Phenylenethynylene derivatives of [2.2]paracyclophane: A relationship between crystal structure and fluorescent properties in a solid state

• Published in: Journal of molecular structure Vol. 1321; p. 140074
• Main Authors: Shapovalov, Alexey V., Antonov, Dmitry Yu, Krasnova, Irina Yu, Dolgushin, Fedor M., Vologzhanina, Anna V., Chamkin, Aleksandr A., Shifrina, Zinaida B.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.02.2025
• Subjects: 1,4-Bis(phenylethynyl)benzene; [2.2]Paracyclophane; Crystal structure; Hirshfeld surface analysis; Luminescence; Polymorph; UV–vis absorption; π–π interactions; π–π interactions; Hirshfeld surface analysis; Luminescence; Polymorph; [2.2]Paracyclophane; 1,4-Bis(phenylethynyl)benzene; UV–vis absorption; Crystal structure
• ISSN: 0022-2860
• DOI: 10.1016/j.molstruc.2024.140074

•Two isomeric [2.2]paracyclophane based compounds containing 1,4-bis(phenylethynyl)benzene moieties were synthesized.•The correlations between fluorescence maxima shifts for compounds in solutions and in solid and the type of intermolecular interactions were established.•The π–π contacts of the proximal paracyclophane groups of neighboring molecules in [2.2]paracyclophane derivatives mainly effect on fluorescent performance than stacking interaction of their bis(phenylethynyl)benzene constituent.•The fluorescence band positions of bis(phenylethynyl)benzene in the solid state depend on the type of polymorphic forms that have been discovered for this compound unlike for [2.2]paracyclophane derivatives for which the only polymorphic form has been observed. Isomeric di- and tetrasubstituted derivatives of [2.2]paracyclophane containing 1,4-bis(phenylethynyl)benzene as a main component were synthesized. It was found that when shifting from 1,4-bis(phenylethynyl)benzene, 1, to pseudo-para-disubstituted 4,16-di-{phenylethynyl(1,4-phenylene)ethynyl}[2.2]paracyclophane, 2, and then to tetrasubstituted 4,7,12,15-tetra-phenylethynyl[2.2]paracyclophane, 3, the difference between fluorescence maxima in solid state and in solution decreases. Analysis of crystal structure using Hirschfeld method revealed that observed phenomenon correlates well with proportion of C-C contacts in crystal packing of compounds. It has been found, that for [2.2]paracyclophane derivatives 2 and 3, the main contribution to this effect is due to π–π contacts of the proximal paracyclophane groups of neighboring molecules, rather than to stacking interactions discovered for 1. The different polymorphic forms of compound 1 that are present both in film and in solid state are discussed. [Display omitted]