Coordination polymers formed by the mono- and dinuclear Cu(II) complexes of 1,1'-methylene/thio-bis(2-naphthoxy) acetic acid

Abstract

A series of five new Cu²⁺ coordination polymers, namely, {[CuL_CH2(DMF)](DMF)}_n (1), {[CuL_CH2(DMF)(2,2'-bipy)](CH₃OH)}_n (2), {[CuL_CH2(2,2'-bipy)](2H₂O)}_n (3), {[CuL_CH2(H₂O)(2,2'-bipy)](2H₂O)}_n (5), {[Cu₂(L_S)₂(DMF)₂](DMF)(CH₃OH)(2H₂O)}_n (6), and three discrete coordination complexes {[Cu₂L_CH2(2,2'-bipy)₂(CH₃O)](ClO₄)(CH₃OH)} (4), {[CuL_S(2,2'bipy)](CH₃OH)} (7), and {[CuL_S(1,10-phen)](DMF)} (8) have been prepared by the reaction of Cu(ClO₄)₂·6H₂O and 1,1'-methylene-bis(2-naphthoxy acetic acid) (L_CH2) or 1,1'-thio-bis(2-naphthoxy acetic acid) (L_S), with or without the presence of 2,2'-bipyridine, under varying reaction conditions or methods of crystallization or both. All the compounds were characterized by elemental analysis, IR, thermogravimetric analysis, and single crystal X-ray diffraction (XRD). The structures of L_CH2 and L_S obtained by single crystal XRD indicated anti- orientation of the pendant arms which upon metal complexation may turn into cis- orientation leading to discrete metal ion complexes or may remain in anti- orientation leading to extended multidimensional co-ordination polymers. The complexation with Cu²⁺ led to five different coordination spheres which in turn resulted in five different lattice structures. Thus, the present paper demonstrates the design of coordination polymers that are rich with mononuclear as well as dinuclear Cu²⁺ centers wherein L_CH2 or L_S coordinates in a monodentate as well as a bridging fashion leading to the formation of one-dimensional curving, helical, and two-dimensional networks.