Organotin(IV) esters of (E)‐3‐furanyl‐2‐phenyl‐2‐propenoic acid: Synthesis,investigation of the coordination modes by IR,multinuclear NMR (1H, 13C, 119Sn) and In Vitro biological studies

Complexes [Me₂SnL₂ ( I ), Me₃SnL ( II ), Et₂SnL₂ ( III ), n‐Bu₂SnL₂ ( IV ), n‐Bu₃SnL ( V ), n‐Oct₂SnL₂ ( VI )], where L is (E)‐3‐furanyl‐2‐phenyl‐2‐propenoate, have been synthesized and structurally characterized by vibrational and NMR (¹H, ¹³C and ¹¹⁹Sn) spectroscopic techniques in combination with mass spectrometric and elemental analyses. The IR data indicate that in both the di‐ and triorganotin(IV) carboxylates the ligand moiety COO acts as a bidentate group in the solid state. The ¹¹⁹Sn NMR spectroscopic data, ¹J[¹¹⁹Sn,¹³C] and ²J[¹¹⁹Sn, ¹H], coupling constants show a four‐coordinated environment around the tin atom in triorganotin(IV) and five‐coordinated in diorganotin(IV) carboxylates in noncoordinating solvents. The complexes have been screened against bacteria, fungi, and brine‐shrimp larvae to assess their biological activity. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:612–620, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20488     

Synthesis, chemical characterization and biological screening for cytotoxicity and antitumor activity of organotin (IV) derivatives of 3,4-methylenedioxy 6-nitrophenylpropenoic acid

A series of mono-, di- and triorganotin compounds with general formulae [RSnL(2)Cl], R = Bu (compound 3), [R(2)SnL(2)], where R = Me, Et, Bu, Oct (compounds 1, 2, 4 and 6) and [R(3)SnL], where R = Bu, Cy and Ph (compounds 5, 7 and 8) and where L = 3,4-methylenedioxy-6-nitrophenylpropenoic acid have been prepared and characterized by elemental analysis, multinuclear ((1)H-, (13)C- and (119)Sn-) NMR and mass spectrometry. The ligand and its respective organotin complexes were screened for cytotoxicity using the brine shrimp lethality assay and for antitumor activity using the crown gall tumor inhibition (potato disc) assay. The bioassay results support the conclusion that the biological activities of these synthetic compounds are in the following order: [RSnL(2)Cl] < [R(2)SnL(2)] < [R(3)SnL].     

(N‐Maleoylglycinato)trimethyltin(IV)

The Sn atom in the crystal structure of the title compound,catena‐poly­[trimethyl­tin‐μ‐[(2,5‐di­oxo‐2,5‐di­hydro­pyrrol‐1‐yl)­acetato‐O:O′]], [Sn(CH₃)₃(C₆H₄NO₄)], adopts a distorted trigonal bipyramidal coordination geometry with three methyl groups defining the trigonal plane [mean Sn—C 2.117 (11) Å] and the axial positions occupied by O atoms from different carboxylate groups, with significantly different Sn—O bond lengths [2.207 (5) and 2.358 (6) Å]. The structure forms a polymeric chain of complex molecules linked via carboxylate moieties.     

GGA and GGA + U Study of ThMn2Si2 and ThMn2Ge2 Compounds in a Body-Centered Tetragonal Ferromagnetic Phase

Our study used the full-potential linearized augmented plane waves (FP-LAPW) method to conduct a first-principles evaluation of the structural, electronic, and magnetic properties of ThMn₂X₂ (X = Si and Ge) compounds. To establish theoretical dependability with the currently available experimental results, computations for the structural findings of ternary intermetallic thorium (Th)-based compounds were achieved using the generalized gradient approximation in the scheme of Perdew–Burke–Ernzerhof (PBE–GGA) potential, while the generalized gradient approximation plus the Hubbard U (GGA + U) approach was employed to improve the electrical and magnetic properties. In contrast with both the paramagnetic (PM) and antiferromagnetic (AFM) phases, the ThMn₂X₂ compounds were optimized in a stable ferromagnetic (FM) phase, which was more suited for studying and analyzing magnetic properties. The electronic band structures (BS) and the density of state (DOS) were computed using the two PBE–GGA and GGA + U approximations. The thorium (Th)-based ThMn₂X₂ compound has full metallic character, due to the crossing and overlapping of bands across the Fermi level of energy, as well as the absence of a gap through both spin (up and down) channels. There was a significant hybridization between (Mn-d and (X = Si and Ge)-p states of conduction band with Th-f states in the valence band. The total magnetic moment of ThMn₂Si₂ in the ferromagnetic phase was 7.94534 μB, while for ThMn₂Ge₂ it was 8.73824 μB with a major contribution from the Mn atom. In addition, the ThMn₂Ge₂ compound’s total magnetic moment confirmed that it exhibits higher ferromagnetism than does the ThMn₂Si₂ compound.     

