Synthesis, Structures, and Assembly of Geodesic Phenine

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Synthesis, structures and assembly of geodesic phenine frameworks with isoreticular networks of [n]cyclo-para-phenylenes Sun Zhe, Tatsuru Mio, Koki Ikemoto, Sota Sato, and Hiroyuki Isobe J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.9b00085 • Publication Date (Web): 14 Feb 2019 Downloaded from http://pubs.acs.org on February 15, 2019

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The Journal of Organic Chemistry

Synthesis, structures and assembly of geodesic phenine frameworks with isoreticular networks of [n]cyclo-para-phenylenes Zhe Sun,†,‡,§ Tatsuru Mio,† Koki Ikemoto,†,‡ Sota Sato,†,‡ Hiroyuki Isobe*,†,‡ †

Department of Chemistry, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-0033,

Japan ‡

JST, ERATO, Isobe Degenerate π-Integration Project, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-0033,

Japan §

Present address: Institute of Molecular Plus, Tianjin University. No. 11 Building, No. 92 Weijin Road,

Nankai District, Tianjin, 300072, P. R. China *

e-mail: [email protected]

Graphics for Table of Contents: ! ! !

! "phenine"

n=3 rigid cylinder

! ! !

n=4

"[n]CPP-GPF"

n

n=5 flexible macrocycle

Abstract: A series of macrocycles were designed by rendering geodesic phenine frameworks in isoreticular networks of [n]cyclo-para-phenylenes. Large, nanometer-sized molecules exceeding molecular weights of 2000 Da were synthesized by 5-step transformations including macrocyclization of [6]cyclo-meta-phenylene panels. The dependence of both the molecular structures and the fundamental properties on the panel numbers was delineated by a combination of spectroscopic and crystallographic analyses with the aid of theoretical calculations. Interestingly, flexibility of the molecules via panel rotations depends on the hoop size, which has not been disclosed with the small 1 ACS Paragon Plus Environment

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isoreticular [n]cylco-para-phenylenes. One of the macrocycles served as a host for C70, and its association behaviors and crystal structures were revealed.

Introduction Various shapes of carbon-rich molecules are being created by chemists, which enriches the structural library of nanocarbon molecules.1 A geodesic phenine framework (GPF) is a novel class of nanocarbon molecule that is based on 1,3,5-trisubstituted benzene (phenine) as its trigonal planar units.2,3,4 Structurally, the GPF molecules possess isoreticular networks of polyarenes whose trigonal units are sp2-carbon atoms,5 and because the GPF molecules utilize the larger trigonal units of phenine, the frameworks readily expand to a nanometer scale. Another unique aspect of the GPF design is the presence of periodic vacancy defects in the structures, which highlights an important role of synthetic chemistry in nanocarbon studies. Synthetically, the GPF design can utilize a rich library of biaryl coupling reactions for framing and thus can readily expand its reach to various nanometer-sized structures. For instance, bowl- and saddle-shaped GPF molecules were synthesized by a combination of coupling reactions mediated/catalyzed by Ni and Pd,2,3 and cylindrical GPF molecules, specifically named phenine nanotube (pNT) molecules, were synthesized by a combination of coupling reactions with Pd, Ni and Pt (Figure 1).4 The pNT molecules particularly demonstrated the robustness of the phenine design by creating a unique framework that was known as an imaginary polyarene of Vögtle belt. As one of the important reactions, the synthesis adopted Yamago's Pt-mediated macrocyclization6 with our boryl-route modification

7

and passed through [n]cyclo-para-phenylenoidal GPF

([n]CPP-GPF) as synthetic intermediates. Considering the current intense interest in [n]CPP congeners in polyarene chemistry,8,9,10 we decided to investigate the synthesis and fundamental structures of 2 ACS Paragon Plus Environment

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isoreticular [n]CPP-GPF. The structures were revealed by spectroscopy, crystallography and theoretical calculations, which showed that careful consideration was required to assert control over the molecular shapes.11 The large nanometer-sized structure was so flexible that it accommodated a guest molecule via structural deformations. R R

R

R

R

R

R

R R

R

R

R

R R

R

R

R

R

R

R R

R

R

[7]circulenoidal GPF “saddle” R

R

R

R

R

R

corannulenoidal GPF “bowl” R

R

R

R

e

d c

R

b a n

R R

R

R

R

R

R

R

R

(12,12)-pNT “cylinder”

R R = t-Bu

[n]cyclo-para-phenylenoidal GPF ([n]CPP-GPF; n = 3, 4, 5)

Figure 1. Geodesic phenine framework (GPF)

Results and discussion Synthesis. To study the fundamental structures, we synthesized a series of [n]CPP-GPF molecules as hydrocarbons devoid of heteroatoms via a synthetic route established for the pNT molecules.4,12 Thus, terphenyl 2 with t-Bu end groups was synthesized by Suzuki-Miyaura coupling,13 and a subsequent [3+3] cyclization with Yamamoto-type coupling afforded [6]cyclo-meta-phenylene ([6]CMP) precursor 3 (Scheme 1).4,14 An Ir-catalyzed C-H borylation of 3 proceeded in a site selective 3 ACS Paragon Plus Environment


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manner to furnish [6]CMP with boryl linkers at the "para" positions.15 Finally, the Pt-mediated macrocyclization with 4 was performed to afford three [n]CPP-GPF molecules that possessed different numbers of the [6]CMP panels. Thus, unlike the macrocyclization for the small CPP molecules,6 the Pt-mediated macrocyclization proceeded with multiple [6]CMP panels for the nanometer-sized congeners of [n]CPP-GPF in a non-selective manner with n = 3, 4 and 5.4,16 The small congeners with panel numbers of 3 and 4 have not been synthesized with phenylene [n]CPP structures.17 Although we do not understand the reason, the replacement of trimethylsilyl (TMS) groups on [6]CMP panels with t-Bu groups affected the yields and the product distributions.4 Synthetically, the TMS/t-Bu replacement is the key design for lengthening of cylinders.

