Synthesis,Spectroscopic Studies,and Biological Activity of Organosilicon(iv) Complexes of Ligands Derived from 2-Aminobenzothiazole Derivatives and 2-Hydroxy-3-Methoxy Benzaldehyde

Abstract

The Schiff bases derived from the condensation of 2-aminobenzothiazole derivatives and 2-hydroxy-3-methoxybenzaldehyde and their silicon(IV) complexes with the general formula R₂Si(L)Cl (R = Et, Bu, Ph, L = 2-(2-hydroxy-3-methoxy) benzylideneaminobenzo-thiazole) have been synthesized. These complexes have been characterized by elemental analysis, molar conductance, and spectroscopic studies including IR and NMR (¹H, ¹³C, and ²⁹Si) spectroscopy. The analytical data suggest trigonal bipyramidal geometry around the silicon atom in the resulting complexes. The ligands and their organosilicon complexes have also been evaluated for in vitro antimicrobial activity against bacteria (Staphylococcus aureus, Bacillus subtilis, and Escherichia coli) and fungi (Aspergillus niger and Candida albicans). The complexes were found to be more potent as compared to the ligands.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Zirconium (IV), Thorium (IV) and Dioxouranium (VI) Complexes of Dibasic Tridentate Schiff Bases

Dibasic tridentate Schiff bases obtained by the condensation of O -aminobenzoic acid with salicyldehyde and its 5-chloro and 5-bromo derivatives were synthesised and used to pracipitate Zr(IV), Th(IV) and UO₂(VI) metals as complexes. The 1:1 (metal-ligand) stoichiometry of these complexes is shown by elemental analysis, gravimetric estimations and conductometric titrations while the structures of the complexes are proved by i.r. spectra and thermogravimetric analysis. The magnetic susceptibility measurements by Gouy method show, these complexes to be monormeic and diamagnetic. The molar conductance values in nitrobenzene indicate the nonelectrolytic behaviour of the complexes. The results show that the complexes of the type Zr(OH)²L.H²O, Th(OH)²L.H²O and UO²L.H²O are formed having solvent molecule in co-ordination with metal ion.     

Zirconium (IV), Thorium (IV) and Dioxouranium (VI) Complexes of Dibasic Tridentate Schiff Bases

Dibasic tridentate Schiff bases obtained by the condensation of O -aminobenzoic acid with salicyldehyde and its 5-chloro and 5-bromo derivatives were synthesised and used to pracipitate Zr(IV), Th(IV) and UO₂(VI) metals as complexes. The 1: 1 (metal-ligand) stoichiometry of these complexes is shown by elemental analysis, gravimetric estimations and conductometric titrations while the structures of the complexes are proved by i.r. spectra and thermogravimetric analysis. The magnetic susceptibility measurements by Gouy method show, these complexes to be monormeic and diamagnetic. The molar conductance values in nitrobenzene indicate the nonelectrolytic behaviour of the complexes. The results show that the complexes of the type Zr(OH)₃L.H₂O₂ Th(OH)₂ L.H₂O and UO₂L.H₂O are formed having solvent molecule in co-ordination with metal ion.     

Lanthanon (III) Complexes of Bifunctional Tridentate and Tetradentate Schiff Bases

Reactions of isopropoxides of praseodymium, neodymium and samarium with bifunctional tridentate and tetradentate schiff bases (i.e. salicylidene-O-aminophenol and bis-salicylaldehyde ethylenediamine) have been carried out in benzene in different stoichiometric ratios resulting in the formation of products with the formula M(OPrⁱ)(C₁₁H₉NO₂), M(C₁₃H₉NO₂)(C₁₃H₁₀NO₂). M₂(C₁₃H₉NO₂) M(OPrⁱ)(C₁₅H₁₄N₂O₂), M(C₁₆H₁₄N₂O₂)(C₁₆H₁₅N₂O₂) and M₂(C₁₆H₁₄N₂O₂)₃ (where M stands for Pr, Nd and Sm). The products were found to be yellow to orange solids soluble in benzene and alcohol. The absorption spectra of these complexes were also recorded in methanol.     