Electrostatic Perturbations from the Protein Affect C−H Bond Strengths of the Substrate and Enable Negative Catalysis in the TmpA Biosynthesis Enzyme

The nonheme iron dioxygenase 2-(trimethylammonio)-ethylphosphonate dioxygenase (TmpA) is an enzyme involved in the regio- and chemoselective hydroxylation at the C¹-position of the substrate as part of the biosynthesis of glycine betaine in bacteria and carnitine in humans. To understand how the enzyme avoids breaking the weak C²−H bond in favor of C¹-hydroxylation, we set up a cluster model of 242 atoms representing the first and second coordination sphere of the metal center and substrate binding pocket, and investigated possible reaction mechanisms of substrate activation by an iron(IV)-oxo species by density functional theory methods. In agreement with experimental product distributions, the calculations predict a favorable C¹-hydroxylation pathway. The calculations show that the selectivity is guided through electrostatic perturbations inside the protein from charged residues, external electric fields and electric dipole moments. In particular, charged residues influence and perturb the homolytic bond strength of the C¹−H and C²−H bonds of the substrate, and strongly strengthens the C²−H bond in the substrate-bound orientation.     

An Unusual Diorganotin Bis-carboxylate Structure: catena-{(μ2-2-methyl-3,5-dinitrobenzoato-O,O′)dibutyltin(IV)}

Abstract  

The structure of n-Bu₂Sn(2-methyl-3,5-dinitrobenzoato)₂ (1) presents a rare structural motif for compounds with the general formula R ₂Sn(O₂CR′)₂ which almost exclusively adopt skew-trapezoidal bipyramidal geometries. By contrast, the structure of (1) is polymeric with the polymer backbone comprising eight-membered {SnOCO}₂ rings linked at the pivotal tin atoms. The coordination geometry is octahedral trans-C₂O₄. The relationship between structural motifs for R ₂Sn(O₂CR′)₂ is discussed. Compound (1) crystallizes in the monoclinic space group P2₁/c with a = 5.0114(2) ?, b = 13.7120(5) ?, c = 19.5956(7) ?, β = 91.385(2)o, and Z = 2.     

Some applications of Miller-Mocanu lemma on certain classes of meromorphic functions

In this paper, making use of a linear operator we introduce and study certain new classes of meromorphic functions. We derive some inclusion results. These classes contain many known classes as a special case.     

3‐Germyl‐3,3‐di­methyl­propionic acid derivatives

The crystal structures of 3,3‐di­methyl‐3‐(tri­chloro­germyl)­propionic acid, [Ge(C₅H₉O₂)Cl₃], 3,3‐di­methyl‐3‐(tri­phenyl­germyl)­propionic acid, [Ge(C₆H₅)₃(C₅H₉O₂)], and 3,3‐di­methyl‐3‐(tri‐p‐toly­lgermyl)­propionic acid, [Ge(C₇H₇)₃(C₅H₉O₂)], have slightly distorted tetrahedral geometries about the Ge atoms. All the structures form dimers via strong O—H·O hydrogen bonds, resulting in eight‐membered rings that can be best described in terms of graph‐set notation (8).     

Structural studies of diethyltin(IV) derivatives and their biological aspects as potential antitumor agents against Agrobacterium tumefacien cells

A series of new diethyltin(IV) derivatives of substituted phenyl acrylates have been synthesized and characterized by elemental analysis, IR, multinuclear NMR (¹H, ¹³C, ¹⁹F and ¹¹⁹Sn) and X‐ray single crystal analysis. X‐ray single crystal diffraction study of complex 8 has shown the formation of secondary O···Sn, F···H and H···O intermolecular interactions. These complexes proved to be good antitumor agents. The antitumor properties are presumably due to the intercalative mode of interaction of these complexes with the tumor cells' DNA. Copyright © 2011 John Wiley & Sons, Ltd.