Song Xiaoming, Hou Xiufang, Zhao Qingxia, Ma Zhihu, Ren Yixia
Shaanxi Key Laboratory of Chemical Reaction Engineering, Laboratory of New Energy and New Function Materials, College of Chemistry and Chemical Engineering, Yan'an University, Yan'an, Shaanxi 716000, China.
Shaanxi Key Laboratory of Chemical Reaction Engineering, Laboratory of New Energy and New Function Materials, College of Chemistry and Chemical Engineering, Yan'an University, Yan'an, Shaanxi 716000, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2024 Mar 5;308:123729. doi: 10.1016/j.saa.2023.123729. Epub 2023 Dec 3.
Nitroaromatic compounds in aqueous undermine environmental sustainability and affect human health. The development of a fluorescent sensor capable of efficiently and selectively detecting trace amounts of nitroaromatic compounds presents a considerable challenge. This study introduced Zn/Cd isomeric coordination polymers (Zn-HCIA-1/Cd-HCIA-2), which are synthesized using 5-((4-carboxybenzyl)oxy)isophthalic acid (5-HCIA) and 1,10-phenanthroline (Phen). The polymers have zero-dimensional discrete crystal structure with a six-coordinated scissor-like shape. The two coordination polymers can be used as fluorescent sensors for detecting nitrobenzene (NB) and demonstrated favorable sensitivity, with detection limits of 1.95 × 10 and 4.66 × 10 mol/L, respectively. Zn-HCIA-1 exhibited stronger fluorescence and a more sensitive response to NB compared with Cd-HCIA-2. To elucidate their fluorescence-quenching mechanisms, we analyzed Zn-HCIA-1 by performing DFT and TD-DFT calculations. The pore structure, density of states, excitation energy, hole-electron distribution, and orbital composition were analyzed. The suitable size of pores in Zn-HCIA-1 is the main reason for its high NB selectivity. Moreover, intermolecular π-π stacking interactions result in an orbital overlap between Zn-HCIA-1 and NB, enabling the transfer of electrons from Zn-HCIA-1 to NB. This electron transfer is identified as the fundamental cause of fluorescence quenching in Zn-HCIA-1.
水中的硝基芳香化合物会破坏环境可持续性并影响人类健康。开发一种能够高效、选择性地检测痕量硝基芳香化合物的荧光传感器是一项重大挑战。本研究介绍了锌/镉异构配位聚合物（Zn-HCIA-1/Cd-HCIA-2），它们是使用5-((4-羧基苄基)氧基)间苯二甲酸（5-HCIA）和1,10-菲咯啉（Phen）合成的。这些聚合物具有零维离散晶体结构，呈六配位剪刀状。这两种配位聚合物可用作检测硝基苯（NB）的荧光传感器，表现出良好的灵敏度，检测限分别为1.95×10和4.66×10 mol/L。与Cd-HCIA-2相比，Zn-HCIA-1对NB表现出更强的荧光和更灵敏的响应。为了阐明它们的荧光猝灭机制，我们通过进行DFT和TD-DFT计算对Zn-HCIA-1进行了分析。分析了其孔结构、态密度、激发能、空穴-电子分布和轨道组成。Zn-HCIA-1中合适的孔径大小是其对NB具有高选择性的主要原因。此外，分子间的π-π堆积相互作用导致Zn-HCIA-1与NB之间的轨道重叠，使得电子能够从Zn-HCIA-1转移到NB。这种电子转移被确定为Zn-HCIA-1中荧光猝灭的根本原因。
