Orange-red emissive coumarin based quadrupolar dyes: Synthesis, photophysical and DFT studies

Designing and synthesized dyes with diethylamino coumarin as fixed and diethylamino coumarin, julolidine, and pyrene-based donors with dicynovinylene acceptor, the effects of donor and π-linker on linear and non-linear optical (NLO) properties were examined. Density functional theory (DFT) and time-dependent DFT were used for this investigation. Maximum absorption and emission were seen in the range of 500–547, 525–569, and 420–429 nm, as well as 576–653, 592–653, and 492–536 nm for diethylamino coumarin, julolidine, and pyrene-based dyes. A julolidine-based donor dye showed red-shifted absorption and emission properties compared to diethylamino and pyrene-based coumarin. All dyes in polar demonstrated significant viscosity sensitivity (PEG: methanol) solutions. Furthermore, above 250°C, the title dyes demonstrated good thermal stability. Additionally, the theoretical analysis suggested that dyes based on julolidine have superior linear and NLO properties in solvent phases and better CT (as determined by FMO, MEP, BLA, and BOA calculations).