Pyridine-and imidazoledicarboxylates of zinc: hydrothermal synthesis, structure, and properties

The reaction of hetrocyclic dicarboxylic acids, such as pyridine-2,5-dicarboxylic acid and imidazole-4,5-dicarboxylic acid, under hydrothermal conditions in the presence of an appropriate zinc salt yields three new zinc coordination polymers 0∞[{Zn2(H2O)4}{C5H3N(COO) 2}2] (1), 1∞ [{Zn(C12H8N2)}{C5H3N(COO) 2}·0.5H2O] (2), and 1∞ [{Zn(C12H8N2)}{C3HN2(COO) 2}] (3). While 1 forms with a zero-dimensional molecular rectangular box structure, 2 and 3 have zig-zag one-dimensional chain structures. The Zn2+ ions are coordinated by both the carboxylate oxygen atoms and also by the nitrogen atoms of the heterocycles. The 1,10-phenanthroline molecules in 2 and 3 act as a secondary ligands and occupy the inter-chain spaces. The moderate hydrogen-bond interaction energy in 1 and the π···π interactions in 2 and 3 appear to play an important role for the structural stability. The structures of 2 and 3 appear to be related, even though they are formed with different carboxylic acids. All three compounds exhibit photoluminescence at room temperature

New photocatalysts based on mixed-metal pyridine dicarboxylates

New photocatalytically active isostructural two-dimensional mixed metal-pyridine dicarboxylates, [M(H2O)3Co{C5N1H3(COO) 2}3])∞], M = Gd (1), Dy (2) and Y (3) have been prepared under hydrothermal conditions. The structure consists of a network of MO6(H2O)3, CoO3N3 polyhedral units connected by the pyridine dicarboxylates forming two-dimensional layers, which are arranged in an AAAA... fashion. The photocatalytic studies on 1 - 3 indicate that they are active catalysts for the degradation of simple organic dyes, such as Remazol brilliant blue R (RBBR) and Orange G (OG) in the presence of UV light. The compounds have also been characterized by powder XRD, IR, TGA, UV-Vis and magnetic studies

Synthesis, structure and optical properties of rare-earth benzene carboxylates

Two series of rare-earth isophthalates of the general formula, [M2(H2O)] [{C6H4(COO)2}2{C6H4(COOH)(COO)}2]·H2O, M = La (I), Pr (Ia), and Nd (Ib) and [M2(H2O)2][{C6H4(COO)2}3]·H2O, M = Y (II), Gd (IIa), and Dy (IIb) have been prepared by the reaction of the corresponding trivalent lanthanide salts and isophthalic acid under mild hydrothermal conditions. The La (I), Pr (Ia) and Nd (Ib) have MO9 polyhedra connected to the isophthalate anions forming a two-dimensional structure, whereas Y (II), Gd (IIa) and Dy (IIb) have MO7 and MO8 polyhedral units connected to the isophthalate anions forming a different, but related two-dimensional structure. Both the structures are stabilized by hydrogen bonding and π···π/CH···π interactions. Partial substitution of Eu and Tb (2 and 4%) at the La (I) and Y (II) sites give rise to characteristic red/pink or green luminescence, indicating a ligand-sensitized metal-centered emission. The Nd (Ib) compound shows interesting UV and blue emission through an up-conversion process

Glucose directly promotes antifungal resistance in the fungal pathogen, Candida spp

Effects of glucose on the susceptibility of antifungal agents are investigated against Candida spp. Increasing the concentration of glucose decreased the activity of antifungal agents, voriconazole was mostly affected drugs followed by amphotericin B. No significant change has been observed for anidulafungin. Biophysical interaction between antifungal agents with glucose molecules were investigated using ITC, FTIR and 1HNMR. Glucose have higher affinity to bind with voriconazole by hydrogen bonding and decrease the susceptibility. In addition to confirm the results observed in vitro, theoretical docking studies demonstrated that voriconazole presented three important hydrogen bonds and amphotericin B presented two hydrogen bonds that stabilized the complex compound-glucose. In vivo results also suggest that the physiologically relevant higher glucose level in blood stream of Diabetes Mellitus (DM) mice might interact with the available selective agents during antifungal therapy, decreased the activity by complex formation. Thus, selection of drugs for DM patient is important to control the infectious diseases

