Department of Chemistry, Gandhigram Rural Institute (Deemed to be University), Gandhigram 624302, India.
Department of Chemistry, Gandhigram Rural Institute (Deemed to be University), Gandhigram 624302, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2019 Apr 15;213:318-323. doi: 10.1016/j.saa.2019.01.074. Epub 2019 Jan 28.
A bisimidazole ensemble (R) possessing naphthoquinone as signaling unit is synthesized and characterized using H and C NMR and LC-MS spectral techniques. Anion sensing behaviour of the receptor has been investigated using electronic and fluorescence spectral techniques. The receptor exhibits a striking colour change from yellow to brown selectively with cyanide in aqueous HEPES buffer-DMSO (1:1 v/v) medium with a detection limit of 1 μM. Job's continuous variation method suggests that the stoichiometry of the interaction is 1:2 (R:CN). The binding constant for receptor-cyanide complex was found to be 8.7 × 10 M. The mechanism of detection of cyanide occurs via deprotonation of imidazole N-H protons, which is well supported by electrochemical study. DFT based theoretical calculations shows that the energy gap between HOMO and LUMO decreases from 3.3086 (in R) to 1.7799 eV (in R + CN), which is responsible for the red-shift observed in the UV-Vis spectrum of R upon addition of cyanide ions. The present quinone-bisimidazole based receptor shows few advantages over similar bisimidazoles reported elsewhere.
一种含有萘醌作为信号单元的双咪唑配合物（R）已通过 H 和 C NMR 以及 LC-MS 光谱技术进行了合成和表征。利用电子和荧光光谱技术研究了受体的阴离子传感性能。该受体在水相 HEPES 缓冲-DMSO（1:1 v/v）介质中，与氰化物选择性地发生从黄色到棕色的显著颜色变化，检测限为 1 μM。Job 连续变化法表明，相互作用的化学计量比为 1:2（R:CN）。发现受体-氰化物配合物的结合常数为 8.7×10 M。氰化物检测的机制是通过咪唑 N-H 质子的去质子化，这一过程得到电化学研究的很好支持。基于密度泛函理论的理论计算表明，HOMO 和 LUMO 之间的能隙从 3.3086（在 R 中）降低至 1.7799 eV（在 R+CN 中），这是在向 R 中加入氰离子后观察到的紫外可见光谱红移的原因。与其他地方报道的类似双咪唑相比，本醌-双咪唑基受体具有一些优势。
