New Schiff base (HL) ligand is prepared via condensation of isatins and amino acids in 1:1 molar ratio. Metal complexes are prepared and characterized by elemental analysis, molar conductance, electronic, infrared, and multinuclear magnetic resonance (1H NMR, 13C NMR, and 119Sn NMR). The analytical data showed that the ligand acts as bidentate toward metal ions via azomethine nitrogen and carboxylate oxygen by a stoichiometric reaction of metal？:？ligand (1？:？2) to from metal complexes (Pb(II)(L)2 and Bu2Sn(L)2, where L is the Schiff base ligands of histidine and methionine). The conductivity values between 15 and 25 Ω？1cm2？mol？1 in DMF imply the presence of nonelectrolyte species. On the basis of the above spectral studies, distorted octahedral and tetrahedral geometry have been proposed for the resulting organotin(IV) and lead(II) complexes. 1. Introduction Metal Schiff-base complexes have continued to play the role of one of the most important stereochemical models in main group and transition metal coordination chemistry due to their preparative accessibility, diversity, and structural variability. In recent years, a number of Schiff bases have been reported to possess significant and diverse biological activities such as antifungal, analgesic, anti-inflammatory, antibacterial, antioxidant, antitumor, local anesthetic, and antimicrobial activities [1–6]. On the other hand, radicals retard the progress of many chronic diseases such as vascular diseases, oxidative stress responsible for DNA, protein and membrane damage, and some forms of cancer [7, 8]. During the last few decades, metal carboxylates have been the subject of extensive investigations because of their remarkable structural diversity [9, 10] as well as significant biological activity, for example, pesticidal, bactericidal, and antitumor agents [11, 12]. In continuation of recent reports from this laboratory on some amino acid Schiff base metal complex systems [13–16], the present studies, ligand (L1H–L4H) is obtained by the condensation reaction between amino acids (L-histidine, DL-methionine) and isatin, chloroisatin with this hope that it may provide us valuable theoretical information for exploring metal-based bacteriostatic and carcinostatic pharmaceuticals with high efficacy and low toxicity. In this effort, we have also introduced an azomethine (–C=N–) linkage with the concern that it may permit a notable variety in the remarkable chemistry and behavior of such compounds. The synthesized Schiff base derived compounds (L1H–L4H) have been exposed to act as bidentate towards Pb(II) and
References
[1]
I. Jarak, M. Kralj, L. ？uman et al., “Novel cyano- and N-isopropylamidino-substituted derivatives of benzo[b]thiophene-2-carboxanilides and benzo[b]thieno[2,3-c]quinolones: synthesis, photochemical synthesis, crystal structure determination, and antitumor evaluation. 2,” Journal of Medicinal Chemistry, vol. 48, no. 7, pp. 2346–2360, 2005.
[2]
P. R. Kumar, S. Raju, P. S. Goud et al., “Synthesis and biological evaluation of thiophene [3, 2-b] pyrrole derivatives as potential anti-inflammatory agents,” Bioorganic and Medicinal Chemistry, vol. 12, no. 5, pp. 1221–1230, 2004.
[3]
A. D. Pillai, P. D. Rathod, F. P. Xavier, K. K. Vasu, H. Padh, and V. Sudarsanam, “Design, synthesis, and pharmacological evaluation of some 2-[4-morpholino]-3-aryl-5-substituted thiophenes as novel anti-inflammatory agents: generation of a novel anti-inflammatory pharmacophore,” Bioorganic and Medicinal Chemistry, vol. 12, no. 17, pp. 4667–4671, 2004.
[4]
C. K. Ryu, S. K. Lee, J. Y. Han, O. J. Jung, J. Y. Lee, and S. H. Jeong, “Synthesis and antifungal activity of 5-arylamino-4,7-dioxobenzo[b] thiophenes,” Bioorganic and Medicinal Chemistry Letters, vol. 15, no. 10, pp. 2617–2620, 2005.
