rich anthracene, parallel-arranged biphenylylene carbons, and mesityl methyl group in 4. The 1:1 complex of 4 with CuOTf exhibited a low field shift of the signals of the anthracene and biphenyl protons in 1H NMR spectra, and a redshift of emission spectrum in the film state. In contrast, AgOTf very weakly interacted with 4 under similar conditions.

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EXPERIMENTAL SECTION

General. NMR spectra were recorded on Bruker DRX-500 (500 MHz 1H NMR and 125 MHz 13C NMR) spectrometers using tetramethylsilane as the intimal standard. UV−vis spectra were recorded on PerkinElmer Lambda 750. Fluorescence emissions were recorded on PerkinElmer FL55 or JASCO FP-8500. Absolute photoluminescence quantum yields were determined by a calibrated integrating sphere system on JASCO FP-8500. High-resolution mass spectra were measured on a Hitachi High Technologies Nano Frontier LD spectrometer by the ESI method (calibration standard: Hitachi High Technologies Standard Sample), or MALDI/TOF mass spectra were recorded on Bruker Daltonics Autoflex speed MALDI TOF/ TOF mass spectrometer (matrix: dithranol). X-ray crystal structure analysis was measured with Bruker APEX-II CCD, Rigaku MicroMax3861



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MS (MALDI-TOF): m/z 892.402 (M+). HRMS (MALDI-TOF) m/z: M+ Calcd for C70H52 892.4069. Found: 892.4053. When the ET oxidation of Lipshutz cuprate derived from 7 was carried out in diethyl ether, 10-mesityl-1,8-diphenylanthracene (8) was obtained in 39% yield together with 4 (5%). 8, pale yellow solid (mp 162−163 °C). 1H NMR (500 MHz, CDCl3): δ (ppm) 8.66 (s, 1H), 7.55 (d, J = 7.6 Hz, 4H), 7.52 (dd, J = 7.4, 2.4, 2H), 7.44−7.35 (m, 10H), 7.13 (s, 2H), 2.49 (s, 3H), 1.80 (s, 6H). 13C NMR (125 MHz, CDCl3): δ (ppm) 140.9, 140.7, 137.6, 137.1, 136.0, 135.1, 130.1, 129.9, 129.8, 128.3, 128.0, 127.1, 126.0, 125.5, 125.3, 123.8, 21.3, 20.1. MS (EI): m/z 448 (M+). HRMS (ESI-TOF) m/z: [M + H]+ Calcd for C35H29: 449.2264. Found: 449.2276. 1,8-Bis(4-biphenylyl)-10-mesitylanthracene (9). To a mixture of 7 (182 mg, 0.3 mmol) and [1,3-bis(diphenylphosphino)propane]nickel(II) chloride (8.5 mg, 0.015 mmol) in diethyl ether (7.5 mL) was added dropwise a solution of PhMgBr (1.5 mL, 1.5 mmol) during 5 min under nitrogen atmosphere. The resulting reddish-brown mixture was refluxed for 19 h. The reaction mixture was quenched with aqueous 3 M HCl. The organic layer was separated, and the aqueous layer was extracted with dichloromethane. The combined organic layer was dried over MgSO4, and the solvent was evaporated in vacuo to give a crude product. The product was column chromatographed on silica gel using hexane/benzene (v/v 10/1) as the eluent. The product was recrystallized from dichloromethane/hexane (v/v 1/ 1) to provide 10-mesityl-1,8-bis(4-biphenylyl)anthracene (9) (115 mg, 64% yield) as pale yellow solid. Mp 226.5−228 °C. 1H NMR (500 MHz, CDCl3): δ (ppm) 8.78 (s, 1H), 7.65 (d, J = 8.2 Hz, 4H), 7.63 (d, J = 8.2 Hz, 4H), 7.54−7.51 (m, 6H), 7.48 (dd, J = 6.6, 1.5 Hz, 2H), 7.42 (dd, J = 8.6, 6.6 Hz, 2H), 7.38−7.33 (m, 6H), 7.15 (s, 2H), 2.50 (s, 3H), 1.82 (s, 6H). 