氧化蒽基二吲哚基甲烷显色现象的研究

Study on the Chromogenic Behaviors of Oxided Anthracyl Bis(indolyl)methane

通过两步反应合成了两个具有显色特性的化合物:氧化2-蒽基二吲哚基甲烷(2-AnBIM)和氧化9-蒽基二吲哚基甲烷(9-AnBIM).比较了它们在不同非质子溶剂、不同阴离子和酸性环境中的光谱行为.在非质子溶剂中,发现这两种化合物仅在CCl4中有很大的红移,该红移现象的本质尚不清楚.浓度效应与NMR证据均表明在CCl4中化合物存在基于氢键的分子间相互作用.在含有不同阴离子的乙腈中,2-AnBIM对F-离子有选择性响应,而9-AnBIM则对F-、Cl-和Ac-等阴离子均有响应;在质子性溶剂中二者均只对HSO4-有选择性响应.2-AnBIM与9-AnBIM在77 K下有荧光发射,而平面性较好的2-AnBIM具有较低的发射能级与较强的发光效率.室温下二者均无明显的荧光发射,这可能与激发态下快速的质子转移导致分子共轭、共平面程度降低有关.

Two chromogenic compounds, oxided 2-anthracyl bis（indolyl）methane （2-AnBIM） and oxided 9-anthracyl bis（indolyl）methane （9-AnBIM） were synthesized via two steps. The medium factors （polarity, anions and pH） on the absorption behaviors of the two compounds were studied. The difference of UV behaviors in other aprotic solvents is that both 2-AnBIM and 9-AnBIM show strong red shift in CCl4. Concentration effect and NMR data show aggregation of titled compounds could be formed at concentration of 1.0 × 10^-5 mol/L in CCl4. In CH3CN, 2-AnBIM acts as a selective colorimetric sensor only for F^-, and 9-AnBIM could be sensitive for F^-, Cl^- and Ac^-. Both compounds are sensitive only for HSO4^- in CH3CN/H2O （4/1） system. Both 2-AnBIM and 9-AnBIM show fluorescence emission of intermolecular charge transfer （ITC） state at 77 K. More planarity of 2-AnBIM gives longer wavelength emission and higher quantum yield compared with 9-AnBIM. No obvious emission from 2-AnBIM and 9-AnBIM at room temperature are found, the reason might be from the fast proton transfer at excited state, which decreases the conjugation degree and co-plane of molecules.