Article Cite This: Inorg. Chem. XXXX, XXX, XXX−XXX
pubs.acs.org/IC
Columnar Liquid-Crystalline Macrocycles Synthesized via Metal IonAssisted Self-Assembly Shin-ichiro Kawano, Takafumi Murai, Takahiro Harada, and Kentaro Tanaka* Department of Chemistry, Graduate School of Science, Nagoya University, Furocho, Chikusa-ku, Nagoya, 464-8602 Japan S Supporting Information *
ABSTRACT: Columnar assemblies of liquid-crystalline (LC) macrocycles hold promise for the construction of nanochannels in fluid materials. Metal-assisted self-assembly is an efficient way to prepare LC macrocycles. A large π-conjugated ligand, 9,10-diphenylanthracene (DPA) bearing two β-diketones, was prepared as a building unit for the macrocycle, and a series of side chains were incorporated into the DPA to yield LC materials. The bis(β-diketone) ligands on DPA allow for the efficient formation of triangular 3:3 metallomacrocycles in the presence of square-planar Cu2+ ions. The copper-containing 3:3 metallomacrocycle with the appropriate side chains exhibited thermotropic columnar LC phases in which the columns were arranged in rectangular arrays over a wide temperature range, and well-ordered birefringent textures were observed under a polarized microscope.
■
INTRODUCTION Well-defined nanospaces in solid materials such as metal− organic frameworks (MOFs) have been attracting much attention because of their ability to allow for the formation of a unique molecular array, as well as transportation and specific reaction of entrapped molecules.1,2 In contrast, the construction of such a nanospace in fluid materials is still not well developed, although such a system holds promise not only for advances in new interdisciplinary fields but also for several attractive applications.3 In particular, thermotropic liquid crystals composed of robust macrocyclic compounds are among the most promising candidates for fluid mediacontaining nanochannels.4−6 The features of a confined nanospace in fluid materials should be significantly dependent on the size, geometry, and chemical properties of the macrocycles. However, the synthesis of such macrocycles through covalent chemistry is one of the primary obstacles because it often requires a specific set of conditions, such as highly diluted solutions or a tedious multistep synthesis.7−10 Our group has devoted itself to exploring thermotropic columnar LCs composed of macrocycles with a large cavity via efficient imine formation.11−13 In this context, it has been recognized that metal-mediated self-assembly can facilitate the synthesis of macrocyclic architectures in solution.14,15 The key to the efficient cyclization is the precise angular design of the coordination bonds and the coordination geometry of the metal centers. Recently, we reported shape-persistent metallomacrocycles consisting of naphthalenedihydroxamate and Cu2+ ions that exhibit thermotropic LC properties.16 The macrocycle formed efficiently via complexation among hydroxamate groups and Cu2+ ions. © XXXX American Chemical Society
However, the resultant LC phase showed a less-ordered lamellar phase with relatively weak birefringence. Herein, we present our synthesis strategy for obtaining columnar LC metallomacrocycles through metal coordination. As the metallomacrocycle has a diphenylanthracene moiety as its large π-panel in the macrocyclic framework,17,18 efficient phase segregation of the macrocyclic moiety against aliphatic side chains can be anticipated (Figure 1). As a rare example, the resulting metallomacrocycles exhibited columnar liquid-crystalline (LC) phases with a well-ordered self-assembled structure.
■
RESULTS AND DISCUSSION Synthesis of Discrete Metallomacrocycles Composed of Transition Metals. Basically, thermotropic LC molecules require an appropriate density of side chains attached to the rigid mesogenic core, and the substantial phase segregation between the side chain and the mesogen often leads to a highly ordered structure in LC phases.4−6 β-Diketones have been well known to be versatile ligands for various metal ions, such as copper(II), cobalt(II), nickel(II), zinc(II), iron(III), and palladium(II), for building a variety of discrete supramolecular metallocomplexes.19−23 To facilitate efficient segregation against the aliphatic side chain, the 9,10-DPA moiety was chosen as the large π-building block. Thus, a series of 9,10-DPA compounds containing two β-diketones were synthesized in a moderate yield of approximately 76% via mild enolate formation in the presence of MgBr2·Et2O (Figure 1). This synthesis strategy can be adapted to the introduction of a Received: January 9, 2018
A
DOI: 10.1021/acs.inorgchem.8b00046 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry
Figure 1. Schematic illustration of columnar LC metallomacrocycles formed through metal coordination with β-diketone ligands containing DPA as a large π-building block.
