Xiao-Li Chen

Four novel Zn(II)/Cd(II) metal–organic frameworks constructed from 4′-(4-pyridyl)-4,2′:6′,4″-terpyridine: hydrothermal synthesis, crystal structures, and luminescent properties

Four novel polymeric frameworks, [Zn(pytpy)Cl2]n (1), [Zn2(pytpy)2(ox)2]n·n(H2O) (2), [Cd(pytpy)(mal)]n·n(H2O) (3) and [Zn2(pytpy)(btc)(OH)]n (4), (pytpy = 4′-(4-pyridyl)-4,2′:6′,4″-terpyridine, H2ox = oxalic acid, H2mal = malic acid and H3btc = 1,3,5-benzenetricarboxylic acid) have been hydrothermally synthesized and structurally characterized. Compound 1 shows infinite helical chains, which are extended into a 3D supramolecular network by intermolecular hydrogen bonds. In the structure of 2, there is coexistence of left- and right-handed helical chains arranged alternately to generate a 2D layer. In 3, an in-situ reaction occurred, maleic acid was converted to malate by the hydroxylation of the ethylene group to prepare the microporous architecture. Compound 4 is a two-fold interpenetrating 3D ploymeric network with an intriguing topological structure. The luminescence properties of 1–4 have been investigated with fluorescence emission spectra and the UV-vis diffuse reflectance spectra in the solid state. Additionally, these four compounds possess great thermal stabilities, especially for 2, the framework is stable up to 400 °C.

Syntheses, crystal structures and luminescence of 2,6- bis - (5-phenyl-1H-pyrazol-3-yl)pyridine and its d10 metal complexes

A new bis-pyrazole derivative, 2,6-bis-(5-phenyl-1H-pyrazol-3-yl) pyridine (H2BPPP), and two d10 metal complexes [Zn(H2BPPP)Cl2](DMF)2 (1), [Cd(H2BPPP)Cl2](DMF)2 (2) have been synthesized and characterized. There is a tautomeric equilibrium of the bis-pyrazole compound in solution and the H atom of pyrazolyl NH can transfer to the adjacent N atoms. X-ray structure analyses reveal the H atom is on the 2-position of pyrazolyl ring in donor solvents, while the H atom is on the 1-position of pyrazolyl ring in metal complexes. The luminescence of the ligand and complexes have been investigated.

Syntheses and characterizations of two metal-organic polymers derived from pyridyl substituted terpyridine and 4,5-imidazole dicarboxylate

Two metal-organic coordination polymers, [Cd(HIDC)(pytpy)] (1) and [Zn(HIDC)(pytpy)] · (H2O) (2), have been synthesized by reactions of 4′-(3-pyridyl)-2,2′ : 6′,2″-terpyridine (pytpy), 4,5-imidazoledicarboxylic acid (H3IDC) with CdCl2 · 2.5H2O and ZnCl2, respectively, in the presence of base. Compound 1 is a one-dimensional (1-D) helical chain with the chains extended into a three-dimensional supramolecular network through two different π ··· π interactions from pytpy ligands. Compound 2 is also a 1-D helical chain and adjacent chains are packed into a 2-D layer through π ··· π interactions between terminal pyridyl and pendant pyridyl rings from pytpy ligands. The photoluminescent properties of the two compounds are also investigated.

Synthesis, structure, and characterization of a silver(I) coordination polymer with μ6-bridging 2,2′-bipyridyl-3,3′-dicarboxylate

A silver(I) coordination polymer, [Ag2(bpdc)] n (1) (H2bpdc = 2,2′-bipyridyl-3,3′-dicarboxylic acid), has been synthesized and characterized. Compound 1 exhibits a 2-D network containing 1-D channels. Each (bpdc)2− is an octadentate μ6-1igand coordinating with six Ag(I)s in 1. This coordination of (bpdc)2− ligand is first observed here. Neighboring networks are arranged in a [ABAB···] pattern to form 3-D supramolecular architecture by π···π stacking. Compound 1 shows intense photoluminescence at room temperature.