13C NMR (125 MHz, CDCl3): δ (ppm) 140.9, 140.8, 140.1, 139.6, 137.7, 137.2, 136.0, 135.0, 130.6, 130.0, 129.9, 128.8, 128.3, 127.2, 127.1, 126.9, 125.7, 125.6, 125.4, 123.9, 21.3, 20.2. MS (MALDI-TOF): m/z 600.936 (M+). HRMS (MALDI-TOF) m/z: M+ Calcd for C47H36: 600.2817. Found: 600.2816. Computational Methods. DFT calculations were carried out with the Gaussian 09 program.17 All geometry optimizations were carried out at the B3LYP/6-31G(d,p) basis set unless otherwise noted. X-ray Crystallographic Data for 4·(THF)2. Molecular formula: C70H52·2C4H8O, monoclinic, space group C2 (No. 5), a = 16.5890(10) Å, b = 9.0335(4) Å, c = 20.6981(10) Å, β = 94.977(7)°, V = 3090.0(3) Å3, T = 200 K, Z = 2, R1 (wR2) = 0.0530 (0.1491) for 501 parameters and 6267 unique reflections. GOF = 1.024. CCDC 1537880. X-ray Crystallographic Data for 4. Molecular formula: C70H52, triclinic, space group P1̅ (No. 2), a = 10.338(4) Å, b = 11.016(6) Å, c = 22.351(9) Å, α = 88.20(4)°, β = 77.272(17)°, γ = 86.40(3)°, V = 2477.6(19) Å3, T = 123 K, Z = 2, R1 (wR2) = 0.0970 (0.1640) for 608 parameters and 8720 unique reflections. GOF = 1.014. CCDC 1539203. ORTEP diagram: Figure S7-2. X-ray Crystallographic Data for 8·Acetone. Molecular formula: C35H28·C3H6O, monoclinic, space group C2/c (No. 15), a = 10.0828 (4) Å, b = 31.5519 (11) Å, c = 9.4547 (5) Å, β = 110.0379 (13)°, V = 2825.8(2) Å3, T = 200 K, Z = 4, R1 (wR2) = 0.0756 (0.2341) for 199 parameters and 3245 unique reflections. GOF = 1.099. CCDC 1537881. X-ray Crystallographic Data for 9. The mesityl groups form some void space within the crystal lattice. These voids are occupied by disordered CHCl3 molecules. The SQUEEZE function equipped in the PLATON program was employed to remove their contribution in voids. Two biphenyl moieties are treated as a disorder. The occupation factors were determined to be 0.46 and 0.54, respectively. All the nonhydrogen atoms were refined with anisotropic displacement parameters. Molecular formula: C47H36, triclinic, P1̅ (No. 2), a = 8.427(2) Å, b = 11.446(3) Å, c = 19.827(5) Å, α = 105.602(4)°, β = 98.716(4)°, γ = 94.253(4)°, V = 1807.4(8) Å3, Z = 2, R1 (wR2) = 0.0785 (0.2076) for 552 parameters and 2606 (I > 2σ) unique reflections. GOF = 0.862. CCDC 1817033.

Article

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.joc.8b00200. Crystallographic information files for compounds 4· (THF)2, 4, 9, and 8 (CIF, CIF, CIF, CIF) 1 H and 13C NMR spectra of all new compounds; X-ray data of 4, 8, and 9; absorption and emission data of 4, 8, and 9 (PDF)

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AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. *E-mail: [email protected]. ORCID

Masahiko Iyoda: 0000-0002-7182-8847 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology, Japan and partly performed under the Cooperative Research Program of “Network Joint Research Center for Materials and Devices” (M.I.). We would like to thank Dr. Tomohiko Nishiuchi (Osaka University) for the Xray crystallographic data analysis and helpful discussions.

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REFERENCES

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10-Mesityl-1,8-diphenylanthracene Dimer: Synthesis, Structure, and

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