9 and 10 positions are in the range of 74.4−76.2°.24 On the other hand, the two β-diketone moieties adopt the anti conformation with respect to the anthracene center. Interestingly, each diphenyl β-diketone moiety at the 9 and 10 positions of the anthracene exists in a planar conformation, which may lead to efficient cyclization (Figure 2b). The anthracenyl group would be oriented perpendicular to the expected macrocycle and may hinder direct stacking of the macrocycles; however, π−π interactions of the anthracenyl groups between the macrocycles are expected to lead to a columnar array of macrocycles. Cu2+ ions are compatible with O,O-ligands and form a stable metal complex with square-planar geometry through metalassisted self-assembly.16,25 Lindoy reported the efficient formation of macrocyclic compounds composed of bis-βdiketone moieties and Cu2+ ions.20,21 Therefore, we designed an LC macrocycle by the combination of our bis-β-diketone ligands L2, L3, L4, and L5, and Cu2+ ions, which were estimated to be discrete 3:3 metallomacrocycles (Scheme 1). Such thermodynamically stable, intramolecular cyclization is favored over intermolecular polymerization, which would require an entropic loss.26 The cyclization of a 1:1 mixture of copper acetate and L4 having tris(ethylene glycol)decyl groups was carried out by heating the solution for 27 h followed by purification by recycling gel-permeation chromatography (GPC), and the 3:3 metallomacrocycle was obtained in 46% yield, which showed a single chromatographic peak in the GPC chart with a shorter retention time than that of precursor ligand L4 (Figure 3a). Electrospray ionization−time-of-flight mass spectroscopy (ESI−TOF MS) also supported the formation of
variety of branched side chains to adjust the phase and structural behavior of the LC assembly.11−13,16 L1 with shorter alkyl chains was suitable for X-ray crystallography analysis to acquire structural information. As shown in Figure 2a, the anthracene moiety in L1 exists in a pseudoperpendicular arrangement with respect to the 9,10-arene groups. The angles between the π-plane of anthracene and the benzene rings at the
Figure 2. (a) Crystal structure of L1. (b) Side view of L1. The anthracene moiety orients almost perpendicular to the benzene rings introduced at the 9- and 10-positions. ORTEP diagram with the thermal ellipsoids at a 50% probability level. All of the hydrogen atoms and substituents are omitted for clarity. B
DOI: 10.1021/acs.inorgchem.8b00046 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry Scheme 1. Synthesis of Liquid-Crystalline Metallomacrocycles
after the reaction was completed in 114 h. The time course demonstrated a typical self-assembly process, including the generation and extinction of the intermediates. The MALDI− TOF MS profile indicated that the symmetrical cyclic product is the 3:3 macrocyclic Pd3L43 (Figure S15). However, the resulting metal complex was not stable during purification by column chromatography due to the low affinity between the Pd2+ ion and the β-diketonate ligand.27 Hence, we proposed that copper complexes are more suitable for LC materials. Recently, we demonstrated a strategy to obtain a kinetically “locked” macrocyclic metal complex by a combination of selfassembly processes based on metal complexation and the subsequent deactivation of the labile bonds.28,29 This approach was applied to the 3:3 macrocycle with ligand L1, which was mixed with Co2+ ions in the presence of pyridine and 1,8diazabicyclo[5.4.0]undec-7-ene (DBU). Subsequent oxidation of Co2+ to Co3+ was achieved by the addition of chloranil for the inertization of the coordination bonds, and the exchange of the counteranion afforded the kinetically “locked” [Co(III)3L13(py)6]·3PF6 in 27% yield (Scheme 2). As shown in the ESI−TOF MS in Figure 5a, the molecular ion peaks of [Co(III)3L13(py)6]·3PF6 were observed