Triorganosilicon(IV) complexes as biocides: Synthetic,spectroscopic and biological studies of N SH and N OH fluoroimines and their chelates

A facile synthesis and study of the stereochemistry and biochemical aspects of some triorganosilicon(IV) complexes derived from fluoroimines having N S and N O systems are reported. The fluoroimines were prepared by the condensation of 2-fluorobenzaldehyde and 1-(2-fluorophenyl)ethanone with semicarbazide and thiosemicarbazide. These imines react with triorganosilicon(IV) chlorides to yield compounds having Si? O/Si? S and Si ← N bonds. The structures of the compounds have been elucidated by physicochemical and spectral (UV, IR, ¹H NMR, ¹³C NMR and ⁹F NMR) studies which clearly point to a trigonal bipyramidal geometry around silicon(IV), as the active lone pair of nitrogen is also included in the coordination sphere. In the search for better fungicides and bactericides, studies were conducted to assess the growth-inhibiting potential of the synthesized complexes against various pathogenic fungal and bacterial strains. These studies demonstrate that the concentrations reached levels which are sufficient to inhibit and kill the pathogens.     

三齿配体杂环五配位有机锡化合物的合成与生物活性

邻氨基苯酚与邻羟基芳香醛(酮)反应,合成了4个三齿Schiff碱配体(2a,2d,2g和2j),2分别与二苄基二氯化锡,二苯基二氯化锡,二正丁基二氯化锡反应合成了12个未见文献报道的三齿配体杂环五配位有机锡配合物(3a~3l),其结构经1HNMR,IR和元素分析确证。体外抗菌和抗癌活性测试结果表明,3b,3c,3f,3i和3k具有较强的抑菌活性;3c和3l具有较好的抗癌活性。     

Diorganotin(IV) Complexes of Some Schiff Bases With a Potential Biological Activity

Diorganotin dichloride compounds, Rl₂SnCl₂ (R=Me, nBu, Ph) react with Schiff bases (L), derived from substituted and non-substituted 2- or 3-aminopyridine with 2-hydroxy-, 2-methoxy- or 2-hydroxy-3-methoxy-benzaldehyde in a 1 : 1 molar ratio, to give complexes of general formula R₂SnCl₂·L. It is suggested that the Schiff bases coordinate with tin in bidentate fashion to give hexacoordinate tin species. Almost all the complexes prepared show some 1 : 1 molar conductivity in ethanol and DMF, indicating on R₂Sn(L)Cl⁺ Cl⁻ ionic structure type. The complexes were screened against seven species of bacteria.     

Thermal Studies of the Dibutyltin(IV) Complexes of Schiff Bases Derived from Amino Acids

The thermal decomposition using TG, DTG and DTA, of seven complexes of the types Bu₂SnL(I) and Bu₂SnL(II) (where H₂L(I)=Schiff base derived from acetylacetone and glycine [H₂L-1(I)] or L-leucine [H₂L-4(I)] or methionine [H₂L-5(I)] or phenylglycine [H₂L-6(I)]; H₂L(II)=Schiff base derived from o-hydroxynaphthaldehyde and β-alanine [H₂L-2(II)] or DL-valine [H₂L-3(II)] or L-leucine [H₂L-4(II)] is shown to fall into one of two categories, viz, (1) Bu₂SnL(I) complexes that decompose without melting to give SnO as the final tin containing product, (2) Bu₂SnL(II) complexes that melt and then decompose to give SnO. Mathematical analysis of TG data using Coats-Redfern equation, Horowitz-Metzger equation, and Fuoss method shows that the first order kinetics is applicable in all the complexes except Bu₂SnL-2(II). Kinetic parameters such as the energy and entropy of activation and pre-exponential factor are reported. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis,Characteristic Spectral Studies and in Vitro Antimicrobial Activity of Organosilicon(IV) Complexes of N-(2-Hydroxynaphthalidene)-Amino Acid Schiff Bases

Fifteen new organosilicon(IV) complexes formulated as R 3 Si[2-HOC 10 H 6 CH=NCH(X)COO] and Me 2 Si[2-OC 10 H 6 CH=NCH(X)COO] (where X = H[H 2 L 1 ], --CH 2 CH(CH 3 ) 2 [H 2 L 2 ], --CH 2 CH 2 -SCH 3 [H 2 L 3 ], --CH 3 [H 2 L 4 ] and --CH(CH 3 ) 2 [H 2 L 5 ] were prepared and characterized by 1 H and 13 C NMR, IR, electronic spectral studies, and elemental analysis. All of the complexes are nonelectrolytes. The spectral studies suggested a distroted trigonal-bipyramidal geometry around the silicon atom. Antimicrobial activity screening for all of the complexes was carried out against various bacteria [ Escherichia coli, Aeromonas formicans, Pseudomonas putida-2252, and Staphylococcus aureus-740 ] and fungi [ Aureobasidium pullulans-1991, Penicillium chrysogenum-1348, Verticillium dahliae-2063, and Aspergillus niger ORS-4 ]. The complexes showed good activity.     

