Organic chromophores consisting of well-separated electron donor (D) and electron acceptor (A) units connected through the π-linkers attract the attention over last few years owing to their rich photophysical properties and applications in optoelectronic devices. The fundamental phenomenon of intramolecular charge transfer (ICT) from the donor to the acceptor turns out to be the key feature behind the fascinating optical properties. The molecular geometry and the spatial arrangement of D and A units has a profound impact on the ICT process. The environment-sensitive ICT emission makes them as a potential candidate for designing optical sensors. Hence, a detail molecular level understanding of the ICT process is a worthy issue to address. We developed a new class of donor-acceptor-donor (D–A–D) type molecules based on pyridoquinoxaline (PQ) acceptor and carbazole (Cz) donor. The T and V-shaped structural isomers (PQCz-T and PQCz-V) were synthesized through the variation of the position of donor connectivity. The extensive steady-state and time-resolved spectroscopic studies helped to establish that the facile conjugation in the V-shaped isomer leads to the diminished ICT as compared to that of the T-shaped isomer. On the other hand, PQCz-T exhibits large Stokes shift, far-red emission in the solid state, remarkable viscosity and temperature-dependent tunable fluorescence including a thermally-induced single-component near white-light emission. This study opens up new avenues to understand the charge transfer mechanism in novel pyridoquinoxaline-based multichromophoric molecules.

Intriguing case of excited state intramolecular charge transfer: T- and V-shaped molecules with pyridoquinoxaline acceptor

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.