at m/z 1282.1 (z = 3) and 967.3 (z = 4), supporting the formation of the 3:3 macrocycle. The 1H NMR of [Co(III)3L13(py)6]·3PF6 in CDCl3 exhibited a highly symmetrical resonance, indicating that the macrocycle has diamagnetic character owing to the low-spin octahedral Co(III) centers with C4 symmetry in the solution (Figure 5b). This trinuclear Co(III) complex may not be adopted for the formation of the columnar LC material at this stage because of the cationic charges on the macrocycle and the steric protrusion of the axial pyridine ligands. Nonetheless, these results showed the versatility of the bis-bidentate ligand for 3:3 macrocyclic formation even when using transition-metal ions with octahedral coordination geometry. Liquid-Crystalline Properties of the Metallomacrocycles. The thermotropic LC properties of the copper(II)macrocycles, Cu3L23, Cu3L33, Cu3L43, and Cu3L53, were evaluated by differential scanning calorimetry (DSC), polarized optical microscopy (POM), and grazing incidence X-ray diffraction (GIXRD) experiments. The phase and structural behaviors of the macrocycles were significantly dependent on the side chains.6−8,10 Cu3L43 had a clearing point of 246 °C, at which it converted into an isotropic liquid, and it showed LC phases below this temperature. In particular, POM observations revealed a well-developed fan-shaped texture with bright
Figure 3. (a) GPC profiles of Cu3L43 after purification and L4. (b) ESI−TOF MS profile of Cu3L43 (positive).
target Cu3L43 based on the signal with m/z 1834 for [M + 4Na+]4+ (Figure 3b). These results clearly showed that the 3:3 metallomacrocycle was preferentially synthesized, as designed, via metal-assisted self-assembly. The self-assembly process was similar when other ligands with different side chains were used (Supporting Information). The size of the inner cavity in the resulting metallomacrocycle was estimated to be more than 5 × 8 Å (Figure S11). In order to investigate the self-assembly process of the cyclization, the reaction of L4 with 1.0 equiv of palladium acetate was monitored by 1H NMR in toluene-d8 at 100 °C. As shown in Figure 4, the 1H NMR of the reaction mixture indicated that several chemical species were present after 13 h of mixing, but the spectrum gradually converged to a simple one, which indicated a highly symmetrical macrocyclic product C
DOI: 10.1021/acs.inorgchem.8b00046 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry
Figure 4. Time dependence of partial 1H NMR spectra suggesting the formation of the metallomacrocycle mixed with L4 in the presence of 1.0 equiv of Pd(OAc)2 (400 MHz, toluene-d8, [L4] = 4.0 mM at 100 °C).
Scheme 2. Synthesis of the Kinetically “Locked” Metallomacrocycle via the Combination of Self-Assembly and Making the Metallomacrocycle Inert
birefringence, which was observed from 81 to 246 °C (Figure 6a,b). The fluid texture easily deformed to birefringent droplets by the physical tapping over a glass plate. The GIXRD profile of Cu3L43 revealed rectangular arrays of the columnar LC phase, with cell parameters of a = 52.6 Å and b = 49.4 Å at 176 °C (Figure 6c, Table S4). As mentioned above, the anthracenyl groups would be oriented perpendicular to the macrocycle and contribute to the formation of the columnar assembly of
Figure 5. (a) 1H NMR (400 MHz, CDCl3, TMS) and (b) ESI−TOF MS profiles of [Co(III)3L13(py)6]·3PF6.
macrocycles. Cu3L33 also formed columnar LC phases with rectangular packing (a = 42.0 Å and b = 35.3 Å) at D
DOI: 10.1021/acs.inorgchem.8b00046 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry
Figure 6. (a) POM image of the liquid-crystalline metallomacrocycle (Cu3L43) at 180 °C. (b) DSC profile of Cu3L43 including first, the cooling and second, the heating (scan rate: 10 °C/min). (c) Cross-section of the columnar packing of Cu3L43 in a rectangular columnar assembly, as expected from the GIXRD.
