Green Synthesis of a New Schiff Base Linker and Its\nUse to Prepare Coordination Polymers

Solid-state synthesis\nis an approach to organic synthesis that\nis desirable because it can offer minimal or no solvent waste, high\nyields, and relatively low energy footprints. Herein, we report the\nsolid-state synthesis of a novel Schiff base, 4-{(<i>E</i>)-[(4-methylpyridin-3-yl)imino]methyl}benzoic acid (<b>4-PIBZ</b>), synthesized through the reaction of an amine and an aldehyde. <b>4-PIBZ</b> was prepared via solvent-drop (water) grinding (SDG)\non a multigram scale with 97% yield and was characterized using FTIR, <sup>1</sup>H NMR, and SCXRD. The pyridyl and carboxylate moiety present\nin <b>4-PIBZ</b> make it suitable for use as a linker ligand\nand indeed <b>4-PIBZ</b> was found to coordinate with Cu(II),\nZn(II), and Cd(II) cations, enabling it to serve as a linker ligand\nfor the assembly of coordination polymers. <b>4-PIBZ</b> thereby\nformed 1D (spiro chain) and 2D (square lattice, <b>sql</b>,\ntopology) coordination polymers via solvent-induced (layering or slurry)\nmethods. The resulting coordination polymers were characterized though\nX-ray diffraction (SCXRD, PXRD) and TGA, further demonstrating the\nutility of green synthesis methods for the preparation of some classes\nof new linker ligands that can in turn be used for the preparation\nof coordination polymers.