Khan Ishaat M, Shakya Sonam
Department of Chemistry, Aligarh Muslim University, Aligarh 202002, India.
ACS Omega. 2019 Jun 7;4(6):9983-9995. doi: 10.1021/acsomega.9b01314. eCollection 2019 Jun 30.
An exceptionally unique, easy-to-prepare, and economic charge transfer complex (CTC), [(IMH)(PA)], was synthesized as a highly selective real-time colorimetric chemosensor material for nitro explosive nitrobenzene (NB) and Co ion. Co and NB are highly potential toxic and hazardous beyond the exposure limits and also classified as carcinogens (group 2B) by IARS and United States Environmental Protection Agency. Unusual sensing ability with appreciatively low detection limits of 0.114 and 0.589 ppb for NB and Co ion, respectively, in the aqueous medium of dimethyl sulfoxide has been reported for the first time among this class of complexes reported so far. The mechanism of the tremendous sensing behavior of this material as chemosensor was ascertained by static quenching mechanism, Dexter electron transfer, and Forster resonance energy transfer dynamic quenching mechanism, which was supported by spectral overlapping and density functional theory (DFT) (B-3LYP/def2-SVP) calculations. Real-time colorimetric sensing behavior of chemosensor was demonstrated by the naked eye test and prestained paper Co strip test. Job's plot and comparative Fourier transform infrared (FTIR) study between CTC and CTC-Co complex revealed the coordination mode between CTC and Co ion and 2:1 stoichiometry. This sensing material [(IMH)(PA)] was synthesized with donor imidazole (IM) and acceptor picric acid (PA), and its characterization was achieved by experimental (single-crystal X-ray diffraction, thermal gravimetric analysis-differential thermal analysis, FTIR, and UV-vis studies) and theoretical methods [DFT/TD-DFT calculations, comparing experimental-theoretical data and obtaining MEP map along with electronic energy gap of HOMO → LUMO (Δ = 3.545 eV) and Hirshfeld surfaces analysis]. The SC-XRD confirms the composition and bonding features, which show hydrogen bond via N-H···O between IM and PA. This N-H···O interaction plays a significant role in Co binding, proving this method of synthesizing CTC as a chemosensor to be a novel approach.
合成了一种极为独特、易于制备且经济的电荷转移络合物（CTC），即[(IMH)(PA)]，作为用于硝基炸药硝基苯（NB）和钴离子的高选择性实时比色化学传感器材料。钴和硝基苯具有高度潜在毒性且超出暴露限值，同时被国际癌症研究机构（IARC）和美国环境保护局列为2B类致癌物。在迄今为止报道的此类络合物中，首次报道了在二甲基亚砜水介质中对NB和钴离子分别具有低至0.114和0.589 ppb的检测限的异常传感能力。该材料作为化学传感器的巨大传感行为机制通过静态猝灭机制、德克斯特电子转移和福斯特共振能量转移动态猝灭机制得以确定，光谱重叠和密度泛函理论（DFT）（B - 3LYP/def2 - SVP）计算对此提供了支持。通过肉眼测试和预染纸钴条测试展示了化学传感器的实时比色传感行为。Job曲线以及CTC与CTC - Co络合物之间的比较傅里叶变换红外（FTIR）研究揭示了CTC与钴离子之间的配位模式和2:1的化学计量比。这种传感材料[(IMH)(PA)]由供体咪唑（IM）和受体苦味酸（PA）合成，其表征通过实验方法（单晶X射线衍射、热重分析 - 差热分析、FTIR和紫外 - 可见光谱研究）和理论方法[DFT/TD - DFT计算、比较实验 - 理论数据并获得分子静电势（MEP）图以及HOMO→LUMO的电子能隙（Δ = 3.545 eV）和 Hirshfeld表面分析]实现。单晶X射线衍射证实了其组成和键合特征，显示出IM和PA之间通过N - H···O形成氢键。这种N - H···O相互作用在钴的结合中起重要作用，证明了这种合成作为化学传感器的CTC的方法是一种新颖的方法。