Figure 7. Phase diagram of the metallomacrocycles. Phase notation: Cr, crystal; Colr, rectangular columnar LC phase; Iso, isotropic liquid; and M, unidentified LC mesophase.
temperatures beyond 114 °C and did not have a clearing point below the decomposition temperature because of the shorter side chains (Figure 7). Cu3L23, possessing n-decyloxy groups, showed only a solid phase without fluid behavior. Cu3L53 with more dense side chains formed a fluid mesophase; however, the orientation was not resolved because of the poor diffraction information from the GIXRD measurements. Consequently, the side chains of Cu3L43 were suitable for the columnar liquid crystals of the macrocycle.
inclusion phenomena using this promising metallomacrocyclic structure by exploiting the large π-panels.
■
EXPERIMENTAL SECTION
Materials and Methods. Synthesis procedures were carried out under a dry nitrogen atmosphere, unless otherwise specified. All of the reagents and solvents were purchased at the highest commercial quality available (Wako, Kanto, TCI, and Aldrich) and used without any further purification, unless otherwise stated. 1H and 13C NMR spectra were recorded on JNM-ECS400 (400 MHz for 1H; 100 MHz for 13C) and JNM-ECA600 (600 MHz for 1H; 150 MHz for 13C) spectrometers at a constant temperature of 298 K. Tetramethylsilane (TMS) was used as an internal reference for 1H and 13C NMR measurements in CDCl3. ESI−TOF MS was performed with a Waters LCT-Premier XE spectrometer controlled by using Masslynx software. Matrix-assisted laser desorption ionization time-of-flight mass spectroscopy (MALDI−TOF MS) was performed with an ultraflex III, Bruker Daltonics, and α-CHCA or trans-2-[3-(4-t-butyl-phenyl)-2methyl-2-propenylidene]malononitrile (DCTB) was used as the matrix. Elemental analyses were performed on a Yanaco MT-6 analyzer. Silica gel column chromatographies and thin-layer (TLC) chromatography were performed using Merck silica gel 60 and Merck silica gel 60 (F254) TLC plates, respectively. GPC was performed using a JAI LC-9204 equipped with JAIGEL columns. Preparation of Cu3L23. A mixture of compound L2 (21 mg, 14 μmol) and Cu(OAc)2 (2.5 mg, 14 μmol) in dry toluene (6.8 mL) was heated to reflux for 22 h. The reaction mixture was allowed to cool to room temperature, filtered, and evaporated. The brownish-green solid was dissolved in CHCl3, filtered with cellulose powder (200−300 mesh), and purified by GPC (JAIGEL 3H-2.5H, CHCl3) to obtain
■
CONCLUSIONS We presented a columnar liquid crystal consisting of macrocycles with a nanometer-sized inner cavity prepared through metal-assisted self-assembly. A bis(β-diketone) ligand with anthracene was synthesized. The stability of the metal-assisted macrocycles consisting of the ligand depended on the metal ions. Cu2+ ions yielded the most stable and structurally robust macrocycle that would serve as a mesogen for the liquid crystal with the ligand. The anthracenyl groups in the ligands would be oriented perpendicular to the macrocycle and could be useful for the future investigation of host−guest chemistry using macrocyclic liquid crystals. The isolated metallomacrocycles having flexible side chains at the periphery of the macrocyclic mesogens exhibited thermotropic LC behavior dependent on the molecular structure of the side chains. The supramolecular strategy efficiently affords LC macrocycles without any elaborate steps. We are now investigating the host−guest E