[5]
L. Pellerito and L. Nagy, “Organotin(IV)n+ complexes formed with biologically active ligands: equilibrium and structural studies, and some biological aspects,” Coordination Chemistry Reviews, vol. 224, no. 1-2, pp. 111–150, 2002.
[6]
K. Shahid, S. Ali, and S. Shahzadi, “The chemistry, properties, and characterization of organotin(IV)complexes of 2-(N-naphthylamido)benzoic acid,” Journal of Coordination Chemistry, vol. 62, no. 17, pp. 2919–2926, 2009.
[7]
I. C. F. R. Ferreira, R. P. Q. Maria-Joao, M. Vilas-Boas, L. M. Estevinho, A. Begouin, and G. Kirsch, “Evaluation of the antioxidant properties of diarylamines in the benzo[b]thiophene series by free radical scavenging activity and reducing power,” Bioorganic and Medicinal Chemistry Letters, vol. 16, no. 5, pp. 1384–1387, 2006.
[8]
T. Nakayama, M. Yamada, T. Osawa, and S. Kawakishi, “Suppression of active oxygen-induced cytotoxicity by flavonoids,” Biochemical Pharmacology, vol. 45, no. 1, pp. 265–267, 1993.
[9]
V. Chandrasekhar, K. Gopal, and P. Thilagar, “Nanodimensional organostannoxane molecular assemblies,” Accounts of Chemical Research, vol. 40, no. 6, pp. 420–434, 2007.
[10]
E. R. T. Tiekink, “Structural chemistry of organotin carboxylates: a review of the crystallographic literature,” Applied Organometallic Chemistry, vol. 5, no. 1, pp. 1–23, 1991.
[11]
M. Gielen, “Review: organotin compounds and their therapeutic potential: a report from the organometallic chemistry department of the free university of brussels,” Applied Organometallic Chemistry, vol. 16, no. 9, pp. 481–494, 2002.
[12]
S. K. Hadjikakou and N. Hadjiliadis, “Antiproliferative and anti-tumor activity of organotin compounds,” Coordination Chemistry Reviews, vol. 253, no. 1-2, pp. 235–249, 2009.
[13]
H. L. Singh, S. S. Chauhan, and H. Sachdeva, “Synthesis and characterization of Pb(II) complexes of Schiff bases derived from 3-methyl-4-fluoroacetophenone and amino acids,” Research on Chemical Intermediates, vol. 36, no. 9, pp. 1037–1047, 2010.
[14]
H. L. Singh, “Synthesis and characterization of tin(II) complexes of fluorinated Schiff bases derived from amino acids,” Spectrochimica Acta A, vol. 76, no. 2, pp. 253–258, 2010.
[15]
H. L. Singh, M. Sharma, and A. K. Varshney, “Studies on coordination compounds of organotin(IV) with schiff bases of amino acids,” Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry, vol. 30, pp. 445–456, 2000.
[16]
H. L. Singh, M. Sharma, M. K. Gupta, and A. K. Varshney, “Coordination behaviour of biologically active Schiff bases of amino acids towards stannous Ion,” Bulletin of the Polish Academy of Sciences, vol. 47, no. 2, pp. 103–110, 1999.
[17]
H. I. Beltran, L. S. Z. Rivera, T. Mancilla, R. Santillan, and N. Farfan, “One-step preparation, structural assignment, and x-ray study of 2,2-di-n-butyl- and 2,2-diphenyl-6-aza-1,3-dioxa-2-stannabenzocyclononen-4-ones derived from amino acids,” Chemistry, vol. 9, no. 10, pp. 2291–2306, 2003.
[18]
H. D. Yin, M. Hong, Q. B. Wang, S. C. Xue, and D. Q. Wang, “Synthesis and structural characterization of diorganotin(IV) esters with pyruvic acid isonicotinyl hydrazone and pyruvic acid salicylhydrazone Schiff bases,” Journal of Organometallic Chemistry, vol. 690, no. 6, pp. 1669–1676, 2005.
