Organic materials possessing solid-state emission responsive to external stimuli have significance in a variety of material, biomedical, and optoelectronic applications. Organic molecules having different donor–acceptor architectures integrated with aggregation-induced emission (AIE) fluorophores have been utilized in development of mechanofluorochromic (MFC) materials. In this work, we have designed and synthesized phenanthroimidazole (PI) based derivatives TPE-PI-1, TPE-PI-2, TPE-PI-3, PTZ-PI-1, PTZ-PI-2, and PTZ-PI-3 where in donors tetraphenylethylene-TPE (D) and phenothiazine-PTZ (D′) of contrasting donor abilities are attached to the N and C atom positions of PI. The position and mode of attachment of the donors have been changed, and an additional PTZ spacer has been introduced which has a direct consequence on their photophysical and electronic properties. The PI derivatives manifest AIE, solvatochromic, and mechanochromic behavior. The single crystal X-ray analysis of TPE-PI-1 and PTZ-PI-2 reveals bent structures for the PTZ unit and a twisted conformation for TPE moieties. The density functional theory calculations were used to obtain optimized ground-state structures of the PI derivatives. The work shows a comprehensive comparison of the photophysical, electronic, AIE, and MFC properties of the PI derivatives as an effect of variations in the position of donor, donor–acceptor strength, and change in molecular conformation on use of spacer.

Development of aggregation induced emission (AIE) active mechanochromic positional isomers of phenanthroimidazole comprising of triphenylamine and tetraphenylethylene.

Stimuli responsive phenothiazine-based donor–acceptor (D–A) molecules were designed and synthesized as positional isomers p-PTZ, m-PTZ and o-PTZ. A comprehensive comparative study of the electronic and photophysical properties has been performed to study the effect of positional change.

Mechanofluorochromic (MFC) materials are a class of luminescent materials that have ability to show changes in their emission when subjected to various mechanical stimuli. A wide range of MFC materials...

Multichromophoric stimuli responsive D–A–A′ molecules were designed and synthesized as positional isomers p-BT, m-BT and o-BT. A comparative study of the photophysical and electronic properties has been carried out to study the effect of position.