Surface modification of chitosan with Ni(II) Schiff base complex: A new heterogeneous catalyst for the synthesis of xanthones.

A new biocomposite of chitosan, chitosan-supported di(pyridine-2-yl)methanone-Ni(II) complex, CS-DPM-Ni, is synthesized for the first time. The biocomposite is thoroughly characterized by FTIR, PXRD, XPS, FESEM, EDX, TGA, ICP-OES, and elemental analysis. The synthesized composite is successfully used as a heterogeneous catalyst in the synthesis of a library of xanthone derivatives by the intermolecular catalytical coupling of 2-substituted benzaldehydes and phenols.