Syntheses, structures, and photoluminescent properties of a series of coordination polymers based on a new 2′-carboxybiphenyl-4-ylmethylaminodiacetic acid and different N-donor ligands

Abstract

Ten new coordination polymers have been synthesized under hydrothermal conditions, namely, [Co₃(L)₂(H₂O)₃]·2H₂O (1), [Zn₃(L)₂(H₂O)₃]·2H₂O (2), [Co₃(L)₂(4,4′-bipy)₂(H₂O)₄] (3), [Ni₃(L)₂(pbib)₃(H₂O)₂]·4H₂O (4), [Co₃(L)₂(bbtz)₂(H₂O)₆]·2H₂O (5), [Ni₃(L)₂(bbtz)₂(H₂O)₆]·2H₂O (6) [Zn₃(L)₂(bbtz)₂(H₂O)₆]·2H₂O (7), [Co₃(L)₂(pbib)₂(H₂O)₄]·4H₂O (8), [Co₃(L)₂(biim-4)₂(H₂O)₄]·4H₂O (9), and [Ni(L)(H₂O)₂]·H₂O (10), where H₃L = 2′-carboxybiphenyl-4-ylmethylaminodiacetic, 4,4′-bipy = 4,4′-bipyridine, pbib = 1,4-bis(imidazole-1-ylmethyl)-benzene, bbtz = 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene, and biim-4 = 1,1′-(1,4-butanediyl)bis(imidazole). Their structures were characterized by infrared spectra (IR), powder X-ray diffraction (PXRD), and elemental analyses. Compounds 1 and 2 are isomorphous, and show the same 3D (3,4)-connected net with the (4·10²)(4·8⁵) topology. Compound 3 displays a typical 3D (3,4)-connected net with the (4·10·12)₂(10·11·12⁴) topology. Compound 4 reveals a 3D (3,6)-connected net with the (4·6²)₂(6⁴·8⁸·10³) topology. Compounds 5–7 are isomorphous, and feature crystallographically distinct chains. Neighboring chains are stacked by π–π interactions to form 2D supramolecular layers, which are further extended by hydrogen-bonding interactions to form a 3D supramolecular architecture. Compounds 8 and 9 are essentially isomorphous with 5, and exhibit crystallographically distinct 1D chain structures. Adjacent chains are further extended into a 3D supramolecular architecture by hydrogen-bonding interactions. Compound 10 shows 1D chains, which are further linked by intermolecular hydrogen bonding interactions to generate a 2D supramolecular layer. The effects of the N-donor ligands and the coordination modes of L anion on the structures of the coordination polymers have been discussed in detail. In addition, the luminescent properties of compounds 2 and 7 have also been studied.