Saroj K. Sharma

Di- and triorganotin(IV) complexes of 2-aminobenzoic acid with and without triphenylphosphine: synthesis, spectroscopy, semi-empirical study, and antimicrobial activities

Eight organotin carboxylates have been synthesized in quantitative yield by reaction of NaL (L = 2-aminobenzoate) with the di- and triorganotin chlorides and triphenylphosphine. All the complexes have been characterized by elemental analysis, IR, multinuclear NMR (1H, 13C, and 119Sn), and mass spectrometry. The spectroscopic data indicate 1 : 2/1 : 1 M : L stoichiometry in 1, 3, 5, and 7 and 1 : 2 : 1/1 : 1 : 1 M : L : PPh3 stoichiometry in 2, 4, 6, and 8. FT-IR spectra clearly demonstrate metal attachment with both oxygens of the ligand and bidentate coordination in 1, 3, 5, and 7 while monodentate ligand for 2, 4, 6, and 8. In solid state, 1, 2, 5, and 6 exhibit six coordination whereas 3, 4, 7, and 8 show five coordination. The structural behavior is confirmed by semi-empirical study. NMR data reveal four-coordinate geometry in solution. These complexes were screened for antimicrobial activity in vitro. The screening tests show that tributyltin carboxylates are more potent antibacterial and fungicidal agents than corresponding methyl derivatives, and triphenylphosphine enhances the antibacterial and fungicidal activities of these complexes.

Synthesis, characterization, semi-empirical study, and biological activities of organotin(IV) complexes with cyclohexylcarbamodithioic acid as biological active ligand

Cyclohexylcarbamodithioic acid has been synthesized by the reaction of cyclohexylamine with carbon disulfide at room temperature. Its complexes have been synthesized by the reaction of cyclohexylcarbamodithioic acid with organotin(IV) chlorides in 1 : 1/1 : 2 molar ratio. The ligand and complexes have been characterized by elemental analysis, infrared (IR), and multinuclear (1H, 13C, and 119Sn) NMR spectroscopy. Elemental data show good agreement between calculated and found values of carbon, hydrogen, nitrogen, and sulfur. IR data show that the ligand is bidentate and complexes exhibit a five-coordinate geometry in the solid state, which is also confirmed by semi-empirical studies. NMR data show that the complexes exhibit tetrahedral geometry in solution state. The ligand and its complexes were screened for their in vitro mutagenic, antimicrobial, MIC, antioxidant activities, and cytotoxicity. Biological screening data demonstrate that complexes show significant activity against various bacterial and fungal strains and are good antioxidants. The cytotoxicity data show positive lethality for complexes as compared to ligand and can play a very significant role in drug development.

Homobimetallic complexes containing Sn(IV) with acetylene dicarboxylic acid: their syntheses and structural interpretation by spectroscopic, semi-empirical, and DFT techniques

Homobimetallic carboxylates with general formulae (R3Sn)2 L (where R = Me, n‐Bu, Ph and L = acetylene dicarboxylate dianion) have been synthesized by refluxing disodium salt of acetylene dicarboxylic acid with triorganotin chlorides in 1 : 2 (L : M) molar ratio in methanol under reflux. These complexes have been characterized by elemental analyses, FTIR, and multinuclear NMR (1H, 13C) spectroscopies. DFT calculations have been performed for structural elucidation and results were compared with semi‐empirical data. FTIR data indicate bidentate chelation of the ligand with tin and the complexes exhibit five‐coordinate geometry in the solid state. Such coordination behavior is also supported by DFT and semi‐empirical studies. NMR data confirm four‐coordinate geometry in solution.

Synthesis, characterization, semi-empirical study and biological activities of homobimetallic complexes of tranexamic acid with organotin(IV)

The Schiff base has been synthesized by reacting tranexamic acid with indol-3-carboxyaldehyde in the first step and then with carbon disulfide at room temperature in the second step. The homobimetallic complexes have been synthesized by reaction of Schiff base with R2SnCl2 and R3SnCl in 1 : 2 M ratio under stirring, where R = methyl, n-butyl and phenyl. The ligand and complexes have been characterized by elemental analysis, FT-IR, multinuclear NMR (1H, 13C and 119Sn) and semi-empirical study. IR data reveal the bidentate nature of the ligand. Five- or six-coordinate geometry was confirmed in solution by NMR spectroscopy. The homobimetallic complexes and ligand were tested in vitro against some pathogenic bacteria and fungi to assess their antimicrobial properties. The complexes show biological activities with few exceptions.

Synthesis, molecular modeling and spectroscopic characterization of nickel(II), copper(II), complexes of new 16-membered mixed-donor macrocyclic schiff base ligand incorporating a pendant alcohol function

Complexes of Cu(II) and Ni(II) of the composition [M(L)X] [where M=Ni(II), Cu(II) and X=Cl-, NO3-, CH3COO-] were synthesized with 1,5-dioxo-9,10-diaza-3,ol-tribenzo-(7,6,10,11,14,15) peptadecane, a N2O2 macrocyclic ligand. The complexes were characterized by elemental analysis, molar conductance measurements, UV-vis, IR, 1H NMR, 13C NMR, EPR and molecular modeling studies. All the complexes are non-electrolyte in nature. On the basis of spectral studies, an octahedral geometry has been assigned for Ni(II) complexes and a tetragonal geometry for Cu(II) complexes.