DOI: 10.1021/acs.inorgchem.8b00046 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry target compound Cu3L23 as a brownish-green solid (16 mg, 3.3 μmol, 72%). MALDI−TOF MS (matrix: DCTB, RP-Mode): m/z = 4866.3 [M + H]+, 4866.5 calcd [M + H]+. Anal. calcd for C312H444O30Cu3: C, 77.02; H, 9.20%. Found: C, 76.98; H, 9.30%. Preparation of Cu3L33. A mixture of compound L3 (62 mg, 36 μmol) and Cu(OAc)2 (6.5 mg, 36 μmol) in toluene (18 mL) was stirred at 100 °C for 21 h. The reaction mixture was allowed to cool to room temperature and evaporated. The brownish-green solid was dissolved in CHCl3, filtered with cellulose powder (200−300 mesh), and purified by GPC (JAIGEL 3H-2.5H, CHCl3) to obtain target compound Cu3L33 as a brownish-green solid (35 mg, 6.5 μmol, 54%). ESI−TOF MS: m/z = 1836.6 [M + 3Na]3+, 1836.6 calcd [M + 3Na]3+. Anal. calcd for C312H444O66Cu3: C, 68.87; H, 8.22%. Found: C, 68.80; H, 8.34%. Preparation of Cu3L43. . A mixture of compound L4 (65 mg, 28 μmol) and Cu(OAc)2 (5.0 mg, 28 μmol) in toluene (14 mL) was stirred at 100 °C for 27 h. The reaction mixture was allowed to cool to room temperature and evaporated. The brown solid was dissolved in CHCl3, filtered with cellulose powder (200−300 mesh), and purified by GPC (JAIGEL 3H-2.5H, CHCl3) to obtain target compound Cu3L43 as a brownish-green solid (31 mg, 4.2 μmol, 46%). ESI−TOF MS: m/z = 1833.8 [M + 4Na]4+, 1833.9 calcd [M + 4Na]4+. Anal. calcd for C420H660O84Cu3: C, 69.63; H, 9.18%. Found: C, 69.53; H, 9.33%. Preparation of Cu3L53. A mixture of compound L5 (55 mg, 12 μmol) and Cu(OAc)2 (2.3 mg, 12 μmol) in dry toluene (6.1 mL) was stirred at 100 °C for 22 h. The reaction mixture was allowed to cool to room temperature and evaporated. The brown solid was dissolved in CHCl3, filtered with cellulose powder (200−300 mesh), and purified by GPC (JAIGEL 3H-2.5H, CHCl3) to obtain target compound Cu3L53 as a brownish-green solid (39 mg, 2.9 μmol, 70%). ESI−TOF MS: m/z = 2307.8 [M + 6Na]6+, 2307.9 calcd [M + 6Na]6+. Anal. calcd for C792H1308O168Cu3: C, 69.39; H, 9.62%. Found: C, 69.23; H, 9.76%. Structural Analysis and Thermal Measurements. DSC measurements were carried out under a N2 atmosphere with a TA Instruments Q2000 DSC equipped with an RCS 90 cooling accessory, and the transition temperatures were determined from the second heating run at a rate of 10 °C/min using Universal Analysis 2000 software. TGA analysis was performed under a N2 atmosphere with a TA Instruments TGAQ50 with the temperature raised from 30 to 600 °C at a rate of 10 °C/min. Polarized optical microscopy (POM) observations were performed with an OLYMPUS BX51 microscope with crossed polarizers and a Linkam LTS 350 heating stage under a N2 atmosphere and an Olympus DP20 camera. GIXRD analyses were measured using a Rigaku R-AXIS IV X-ray diffractometer (Cu Kα) equipped with a temperature-controlled heating stage and an imaging plate for collection of the diffracted patterns. GIXRD analysis of the sample placed on the glass plate was measured with the temperaturecontrolled heating stage heated at the various temperatures. The angle of incidence was set to ∼0.4°. The diffracted radiation was recorded by an imaging plate that has a sample-to-detector distance of 30 cm.
■
via www.ccdc.cam.ac.uk/data_request/cif, or by emailing data_
[email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
■
AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. ORCID
Kentaro Tanaka: 0000-0002-6395-4536 Notes
The authors declare no competing financial interest.
■
ACKNOWLEDGMENTS We thank Dr. Kinichi Oyama of the Chemical Instrumentation Faculty, Research Center for Materials Science, Nagoya University, for the elemental analysis. This work was supported by a JSPS KAKENHI grant-in-aid for scientific research (A) (no. 15H02167) to K.T. and a JSPS KAKENHI grant-in-aid for scientific research (C) (no. 15K05473) for S.-i.K.
