Studies on Aromatic Trichromophore Systems Incorporating Anthracene Moieties. II. Crystal Structures of 2-(9-Anthryl)-1-(9-anthrylmethyl)ethyl 2-(9-Phenanthryl)-ethyl Succinate (A₂PHEN) and 2-(9-Anthryl)-1-(9-anthrylmethyl)ethyl Methyl Succinate (A₂SC) and Their Fluorescence in the Solid State

Abstract

The structures of 2-(9-anthryl)-1-(9-anthrylmethyl)ethyl 2-(9-phenanthryl)ethyl succinate (A₂PHEN) and 2-(9-anthryl)-1-(9-anthrylmethyl)ethyl methyl succinate (A₂SC) have been determined by X-ray diffraction, and the molecular fluorescence of the crystals has been established. The two crystals are monoclinic. A₂PHEN: C 2/c, a 39.47(1), b 9.718(2), c 19.924(8) Ǻ; β 97.81(3)°; R 0.036 for 2903 unique reflections. A₂SC: P 2₁/c, a 16.248(2), b 10.325(2), c 18.052(2) Ǻ. β 114.20(3)°; R 0.044 for 2586 unique reflections. For both structures, the bisanthracene moiety and a large part of the ester chain show similar conformations. The crystal cohesion is due to intermolecular π overlapping between one of the anthracene components of the bichromophore moiety and to numerous van der Waals interactions. No intramolecular interactions between the phenanthrene and the anthracene moieties are observed in A₂PHEN. The fluorescence emissions of A₂PHEN and A₂SC are of excimer type, and correlate well with the intermolecular interactions between the anthracene rings.