Scheme 1. Synthesis of [n]CPP-GPF

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R R

Br

Br

Br Pd(PPh3)4 K2CO3

Bpin

DMF/H2O, 80 °C 60%

Bpin

Br 1

2

R R Ni(cod)2 1,5-cyclooctadiene 2,2’-bipyridine

R

X

X

DMF/toluene, 80 °C 79%

R

R

(Bpin)2 [Ir(cod)OMe]2 dtbpy THF, 65 °C 97%

3: X = H 4: X = Bpin 1. PtCl2(cod) CsF THF, 65 °C 2. PPh3 toluene, 100 °C

R = t-Bu

[3]CPP-GPF, 3% [4]CPP-GPF, 6% [5]CPP-GPF, 3%

Bpin =

O B O

N

N

dtbpy = R

R

Spectroscopic properties. Spectroscopic analyses of the [n]CPP-GPF molecules were carried out. MALDI mass spectrometry confirmed the enormous molecular weights of 2037, 2716 and 3394 (m/z values of [M]+) for n = 3 (C156H162), 4 (C208H216) and 5 (C260H270), respectively (Figure 2a). Photophysical properties were investigated by UV-vis absorption and fluorescence spectroscopy. As shown in Figure 2b, absorption peaks were observed at approximately 250 nm, commonly, for [n]CPP-GPF with n = 3, 4 and 5, and fluorescence peaks were likewise observed at approximately 360 nm. Independence of the absorption peaks from the panel numbers was similarly observed with [n]CPP.18 A small yet evident difference in the absorption spectra was noted with [3]CPP-GPF as a broad shoulder at approximately 300 nm. Such redshifts are most likely due to rigid belt shapes that 5 ACS Paragon Plus Environment


effectively extend the π-conjugations.16,17,19 We did not observe dependency of the fluorescence peaks on the panel numbers, which was different from previous observations with small isoreticular [n]CPPs. Photophysical properties of [n]CPP molecules are currently under intense investigation,20 and the present observations provide another experimental basis for further in-depth theoretical studies. (a) MALDI MS

(b) UV-vis/fluorescence

n=3

n=3 0.5

Absorbance

2037

2000

m/z

3000

4000

n=4

0 250

300

350 400 450 wavelength (nm)

500

m/z

3000

Absorbance

0.4 0.3 0.2 0.1 300


500

n=5

2000

m/z

3000

4000

a,b d

8.0

7.5 ppm

d

ec

b a

8.0

8.5

7.5 ppm

n=5

0.5

Normalized FL

3394

8.5

e

n=4

0 250

4000

c

Normalized FL

2000

n=5

1000

0.1

0.5

2716

1000

0.4 0.3 0.2

n=4

Absorbance

1000

(c) 1H NMR n=3 Normalized FL

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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0.4 0.3 0.2 0.1 0 250

300


500

b

8.5

c

e

d

a

8.0

7.5 ppm

Figure 2. Representative spectra of [n]CPP-GPF. (a) MALDI mass spectra (positive). Matrix = pyrene. (b) UV-vis/fluorescence spectra in CHCl3. Concentrations: 1.37 × 10–6 M (n = 3), 1.03 × 10–6 M (n = 4) and 5.94 × 10–7 M (n = 5). Excitation for fluorescence = 254 nm. (c) Aromatic regions of proton NMR spectra in CDCl3. See also Figure 1 for the position labels.

Aromatic regions of 1H NMR spectra (CDCl3) are shown in Figure 2c. The number of aromatic protons in [n]CPP-GPF are 54 (n = 3), 72 (n = 4) and 90 (n = 5). These multiple aromatic 6 ACS Paragon Plus Environment

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protons of [n]CPP-GPF converged into four (n = 3) and five (n = 4 and 5) resonances in 1H NMR spectra and were fully assigned with the aid of NOESY spectra (see Supporting Information). The number of resonances was consistent with the highest reachable point symmetry of Dnh (n = 3-5), and the Dnh cylindrical shapes of molecules were spectroscopically indicated as time-average structures. However, the presence and validity of the symmetric structures in solution should be carefully examined (see below).11,21 Although most of the resonances shifted towards downfield regions upon increasing the numbers of panels (except proton "c"),22 we do not think that this tendency can be ascribed to a single origin, as mentioned in the discussion of crystal structures and theoretical dynamic structures (see below). Similarly, the aromatic sp2-carbons in [n]CPP-GPF (n = 3: 108 sp2-C; n = 4: 144 sp2-C; n = 5: 180 sp2-C) converged into ten aromatic resonances in

13

C NMR spectra (Supporting

Information). Crystal structures. Molecular structures of the [n]CPP-GPF congeners were fully revealed by X-ray crystallographic analysis of single crystals. As shown in Figure 3, [n]CPP-GPF molecules commonly exhibited nanometer-sized pores at the center of macrocyclic structures. Overall shapes deviated from the expected cylindrical shapes, and the structural deviations were dependent on the panel numbers. Severe deformations were particularly apparent with larger [4]- and [5]CPP-GPF molecules, and the deviations from cylinders were quantified in terms of dihedral angles. The dihedral angles of the three biaryl linkages (c-c, a-b and b-b) were thus measured (Figure 3d), revealing that the smallest structural deviation was exhibited by the [3]CPP-GPF molecule. As was observed with pNT molecules with a cylindrical shape,4 the dihedral angles were small at the circumference for the [3]CPP-GPF molecule, and the smallest coplanar value of 0.8±0.7° was recorded at the biaryl bonds connecting the [6]CMP panel (c-c). The standard deviations of the dihedral angles were also small for 7 ACS Paragon Plus Environment


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the [3]CPP-GPF molecule. These observations indicated persistency of the molecular structure as well as the cylindrical shape (see below). The larger congeners possessed large dihedral angles and deviated from a cylindrical shape. Except for the c-c dihedral angles of [4]CPP-GPF, the standard deviations were also considerably large. These observations indicated fluctuating structures of larger congeners, which was consistent with the theoretical pictures (see below). (a)

(b)

top

top

side

(c)

side (d)

b-b a-b c-c c n 3 4 5

top

b

b

a c

c-c 0.8±0.7° 35.8±2.3° 23.3±13.1°

a-b 44.5±2.5° 40.7±14.4° 35.8±13.2°

b-b 12.7±6.6° 26.8±7.6° 15.7±8.9°

side

Figure 3. Crystal structures. Representative structures are shown from disordered structures. (a) [3]CPP-GPF. (b) [4]CPP-GPF. (c) [5]CPP-GPF. (d) Average dihedral angles with standard deviations.