The use of hydrothermal methods in the synthesis of novel open-framework materials

The preparation of inorganic compounds, exhibiting open-framework structures, by hydrothermal methods has been presented. To illustrate the efficacy of this approach, few select examples encompassing a wide variety and diversity in the structures have been provided. In all the cases, good quality single crystals were obtained, which were used for the elucidation of the structure. In the first example, simple inorganic network compounds based on phosphite and arsenate are described. In the second example, inorganic-organic hybrid compounds involving phosphite/arsenate along with oxalate units are presented. In the third example, new coordination polymers with interesting structures are given. The examples presented are representative of the type and variety of compounds one can prepare by careful choice of the reaction conditions

Non-carboxylate based metal-organic frameworks (MOFs) and related aspects

The metal-organic frameworks, in recent years, show a variety of new developments that includes new methods of preparation, post synthesis modifications and novel class of compounds. Though most of the developments happened in the carboxylate based family of compounds, the other related systems are also equally interesting. In this article,we have highlighted some of the developments that have taken place in the family of non-carboxylate metal-organic frameworks. We have also highlighted some of the recent attempts at modifying the surfaces and pores of the MOFs by careful chemical manipulations. (C) 2009 Elsevier Ltd. All rights reserved

A New Series of Three-Dimensional Metal-Organic Framework, [M2(H2O)][C5N1H3(COO)2]3⋅2H2O,M=La,Pr,[M_2(H_2O)][C_5N_1H_3(COO)_2]_3\cdot 2H_2O, M = La, Pr, and Nd: Synthesis, Structure, and Properties

A new series of lanthanide pyridine dicarboxylates of the general formula, $[M_2(H_2O)][C_5N_1H_3(COO)_2]_3\cdot 2H_2O$, M= La (1), Pr (2), and Nd (3), has been prepared by the reaction of trivalent lanthanide salts and pyridine dicarboxylic acids employing a mild condition hydrothermal reaction. The structures are built up from $MO_8N$ and $MO_7N_2$ (M= lanthanide) polyhedra connected to the dicarboxylate anions forming the three-dimensional structure with onedimensional channels. A striking feature of this structure is the presence of an unusual Z-shaped tetramer of the formula $M_4O_{24}N_6$. Extraframework water molecules, located within the open channels, are reversibly adsorbed. Detailed in situ and ex situ investigations using FTIR and PXRD studies clearly show that the removal of the water molecules is reversible and accompanied by changes in the size of the channel. Partial substitution at the La sites by Eu gives rise to characteristic red-pink luminescence, indicating a ligand-sensitized metal-centered emission

The first observation of a Na2TiS2 related structure in a 2-D anionic manganese trimesate intercalated by cationic imidazole

A hydrothermal reaction of Mn(OAc)2·4H2O, trimesic acid, imidazole, KOH and water at 75 °C for 24 h gave rise to a 2-D compound, [HImd][Mn(BTC)(H2O)] (Imd = imidazole; BTC = trimesate), with protonated imidazole molecules occupying the inter-lamellar space, and the structure resembles the classic inorganic compound, the sodium intercalated TiS2 (Na2TiS2)

Metal-organic framework structures - how closely are they related to classical inorganic structures?

Metal-organic frameworks (MOFs) have emerged as an important family of compounds for which new properties are increasingly being found. The potential for such compounds appears to be immense, especially in catalysis, sorption and separation processes. In order to appreciate the properties and to design newer frameworks it is necessary to understand the structures from a fundamental perspective. The use of node, net and vertex symbols has helped in simplifying some of the complex MOF structures. Many MOF structures are beginning to be described as derived from inorganic structures. In this tutorial review, we have provided the basics of the node, the net and the vertex symbols and have explained some of the MOF structures. In addition, we have also attempted to provide some leads towards designing newer structures/topologies