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Articles by Yip-Foo Win
Total Records ( 3 ) for Yip-Foo Win
  Yip-Foo Win , Siang-Guan Teoh , Tengku-Sifzizul Tengku-Muhammad , Yasodha Sivasothy and Sie-Tiong Ha
  Problem statement: Many studies have been carried out on organotin(IV) complexes derivative of carboxylate anions. However, the synthesis and characterization as well as the cytotoxic assay of organotin(IV) carboxylate derived of 3-(dimethylamino)benzoic acid have not been studied. Approach: Organotin(IV) carboxylate complexes derivative of 3-(dimethylamino)benzoic acid, 3-[N(CH3)2]C6H4COOH have been successfully synthesized. Two types of diorganotin(IV) complexes, [{3-[N(CH3)2]C6H4COO(R)2Sn}2O]2 dimer (R = methyl 1, butyl 3) and {3-[N(CH3)2]C6H4COO}2(C4H9)2Sn, 2 (monomer) as well as 3-[N(CH3)2]C6H4COO(C6H5)3Sn, 4 were successfully synthesized and obtained in solid state. The acid and complexes 1-4 obtained were characterized quantitatively using C, H, N and Sn elemental analysis as well as spectroscopic methods such as infrared (FTIR) and nuclear magnetic resonance (1H, 13C, 1H-13C HMQC and 119Sn NMR). In addition, complexes 1-4 obtained were screened for their cytotoxicity activity against HepG2 cells line. Results: Infrared spectroscopy showed that the coordination took place via oxygen atoms from the carboxylate anions. This indicated that the carboxylate anion acts as monodentate ligand in complexes 2 and 4. However, for distannoxane dimer (complexes 1 and 3), the carboxylate anions are found to exhibit monodentate and bidentate manner. In 119Sn NMR solution study, the tin atoms of complexes 1-3 were five-coordinated and four-coordinated in complex 4. From the 119Sn NMR, the tin atom of complex 2 was five-coordinated, this might be upon dilution, the crystal lattice were broken up resulting the carboxylate anions assembly self-arrangement. Hence, one of the carboxylate anions was located close to the tin atoms and exhibited bidentate chelation while the other carboxylate anion exhibited monodentate chelation in complex 2. Conclusion: Pure complexes 1-4 have been successfully obtained and complex 4 possessed promising biological screening activity compared to the parent acid and complexes 1-3.
  Sie-Tiong Ha , Lay-Khoon Ong , Yip-Foo Win , Guan-Yeow Yeap , Nilesh L. Bonde and Peng-Lim Boey
  Problem statement: Numerous studies have been conducted on the Schiff base’s alkyl and alkyloxy possessing aromatic core. However, the thermo tropic properties of Schiff base’s ester (or alkanoyloxy) with pyridine core was rare studied. Approach: To study spectral, thermal and optical behaviors of Schiff base ester possessing heterocyclic (pyridine) terminal core. A series of 4-[(pyridin-3-ylmethylene) amino] phenylalkanoates were prepared and all the members are differed by the length of alkanoyloxy chain, Cn-1H2n-1COO, where n = 12, 14, 16 and 18. The thermal and optical characteristics were studied using differential scanning calorimetry and polarizing optical microscopy. Results: DSC studies showed that all of the title compounds exhibited direct isotropization and recrystallization during heating and cooling cycles, respectively. Under polarizing optical microscope, crystal phase texture was observed to change to dark region isotropic without displaying any liquid crystal phase. Conclusion: The presence of terminal pyridine core suppressed the formation of mesosphere in the compounds studied.
  Yip-Foo Win , Siang-Guan Teoh , M. R. Vikneswaran , Mun-Yee Chan , Sie-Tiong Ha and Pazilah Ibrahim
  Problem statement: Tremendous studies have been carried out on organotin(IV) complexes derivatives of carboxylate anions. However, the synthesis and characterization as well as the in vitro antibacterial screening activity of organotin(IV) carboxylate derived of 2-amino-5-nitrobenzoic acid have not been carried out. Approach: Organotin(IV) carboxylate complexes derivative of 2-amino-5-nitrobenzoic acid, 2-NH2-5-NO2-C6H3COOH have been successfully synthesized. The acid and complexes obtained were characterized quantitatively using C, H, N and Sn elemental analysis as well as spectroscopic methods such as infrared (FTIR) and nuclear magnetic resonance (1H, 13C, 1H-13C HMQC and 119Sn NMR). Moreover, the complexes obtained were screened for their in vitro antibacterial screening activity. Results: Monomeric R2Sn (2-NH2-5-NO2-C6H3COO)2 (R = methyl 1, butyl 2) and dimeric {[(Bu2Sn(2-NH2-5-NO2-C6H3COO)]2O}2 3 as well as Ph3Sn(2-NH2-5-NO2-C6H3COO) 4 are obtained in solid state. Results of the infrared spectroscopy on the acid and complexes showed that the coordination took place via oxygen atoms from the carboxylate anions. Based on the 119Sn NMR solution study, the tin atom of both complexes 1 and 2 exhibit six-coordination respectively and complex 3 exhibits five- and six-coordination whereas the tin atom of complex 4 exhibits five-coordination. Conclusion: Pure complexes derived of 2-amino-5-nitrobenzoic acid have been successfully obtained. Triphenyltin(IV) are found to possess better in vitro antibacterial screening activity on two gram-positive bacterial compared to the parent acid.
 
 
 
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