Fluctuations of structures. To elucidate intrinsic structural fluctuations of the phenine frameworks, we performed conformation search calculations of [n]CPP-GPF(H) congeners lacking t-Bu groups. Thus, MMFF94 force field calculations 23 with a low-mode sampling sequence 24 exploiting 2000 structures were performed to afford the ≤5-kcal/mol conformers shown in Figure 4. As was indicated by the crystal structure, the smallest [3]CPP-GPF(H) did not show conformational flexibility with small structural deviations from the global minimum. The structure of the global 8 ACS Paragon Plus Environment

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minimum was similar to the crystal structure possessing the cylinder-like shape with coplanar biaryl bridges (see also Figure 3). This result was consistent with the solution-phase UV-vis spectrum showing redshifted shoulders that indicated π-extension over the rigid structure.16,21,25 In contrast, the largest congener, [5]CPP-GPF(H), showed a diverse range of conformations, suggesting a flexible molecular structure. In addition, as was indicated by the c-c dihedral angles (23.3±13.1°) of the crystal structure of [5]CPP-GPF, the planarity at the circumference of the molecule was not observed in the conformers.11 These two characteristics (i.e., flexible structure and non-cylindrical shape) of the largest congener were in stark contrast to those found with the smallest [3]CPP-GPF congener. As expected, the middle-size congener, [4]CPP-GPF(H), showed intermediary characteristics. Thus, as was seen in the conformation picture, the deviation of the conformers from the global minimum was not as extreme as that observed with [5]CPP-GPF. However, deviations of conformations from a cylindrical shape were noticeable, mostly due to the large c-c dihedral angles at the circumference. As was observed in the crystal structure as 35.8±2.3°, the dihedral angles of c-c linkages were mostly found around a standard biaryl angle of ca. 30°.18,11 The observations showed that the cylindrical shape found in the lengthened molecule [(12,12)-pNT] with the identical width originated from the doubly/triply connected frameworks.4 Such unique comparisons have not been made with polyarenes, as fully belted congeners of [n]CPP have scarcely been prepared.26 The dependency of the structural flexibility of [n]CPP-GPF on the panel numbers was similarly observed in small cyclonaphthylenes.27



[3]CPP-GPF(H)

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[4]CPP-GPF(H)

[5]CPP-GPF(H)

Figure 4. Lowest-energy conformers of [n]CPP-GPF (≤5 kcal/mol). Global minima are shown in red. The conformation search was performed with the MMFF94 force field for low-mode sampling of 2000 structures.

Porosities of crystals. Close examination of the crystal packings revealed an interesting porous nature of the crystals. As was observed with the pNT molecules,4 cylindrical pores of molecules were aligned to form nanopores with [3]- and [5]CPP-GPF molecules (Figure 5). The packing structure of [4]CPP-GPF was different, and a pore of one molecule was crowned by a rim of neighboring molecules. Because the [4]CPP-GPF molecule possessed the identical geometrical width as the (12,12)-pNT molecule, we did not expect this packing deviation with [4]CPP-GPF molecules. Among various factors that could affect packing structures, we think that the flexibility of the molecule may play an important role. Indeed, the shape of [4]CPP-GPF was severely deformed as oval shapes in the 10 ACS Paragon Plus Environment

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crystal (see Figure 3). The difference in the packing structure also resulted in a difference in the void fractions.28 Thus, the void fractions of nanoporous crystals of [3]- and [5]CPP-GPF exceeded 50%, whereas that of [4]CPP-GPF was below 50% (Figure 5).

top

side [3]CPP-GPF (void fraction = 53%)

top


top


Figure 5. Crystal packings of [n]CPP-GPF. The void fractions were calculated at procrystal electron density of 0.002 au.28 11 ACS Paragon Plus Environment


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[4]CPP-GPF as a host for C70. Considering the void spaces in the crystalline state, we investigated the host-guest chemistry of [n]CPP-GPF molecules to find unique supramolecular complexes with fullerene molecules. In their ideal cylindrical shapes, the diameters of [n]CPP-GPF are 1.24, 1.65 and 2.06 nm for n = 3, 4 and 5, respectively.29,30 The diameter of [3]CPP-GPF was smaller than those of [10] and [11]CPP (1.37/1.51 nm) that were known as hosts for C60/C70 fullerenes.31,32 On the other hand, the diameters of [4]/[5]CPP-GPF were larger than those of [10] and [11]CPP hosts. Thus, the changes noted by NMR spectroscopy were not fully expected. When we mixed each of the [n]CPP-GPF molecules with C60 or C70, we noted considerable changes in the 1H NMR spectra with a combination of [4]CPP-GPF and C70 among the six possible combinations (Figure 6). The middle-sized molecule, [4]CPP-GPF, hence accommodated C70 in solution, which was unexpected, given that [12]CPP with an identical diameter failed to serve as a host for C60/C70.31 As shown in Figure 6, the aromatic 1H NMR resonances of [4]CPP-GPF shifted towards upfield regions upon increasing the C70 guest, which also indicated the presence of rapid in-and-out exchange processes.2,33 The stoichiometry of the complexation was determined to be 1:1 by the Job plot analysis with the most affected resonance (proton c; Figure 6). The association constant was also determined to be 4.7 × 104 M–1, which was slightly lower than that reported for a smaller host of [11]CPP ([11]CPP⊃C70, Ka = 5.3 × 105 M–1).31


