Zn(ii) and Cu(ii) coordination polymers assembled from V-shaped tetracarboxylate ligands and N-donor ancillary ligands: syntheses, structures and properties

Abstract

Six novel zinc(II) and cupric(II) metal coordination polymers with V-shaped ligands and N-donor ligands, [Zn₂(SA)(phen)₂]·2H₂O (1), Zn₂(FA)(phen)₂(H₂O)·H₂O (2), Cu₃(H₂FA)₃(phen)₃·H₂O (3), Cu(H₂FA)(2,2′-bipy)·1.54(H₂O) (4), [Cu₂(SA)(4,4′-bipy)_1.5]·2.7(H₂O) (5) and [Zn₂(SA)(4,4′-bipy)₂]·8H₂O (6) (H₄SA = 3,3′,4′,4′-diphenyl-sulfonetetracarboxylate acid, H₄FA = 4,4′-(hexafluoroisopropylidene)diphthalic acid, phen = 1,10-phenanthroline, 2,2′-bipy = 2,2′-bipyridine and 4,4′-bipy = 4,4′-bipyridine), have been synthesized and structurally characterized by elemental analysis, IR and X-ray diffraction. Complex 1 has a two-dimensional (2D) layer network, whereas complex 2 exhibits a 1D helical chain structure because of the introduction of a H₄FA ligand. Complex 3 shows a complicated 2D framework. Complex 4 has a 1D chiral structure with an open channel by incorporating the auxiliary ligand 2,2′-bipy, while complexes 5 and 6 have a complicated 3D framework which is of particular interest because it adopts interesting and rare framework topologies. The results indicate that the multicarboxylate H₄SA and H₄FA ligand can adopt varied coordination modes in the formation of the complexes and the configuration and flexibility of the ligands play a key role in directing the related properties of the complexes. The photoluminescence properties of H₄SA and H₄FA, 1, 2, 6 were studied in the solid state at room temperature. Moreover, nonlinear optical measurements showed that 4, 5 displayed a second-harmonic-generation (SHG) response of 0.8 and 0.7 times that for urea, respectively.