Ullah Shaheed, McKee Michael L, Samokhvalov Alexander
Department of Chemistry, Morgan State University, 1700 East Cold Spring Lane, Baltimore, MD 21251, USA.
Department of Chemistry and Biochemistry, 179 Chemistry Building, Auburn University, Auburn, AL 36849, USA.
Phys Chem Chem Phys. 2023 Nov 29;25(46):31884-31897. doi: 10.1039/d3cp03779g.
We report a mechanistic study of the interactions in the sorption of volatile organic sulfur compound (VOSC) diethyl sulfide (DES) by zinc porphyrin aluminum MOF (actAl-MOF-TCPPZn) compound 3. First, interactions were studied under dynamic conditions with the vapor of DES in flowing air, using time-dependent ATR-FTIR spectroscopy in a controlled atmosphere with a new facile spectroscopic mini-chamber. The first binding site includes (O-H) and COO groups as detected by characteristic peak shifts. Control experiments with a model compound, which lacks porosity and these groups, show no peak shifts. An additional insight was obtained by DFT computations using small clusters. The kinetics of sorption of DES by compound 3 is of the Langmuir adsorption model and pseudo-first order with rate constant = 0.442 ± 0.056 min. Sorption of DES under static conditions in saturated vapor results in stoichiometric adsorption complex Al-MOF-TCPPZn characterized by spectroscopic, structural and gravimetric methods; the adsorbed amount is very high (381 mg g sorbent). The repetitive sorption and desorption of DES are conducted, with facile regeneration. Finally, the mechanistic details were determined by Raman and photoluminescence (PL) spectroscopy using a confocal Raman microscope. Photoexcitation of compound 3 at 405 nm into the Soret band of the metalloporphyrin linker shows the characteristic PL peaks of Q-bands: the purely electronic Q(0-0) and first vibronic Q(0-1) bands. Upon interaction with DES, preferential quenching of PL from the Q(0-0) band occurs with a significant increase of the signal of the vibronic Q(0-1) band, reflecting bonding to the metalloporphyrin ring. Compound 3 is of interest to mechanistic studies of VOSCs, their removal from air, and optical chemo-sensing.
我们报告了一项关于锌卟啉铝金属有机框架化合物（actAl-MOF-TCPPZn，化合物3）对挥发性有机硫化合物（VOSC）二乙硫醚（DES）吸附过程中相互作用的机理研究。首先，在动态条件下，于流动空气中使用DES蒸汽，在可控气氛中利用新型便捷光谱微型腔室中的时间分辨衰减全反射傅里叶变换红外光谱（ATR-FTIR）对相互作用进行研究。通过特征峰位移检测到第一个结合位点包括（O-H）和COO基团。使用缺乏孔隙率和这些基团的模型化合物进行的对照实验未显示出峰位移。通过使用小簇的密度泛函理论（DFT）计算获得了额外的见解。化合物3对DES的吸附动力学符合朗缪尔吸附模型且为准一级动力学，速率常数k = 0.442 ± 0.056 min⁻¹。在饱和蒸汽的静态条件下对DES的吸附产生了化学计量吸附络合物Al-MOF-TCPPZn，通过光谱、结构和重量法对其进行了表征；吸附量非常高（381 mg g⁻¹吸附剂）。进行了DES的重复吸附和解吸，且再生简便。最后，使用共聚焦拉曼显微镜通过拉曼光谱和光致发光（PL）光谱确定了机理细节。在405 nm处将化合物3光激发到金属卟啉连接体的Soret带中，显示出Q带的特征PL峰：纯电子Q(0-0)和第一振动Q(0-1)带。与DES相互作用时，Q(0-0)带的PL优先猝灭，同时振动Q(0-1)带的信号显著增加，这反映了与金属卟啉环的键合。化合物3对于VOSCs的机理研究、从空气中去除VOSCs以及光学化学传感具有重要意义。