Synthesis, Characterization, and Semi-Empirical Study of Organotin(IV) Complexes with 4-(Hydroxymethyl)piperidine-1-carbodithioic Acid: X-Ray Structure of Chlorodimethyl-(4-hydroxymethyl piperidine-1-carbodithioato-S,S′)tin(IV)

Abstract Organotin complexes with the general formulae R2SnL2, R2Sn(Cl)L, and R3SnL have been synthesized where R = CH3, n-C4H6, C6H5, C6H11, and L = 4-(hydroxy methyl)piperidine-1-carbodithioic acid. The newly synthesized complexes have been characterized by elemental analysis, IR, NMR (1H, 13C and 119Sn), and, for one example, a single crystal x-ray structure. The FT-IR data shows the bidentate nature of the ligand. This coordination behavior is also confirmed by semi-empirical study. In the solid state, diorganotin complexes exhibit the penta/hexacoordinated geometry, whereas the triorganotin(IV) complexes show the five coordinated geometry. 119Sn NMR data reveal that triorganotin(IV) complexes exhibit the four coordinated geometry in solution, whereas the diorganotin(IV) compounds show the higher coordination, probably five or six. X-ray diffraction analysis of complex (2) shows a square pyramidal geometry around the tin atom on the basis of τ value. Supplemental materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. GRAPHICAL ABSTRACT

Synthesis, Characterization, Semiempirical and Biological Activities of Organotin(IV) Carboxylates with 4-Piperidinecarboxylic Acid

Organotin (IV) carboxylates with the general formulae R2Sn(Cl)L [R = Me (1), n-Bu (2), Ph (3)] and R3SnL [R = Me (4), Ph (5)] have been synthesized by the reaction of 4-piperidinecarboxylic acid (HL) with KOH and R2SnCl2 (R = Me, n-Bu, Ph)/R3SnCl (R = Me, Ph) in methanol under stirring conditions. The metal ligand binding site, structure, and stability of complexes have been verified by FT-IR, (1H, 13C) NMR, EI-MS technique, and semiempirical study. The FT-IR data indicate the bidentate chelating mode of the carboxylate ligand which is also confirmed by semiempirical study. In solution state, five and four coordinated geometry around tin was confirmed by NMR spectroscopy. The EI-MS data agreed well with the molecular structure of the complexes. Thermodynamic parameters and molecular descriptors were calculated by using semiempirical PM3 method. HOMO-LUMO calculations show that chlorodiorganotin complexes are more susceptible to nucleophilic attack as compared to triorganotin complexes. Computed negative heat of formation indicates that complexes 1–4 are thermodynamically stable. The organotin(IV) carboxylates displayed powerful antimicrobial activities against various strains of bacteria and fungi and their minimal inhibitory concentration were also evaluated. The complexes exhibited comparatively higher hemolytic activity as compared to free ligand.

New hexadentate macrocyclic ligand and their copper(II) and nickel(II) complexes: Spectral, magnetic, electrochemical, thermal, molecular modeling and antimicrobial studies.

Ni(II) and Cu(II) complexes were synthesized with a hexadentate macrocyclic ligand [3,4,8,9tetraoxo-2,5,7,10tetraaza-1,6dithio-(3,4,8,9) dipyridinedodecane(L)] and characterized by elemental analysis, molar conductance measurements, mass, NMR, IR, electronic, EPR spectral, thermal and molecular modeling studies. All the complexes are 1:2 electrolytes in nature and may be formulated as [M(L)]X(2) [where, M=Ni(II) and Cu(II) and X=Cl(-), NO(3)(-), ½SO(4)(2-), CH(3)COO(-)]. On the basis of IR, electronic and EPR spectral studies an octahedral geometry has been assigned for Ni(II) complexes and tetragonal geometry for Cu(II) complexes. The antimicrobial activities and LD(50) values of the ligand and its complexes, as growth inhibiting agents, have been screened in vitro against two different species of bacteria and plant pathogenic fungi.

Synthesis, characterization, HOMO–LUMO study, and antimicrobial activity of organotin(IV) complexes of 4-piperidine carboxamide and its Schiff base

A series of organotin(IV) complexes has been synthesized by reacting 4-piperidine carboxamide with CS2 and R2SnCl2/R3SnCl in 1 : 1 M/L ratio at room temperature. The synthesized complexes were further treated with benzaldehyde to synthesize Schiff bases under stirring. All the complexes were characterized by elemental analysis, FT-IR, 1H and 13C NMR. FT-IR and semi-empirical study confirm the bidentate nature of ligand. The complexes exhibit four-coordinate geometry in solution. Thermodynamic parameters and molecular descriptors were calculated by using semi-empirical PM3 method. HOMO–LUMO calculations show that chlorodiorganotin complexes are more susceptible to nucleophilic attack when compared with triorganotin complexes. Negative heats of formation at 298 K demonstrate that 1, 4, and 7 are thermodynamically stable. The antimicrobial results have shown that complexes containing Schiff base exhibit significantly better activity compared to complexes with carboxamide derivatives. Graphical Abstract

Synthesis, characterization, semi-empirical study, and biological activities of organotin(IV) and transition metal complexes with o-methyl carbonodithioate

Three transition metal and six organotin(IV) complexes have been synthesized by treating potassium o-methyl carbonodithioate with ZnCl2/CdCl2/HgCl2 and R2SnCl2/R3SnCl under stirring. The complexes were characterized by IR, 1H, and 13C NMR spectroscopies. IR results show that the ligand is bidentate in 1–3 while monodentate in 4–9, which is also confirmed by semi-empirical study. NMR data reveal four-coordinate geometry in solution. HOMO–LUMO study shows that 7 and 9 are thermodynamically unstable. The enzyme inhibition study shows that 1 is a potent inhibitor of ALP, EC 3.1.3.1, resulting in very slow rate of formation and breakdown of enzyme–substrate complex. UV/visible spectroscopy was used to assess the mode of interaction and binding of the complexes with DNA which shows that 9 exhibits higher binding constant when compared to 6. In protein kinase inhibition assay, 1 was active, while antifungal activity shows that organotin(IV) complexes are more active than transition metal complexes. Graphical Abstract