Preparation of a porphyrin-polyoxometalate hybrid and its photocatalytic degradation performance for mustard gas simulant 2-chloroethyl ethyl sulfide

• Published in: Chinese chemical letters 2022-05, Vol.33 (5), p.2625-2629
• Main Authors: Yang, Ying, Tao, Fangsheng, Zhang, Lijuan, Zhou, Yunshan, Zhong, Yuxu, Tian, Shubo, Wang, Yong'an
• Format: Article
• Language: English
• Subjects: Chemical warfare agent; Mustard gas simulant; Photooxidation; Polyoxometalate; Porphyrin
• ISSN: 1001-8417; 1878-5964
• DOI: 10.1016/j.cclet.2021.09.093

By combining 5,10,15,20-tetra(4-chlorine)phenylporphyrin (TClPP) and α-Keggin polyoxometalate H5PV2Mo10O40 (H5PVMo) via a simple ion-exchange method, an organic-inorganic hybrid material [C44H28N4Cl4]1.5[H2PMo10V2O40]·2C2H6O (H2TClPP-H2PVMo) was prepared and thoroughly characterized by a variety of techniques. The homogeneous photocatalytic degradation of 2-chloroethyl ethyl sulfide (CEES) (5 µL) by H2TClPP-H2PVMo (1 × 10−6 mol/L) was studied in methanol and methanol-water mixed solvent (v/v = 1:1), in which the degradation rate of CEES reached 99.52% and 99.14%, respectively. The reaction followed first-order reaction kinetics, and the half-life and kinetic constant in methanol and the mixed solvent were respectively 33.0 min, −0.021 min−1 and 15.7 min, −0.043 min−1. Mechanism analysis indicated that under visible light irradiation in the air, CEES was degraded via oxidation and alcoholysis/hydrolysis in methanol and the mixed solvent. O2·− and 1O2 generated by H2TClPP-H2PVMo selectively oxidized CEES into a nontoxic sulfoxide. Singlet oxygen capture experiments showed that H2TClPP-H2PVMo (ϕ = 0.73) had a higher quantum yield of singlet oxygen than TClPP (ϕ = 0.35) under an air atmosphere and visible light irradiation. Superoxide radicals and singlet oxygen generated by a new organic-inorganic hybrid material obtained by reacting a porphyrin and an α-Keggin type H5PV2Mo10O40 were found to efficiently and selectively oxidize CEES in methanol and water/methanol to nontoxic sulfoxide under visible light irradiation in air. Hydrolysis, alcoholysis and oxidation degradation mechanisms were involved in the processes. [Display omitted]