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(a)

25 °C [4]CPP-GPF + C70

host:guest 10:0 c

toluene-d8

[4]CPP-GPF⊃C70

e

d

a

b

9:1 8:2 7:3 6:4 5:5 4:6 3:7 2:8 1:9

0.02 0.01

8.2

8.0 (c) 0.10

7.8 ppm

Δδ

8.4 (b) 0.03

χΔδ

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


0.05

0 1.0 0 0.5 Molar fraction of C70 (χ)

0 0

Ka = 4.7 × 104 M–1 4 8 12 [C70]/[[4]CPP-GPF]

Figure 6. Solution-phase complexation of [4]CPP-GPF with C70. (a) Aromatic region of 1H NMR spectra in tolulene-d8 (25 °C, total concentration = 4.3 × 10–5 M; see Supporting Information for details). Resonances were assigned by the NOESY spectrum (see Supporting Information). The resonance of proton c showed the largest change upon addition of C70 and was used for the Job plot and binding analyses. (b) The Job plot. (c) Fitting analysis to determine the association constant.

Single crystals of [4]CPP-GPF encapsulating C70 were obtained, but we were surprised by unexpected compositions and structures. Single crystals were grown with two different host-to-guest ratios, i.e., 1:1 and 1:2, to reveal common structures having an unexpected host-to-guest ratio (see Supporting Information for details). Thus, as shown in Figure 7, a 1:3 complex of [4]CPP-GPF and C70 13 ACS Paragon Plus Environment


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was found in the crystal with one C70 molecule entrapped at the center and two C70 molecules located at the side (Figure 7). As we only detected the 1:1 complex in the solution-phase analyses, we believe that the two extra C70 molecules at the side were entrapped to fill the void space potentially created by [4]CPP-GPF in the absence of C70 (void fraction = 45%; see Figure 5). This filling effect of C70 may also account for the 1:3 complex of (12,12)-pNT and C70 molecules in the crystal.4 The structural deformation of the [4]CPP-GPF host was another interesting feature noted for the co-crystal of C70. Thus, the dihedral angles of the C70-free crystal were 35.8±2.3° (c-c), 40.7±14.4° (a-b) and 26.8±7.6° (b-b) (Figure 3d), which were altered to 42.9±6.0° (c-c), 40.1±9.1° (a-b) and 14.2±10.0° (b-b) upon complexation with C70. Thus, the C-C bonds located at the circumference were considerably deformed to encapsulate the C70 guests.

top

side

Figure 7. Crystal structures of [4]CPP-GPF with C70. Solvent molecules and hydrogen atoms are 14 ACS Paragon Plus Environment

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omitted for clarity. Colors of C70 show three different locations (green = inside; orange/purple = outside).

Conclusions In summary, we have synthesized GPF hydrocarbons that possess isoreticular frameworks of [n]CPP. The Pt-mediated macrocyclization allowed for the synthesis of three congeners with differing panel numbers. A combination of various structural analyses revealed structural features unique to each panel number. The smallest [3]CPP-GPF congener possessed a rigid cylindrical shape that can be regarded as a (9,9)-carbon nanotube segment with periodic vacancy defects (tf = 4.0, Fa = 67%, Fb = 57%).4,21 A unique fluctuating structure was indicated with the largest [5]CPP-GPF congener. The structural fluctuations of the middle-size [4]CPP-GPF congener resulted in an apparent change in the packing structure, which showed a stark difference from that found with the lengthened, rigid pNT molecules. The induced-fit encapsulation of C70 is another unique feature of the flexible GPF. We believe that explorations of the [n]CPP-GPF derivatives should enrich the chemistry related to [n]CPP. To deepen our understanding of periodic defects with the nanocarbon molecules, further careful analyses of unique structures are particularly important.

Experimental section General. All the reactions were performed under N2 atmosphere. Flash silica gel column chromatography was performed on silica gel 60N (spherical and neutral gel, 40–50 µm, Kanto). Gel permeation chromatography was performed on YMC LC-forte/R (columns: YMC GPC T2000 and T4000) and JAI LC-9104 (columns: JAIGEL-1H-40, 2H-40 and 2.5H-40) both equipped with UV and 15 ACS Paragon Plus Environment


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RI detectors with chloroform as the eluent. Preparative high-performance liquid chromatography (HPLC) was performed on JASCO LP-2000 Plus series systems equipped with a UV detector with COSMOSIL Buckyprep 20 φ × 250 mm or COSMOSIL Cholester 20 φ × 250 mm. Analytical HPLC was performed on JASCO LP-2000 Plus series systems with COSMOSIL Buckyprep 4.6 φ × 250 mm at the flow rate of 1.0 mL/min at 40 ºC in a column oven under UV detection at 260 nm. Proton (1H), carbon (13C) NMR spectra were recorded on JEOL JNM-ECA 600 II (1H: 600 MHz; and JEOL JNM-ECS 400 (1H: 400 MHz;

13

13

C: 150 MHz)

C: 100 MHz). Chemical shift values are given in ppm

relative to internal CHCl3 (1H NMR: δ 7.26;

13

C NMR: δ 77.16). Ultraviolet-visible (UV-vis)

spectroscopy was performed on JASCO V-670 equipped with JASCO ETC-717 temperature controller. Fluorescence spectroscopy was performed on JASCO FP-8500 equipped with JASCO ETC-815 temperature controller. High-resolution mass spectrometry was performed on Bruker autoflex speed by matrix-assisted laser desorption/ionization (MALDI) method and on Bruker micrOTOF II by atmospheric pressure photoionization (APPI) and atmospheric pressure chemical ionization (APCI) methods. Solvents and reagents were purchased from TCI Co., Ltd., Wako Pure Chemical Industries, Ltd., Kanto Chemical Co., Inc., and Sigma-Aldrich Co. Anhydrous THF, DMF and toluene were purified by a solvent purification system (GlassContour) equipped with columns of activated alumina and supported copper catalyst (Q-5). All other chemicals were of reagent grade and used without any further purification. Synthesis of Substrates. 1,3-Benzenediboronic acid bis(pinacol) ester (1): To a mixture of bis(pinacolato)diboron (59.2 g, 233 mmol), PdCl2(dppf)•CH2Cl2 (8.66 g, 10.6 mmol) and KOAc (52.0 g, 529 mmol) in DMSO (500 mL) was added 1,3-dibrorobenzene (25.0 g, 106 mmol). The mixture was 16 ACS Paragon Plus Environment