■
REFERENCES
(1) Eddaoudi, M.; Moler, D. B.; Li, H.; Chen, B.; Reineke, T. M.; O’keeffe, M.; Yaghi, O. M. Modular chemistry: Secondary building units as a basis for the design of highly porous and robust metal− organic carboxylate frameworks. Acc. Chem. Res. 2001, 34, 319−330. (2) Kitagawa, S.; Kitaura, R.; Noro, S. Functional porous coordination polymers. Angew. Chem., Int. Ed. 2004, 43, 2334−2375. (3) Giri, N.; Pópolo, M. G. D.; Melaugh, G.; Greenaway, R. L.; Rätzke, K.; Koschine, T.; Pison, L.; Gomes, M. F. C.; Cooper, A. I.; James, S. L. Liquids with permanent porosity. Nature 2015, 527, 216− 220. (4) Handbook of Liquid Crystals: Non-conventional Liquid Crystals;Goodby, J. W., Collings, P. J., Kato, T., Tschierske, C., Gleeson, H. F., Raynes, P., Eds; Wiley-VCH Verlag GmbH & Co. KGaA, 2nd ed, 2014; Vol. 5. (5) Laschat, S.; Baro, A.; Steinke, N.; Giesselmann, F.; Hägele, C.; Scalia, G.; Judele, R.; Kapatsina, E.; Sauer, S.; Schreivogel, A.; Tosoni, M. Discotic liquid crystals: From tailor-made synthesis to plastic electronics. Angew. Chem., Int. Ed. 2007, 46, 4832−4887. (6) 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. (7) Zhang, J.; Pesak, D. J.; Ludwick, J. L.; Moore, J. S. Geometricallycontrolled and site-specifically-functionalized phenylacetylene macrocycles. J. Am. Chem. Soc. 1994, 116, 4227−4239. (8) Zhang, W.; Moore, J. S. Shape-persistent macrocycles: Structures and synthetic approaches from arylene and ethynylene building blocks. Angew. Chem., Int. Ed. 2006, 45, 4416−4439. (9) Finke, A. D.; Gross, D. E.; Moore, J. S. Engineering solid-state morphologies in carbazole−ethynylene macrocycles. J. Am. Chem. Soc. 2011, 133, 14063−14070. (10) Feng, W.; Yamato, K.; Yang, L.; Ferguson, J. S.; Zhong, L.; Zou, S.; Yuan, L.; Zeng, X. C.; Gong, B. Efficient Kinetic macrocyclization. J. Am. Chem. Soc. 2009, 131, 2629−2637. (11) Kawano, S.; Ishida, Y.; Tanaka, K. Columnar Liquid-Crystalline Metallomacrocycles. J. Am. Chem. Soc. 2015, 137, 2295−2302. (12) Kawano, S.; Hamazaki, T.; Suzuki, A.; Kurahashi, K.; Tanaka, K. Metal-ion-induced switch of liquid crystalline orientation of metallomacrocycles. Chem. - Eur. J. 2016, 22, 15674−15683. (13) Kawano, S.; Kato, M.; Soumiya, S.; Nakaya, M.; Onoe, J.; Tanaka, K. Columnar Liquid Crystals from a Giant Macrocycle Mesogen. Angew. Chem., Int. Ed. 2018, 57, 167−171. (14) Yoshizawa, M.; Klosterman, J.; Fujita, M. Functional Molecular Flasks: New Properties and Reactions within Discrete, Self-assembled Hosts. Angew. Chem., Int. Ed. 2009, 48, 3418−3438.
