Huizhen Zhu

Metal–organic frameworks constructed from mixed-ligand 1,2,3,4-tetra-(4-pyridyl)-butane and benzene-polycarboxylate acids: syntheses, structures and physical properties

Three novel coordination polymers, [Mn(TPB)0.5(IPA)(H2O)2]n (1), [Zn1.5(TPB)0.5(TMA)(H2O)·(H2O)]n (2), and [Co(TPB)0.5(PMA)0.5(H2O)2·(H2O)]n (3) (TPB = 1,2,3,4-tetra-(4-pyridyl)-butane; H2IPA = isophthalic acid; H3TMA = trimesic acid; and H4PMA = pyromellitic acid), have been synthesized under hydrothermal conditions and structurally characterized. Complex 1 features a 2D infinite layer framework consisting of bi-manganese clusters, which is further stacked along the [11] direction via strong interlayer π⋯π interactions to form a 3D supramolecular architecture. Complex 2 has a 3D complicated framework comprised of two kinds of infinite 1D chains. The 3D framework of complex 3 possesses three topologically nonequivalent 4-connected nodes synchronously and exhibits an unprecedented (64·102)(42·84)(4·65)2 topology. The magnetic susceptibility data of complex 1 show strong antiferromagnetic interactions in the dinuclear Mn(II) units. Complex 2 exhibits strong fluorescent emissions in the solid state at room temperature and may be suitable as a candidate of blue-fluorescent material.

Two types of novel layer framework structures assembled from 5-sulfosalicylic acid and lanthanide ions

Hydrothermal reactions of lanthanide chlorides with 5-sulfosalicylic acid (H3SSA) led to seven novel coordination polymers, [Ln(SSA)(H2O)2]n·nH2O [Ln = Gd (1, Sm (2, Nd (3, Tb (4, Eu (5, Yb (6 and Dy (7]. Their structures have been established by X-ray single crystal diffraction. Complexes 1–5 are isostructural and feature 2D wavelike layers, while the isostructural 6 and 7 feature 2D flat layers. All these 2D layers are further interlinked via hydrogen bonds resulting in 3D architecture. In addition, complex 4 exhibits strong and sharp emission bands in the visible region.

Design and constructions of three novel metal–organic frameworks based on pillared-layer motifs

Three novel 3D metal–organic frameworks, [Co2(butca)(o-bix)2·8H2O]n (1), [Co2(butca)(m-bix)2·2H2O]n (2) and [Co2(butca)(p-bix)2·3H2O]n (3) (butca = 1,2,3,4-butane-tetracarboxylic acid; o-bix = 1,2-bis(imidazol-1-ylmethyl)-benzene; m-bix = 1,3-bis(imidazol-1-ylmethyl)-benzene; and p-bix = 1,4-bis(imidazol-1-ylmethyl)-benzene), have been successfully synthesized from a 2D layer compound [Co2(butca)(H2O)5·2H2O]n (0) employing a three isomer pillars insertion reaction, and their structures were determined by single-crystal X-ray diffraction studies. Complexes 1 and 2 are isostructural. Interestingly, there exist metal-bix double-helical chains in these two 3D frameworks, which are arranged left- and right-handed alternately. Different from 1 and 2 which have only one coordination model, Co atoms in 3 have two types of different coordination enviroments. The Co1 ions are exclusively bridged by cis-bix ligands to give one 26-number ring through spontaneous resolution. At the same time, the Co2 ions are wholely connected with tran-bix ligands to form a 1-D zigzag chain. Moreover, the relationship between a 2D layer structure and 3D metal–organic frameworks based on the pillared-layer motifs is discussed. This work has significant potential for the study of crystal engineering of transition metal coordination networks.