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stirred at 80 ºC for 16 h, and H2O (500 mL) was added to it. The precipitate was collected by vacuum filtration, washed with water and methanol, dried over Na2SO4 and purified by silica gel chromatography (eluent: hexane/ethyl acetate = 10:1). The title compound was obtained as a white powder in 91% yield (31.8 g, 96.3 mmol). Spectra of 1 were identical to the data found in literature.34 3,3''-Dibromo-5,5''-di-tert-butyl-1,1':3',1''-terphenyl (2): A mixture of diboronate ester 1 (2.00 g, 6.06 mmol), 1,3-dibromo-5-tert-butylbenzene (5.31 g, 18.2 mmol) and Pd(PPh3)4 (350 mg, 0.303 mmol) and K2CO3 (12.6 g, 91.2 mmol) in DMF (150 mL) was added a solution of K2CO3 (4.18 g, 30.3 mmol) in water (30 mL). The mixture was stirred at 80 ºC for 16 h and extracted with ethyl acetate (1 L). The organic layer was dried over Na2SO4, concentrated and purified by silica gel column chromatography (eluent: hexane) to afford the title compound as a colorless oil in 60% yield (1.80 g, 3.61 mmol). 1H NMR (400 MHz, CDCl3) δ 7.66 (s, 1H), 7.58 (t, J = 1.6 Hz, 2H), 7.54–7.52 (m, 7H), 1.37 (s, 18H);

13

C{1H} NMR (100 MHz, CDCl3) δ 153.9, 142.8, 141.1, 129.3, 127.7, 127.5, 126.7,

126.3, 123.3, 122.8, 35.1, 31.2; HRMS (APCI) m/z [M]+ calcd for C26H28Br2 500.0532, found 500.0546. [6]CMP derivative 3: A mixture of Ni(cod)2 (6.08g, 22.1 mmol), 2,2′-bipyridine (3.42 g, 21.9 mmol) and cycloocta-1,5-diene (2.70 mL, 21.8 mmol) was stirred at 80 ºC in a mixed solvent of DMF (120 mL) and toluene (400 mL) for 1 h. To the mixture was slowly added terphenyl 2 (3.63 g, 7.26 mmol) in toluene (200 mL) over 30 min. After an additional stir for 18 h, the mixture was cooled down to ambient temperature and was stired overnight after addition of aqueous solution of HCl (3 M, ca. 500 mL). After removal of the aqueous layer, the organic layer was concentrated and the resulting solid was washed with methanol (300 mL) and CHCl3 (20 mL) to afford the title compound as a white powder in 79% yield (1.96 g, 2.88 mmol). 1H NMR (400 MHz, CDCl3) δ 8.34 (s, 2H), 8.13 (s, 4H), 17 ACS Paragon Plus Environment


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7.76–7.72 (m, 12H), 7.58 (t, J = 7.6 Hz, 2H), 1.49 (s, 36H); 13C{1H} NMR (100 MHz, CDCl3) δ 152.3, 141.7, 141.6, 129.3, 127.7, 125.2, 124.9, 122.6 (2C), 35.1, 31.6; HRMS (APPI) m/z [M]+ calcd for C52H56 680.4376, found 680.4391. [6]CMP derivative 4: A mixture of 3 (400 mg, 0.590 mmol), bis(pinacolato)diboron (598 mg, 2.35 mmol), [Ir(cod)(OMe)]2 (78.0 mg, 0.560 mmol) and 4,4′-di-tert-butyl-2,2′-bipyridine (63.0 mg, 0.240 mmol) in THF (115 mL) was stirred at 65 ºC for 24 h. The solvent was removed in vacuo and the residue was washed with methanol to afford the title compound as a white powder in 97% yield (534 mg, 0.573 mmol). 1H NMR (400 MHz, CDCl3) δ 8.39 (s, 2H), 8.14 (s, 4H), 8.05 (s, 4H), 7.79 (s, 4H), 7.71 (s, 4H), 1.50 (s, 36H), 1.44 (s, 24H);

13

C{1H} NMR (100 MHz, CDCl3) δ 152.2, 141.5, 141.3,

141.0, 131.5, 131.0, 124.9, 122.9, 122.7, 84.0, 35.1, 31.7, 24.9; HRMS (APPI) m/z [M]+ calcd for C64H78B2O4 932.6081, found 932.6082. Synthesis of [n]CPP-GPF. A mixture of 4 (200 mg, 0.210 mmol), PtCl2(cod) (80.4 mg, 0.210 mmol) and CsF (320 mg, 2.10 mmol) in THF (21 mL) was stirred at 65 ºC for 24 h. The solvent was removed by vacuo, and the residue was diluted with toluene (10 mL). After addition of PPh3 (550 mg, 2.10 mmol), the mixture was stirred at 100 ºC for 17 h. The resulting mixture was poured into methanol (1 L) to afford a crude solid material. The crude material was roughly purified by passing through a pad of silica gel and then separated by GPC and HPLC to afford [3]CPP-GPF in 3% (4.0 mg, 2.0 µmol), [4]CPP-GPF in 6% (8.2 mg, 3.0 µmol) and [5]CPP-GPF in 3% yields (3.7 mg, 1.1 µmol) as white powders. [3]CPP-GPF: 1H NMR (600 MHz, CDCl3) δ 7.99 (d, J = 1.4 Hz, 12H), 7.80 (s, 12H), 7.70 (s, 12H), 7.70 (s, 6H), 7.66 (s, 12H), 1.46 (s, 108H);

