Triphenylamine derived coumarin chalcones and their red emitting OBO difluoride complexes: Synthesis, photophysical and NLO property study

•Synthesized and characterized the triphenylamine derived coumarin chalcones and their BF2 complexes.•Push-pull chromophores with D-π-A systems exhibit significant ICT character on the virtue of GMH and FMO analysis.•Non linear optical properties are illustrated by spectroscopic, theoretical (TDDFT) methods and Z-scan technique.•Use of triphenylamine as a donor in place of N-ethyl groups results into increased thermal stability of NLOphores.•Increased branching in chromophores enhances their thermal stability and NLO response.

The auxiliary methoxy aided triphenylamine donors derived coumarin chalcones and their OBO complexes with branched donor-pi-acceptor systems are synthesized and characterized. Their photophysical properties are extensively studied in solvents of different polarity. They show strong emission solvatochromism and have quantum yields up to 0.87. The BF2-complexation of coumarin chalcones enhanced the quantum efficiency by approximately 1.4 times compared to the uncomplexed chalcones. Frontier molecular orbital analysis and Generalised Mulliken Hush analysis revealed a strong intramolecular charge transfer character of these chromophores. The first, second and third order polarizability of these chromophores are evaluated by the solvatochromic method and supported by Density Functional Theory calculations using CAM-B3LYP/6-31g(d) method. The third order nonlinear optical susceptibilities of these chromophores obtained by Z-scan analysis showed very less values of the imaginary part. Replacement of N-ethyl donors by aryl amine groups provided branched push-pull systems with enhanced thermal stability and nonlinear optical response.

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