Abstract Intra-molecularly hydrogen bonded compound 2-(1,4-dioxo-1,4-dihydronaphthalen-2-yl-amino)benzoic acid (ANQ) shows emission at single wavelength upon excitation in UV-region whereas it shows dual fluorescence emissions on excitation in visible region. Such emissions depend on solvent, concentration and pH. Solvent dependent structural changes of ANQ are reflected in solution studies carried out by 1 HNMR, UV–visible and fluorescence spectroscopy. DLS study has showed that in addition to monomers, self-assemblies with 415 nm average sized particles are formed in DMF solution. HOMO-LUMO of three tautomeric forms of the compound was calculated by DFT using CAMB3LYP/6-31 + G(d,p) as basis set shows that naphthoquinone form has about 86.30 kJ/mol higher stability over an imino-quinone form. From various studies relating concentration dependence, pH, life-time, study on dual-emissions caused by visible excitation has established the observed emissions to originate from aggregation contributing as charge-transfer and deprotonated species. Whereas the single emission caused by UV-excitation occurs through excited state intra-molecular proton transfer.

中文翻译：

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2-(1,4-dioxo-1,4-dihydro-naphthalen-2-yl-amino)benzoic acid 双荧光模式和发射的调制

摘要 分子内氢键化合物 2-(1,4-dioxo-1,4-dihydronaphthalen-2-yl-amino)benzoic acid (ANQ) 在紫外区激发时显示单波长发射，而显示双荧光发射在可见光区激发。此类排放取决于溶剂、浓度和 pH 值。ANQ 的溶剂依赖性结构变化反映在通过 1 HNMR、UV-可见光和荧光光谱进行的溶液研究中。DLS 研究表明，除单体外，在 DMF 溶液中还会形成平均粒径为 415 nm 的自组装体。化合物的三种互变异构形式的 HOMO-LUMO 使用 CAMB3LYP/6-31 + G(d,p) 作为基组通过 DFT 计算表明萘醌形式比亚氨基醌形式具有约 86.30 kJ/mol 更高的稳定性。从有关浓度依赖性的各种研究中，pH、寿命、对可见激发引起的双发射的研究已经确定观察到的发射源自作为电荷转移和去质子化物质的聚集。而由紫外线激发引起的单次发射是通过激发态分子内质子转移发生的。