13

C{1H} NMR (150 MHz, CDCl3) δ 152.3, 144.3,

142.6, 138.2, 137.1, 128.1, 126.2, 123.4, 122.2, 120.6, 35.1, 31.6; HRMS (MALDI-TOF) m/z [M]+ 18 ACS Paragon Plus Environment

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calcd for C156H162 2036.2705, found 2036.2728; UV-vis (1.37 × 10–6 M, CHCl3): lmax = 253 nm (Abs = 0.362), 303 nm (Abs = 0.065); fluorescence (excitation = 254 nm, 1.37 × 10–6 M, CHCl3): lmax = 360 nm. A single crystal of [3]CPP-GPF suitable for X-ray crystallographic analysis was obtained by vapor diffusion of MeOH into a 1,2-dichloroethane solution of [3]CPP-GPF at 25 °C. [4]CPP-GPF: 1H NMR (600 MHz, CDCl3) δ 8.08 (s, 16H), 7.97 (s, 8H), 7.88 (s, 16H), 7.86 (d, J = 1.6 Hz, 16H), 7.73 (s, 16H), 1.48 (s, 144H); 13C{1H} NMR (150 MHz, CDCl3) δ 152.3, 143.5, 141.9, 141.1, 138.3, 127.5, 124.8, 124.7, 122.6, 120.8, 35.2, 31.6; HRMS (MALDI-TOF) m/z [M]+ calcd for C208H216 2715.6964, found 2715.6961; UV-vis (1.03 × 10–6 M, CHCl3): lmax = 259 nm (Abs = 0.445); fluorescence (excitation = 254 nm, 1.03 × 10–6 M, CHCl3): lmax = 356 nm. A single crystal of [4]CPP-GPF suitable for X-ray crystallographic analysis was obtained by vapor diffusion of 2-propanol into a CHCl3 solution of [4]CPP-GPF at 25 °C. [5]CPP-GPF: 1H NMR (600 MHz, CDCl3) δ 8.27 (s, 20H), 8.17 (s, 10H), 8.01 (d, J = 1.2 Hz, 20H), 7.91 (s, 20H), 7.82 (s, 20H), 1.49 (s, 180H); 13C{1H} NMR (150 MHz, CDCl3) δ 152.5, 142.8, 141.4, 141.3, 138.7, 126.9, 124.3, 124.0, 122.6, 121.2, 35.2, 31.6; HRMS (MALDI-TOF) m/z [M]+ calcd for C260H270 3394.1189, found 3394.1166; UV-vis (5.94 × 10–7 M, CHCl3): lmax = 261 nm (Abs = 0.301); fluorescence (excitation = 254 nm, 5.94 × 10–7 M, CHCl3): lmax = 359 nm. A single crystal of [5]CPP-GPF suitable for X-ray crystallographic analysis was obtained by vapor diffusion of MeOH into a CHCl3 solution of [5]CPP-GPF at 25 °C. Complexation of [4]CPP-GPF with C70. The association behavior between [4]CPP-GPF and C70 was analyzed by 1H NMR spectroscopy. We first prepared solutions of [4]CPP-GPF (4.0 × 10–5 M in toluene-d8) and C70 (4.6 × 10–5 M in toluene-d8). Aliquots of each solution were then mixed by varying their ratio so that the total concentration became 4.3 × 10–5 M, and the mixed solutions were 19 ACS Paragon Plus Environment


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subjected to the NMR analysis at 25 °C. The chemical-shift of the five proton resonances moved upfield as the mole fraction of C70 increased (Figure 6a). The most prominent change was observed in the resonance labeled c, and thus it was used for the analysis. The chemical shift changes relative to free [4]CPP-GPF (Dd) were used for the Job plot analysis, revealing the 1:1 complexation (Figure 6b). The Dd values were also plotted against the molar fraction of C70 to obtain a binding isotherm (Figure 6c). The binding isotherm was subjected to curve fitting analyses with the following equation35 2 ⎧ ⎫ ⎛ ⎞ δΔHG ⎪ [C 70 ] 1 [C 70 ] 1 [C 70 ] ⎪ Δδ = + − ⎜1+ + ⎨1+ ⎬ ⎟ −4 [Host] Ka[Host] ⎠ [Host] ⎪ 2 ⎪ [Host] Ka[Host] ⎝ ⎩ ⎭

to elucidate two variables, Ka and dΔHG, where Ka is the association constant and dΔHG is the change of the chemical shift between free [4]CPP-GPF and the complex. A single crystal of the complex suitable for X-ray crystallographic analysis was obtained by slow evaporation of a solution of 1:2 mixture of [4]CPP-GPF and C70 in chlorobenzene/2-propnaol at 25 °C. We also got a single crystal from a 1:1 mixture of [4]CPP-GPF and C70 in o-dichlorobenzene/2-propnaol at 25 °C. Both of the crystals shared a similar structure with the 1:3 stoichiometry of [4]CPP-GPF and C70 according to single-crystal X-ray diffraction analyses. Crystallographic Analysis. Single-crystal X-ray diffraction analyses were carried out with synchrotron X-ray source at the beamline BL38B1 in the SPring-8 with a Rayonix CCD MX225HE detector or at the beamline BL2S1 in the Aichi Synchrotron Radiation Research Center with an ADSC CCD Q315r detector. The collected diffraction data were processed with the XDS software program.36 The structure was solved by the direct method with SHELXT program37 and refined by full-matrix least-squares on F2 using the SHELXL program suite38 running on the Yadokari-XG 2009 software program. 39 In the refinements, electron densities attributed to the severely disordered solvent 20 ACS Paragon Plus Environment

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molecules are not modeled and subjected to the PLATON/SQUEEZE protocol.40,41 The non-hydrogen atoms were analyzed anisotropically, and hydrogen atoms were input at the calculated positions and refined with a riding model.

