Evolution of Spherical Assemblies to Fibrous Networked Pd(II) Metallogels from a Pyridine-Based Tripodal Ligand and Their Catalytic Property

A series of metal-organic gels (MOGs) were formed in CH3OH-CHCl3 solution based on L1 and Pd(COD)(NO3)(2) (L1 = 4,4',4 ''-(1,3,5-triazine-2,4,6-triyl)tris(N-(pyridin-3-ylmethyl)benzamide, COD = cycloocta-1,5-diene) at different ratios. FT-IR, NMR, and fluorescence spectroscopy show that hydrogen bonding, pi-pi interaction, and coordination bonding are involved in the gel formation. The morphologies of these metallogels are Pd/L1 ratio dependent ranging from spheres to fibers. The fibrous networked gel shows higher catalytic activity in Suzuki-Miyaura coupling reaction than the spherical gel, acting as recyclable Pd(II) catalyst supported by the air-stable networked gel/xerogel.