Substituent‐directed ESIPT‐coupled Aggregation‐induced Emission in Near‐infrared‐emitting Quinazoline Derivatives

• Published in: Chemphyschem 2018-10, Vol.19 (20), p.2672-2682
• Main Authors: Dwivedi, Bhupendra Kumar, Singh, Vishwa Deepak, Paitandi, Rajendra Prasad, Pandey, Daya Shankar
• Format: Article
• Language: English
• Subjects: Agglomeration; aggregation; Color; Derivatives; Emission analysis; fluoroscence; keto-enol tautomerisation; Morphology; NMR; Nuclear magnetic resonance; Optoelectronic devices; quinazoline; solid-state emissions
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201800579

A series of ESIPT (excited state intramolecular proton transfer) active systems (HQz1–HQz6) derived from quinazoline have been reported. The ESIPT emission for these derivatives gets completely quenched in solvents with diverse polarities which have been restored via aggregation‐induced emission (AIE) with large Stokes shift (up to 314 nm). It varied from 450 to 701 nm just by altering substituents at the para position of hydroxy group in the central phenyl ring. As well, HQz1–HQz6 displayed solid state emission [∼455 (blue) to ∼704 nm (red)]. The formyl group on the central hydroxy‐phenyl ring of these derivatives induces ESIPT by increasing acidity of the hydroxy proton which has been followed by 1H NMR studies. Further, it has been clearly shown that emission colour and aggregate morphology can be fine tuned by incorporating apt substituents. The present study offers a simple route to obtain colour tunable ESIPT emission via AIE which is very important for biological imaging and fabrication of optoelectronic devices. Excited state intramolecular proton transfer (ESIPT) active systems derived from quinazoline are studied. The ESIPT emission of these derivatives is completely quenched in solvents with diverse polarities but can be restored via aggregation‐induced emission (AIE) with large Stokes shift (up to 314 nm). This study offers a simple route to obtain color‐tunable ESIPT emission via AIE, which is important for biological imaging and the fabrication of optoelectronic devices.