Four new cadmium carboxyphosphonates with 2D layered and 3D supramolecular structure have been hydrothermally synthesized. Their luminescence and molecular recognition properties have been studied.

Three novel metal carboxyphosphonates with a 3D pillared-layered structure, namely, [Mn(HL)] (1), [Co(HL)]·H2O (2), and [Cd3(L2)(H2O)3] (3), (H3L = 4-HOOCC6H4CH2NHCH2PO3H2), have been hydrothermally synthesized. Compounds 1–3 all feature three-dimensional (3D) framework structures with two-dimensional (2D) inorganic layers pillared by H3L. In compounds 1 and 2, each {MO4} (M = Mn, Co) tetrahedron is linked via corner-sharing by three {CPO3} tetrahedra to form a two-dimensional (2D) inorganic layer. The adjacent layers are further pillared by the organic backbone {−C6H4CH2NHCH2−} of the carboxyphosphonate ligand, generating a 3D pillared-layered structure. For compound 3, interconnection of {Cd(1)O5N}, {Cd(2)O5N}, and {CPO3} polyhedra via edge- and corner-sharing forms a two-dimensional (2D) inorganic layer. Such neighboring 2D inorganic layers are further cross-linked via the organic backbone {−C6H4CH2NHCH2−} of the carboxyphosphonate ligands and {Cd(3)O6} polyhedra, generating a 3D pillared-layered structure. Surface photovoltage properties of the compounds 1 and 2 have been studied. An interesting feature of compound 2 is the presence of dehydration/hydration properties. The molecular recognition properties of compound 3 in alkyl alcohol emulsions have also been studied.

2 ), have been synthesized under mixed-solvothermal conditions and structurally characterized. Compounds 1 and 2 are isostructural and adopt a 3D framework structure. The {M(1)O 5 N} octahedra and {CPO 3 } tetrahedra are interconnected into a 1D chain via corner-sharing, which is further linked to adjacent chains through pyridyl rings to form a 2D layer structure. Neighboring layers are bridged through {M(2)O 6 }, leading to a 3D framework structure with a 1D channel system along the baxis. For compound 3, the {Zn(1)O 4 } and {Zn(2)O 4 } polyhedra are interconnected by phosphonate groups into a 1D double chain, and the double chain is further connected to adjacent chains through hydrogen bonds to form a 2D supramolecular network. Then these neighboring layers are further connected through hydrogen bonding interactions to give rise to a 3D supramolecular structure. Surface photovoltage spectroscopy (SPS) and field-induced surface photovoltage spectroscopy (FISPS) of compounds 1 and 2 indicate that they possess a positive SPV response in the range of 300-800 nm and show p-type semiconductor characteristics. Compound 3 has been realized for the sensitive sensing of N,N-dimethylformamide (DMF) by a luminescent method. † Electronic supplementary information (ESI) available: X-ray crystallographic les in CIF format for compounds 1 and 3. IR spectra of compounds 1-3, XRD patterns of the experiments compared to those simulated from X-ray single-crystal data for compounds 1-3, TG curves of compounds 1-3. CCDC 1040904 and 1040905. See Fig. 7 (a) The connectivity of hydrogen bonds for compound 3; (b) side view of the 3D supramolecular network connected by hydrogen bonds.This journal is