Luminescent triazolo-fused pyrido[3,4-b]pyrazines as novel fluorophores

A series of organic fluorophores based on novel [1,2,4]triazolo [4′,3':1,2]pyrido [3,4-b]pyrazine architecture were synthesized by a simple two-step protocol. Synthesized organic fluorophores exhibit blue-to-green fluorescence and their UV absorption and fluorescent emission properties were studied. The photophysical properties of synthesized derivatives were tuned by introducing functionalities of varying electronic nature on the core nucleus. The luminescence maxima of the synthesized compounds are found in the range from 427 nm to 503 nm, and the quantum yields ranging from 0.01 to 0.64 were calculated. Among various synthesized molecules, 3-(4-bromophenyl)-8,9-bis(4-methoxyphenyl)-[1,2,4]triazolo [4′,3':1,2]pyrido [3,4-b]pyrazine showed highest quantum yield (ΦF = 0.64), and was further explored for its solvatochromic, acidochromic, aggregation induced fluorescence studies along with theoretical HOMO-LUMO calculations. [Display omitted] •Novel series of organic luminophores, namely [1,2,4]triazolo [4′,3':1,2]pyrido [3,4-b]pyrazines were designed, synthesized and characterized.•UV absorption and fluorescent emission properties of all synthesized compounds were studied.•3-(4-Bromophenyl)-8,9-bis(4-methoxyphenyl)-[1,2,4]triazolo [4′,3':1,2]pyrido [3,4-b]pyrazine showcased highest quantum yield (ΦF = 0.64) in methanol, and was further explored for its acidochromic and aggregation induced fluorescence studies.