Nano-assembled oligosilane–pyrazoline structures and their optical properties

Abstract Specific interactions between low molecular weight poly[diphenylsilane-co-methyl(H)silane] and 1,3-diphenyl-5-{4-[(4-vinylbenzyl)oxy]phenyl}-4,5-dihydropyrazole in solution have been investigated. Thus, a concentrated polysilane solution containing low amounts of pyrazoline was irradiated with UV light using predetermined conditions to produce a photo-induced fragmentation of the polysilane backbone. Spectrophotometric analysis of the bicomponent solution before and after UV irradiation suggested that polysilane and pyrazoline interact, which leads to their aggregation. Quantum chemical calculation indicated that a nano-assembling process between the two components is possible, and proved the Van der Waals (VdW) nature of the main interactions between the two components. The association between polysilane and pyrazoline modifies considerably the internal charge transfer within pyrazoline's chromophore, which results in fluorescence quenching. The electronic effects within the aggregate were studied using quantum computational calculations. Owing to the polysilane influence, polysilane–pyrazoline nanostructures have specific optical properties, which could be used to develop novel materials with fluorescence sensing ability.