Molecular Structure of Chlorocycloheptane in Inclusion Compound with 9,9′-Bianthryl and Gelation during Crystallization

Abstract

9,9¤-Bianthryl formed an inclusion compound with chlorocycloheptane in a 2:1 ratio. X-ray analysis revealed that two guest molecules were accommodated in a cavity surrounded by eight host molecules. The guest molecules were conformationally fixed in each cavity into either of two twist-chair forms that differed in the position of the chloro group. These conformations were compared with the calculated ones for chlorocycloheptane itself by DFT calculation. When the inclusion compound was prepared from a concentrated solution of 9,9¤-bianthryl in chlorocycloheptane, the gelation was followed by crystallization. This phenomenon is unusual for relatively small molecules lacking strong intermolecular interactions.9,9¤-Bianthryl (1) and related compounds are found to form inclusion compounds with a wide range of small organic molecules. 1Í5 In each molecule, the two anthracene planes are nearly perpendicular (dihedral angle 80.5°) 6 and the rotation about the C9ÍC9¤ bond is considerably restricted.7 These structural features facilitate the formation of cavities for guest molecules upon assembly. X-ray structures of inclusion compounds of 9,9¤-bianthryl so far reported reveal that guest molecules are occasionally accommodated in cavities in a less stable conformation to fit the cavity size and shape.3Í5 For example, chlorocyclohexane (2) form an inclusion compound with 1 in the axial conformation (Scheme 1), 4 which is less stable than the equatorial conformation, 8 while this guest molecule is included by another host derived from tartaric acid in the equatorial conformation.9 Conformational analysis of cycloheptane derivatives is more complicated than that of cyclohexane derivatives because of facile interconversions around several possible conformers.10 Even in the inclusion compound with tris(5-acetyl-3-thienyl)methane, cycloheptane molecules are significantly disordered even at 220 K.11 Therefore, we employed this unique hydrocarbon host to elucidate the conformation of cycloheptanes in crystal cavities, and used chlorocycloheptane (3) as a typical monosubstituted cycloheptane for this purpose. We herein report the X-ray structure of the inclusion compound focusing on the mode of inclusion and the conformation of seven-membered ring moieties. We also found an interesting phenomenon, gelation of a solution of 9,9¤-bianthryl in chlorocycloheptane, during the preparation of

Photoluminescence, Redox Properties, and Electrogenerated Chemiluminescence of Twisted 9,9′-Bianthryls

“…As 9,9′-bianthryls lack the ability to undergo π–π stacking, they show good solubility both in nonpolar and polar solvents of different dielectric constants (ϵ). As such, BAHO , BABR , BAET , and BATA (Chart ) exhibit decent solubility (7 × 10 –4 M) even in highly polar acetonitrile (polarity index P ′ = 6.2 and ϵ = 37.5), allowing us to explore measurements in more than one solvent.…”

“…This interpretation is in line with previously determined dihedral angles of the two anthracenyl planes of 9,9′-bianthryl and its 10,10′-functionalized derivatives in solution (ca. 80.5–88.7°) as well as in the solid state (ca. 81.5–85.9°).…”

“…9,9′-Bianthryl and its derivatives , (here called “bianthryls”) are bulky and conformationally restricted structures that are easily accessible by zinc-mediated reductive coupling of the corresponding 9-anthrones. Because of the intramolecular H–H repulsion between hydrogen atoms at the 1,1′- and 8,8′-positions, the two anthracene chromophores are oriented perpendicular to each other with dihedral angles of 82°–86° depending on the substituents .…”

“…9,9′-Bianthryl and its derivatives , (here called “bianthryls”) are bulky and conformationally restricted structures that are easily accessible by zinc-mediated reductive coupling of the corresponding 9-anthrones. Because of the intramolecular H–H repulsion between hydrogen atoms at the 1,1′- and 8,8′-positions, the two anthracene chromophores are oriented perpendicular to each other with dihedral angles of 82°–86° depending on the substituents . As a consequence, the HOMO–LUMO energy gaps and photophysics of bianthryls roughly resemble those of arylanthracenes. ,, Nevertheless, their photochemical and electrochemical properties are quite useful because bianthryls undergo neither photochemical oxidation nor electrochemical decomposition, quite in contrast to the situation in arylanthracenes .…”

“…As a consequence, the HOMO–LUMO energy gaps and photophysics of bianthryls roughly resemble those of arylanthracenes. ,, Nevertheless, their photochemical and electrochemical properties are quite useful because bianthryls undergo neither photochemical oxidation nor electrochemical decomposition, quite in contrast to the situation in arylanthracenes . Accordingly, bianthryls have been extensively utilized in non-photodegradable electroconducting films, photovoltaic cells, electrochromic materials, and so on. , …”