Abstract

In this study, we decided to synthesize some new chalcone-type dyes derived from dehydroacetic acid (DHA) by the condensation of 4-amino-substituted benzaldehyde with DHA under the base-catalyzed condition and investigate their ability for rearrangement in acidic condition. For this purpose, initially we prepared the 4-aminobenzaldehyde derivatives via nucleophilic aromatic substitution reaction of 4-fluorobenzaldehyde with variety of amines in the presence of K₂CO₃ as base in DMF. The Knoevenagel condensation of DHA with 4-aminobenzaldehyde derivatives results in the desired compounds. In continuation, Fries rearrangement applied on DHA-chalcone compounds results in characterization of new pyranilidene-type derivatives. The optical responses of new dyes containing UV–Vis absorption and fluorescence spectroscopy were measured in dichloromethane (ET = 40 kcal/mol). Pyranilidene derivatives show low λ_max values in comparison with chalcones, and molecule with strong dipole, in polar solvents, shows the bathochromic shift due to more stabilization of excited state in compared with ground state of molecule. Large stocks shifts were obtained for synthesized compounds.

Graphic abstract

中文翻译：

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脱氢乙酸基查耳酮的设计，合成，表征和荧光性质评估

摘要

在这项研究中，我们决定通过在碱催化条件下4-氨基取代的苯甲醛与DHA的缩合反应合成一些新的由脱氢乙酸（DHA）制成的查尔酮型染料，并研究它们在酸性条件下的重排能力。为此，我们首先在K ₂ CO ₃存在下，通过4-氟苯甲醛与各种胺类的亲核芳香取代反应制备了4-氨基苯甲醛衍生物。作为DMF的基础。DHA与4-氨基苯甲醛衍生物的Knoevenagel缩合反应生成所需化合物。继续，对DHA-查尔酮化合物进行的弗里斯重排导致了新的吡咯烷类衍生物的表征。在二氯甲烷（ET = 40 kcal / mol）中测量了含有UV-Vis吸收和荧光光谱的新型染料的光学响应。Pyranilidene衍生物显示出低λ_最大与查耳酮比较红移值，并且分子具有较强的偶极子，在极性溶剂中，示出了由于激发态的分子与基态相比，在更稳定化。合成化合物的库存变化较大。

图形摘要