Acknowledgement. This study is partly supported by JST ERATO (JPMJER1301) and KAKENHI (17H01033, 17K05773, 17K05772, 16K04864, 25102007). We were granted access to the X-ray diffraction instruments in the SPring-8 BL38B1 beamline (no. 2016B1489, 2017A1439 and 2017B1263) and Aichi Synchrotron Radiation Research Center BL2S1 beamline (no. 2017N4005).

Supporting Information. Analytical data, X-ray crystallographic analysis. The Supporting Information is available free of charge via the Internet at http://pbs.acs.org.

References and notes 1 Segawa, Y.; Ito, H.; Itami, K. Structurally uniform and atomically precise carbon nanostructures. Nat. Rev. Mater. 2016, 1, 1-14. 2 (a) Ikemoto, K.; Kobayashi, R.; Sato, S.; Isobe, H. Synthesis and bowl-in-bowl assembly of a geodesic phenylene bowl. Angew. Chem., Int. Ed. 2017, 56, 6511-6514. (b) Ikemoto, K.; Kobayashi, R.; Sato, S.; Isobe, H. Entropy-driven ball-in-bowl assembly of fullerene and geodesic phenylene bowl. Org. Lett. 2017, 19, 2362-2365. 3 Ikemoto, K.; Lin, J.; Kobayashi, R.; Sato, S.; Isobe, H. Fluctuating carbonaceous networks with a persistent molecular shape: a saddle-shaped geodesic framework of 1,3,5-trisubstituted benzene (phenine). Angew. Chem., Int. Ed. 2018, 57, 8555-8559. 4 Sun, Z.; Ikemoto, K.; Fukunaga, T. M.; Koretsune, T.; Arita, R.; Sato, S.; Isobe, H. Finite phenine nanotubes with periodic vacancy defects. Science 2019, 363, 151-155. 5 Scott, L. T.; Bronstein, H. E.; Preda, D. V.; Ansems, R. B. M.; Bratcher, M. S.; Hagen, S. Geodesic polyarenes with exposed concave surfaces. Pure Appl. Chem. 1999, 71, 209-219. 6 Yamago, S.; Watanabe, Y.; Iwamoto, T. Synthesis of [8]cycloparaphenylene from a square-shaped 21 ACS Paragon Plus Environment


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tetranuclear platinum complex. Angew Chem., Int. Ed. 2010, 49, 757-759. 7 Hitosugi, S.; Nakanishi, W.; Yamasaki, T.; Isobe, H. Bottom-up synthesis of finite models of helical (n, m)-single-wall carbon nanotubes. Nat. Commun. 2011, 2, 492. 8 Darzi, E. R.; Jasti, R. The dynamic, size-dependent properties of [5]–[12] cycloparaphenylenes. Chem. Soc. Rev. 2015, 44, 6401-6410. 9 Yamago, S.; Kayahara, E.; Iwamoto, T. Organoplatinum-mediated synthesis of cyclic π-conjugated molecules: towards a new era of three-dimensional aromatic compounds. Chem. Rec. 2014, 14, 84-100. 10 Lewis, S. E. Cycloparaphenylenes and related nanohoops. Chem. Soc. Rev. 2015, 44, 2221-2304. 11 Sun, Z.; Matsuno. T.; Isobe, H. H. Stereoisomerism and structures of rigid cylindrical cycloarylenes. Bull. Chem. Soc. Jpn. 2018, 91, 907-921. 12 The hoop size of [n]CPP-GPF is identical to that of [3n]CPP. 13 Miyaura, N.; Suzuki, A. Palladium-catalyzed cross-coupling reactions of organoboron compounds. Chem. Rev. 1995, 95, 2457-2483. 14 Yoshii, A.; Ikemoto, K.; Izumi, T.; Kita, H.; Taka, H.; Sato, S.; Isobe, H. Communication-structural modulation of macrocyclic materials for charge carrier transport layers in organic light-emitting devices. ECS J. Solid State Sci. Technol. 2017, 6, M3065-M3067. 15 Ishiyama, T.; Takagi, J.; Ishida, K.; Miyaura, N.; Anastasi, N. R.; Hartwig, J. F. Mild iridium-catalyzed borylation of arenes. High turnover numbers, room temperature reactions, and isolation of a potential intermediate. J. Am. Chem. Soc. 2002, 124, 390-391. 16 Hitosugi, S.; Sato, S.; Matsuno, T.; Koretsune, T.; Arita, R.; Isobe, H. Pentagon-embedded cycloarylenes with cylindrical shapes. Angew. Chem., Int. Ed. 2017, 56, 9106-9110. 17 (a) Evans, P. J.; Darzi, E. R.; Jasti, R. Efficient room-temperature synthesis of a highly strained carbon nanohoop fragment of buckminsterfullerene. Nat. Chem. 2014, 6, 404-408. (b) Kayahara, E.; Patel, V. K.; Yamago, S. Synthesis and characterization of [5]cycloparaphenylene. J. Am. Chem. Soc. 2014, 136, 2284-2287. 18 (a) Jasti, R.; Bhattacharjee, J.; Neaton, J. B.; Bertozzi, C. R. Synthesis, characterization, and theory of [9]-, [12]-, and [18]cycloparaphenylene: carbon nanohoop structures. J. Am. Chem. Soc. 2008, 130, 17646-17647. (b) Iwamoto, T.; Watanabe, Y.; Sakamoto, Y.; Suzuki, T.; Yamago, S. Selective and random syntheses of [n]cycloparaphenylenes (n = 8-13) and size dependence of their electronic properties. J. Am. Chem. Soc. 2011, 133, 8354-8361. (c) Segawa, Y.; Fukazawa, A.; Matsuura, S.; Omachi, H.; Yamaguchi, S.; Irle, S.; Itami, K. Combined experimental and theoretical studies on the 22 ACS Paragon Plus Environment

