The rational design of chemically modified biopolymer supports is critical for tailoring metal coordination environments in functional materials. Chitosan was selectively quaternized with benzyl chloride to form a polymeric matrix that facilitates nickel complex formation. The modified biopolymer was coordinated with Ni²⁺ ions from NiCl₂·6H₂O, yielding a benzyl-quaternized chitosan–nickel composite. Structural changes were investigated using FTIR and XRD. FTIR confirmed successful incorporation of benzyl quaternary ammonium and revealed spectral shifts indicative of coordination interactions between nickel ions and chitosan. XRD patterns showed new diffraction features in the nickel-loaded composite compared to pristine chitosan, indicating the formation of nickel-containing domains and polymer microstructure rearrangement upon quaternization and metal coordination. These findings demonstrate that benzyl chloride quaternization effectively modulates chitosan's structure, creating a favorable coordination environment for nickel complexes. This strategy offers a versatile platform for designing functional metal–biopolymer hybrid materials with potential applications in advanced materials.

Keywords: quaternized chitosan, benzyl chloride, nickel complexes, biopolymer support.