Synthesis of newly crystalline-porous- Pd(II)- (E,E)-2, 4-hexadienoic acid complex-leads to 3D-MOFs for hydrogen storage

Abstract

In the present investigations, a newly crystalline tetra-chelates-Pd(II)-(E,E)-2, 4-Hexadienoic acid (Sorbic acid) complex was initially synthesized and sucessfully produce a 3D- polymeric MOFs under microwave assist hydrothermal technique. Modified metal insertion template to the ligand solution was applied for the first time. The synthesized cystalline Pd(II)-sorbic acid complex was well structurally characterized by micro-elemental analyses (C, H, O, M), X-ray diffraction, X-ray photoelectron spectra (XPS), FT-IR spectra, Uv-spectra and BET-specific surface area measurements. Rietveld XRD structural phase investigations, confirmed that, Pd(II)-sorbic acid complex is belonging to monoclinic crystal form (C2/c space group) with lattice parameters of a = 19.987(2), b = 4.126(5) and c = 15.913(6)Å respectively .The confirmed proposed structure was based on DFT-calculations and suitability of ionic radius of each palladium(II) ion to insert successfully in the cavities between four monodentate sorbate ligand molecules and form tetra-chelated coordinated MOFs, which stabilized and reinforced by presence of hydrogen bonding. Brunauer–Emmet–Teller (BET) specific surface area for Pd(II)-sorbate MOFs was found to be 465 m2/g which is promising value with large pore size distribution (BJH) of 11.2 Å. These features qualify Pd(II)-MOFs to be an active potential candidate as surface active porous material for hydrogen storage.