0D, 2D and 3D metal phosphonates assembled from a new 2′-carboxybiphenyl-4-ylmethylphosphonic acid: Syntheses, topological structures and photoluminescent properties

Abstract

A series of metal phosphonates, namely, [Cu(HL)(H₂O)] (1), [Cu₅(L)₂(OH)₄]·H₂O (2), [Zn₃(L)₂(H₂O)] (3), [Zn₃(L)₂(phen)₂(H₂O)₂] (4), [Cd₃(L)₂(H₂O)₂] (5), [Cd₂(L)(OH)(H₂O)_1.5] (6), and [Cd(HL)(phen)₂]·2.5H₂O (7), where H₃L = 2′-carboxybiphenyl-4-ylmethylphosphonic acid, and phen = 1,10-phenanthroline, have been synthesized under hydrothermal conditions. Compound 1 exhibits a 2D layer structure with the 4-connected (4²·6⁴) topology. Compound 2 shows a 2D (3,10)-connected (3²·6)(3⁸·4⁸·5¹²·6⁹·7⁴·8⁴) topology. Compound 3 displays a 2D (3,6)-connected (4²·6)₂(4⁷·6⁶·8²) topology. Compound 4 is a 3D framework with the (4²·6)₂(4⁷·6⁶·8²) topology. Compound 5 shows a 2D (4,6)-connected (4⁴·6²)(4⁶)(4¹⁰·6⁵) topology. Compound 6 exhibits a 2D (3,6)-connected (4²·6)(4⁶·6⁶·8³) topology. Compound 7 displays a 0D closed loop structure. Furthermore, compounds 1, 5 and 7 are consolidated by the intramolecular O–H⋯O hydrogen bonds. All the compounds have been characterized by infrared spectra (IR), elemental analyses, powder X-ray diffraction (PXRD) and thermogravimetric (TG) analyses. The luminescent properties of 3–7 have also been studied.