A Novel Multifunctional Cd-MOF Containing Thiazolo[5,4-d]thiazole and Azo Moieties for Highly Efficient Adsorption of Iodine and Catalytic CO2 Cycloaddition

A novel complex, {[Cd(NO₃)(4,4′-Azo)_0.5(DPTzTz)]·DMF}_n (MOF-1), was obtained by assembling photoactive ligand 2,5-di(pyridin-4-yl)thiazolo[5,4-d]thiazole (DPTzTz) and azo-functionalized dicarboxylic acid linker (4,4′-azodibenzoic acid = 4,4′- H₂Azo) under solvothermal conditions. MOF-1 bears a 2-fold interpenetrated 3D framework with 1D open channels. The channel wall was decorated with Lewis acidic Cd(II) center and Lewis basic groups (N═N, TzTz). The title complex exhibited excellent thermal stability and robust chemical stability. After activation, the sample (MOF-1a) can act as a heterogeneous catalyst for the CO₂ cycloaddition reaction under mild conditions. Moreover, it can encapsulate 680.1 mg·g^–1 and 737.2 mg·g^–1 iodine in the vapor phase and in cyclohexane solution (320 mg·L^–1), respectively. MOF-1a shows easy recovery and reuse without an obvious decrease of catalytic activity and adsorption capacity. Therefore, MOF-1 is a multifunctional and stable material for iodine adsorption and catalytic CO₂ cycloaddition.