三苯基咪唑共轭Schiff碱的合成及其光学性能

联苯甲酰、对硝基苯甲醛和乙酸铵在冰乙酸介质中经缩合反应制得2-(4-硝基苯基)-4,5-二苯基咪唑(1); 1经铁粉还原制得2-(4-氨基苯基)-4,5-二苯基咪唑(2); 2与4-二甲氨基苯甲醛经缩合反应合成了一种具有D-π-A结构的新型三苯基咪唑Schiff碱（3）,其结构经¹H NMR,¹³C NMR, IR和MS(ESI)表征。利用紫外-可见吸收光谱和荧光光谱研究了3在不同溶剂中的光物理行为。结果表明：3的最大吸收峰位于311~332 nm和378~380 nm,荧光发射峰位于433~436 nm和457~461 nm。由于具有D-π-A结构,3表现出明显的扭曲分子内电荷转移现象。     

Synthesis,Characterization, and Antibacterial Studies of Oxovanadium(IV) Complexes with Thiazole-Derived Schiff Bases

Oxovanadium(IV) complexes of Schiff bases, derived from 2-amino-4-phenyl thiazole/substituted 2-amino-4-phenyl thiazoles and thiophene-2-aldehyde have been synthesized and characterized on the basis of elemental analysis, molar conductance measurements, magnetic susceptibility data, and UV-visible, and IR spectral studies. All the complexes are monomeric possessing a 1:2 (metal:ligand) stoichiometry. On the basis of these data, a square pyramidal geometry has been assigned for the complexes. A few complexes have been subjected to thermal decomposition studies. The ligands and their metal complexes have been screened for their antibacterial activities.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Organotin(IV) complexes of dibasic tridentate Schiff bases containing ONO donor atoms

Organotin(IV) Schiff base complexes of the type (L)SnR₂ [where R?CH₃, C₆H₅ or CH₂CH₂CO₂ CH₃], (LH)Sn(C₆H₅)₃ and (L)SnCl(CH₂CH₂CO₂ CH₃) [where LH₂?2-N-salicylideneimino-2-methyl-1-propanol, derived from the condensation of salicylaldehyde and 2-amino-2-methyl-1-propanol] have been prepared and characterized on the basis of their elemental analyses, IR, ¹H, ¹³C and ¹¹⁹Sn NMR studies. In these mononuclear complexes the Schiff base acts either as a dianionic tridentate or as a monobasic bidentate moiety by coordinating through an alkoxy group, an azomethine nitrogen and a phenoxide ion to tin. Sulphur dioxide inserts in the tin–methyl/–phenyl bond in the above Schiff base complexes to give tin–O–sulphinates of formulae (L)RSn(SO₂R) and (LH)(C₆H₅)₂Sn(SO₂C₆H₅).     

Copper(II), Nickel(II) and Cobalt(II) Complexes of Dibasic Tridentate Schiff Bases

Complexes of Cu(II), Ni(II) and Co(II) with the Schiff bases derived from o-aminobenzoic acid with salicylaldehyde and its 5-chloro and 5-bromo derivatives have been prepared. The 1:1 (metal-ligand) stoichiometry of these complexes is shown by elemental analysis, gravimetric estimations and conductometric titrations while the structures of the complexes are proved by i.r. spectra and thermogravimetric analysis. The magnetic susceptibility and electronic spectra of Cu(II) complexes indicate the nonplanar binuclear structures while that of Ni(II) and Co(II) show their paramagnetic octahedral geometry. The molar conductance values in nitrobenzene indicate the nonelectrolytic behaviour of the complexes. The results show that the complexes of the type (Cu·L)₂, Ni·L·3H₂O and Co·L·3H₂O are formed having solvent molecule in coordination with the metal ion. The monopyridine and monoammonia adducts of Cu(II) complexes were found to be monomeric.     

