Synthesis and Use of Valsartan Metal Complexes as Media for Carbon Dioxide Storage

To address global warming through carbon dioxide storage, three valsartan metal complexes were synthesized in excellent yields (87-92%) through a reaction of the appropriate metal chloride (tin chloride, nickel chloride hexahydrate, or magnesium chloride hexahydrate) and excess valsartan (two mole equivalents) in boiling methanol for 3 h. The structures of the metal complexes were established based on the data obtained from ultraviolet-visible, Fourier transform infrared, and proton nuclear magnetic resonance spectra, as well as from elemental analysis, energy-dispersive X-ray spectra, and magnetic susceptibility. The agglomeration and shape of the particles were determined using field emission scanning electron microscopy analysis. The surface area (16.63-22.75 m²/g) of the metal complexes was measured using the Brunauer-Emmett-Teller method, whereas the Barrett-Joyner-Halenda method was used to determine the particle pore size (0.011-0.108 cm³/g), total average pore volume (6.50-12.46 nm), and pore diameter (6.50-12.47 nm), for the metal complexes. The carbon dioxide uptake of the synthesized complexes, at 323 K and 4 MPa (40 bar), ranged from 24.11 to 34.51 cm²/g, and the nickel complex was found to be the most effective sorbent for carbon dioxide storage.