ASSOCIATED CONTENT
S Supporting Information *
The following files are available free of charge. X-ray data for L1 (CCDC 1585184) (CIF). The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.8b00046. Synthesis and characterization data of the metallomacrocycles, including X-ray crystallographic data of L1 and the LC properties of the metallomacrocycles characterized by TGA, DSC, POM observations, and GIXRD (PDF) Accession Codes
CCDC 1585184 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge F
DOI: 10.1021/acs.inorgchem.8b00046 Inorg. Chem. XXXX, XXX, XXX−XXX
Article
Inorganic Chemistry (15) Chakrabarty, R.; Mukherjee, P. S.; Stang, P. J. Supramolecular Coordination: Self-Assembly of Finite Two- and Three-Dimensional Ensembles. Chem. Rev. 2011, 111, 6810−6918. (16) Kawano, S.; Inada, H.; Tanaka, K. Self-assembled synthesis and liquid crystalline property of metallomacrocycle composed of naphthalenedihydroxamate and Cu2+ ion. Chem. Lett. 2016, 45, 1105−1107. (17) Kishi, N.; Li, Z.; Yoza, K.; Akita, M.; Yoshizawa, M. An M2L4 Molecular capsule with an anthracene shell: Encapsulation of large guests up to 1 nm. J. Am. Chem. Soc. 2011, 133, 11438−11441. (18) Kishi, N.; Akita, M.; Kamiya, M.; Hayashi, S.; Hsu, H.-F.; Yoshizawa, M. Facile catch and release of fullerenes using a photoresponsive molecular tube. J. Am. Chem. Soc. 2013, 135, 12976−12979. (19) Clegg, J. K.; Bray, D. J.; Gloe, K.; Gloe, K.; Hayter, M. J.; Jolliffe, K. A.; Lawrance, G. A.; Meehan, G. V.; McMurtrie, J. C.; Lindoy, L. F.; Wenzel, M. Neutral (bis-β-diketonato) iron(III), cobalt(II), nickel(II), copper(II) and zinc(II) metallocycles: structural, electrochemical and solvent extraction studies. Dalton Trans. 2007, 1719−1730. (20) Clegg, J. K.; Bray, D. J.; Gloe, K.; Gloe, K.; Jolliffe, K. A.; Lawrance, G. A.; Lindoy, L. F.; Meehan, G. V.; Wenzel, M. Synthetic, structural, electrochemical and solvent extraction studies of neutral trinuclear Co(II), Ni(II), Cu(II) and Zn(II) metallocycles and tetrahedral tetranuclear Fe(III) species incorporating 1,4-aryl-linked bis-β-diketonato ligands. Dalton Trans. 2008, 1331−1340. (21) Clegg, J. K.; Lindoy, L. F.; Moubaraki, B.; Murray, K. S.; McMurtrie, J. C. Triangles and tetrahedra: metal directed self-assembly of metallo-supramolecular structures incorporating bis-β-diketonato ligands. Dalton Trans. 2004, 2417−2423. (22) Clegg, J. K.; Gloe, K.; Hayter, M. J.; Kataeve, O.; Lindoy, L. F.; Moubaraki, B.; McMurtrie, J. C.; Murray, K. S.; Schilter, D. New discrete and polymeric supramolecular architectures derived from dinuclear (bis-β-diketonato)copper(II) metallocycles. Dalton Trans. 2006, 3977−3984. (23) Li, F.; Clegg, J. K.; Jensen, P.; Fisher, K.; Lindoy, L. F.; Meehan, G. V.; Moubaraki, B.; Murray, K. S. Predesigned hexanuclear CuII and CuII/NiIImetallacycles featuring six-node metallacoronand structural motifs. Angew. Chem., Int. Ed. 2009, 48, 7059−7063. (24) Adams, J. M.; Ramdas, S. The crystal structure of solutiongrown 9,10-diphenylanthracene. A combined computational and X-ray study. Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. 1979, 35, 679−683. (25) Hori, A.; Shinohe, A.; Yamasaki, M.; Nishibori, E.; Aoyagi, S.; Sakata, M. 1:1 Cross-assembly of two β-diketonate complexes through arene−perfluoroarene interactions. Angew. Chem., Int. Ed. 2007, 46, 7617−7620. (26) Montoro-García, C.; Mayorai, M. J.; Chamorro, R.; GonzálezRodoríguez, D. How large can we build a cyclic assembly? Impact of ring size on chelate cooperativity in noncovalent macrocyclizations. Angew. Chem., Int. Ed. 2017, 56, 15649−15653. (27) Albéniz, A. C.; Espinet, P. Encyclopedia of Inorganic Chemistry; Wiley & Sons, Ltd., 2006. (28) Nishino, T.; Yamada, Y.; Akine, S.; Sugimoto, K.; Tanaka, K. Kinetically “locked” metallomacrocycle. Dalton Trans. 2016, 45, 3831− 3837. (29) Symmers, P. R.; Burke, M. J.; August, D. P.; Thomson, P. I. T.; Nichol, G. S.; Warren, M. R.; Campbell, C. J.; Lusby, P. J. Nonequilibrium cobalt(III) “click” capsules. Chem. Sci. 2015, 6, 756−760.
G
DOI: 10.1021/acs.inorgchem.8b00046 Inorg. Chem. XXXX, XXX, XXX−XXX
