The new benzimidazole ligands (3a-e) were synthesized using ethyl 4-(butylamino)-3-nitrobenzoate and substituted salicylaldehyde in the presence of sodium dithionite reagent which undergoes “one-pot’’ nitro reductive cyclization. Here benzimidazole moiety acts as an electron-acceptor (A) whereas substituted 2-hydroxyphenyl moiety acts as an electron-donor (D) unit. The molecular structures were characterised by FTIR, ¹H NMR, ¹³C NMR, single crystal XRD and MS analysis. Optoelectronic properties were determined by UV–vis, solution and solid photoluminescence, quantum yield and lifetime. The solvent-dependent absorption and emission were studied using both polar protic and polar aprotic solvents. All the derivatives exhibited ESIPT, especially compound ethyl 1-butyl-2-(3,5-dichloro-2-hydroxyphenyl)-1H-benzo[d]imidazole-5-carboxylate (3e) displayed dual emission in both polar protic and polar aprotic solvents. The compound stability and electrochemical property were determined by thermal gravimetric analysis (TGA) and cyclic voltammetry (CV) respectively. The compounds emit intense blue-green fluorescence with high to moderate quantum yield. Also, these derivatives exhibited a high Stokes shift. The computational studies like Density-Functional Theory (DFT) and Molecular Electrostatic Potential (MEP) were conducted to provide important insights into the structure-property relationships. The crystal packing is stabilized through intermolecular hydrogen bonds (C---H…O) and intermolecular interactions (π… π). The findings of results help in developing novel ligands in the field of organic optoelectronics.

在连二亚硫酸钠试剂存在下，通过“一锅法”硝基还原环化反应，使用4-（丁基氨基）-3-硝基苯甲酸乙酯和取代的水杨醛合成了新的苯并咪唑配体（3a-e）。在此，苯并咪唑部分充当电子受体（A），而取代的2-羟基苯基部分充当电子给体（D）单元。分子结构通过FTIR，¹ H NMR，¹³表征13 C NMR，单晶XRD和MS分析。光电特性由紫外可见，溶液和固体光致发光，量子产率和寿命决定。使用极性质子和极性非质子溶剂研究了溶剂依赖性的吸收和发射。所有衍生物均表现出ESIPT，特别是化合物1-丁基-2-（3,5-二氯-2-羟苯基）-1 H-苯并[ d ]咪唑-5-羧酸酯（3e）在极性质子和非质子溶剂中均显示出双重发射。分别通过热重分析（TGA）和循环伏安法（CV）测定化合物的稳定性和电化学性能。这些化合物发出强烈的蓝绿色荧光，量子产率高到中等。而且，这些导数表现出高的斯托克斯位移。进行了诸如密度泛函理论（DFT）和分子静电势（MEP）的计算研究，以提供对结构-性质关系的重要见解。晶体堆积通过分子间氢键（C --- H…O）和分子间相互作用（π…π）稳定。结果的发现有助于开发有机光电子学领域的新型配体。