Multiple Construction of a Hierarchical Nanoporous Manganese(II)-Based Metal–Organic Framework with Active Sites for Regulating N<sub>2</sub> and CO<sub>2</sub> Trapping
Saeideh Salimi, Kamran Akhbari, S. Morteza F. Farnia, Jonathan M. White
Abstract
A new metal–organic framework with a three-dimensional (3D) nanoporous structure was formed from the self-assembly of 2,5-thiophenedicarboxylic acid (H2TDC) with Mn(NO3)2·4H2O in dimethylacetamide (DMA). It crysallizes in the monoclinic crystal system with the space group C2/c and 1D channels in the b axis direction with the chemical formula of [Mn4(TDC)4(DMA)3(H2O)2]n (MUT-5). The synthesis of MUT-5 by three methods was performed by optimizing reaction conditions such as the reaction time and temperature, and their effects on the morphology and yield of the products were investigated. The physicochemical properties and crystalline structure were characterized by single-crystal X-ray crystallography, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), and N2 adsorption/desorption. The results revealed that the utilization of sonochemical method gives sufficient yield with enhanced properties such as uniform particles of less than 100 nm, a higher surface area, and better capacity in nitrogen capture (82.6 cm3 g–1 at 77 K and 1 bar) relative to the other two methods. Moreover, due to the presence of electroactive sulfur heteroatoms and open metal coordination sites in the channels of MUT-5, it provides strong binding sites for CO2 adsorption of 1.14 mmol g–1 at 298 K and 1 bar, which is higher than the adsorption capacities of other famous MOFs. Thereby it is a promising match for carbon dioxide storage and capture.