Ren-Gen Xiong

Bio: Ren-Gen Xiong is an academic researcher from University of Puerto Rico. The author has contributed to research in topics: 4,4'-Bipyridine. The author has an hindex of 1, co-authored 1 publications receiving 75 citations.

Functional Micropore Chemistry of Crystalline Metal Complex-Assembled Compounds

Abstract: Syntheses of new porous frameworks with specific pore size and type are of considerable interest for the appearance of zeolite-like functionalities. It is useful to take advantage of metal complex-assembled compounds because of designable frameworks, high microporosity, and flexible frameworks based on a variety of coordination geometries of metal centers and multifunctionality of bridging organic parts. Many recent reports show that the synthesis procedures are developing from serendipitious to rational level. Therefore, the micropore chemistry of metal complex-based assemblages is directed toward not only new frameworks but also functionalities such as gas and small molecule adsorption, ion exchange, heterogeneous catalysis, photo-chemical and -physical properties. For chemical and physical functionalities robustness of a framework is required even in the absence of guest molecules in the cavity. The stability is largely dependent on the structural dimensionality of the assemblages. A wide variety of st...

Cyano-Bridged Re6Q8 (Q = S, Se) Cluster-Cobalt(II) Framework Materials: Versatile Solid Chemical Sensors

Abstract: Face-capped octahedral clusters of the type [Re6Q8(CN)6]4- (Q = S, Se) are used to space apart partially hydrated Co2+ ions in extended solid frameworks, creating porous materials that display dramatic color changes upon exposure to certain organic solvents. The clusters react with cobaltous ions in aqueous solution to precipitate the new solid phases [Co2(H2O)4][Re6S8(CN)6]·10H2O (1), Cs2[Co(H2O)2][Re6S8(CN)6]·2H2O (2), and [Co(H2O)3]4[Co2(H2O)4][Re6Se8(CN)6]3·44H2O (3). The structures of 1·2H2O and 3 were determined by single-crystal X-ray analysis. The former consists of an expanded Prussian blue type framework with [Re6S8]2+ and [Co2(μ-OH2)2]4+ cluster cores occupying alternate metal ion sites, and features cubelike cages enclosing water-filled cavities approximately 258 A3 in volume. The latter structure exhibits a network of Co2+ ions and [Co2(μ-OH2)2]4+ cores connected through [Re6Se8(CN)6]4- clusters, defining an array of one-dimensional channels with minimum internal diameters of 4.8 A. A Rietvel...

Hydrothermal synthesis and crystal structures of three-dimensional co-ordination frameworks constructed with mixed terephthalate (tp) and 4,4′-bipyridine (4,4′-bipy) ligands: [M(tp)(4,4′-bipy)] (M = CoII, CdII or ZnII)

Abstract: Three new metal–organic co-ordination frameworks formulated as [M(tp)(4,4′-bipy)] [M = CoII1, CdII2 or ZnII3; tp = terephthalate; 4,4′-bipy = 4,4′-bipyridine] have been hydrothermally prepared and structurally characterized. Each pair of metal atoms in the three compounds are bridged by bis-bidentate or chelating/bridging bis-bidentate tp ligands to form a linear or zigzag co-ordination chain, and adjacent chains are further linked by chelating or monodentate bis-bidentate tp ligands to form two-dimensional rectangular or parallelogram-like [M(tp)] sheets with dimensions of 10.30 × 11.37, 10.08 × 11.68 and 10.28 × 10.98 A for complexes 1, 2 and 3, respectively. Adjacent sheets are pillared by 4,4′-bipy spacers into a three-dimensional co-ordination network through the covalently linking mode of ⋯4,4′-bipy–MII–4,4′-bipy–MII⋯, which feature cuboidal [M16(tp)8(4,4′-bipy)8] structural units. Twofold interpenetration of the above three-dimensional co-ordination networks results in stable crystal structures of the three compounds.

A second-order nonlinear optical material prepared through in situ hydrothermal ligand synthesis.

Abstract: The in situ hydrothermal reactions of ZnCl2 with benzonitrile, 2-amino-5-cyanopyridine, and trans-2,3-dihydro-2-(4‘ ‘-cyanophenyl)-benzo[e]indole in the presence of NaN3 and water afford two 3D-diamond-like networks, (CN4−C6H5)2Zn (1) and (NH2−C5H3N−CN4)2Zn (2), and one 2D square grid network, [(CN4−C6H4−C12H7N−C5H4N)2Zn]·1.5H2O (3), in which these ligands gradually involve a noncenter-A−D (acceptor−donor) system, a one-center-A−D system, and a two-center-A−D system, respectively. All three compounds crystallize in noncentrosymmetric space groups (I42d for 1 and 2 and Fdd2 for 3) and display strong second harmonic generation (SHG) responses. Among the three new complexes, 3 shows the largest SHG effect, which is about 50 and 500 times that of urea and KDP (KH2PO4), respectively. The two-center-A−D system (multicenter push−pull electronic effect) in 3 may be responsible for it having the largest SHG effect. Interestingly, the three compounds exhibit strong fluorescent emissions at different wavelengths, 1...