A comparative study of aggregation-induced emission in ethynyl-bridged and non-bridged AIEgens derived from tetraphenylethene and naphthalimide

Designing efficient organic luminophores with strong emission in the aggregated state remains a challenge due to the common problem of aggregation-caused quenching (ACQ). In this study, we present a comparative analysis of two naphthalimide and triphenylethylene (TPE) derivatives, one featuring an ethynyl (-C C-) linker between the two (N1N2) and the other directly coupled (NTPE). The introduction of a rigid ethynyl spacer was aimed at minimizing non-radiative decay through restricted intramolecular motions and at suppressing π–π stacking, thereby promoting aggregation-induced emission (AIE) behavior. The AIE characteristics of synthesized scaffolds were confirmed by increased emission intensity and quantum yield in DMSO–water, THF–water mixtures, with aggregation further supported by dynamic light scattering (DLS), HRTEM, and crystal packing data. With rising water content, both particle size and quantum yield also improved, signifying the interrelation between aggregation and emission enhancement. This work emphasizes the role of linker engineering in tuning AIE properties and provides useful insights into how structural variations influence aggregation behaviour and emission efficiency in AIE-active fluorophores . • Two naphthalimide and triphenylethene derived fluorophores N1N2 and NTPE were synthesized. • Structure-property relationships were studied to investigate AIE-activity. • Aggregation-induced emission (AIE) was observed in solvent–water mixtures. • Solvatofluorochromic response and large stokes shift were detected. • AIE was supported by enhanced PLQY, and increased particle size.