STUDIES ON AROMATIC TRICHROMOPHORE SYSTEMS INCORPORATING ANTHRACENE MOIETIES .3. CRYSTAL-STRUCTURES OF 2-(9-ANTHRYL)-1-(9-ANTHRYLMETHYL)ETHYL 2-(9-ANTHRYL)ETHYL SUCCINATE (A(2)A) AND 2-(9-ANTHRYL)ETHYL ACETATE(AM) AND THEIR FLUORESCENCE IN THE SOLID-STATE

The structures of 2-(9-anthryl)-1-(9-anthrylmethyl)ethyl 2-(9-anthryl) ethyl succinate (A(2)A) and 2-(9-anthryl)ethyl acetate (AM) have been determined by X-ray diffraction, and the molecular fluorescence of the crystals has been established. The A(2)A crystal is triclinic while t he AM crystal is monoclinic. AZA: P1, a 18.514(5), b 11.802(3), c 10.8 36(3) Angstrom; alpha 99.63(2), beta 85.75(2), gamma 79.67(2)degrees, R 0.053 for 3547 observed reflections. AM: P 2(1)/c, a 12.568(2), b 12 .991(2), c 8.805(2) Angstrom, beta 97.84(1)degrees, R 0.040 for 1519 o bserved reflections. For the A(2)A molecule as for the previously stud ied A(2)PHEN and A(2)SC (see Part II), the bisanthracene moiety and a large part of the ester chain show similar conformations. The crystal cohesion is due to numerous van der Waals interactions in both compoun ds and to pi intermolecular overlap between the anthracene moieties of neighbouring molecules of AM. The fluorescence emission of the AM cry stal is of excimer type and correlates with the intermolecular stackin g of the anthracene rings. In contrast, the emission from the A(2)A cr ystal was found to be very weak and with some similarity with the emis sion of the dilute solution. This is probably due to defects, not acco unted for by the X-ray determination, permitting intramolecular intera ctions in the solid.