[19]
H. L. Singh and A. K. Varshney, “Synthesis and spectral studies of organotin(IV) complexes with bifunctional tetradentate Schiff bases,” Main Group Metal Chemistry, vol. 22, no. 9, pp. 529–532, 1999.
[20]
D. Maity, S. Chattopadhyay, A. Ghosh, M. G. B. Drew, and G. Mukhopadhyay, “Syntheses, characterization and X-ray crystal structures of a mono-and a penta-nuclear nickel(II) complex with oximato Schiff base ligands,” Inorganica Chimica Acta, vol. 365, no. 1, pp. 25–31, 2011.
[21]
N. S. Gupta, M. Mohan, N. K. Jha, and W. E. Antholine, “Magnetic and m？ssbauer characterization of the discontinuous high-spin (6A1) ？ low-spin (2T2) transition in solid bis(pyridoxal 4-phenylthiosemicarbazonato)iron(III) chloride,” Inorganica Chimica Acta, vol. 184, no. 1, pp. 13–21, 1991.
[22]
Q. Xie, Z. Yang, and L. Jiang, “Preparation, structure and biological activities of mixed methyldicyclohexyltin carboxylates,” Main Group Metal Chemistry, vol. 19, no. 8, pp. 509–520, 1996.
[23]
Y. F. Win, T. S. T. Muhammad, S. T. Ha, Y. Sivasothy, and S. G. Teoh, “Synthesis and structural characterization of organotin (IV) complexes derived of 4- (Diethylamino) benzoic acid: cytotoxic assay on human liver carcinoma cells (HepG2),” Australian Journal of Basic and Applied Sciences, vol. 4, no. 6, pp. 1383–1390, 2010.
[24]
M. A. Choudhary, M. Mazhar, S. Ali, U. Salma, S. Ashraf, and A. Malik, “Synthesis, characterization and biological activity of triorganotin carboxylates containing germanium,” Turkish Journal of Chemistry, vol. 26, no. 1, pp. 125–131, 2002.
[25]
M. Nath, H. Singh, G. Eng, X. Song, and A. Kumar, “Syntheses, characterization and biological activity of diorganotin(IV) derivatives of 2-amino-6-hydroxypurine (guanine),” Inorganic Chemistry Communications, vol. 12, no. 10, pp. 1049–1052, 2009.
[26]
B. S. Saraswat, G. Srivastava, and R. C. Mehrotra, “Schiff base complexes of organotin(IV): infrared and m？ssbauer studies on the addition complexes of N-alkyl(aryl)salicylideneimines,” Journal of Organometallic Chemistry, vol. 164, no. 2, pp. 153–158, 1979.
[27]
H. L. Singh, “Synthesis, spectroscopic characterization, and 3D molecular modeling of lead(II) complexes of unsymmetrical tetradentate Schiff-base ligands,” Advances in Physical Chemistry, vol. 37, no. 8, pp. 1087–1101, 2011.
[28]
L. L. Yeap and S. G. Teoh, “Synthesis, spectral characterization and X-ray crystal structure of some triphenyltin(IV) carboxylate compounds,” Journal of Coordination Chemistry, vol. 56, no. 8, pp. 701–708, 2003.
[29]
R. V. Singh, S. C. Joshi, A. Gajraj, and P. Nagpal, “Studies of biologically potent organotin(IV) and organosilicon(IV) complexes of a sulfur donor ligand derived from 1-acetylferrocene,” Applied Organometallic Chemistry, vol. 16, no. 12, pp. 713–720, 2002.
[30]
J. Hole？ek, M. Nádvorník, K. Handlí？, and A. Ly？ka, “13C and 119Sn NMR spectra of Di-n-butyltin(IV) compounds,” Journal of Organometallic Chemistry, vol. 315, no. 3, pp. 299–308, 1986.
[31]
H. L. Singh, “Synthesis, spectral, and 3D molecular modeling of tin(ii) and organotin(iv) complexes of biologically active schiff bases having nitrogen and sulfur donor ligands,” Phosphorus, Sulfur and Silicon and the Related Elements, vol. 184, no. 7, pp. 1768–1778, 2009.
