Pigment Yellow 101 analogs from 3-(1,3-benzothiazol-2-yl)-2-hydroxynaphthalene-1-carbaldehyde – Synthesis and characterization

•Synthesis and characterization of Pigment Yellow 101 analogs 6a–6d.•Two analogs show pigment properties with solid state fluorescence and remaining show properties like dyes.•Existence of ESIPT has been theoretically confirmed by computational method.•Photophysical properties have been studied experimentally and correlated to computational results.

Pigment Yellow 101 analogs have been synthesized from 3-(1,3-benzothiazol-2-yl)-2-hydroxynaphthalene-1-carbaldehyde by combining with different aromatic diamines. Out of the four synthesized aldazines two show pigment properties and remaining show properties like dyes. Existence of excited state intramolecular proton transfer process between phenolic –OH and azomethine linkage (N–) has been computationally ascertained. Two pigment analogs showed solid state fluorescent which were compared with commercially available Pigment Yellow 101. For dyes analogs, effects of solvent polarity on photophysical properties such as absorption, emission have been studied. Density functional theory and time dependent density functional theory computations have been used to investigate structural parameters and understanding photophysical properties of synthesized analogs. All these aldazines show good thermal stability.

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