Synthesis and Structures of New Pyromellitate Coordination Polymers with Piperazine as a Ligand

Abstract

Two new coordination polymers of the pyromellitic acid, [Zn(2)(H(2)O)(C(10)H(2)O(8))(C(4)N(2)H(8))]( infinity ), I, and [Cd(4)(H(2)O)(2)(C(10)H(2)O(8))(2)(C(4)N(2)H(8))(3)]( infinity ), II, have been prepared employing hydrothermal methods in the presence of piperazine. The structures have three-dimensional connectivity involving both the carboxylate and the amine molecule. The amine molecule acts as a ligand connecting two different metal centers giving rise to a simple dimer in I, and a two-dimensional layer structure in II. There are two types of pyromellitates in I and only one type in II. Of the two types of acids in I, acid-1 has all the oxygen atoms connected to Zn with monodendate connectivity and acid-2 has only four monodendate connectivity and possesses four terminal C-O linkage. In II, two of the carboxylates have bidendate connectivity and the other two have monodendate connectivity and possess one terminal C-O bond. The projection of the bound amine molecules, in II, into the large elliptical channels is noteworthy. These amine molecules may be amenable for chemical manipulations. Both the coordination polymers exhibit photoluminescence at room temperature, the main emission being at 380 and 410 nm, respectively, for I and II, which is due to the ligand-to-metal charger transfer (LMCT).

Crystal structure of hexaaquamagnesium(II) 3,3'-azobenzenedicarboxylate — 1,2-di(4-pridyl)ethylene — water (1:1:2), [Mg(H2O)6][C14H8N2O4] ·C12H10N2 ·2H2O

“…Hydrogen bond, one of the weak intermolecular interactions, is the most powerful tool among the directional intermolecular interactions in supermolecular assembly, and operative in determining the molecular conformation, supramolecular aggregation, and function of alarge number of chemical systems such as organic, material and biological chemistry [1][2][3][4][5][6][7][8][9][10]. Using a "building block" methodology, anumber of discrete and awide range of infinite solid-state coordination frameworks have already been generated with simple organic spacers, such as 1,2-di(4-pridyl)ethylene (bpe).…”

Crystal structure of 4,4'-bipyridine 3-(sulfonyl-glycine)benzoic acid (1:1), C10H8N2 · C6H5O6S

“…Beside from the fundamental and strong metal-ligand coordination driven force, other relatively weak intermolecular interactions such as hydrogen bonding and aromatic stacking are also useful tools in construction of the crystalline materials, and a variety of infinitely extended networks have been generated via interplay of these valid interactions [1][2][3][4][5][6][7][8][9][10]. Using a building block methodology, a number of discrete and a wide range of infinite solid-state coordination frameworks have already been generated with simple organic spacers, such as 4,4-bipyridine.…”

Crystal structure of tetrakis(melaminium) 1,2,4,5-benzenetetracarboxylate octahydrate, (C3H7N6)4[C6H2(COO)4] · 8H2O

“…Of particular interest are compounds that are capable of forming very strong hydrogen bonds like some salts of pyromellitic acid. The 1,2,4,5-benzenetetracarboxylic acid, also known as pyromellitic acid, possesses several interesting characteristics: (a) it has four carboxyl groups which may be completely or partially deprotonated, inducing rich coordination modes and allowing interesting structures with higher dimensions; (b) it can act not only as hydrogen-bond acceptor but also as hydrogen-bond donor, depending upon the numbers of deprotonated carboxyl groups [1][2][3][4][5][6][7][8]. The structure of the title compound comprises four melamine cations, a 1,2,4,5-benzenetetracarboxylate anion and four water molecules (figure, top).…”