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 5;212:160-166. doi: 10.1016/j.saa.2018.12.056. Epub 2019 Jan 3.
A Novel chemosensor R possessing napthoquinone substituted benzaldehyde has been successfully designed, synthesized and characterized using NMR and mass spectral techniques. The receptor exhibits striking colour change from pale yellow to intense green with sodium cyanide in DMF-HO (80-20% v/v) in a wide range of pH (3-12). Based on the results of spectral (UV-Vis, fluorescence and NMR), electrochemical and kinetic studies a plausible mechanism has been proposed for the cyanide detection process. The mechanism of sensing of cyanide by R is through the formation of cyanohydrin in acidic, neutral and basic solutions, which is the novelty of the receptor. The pseudo-first-order rate constants for the formation of cyanohydrin are found to be 2.9 × 10, 3.9 × 10 and 4.6 × 10 min at pH values 5, 7 and 10, respectively in DMF-HO (80-20% v/v) medium, supporting the ability of R to form cyanohydrin with equal ease in different pH values. The results of Job's continuous variation method indicates a 1:2 (R:CN) stoichiometry for the interaction. The only minor drawback with the receptor is the time taken to impart visible colour change with cyanide ion, which is not instantaneous.
一种新型的化学传感器 R 已经被成功设计、合成和表征，其结构中包含萘醌取代的苯甲醛，通过 NMR 和质谱技术可以实现。该受体在 DMF-HO（80-20%v/v）中，在 pH 值为 3-12 的很宽范围内，与氰化钠反应时会发生明显的颜色变化，从浅黄色变为深绿色。基于光谱（紫外-可见、荧光和 NMR）、电化学和动力学研究的结果，提出了一种可能的氰化物检测过程的机制。R 对氰化物的感应机制是通过在酸性、中性和碱性溶液中形成氰醇，这是受体的新颖之处。在 DMF-HO（80-20%v/v）介质中，pH 值为 5、7 和 10 时，氰醇形成的假一级速率常数分别为 2.9×10、3.9×10 和 4.6×10 min-1，这表明 R 能够在不同的 pH 值下以相同的容易程度形成氰醇。Job 连续变化法的结果表明，相互作用的化学计量比为 1:2（R:CN）。受体的唯一缺点是与氰离子相互作用时，产生可见颜色变化所需的时间不是瞬间的。