Polymeric Coordination Compounds Derived from Transition Metal(II) with Tetradentate Schiff‐base: Synthetic,Spectroscopic, Magnetic and Thermal Approach

The polymeric coordination compounds have been synthesized using the dipotassium salt of N,N′‐di(carboxymethylene)terephthalaldehydediimine (K₂SB¹) or N,N′‐di(carboxyethylene)terephthalaldehydediimine (K₂SB²) with manganese(II), cobalt(II), nickel(II), copper(II), zinc(II), and cadmium(II). The ligands have been characterized by ¹H‐NMR, and ¹³C‐NMR spectra. The polychelates have been characterized by elemental analyses, magnetic measurements, thermogravimetric analyses, electronic spectra and infrared spectra. The coordination compounds are colored, and the central metal ions are octahedrally coordinated with two water molecules and the Schiff bases. The Schiff bases act as di‐negative tetradentate ligands, in which bonding occurs through two oxygen and two nitrogen atoms. The polymers are insoluble in all common organic solvents such as acetone, methanol, ethanol, N,N‐dimethylformamide and dimethylsulfoxide.     

邻香草醛缩氨基酸钾Schiff碱及其三苄基锡(IV)配合物的合成与表征

Six schiff bases derived from o－vanillin and amino acids and their tribenzyltin(IV) complexes have been synthesezed. The ligands and complexes were characterized by elemental analysis, IR ,UV and 1H NMR. The tin atom is five－coordinated in tribenzyltin(IV) complexes. There is intramolecular Sn←N of imine N atom.     

Synthesis,Spectroscopic Studies,and In Vitro Antifungal Activity of Organosilicon(IV) and Organotin(IV) Complexes of 4-Amino-5-mercapto-3-methyl-S-triazole Schiff Bases

The Schiff bases derived from condensation of s-triazole with heterocyclic aldehydes and their 1:1 and 1:2 complexes have been synthesized. These complexes have been characterized by elemental analyses, molar conductance and spectroscopic studies, including UV, IR, ¹H, ¹³C, ²⁹Si, and ¹¹⁹Sn NMR spectroscopy. On the basis of these studies, the resulting complexes have been proposed to have trigonal bipyramidal and octahedral geometries. The biological activity of these complexes against various fungi has been investigated.     

Lanthanons(III) Complexes of Bifunctional Tridentate Schiff's Bases

A systematic study of the reactions of isopropoxides of praseodymium, neodymium and samarium with bifunctional tridentate Schiff bases (acetylacetone-O-aminophenol and benzoylacetone-O-aminophenol) in equimolar ratios resulting in the formation of products with formula M(OPrⁱ) (SB), M(SB) (SBH) and M₂(SB)3 (where SB is Schiff base anion, SBH is Schiff base and M is metal). The reactions have been found to be quite facile even at the room temperature as observed by immediate change of colour. The intensity of the colour of acetylacetone-O-aminophenol derivatives of rare earths decreased with the increasing stoichiometric ratio of the ligand i.e. from yellow to light yellow.     

Coordination Complexes of Some Group(IV) Halides with Monodentate Schiff Bases

Coordination compounds resulting from the interaction of N-(phenyl)benzalaldimine and its derivatives containing a methyl group in different positions of the aniline ring and group(IV) halides, MX₄ (where M = Si or Sn and X = Cl or Br), have been prepared and characterized by elemental analyses and electronic, infrared and Raman spectra.     

A Spectroscopic Study of Thorium(IV) Complexes with bidentate SCHIFF Bases

The complexes of thorium(IV) chloride with bidentate SCHIFF bases have been prepared. The analytical data indicate 1:2 stoichiometry. The complexes are yellow in colour, non-electrolytes in DMF and appear to be octahedral. The UV, IR and NMR spectra of the ligands and the complexes are reported.     

Microwave-Assisted Synthesis,and Stereochemical and Biological Aspects of Some Antimony(III) and Bismuth(III) Complexes with Biologically Potent Bidentate Schiff Bases

Tetra- and pentacoordinated antimony and bismuth derivatives have been prepared by the interactions of monophenylantimonydichloride(III), trichlorostibane, and trichlorobismuthane with the sodium salts of 3-(indolin-2-one)hydrazinecarbothioamide (L¹H) and 3-(indolin-2-one)hydrazinecarboxamide (L²H), under microwave irradiation as well as by conventional heating. These compounds were further characterized by analytical and spectroscopic techniques including UV, IR, ¹H NMR, and ¹³C NMR spectra. Newly synthesized complexes with their corresponding ligands were also tested for their antifungal and antibacterial activities.