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A Cu(II)-methylmalonate complex, (C3H7N6)4[Cu(II)(C4H4O4)2](H2O)4Cl2(1) (where C3H7N6 = protonated melamine, C4H4O4 = methylmalonic acid), has been synthesized from aqueous media and its crystal structure was determined by single-crystal X-ray diffraction. The anionic Cu(II)-methylmalonate complex mediated formation of interesting supramolecular assemblies in the solid state by means of ionic interactions with protonated melamine. Moreover, other forces such as antielectrostatic H-bonding andπ+–π+interactions also play a crucial role in defining the final 3-D architecture of1. An interesting stacking among protonated melamine molecules is studied by DFT calculations. Lattice water molecules and chlorides form various hydrogen bonds to take part in the self-assembly processes. [ABSTRACT FROM AUTHOR]

Herein we report the synthesis and X-ray characterization of a neutral mercury(II) complex of composition [Hg(L) 2 ] n ( 1 ), [L = N 1 -(3-hydroxypropyl)-5-fluorouracilate]. The Hg(II) is bound to the N(3) atoms of both ligands in an essentially linear geometry. Mercury also interacts through short contacts with the O(4) atoms of the uracil rings. The two bases are almost coplanar. Surprisingly, two hydroxyl groups from two different units are also weakly bound in apical positions. Single-crystal X-ray crystallography showed that the molecular complex aggregates into a coordination polymer. The packing assemblies observed in the solid state have been analysed and studied by means of theoretical DFT calculations. Unprecedented antiparallel C O⋯C–F interactions are described since they have a strong influence in the crystal packing of the complex. We have also used the Cambridge Structural Database to examine the occurrence of C O⋯C–F interaction in the solid state of X-ray structures. [ABSTRACT FROM AUTHOR]

The present report describes the synthesis and structural characterizations of six new manganese(III) complexes with redox-active tetrachlorocatecholate ligand in the presence of different ancillary ligands (pyridines and imidazole). X-ray crystal structure analysis reveals that the geometry of manganese(III) centres in 1 and 2 is essentially square pyramidal, while it is discrete octahedron in compounds 3 – 6 . These preferential structural diversities in these systems have been critically analysed by theoretical calculations. Remarkably, the characterization of both π ⋯ π stacking interactions and Mn Mn bonds in the supramolecular dimeric aggregates in the solid state in 1 and 2 by means of the Bader's theory of “atoms in molecules” (AIM) is quite interesting as that nicely corroborates the experimental fact. All the complexes are active toward the phenoxazinone synthase like activity and the detailed kinetic analysis was performed to get better insight into their catalytic efficiency. Electrochemical property of these complexes as well as different donor property of the ancillary ligands clearly establish that the ease of reduction of the metal centre i.e., the catalytic ability is favoured when the metal centre is bonded to the electron deficient pyridyl systems. EPR spectroscopy and theoretical study are further helpful to get insight into origin of the catalytic activity in these compounds. The present report overall highlights that tuning of the geometry and catalytic activity of manganese(III) complexes with tetrachlorocatecholate ligand can be attained by the introduction of different substitutions in ancillary pyridine ligands. [ABSTRACT FROM AUTHOR]

Nickel(II), cobalt(II) and zinc(II) mononuclear Schiff base complexes of general formula [M II L(H 2 O) 3 ]·2H 2 O (where M = Ni, Co and Zn) have been synthesized using a new Schiff base ligand (LH 2 = 2-((Pyridin-2-yl)methyleneamino)benzene-1,4-dioic acid). All the complexes and the ligand have been characterized by various physical measurements such as elemental analyses, FT-IR and UV–Vis spectroscopic techniques. The crystal structure analyses of the complexes revealed that extensive supramolecular interactions such as hydrogen bond and π – π stacking results 3D array of packing. The hydrogen bonding interaction distances are very similar in all complexes and are around 2.0 Å and for the π – π interactions the values are close to 3.8 Å. The interaction energies are comparable for Ni and Co complexes and is somewhat stronger for Zn complex. The strength of the aforementioned interactions have been evaluated by means of DFT calculations. For in vitro antimicrobial activity study, the complexes were screened against some bacteria and fungi. This study shows that the zone of inhibition against growth of microorganisms is much larger for Zn complex due to strong binding energy. The Hirshfeld surfaces of Ni, Co and Zn complexes were also analyzed to clarify the nature of the intermolecular interactions. Thermogravimetric analyses were performed to investigate the thermal stability of the complexes. [ABSTRACT FROM AUTHOR]