Page 23 of 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


photophysical properties of cycloparaphenylenes. Org. Biomol. Chem. 2012, 10, 5979-5984. 19 Sun, Z.; Miyamoto, N.; Sato, S.; Tokuyama, H.; Isobe, H. An obtuse-angled corner unit for fluctuating carbon nanohoops. Chem. Asian J. 2017, 12, 271-275. 20 (a) Camacho, C.; Niehaus, T. A.; Itami, K.; Irle, S. Origin of the size-dependent fluorescence blueshift in [n]cycloparaphenylenes. Chem. Sci. 2013, 4, 187-195. (b) Fujitsuka, M.; Cho, D. W.; Iwamoto, T.; Yamago, S.; Majima, T. Size-dependent fluorescence properties of [n]cycloparaphenylenes (n = 8-13), hoop-shaped π-conjugated molecules. Phys. Chem. Chem. Phys. 2012, 14, 14585-14588. (c) Noguchi, Y.; Sugino, O. Molecular size insensitivity of optical gap of [n]cycloparaphenylenes (n = 3-16). J. Chem. Phys. 2017, 146, 144304. 21 Matsuno, T.; Naito, H.; Hitosugi, S.; Sato, S.; Kotani, M.; Isobe, H. Geometric measures of finite carbon nanotube molecules: A proposal for length index and filling indexes. Pure Appl. Chem. 2014, 86, 489-495. 22 This downfield-shift tendency was similar to those observed with [n]CPP with n = 8-12. See ref. 8 and 18. 23 Halgren, T. A. Merck molecular force field. I. Basis, form, scope, parameterization, and performance of MMFF94. J. Comput. Chem. 1996, 17, 490-519. 24 Kolossváry, I.; Guida, W. C. Low mode search. An efficient, automated computational method for conformational analysis: Application to cyclic and acyclic alkanes and cyclic peptides. J. Am. Chem. Soc. 1996, 118, 5011-5019. 25 Considering the rigid cylindrical structure of [3]CPP-GPF, we may apply vector descriptions of (9,9)-carbon nanotube to this molecule: length index (tf) = 4.0, bond-filling index (Fb) = 57% and atom-filling index (Fa) = 67% (ref. 21). 26 Povie, G.; Segawa, Y.; Nishihara, T.; Miyauchi, Y.; Itami, K. Synthesis of a carbon nanobelt. Science 2017, 356, 172-175. 27 Sun, Z.; Suenaga, T.; Sarkar, P.; Sato, S.; Kotani, M.; Isobe, H. Stereoisomerism, crystal structures, and dynamics of belt-shaped cyclonaphthylenes. Proc. Natl. Acad. Sci. U.S.A. 2016, 113, 8109-8114. 28 Turner, M. J.; McKinnon, J. J.; Jayatilaka, D.; Spackman, M. A. Visualisation and characterisation of voids in crystalline materials. CrystEngComm 2011, 13, 1804-1813. 29 Saito, R.; Dresselhaus, G.; Dresselhaus, M. S. Physical Properties of Carbon Nanotubes; Imperial College Press: London, 1998. 30 The diameters of [3]-, [4]- and [5]CPP-GPF are identical to those of [9]-, [12]- and [15]CPP. 31 (a) Iwamoto, T.; Watanabe, Y.; Sadahiro, T.; Haino, T.; Yamago, S. Size-selective encapsulation of 23 ACS Paragon Plus Environment


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C60 by [10]cycloparaphenylene: formation of the shortest fullerene-peapod. Angew. Chem., Int. Ed. 2011, 50, 8342-8344. (b) Iwamoto, T.; Watanabe, Y.; Takaya, H.; Haino, T.; Yasuda, N.; Yamago, S. Size-and orientation-selective encapsulation of C70 by cycloparaphenylenes. Chem. Eur. J. 2013, 19, 14061-14068. (c) Nakanishi, Y.; Omachi, H.; Matsuura, S.; Miyata, Y.; Kitaura, R.; Segawa, Y.; Itami, K.; Shinohara, H. Size-selective complexation and extraction of endohedral metallofullerenes with cycloparaphenylene. Angew. Chem., Int. Ed. 2014, 53, 3102-3106. 32 Matsuno, T.; Sato, S.; Isobe, H. Curved p-Receptors. In Comprehensive Supramolecular Chemistry II; Atwood, J. L., Ed.; Elsevier: Oxford, 2017, pp 311-328. 33 Matsuno, T.; Fujita, M.; Fukunaga, K.; Sato, S.; Isobe, H. Concyclic CH-π arrays for single-axis rotations of a bowl in a tube. Nat. Commun. 2018, 9, 3779. 34 Han, F. S.; Higuchi, M.; Kurth, D. G. Diverse synthesis of novel bisterpyridines via Suzuki-type cross-coupling. Org. Lett. 2007, 9, 559-562. 35 Thordarson, P. Determining association constants from titration experiments in supramolecular chemistry. Chem. Soc. Rev. 2011, 40, 1305-1323. 36 Kabsch, W. Automatic processing of rotation diffraction data from crystals of initially unknown symmetry and cell constatns. J. Appl. Cryst. 1993, 26, 795-800. 37 Sheldrick, G. M. SHELXT-Integrated space-group and cyrstal-structure determination. Acta Crystallogr. A 2015, 71, 3-8. 38 Sheldrick, G. M. A short history of SHELX. Acta Crystallogr. A 2008, 64, 112-122. 39 Kabuto, C.; Akine, S.; Nemoto, T.; Kwon, E. Release of software (Yadokari-XG 2009) for crystal structure anslyses. J. Cryst. Soc. Jpn. 2009, 51, 218-224. 40 Spek, A. L. Single-crystal structure validation with the program PLATON. J. Appl. Cryst. 2003, 36, 7-13. 41 van der Sluis, P.; Spek, A. L. BYPASS: an effective method for the refinement of crystal structures containing disordered solvent regions. Acta Crystallogr A 1990, 46, 194-201.


Synthesis, Structures, and Assembly of Geodesic Phenine

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