Different structures of two Cu(I) complexes constructed by bridging 2,2-(1,4-butanediyl) bis-1,3-benzoxazole ligand: Syntheses, structures and properties

Reaction of 2,2-(1,4-butanediyl) bis-1,3-benzoxazole (BBO) ligand with [Cu(CH3CN)(2)(PPh3)(2)][X] (X = ClO4, PF6) afforded a copper(I) coordination polymer (CP) {[Cu(BBO)(PPh3)](ClO4)-Cl-center dot}(infinity) (1) and a binuclear complex [Cu-2(BBO)(PPh3)(4)](center dot)2PF(6)(center dot)2CH(2)Cl(2) (2) (where PPh3 = triphenylphosphine). Two complexes have been characterized. The structural analysis revealed that in complexes 1-2, all Cu(I) ions are tri-coordinated and the geometric structure around the central Cu(I) atom can be described as planar trigonal configuration. Complex 1 exhibits a one-dimensional coordination polymer by two BBO bridging adjacent copper(I) ions and extending along the b axis, forming a single-stranded helix chain structure that extends into 2-D layer frameworks through pi center dot center dot center dot pi interactions. Complex 2 shows a binuclear structure and the unit extends to a 2D supramolecular layered framework through C-H center dot center dot center dot F interactions. Moreover, compared with emissive bands of the free ligand in the solid state, the photoluminescent transition of the Cu(I) complexes 1-2 may be attributed to metal-to-ligand charge-transfer [MLCT]. (C) 2017 Elsevier B.V. All rights reserved.