Publications by authors named "Kian-Eang Neo"

Chiral enantiomers [Cu(phen)(L-threo)(H2O)]NO3 1 and [Cu(phen)(D-threo)(H2O)]NO3 2 (threo = threoninate) underwent aldol-type condensation with formaldehyde, with retention of chirality, to yield their respective enantiomeric ternary copper(II) complexes, viz. L- and D-[Cu(phen)(5MeOCA)(H2O)]NO3·xH2O (3 and 4; phen = 1,10-phenanthroline; 5MeOCA = 5-methyloxazolidine-4-carboxylate; x = 0-3) respectively. These chiral complexes were characterized by FTIR, elemental analysis, circular dichroism, UV-Visible spectroscopy, fluorescence spectroscopy (FL), molar conductivity measurement, ESI-MS and X-ray crystallography.

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Two ternary Zn(II) complexes, with 1,10-phenanthroline (phen) as the main ligand and a carboxylate-containing ligand [dipicolinate (dipico) or L-threoninate (L-Thr)] as the subsidiary ligand, were prepared and characterized by elemental analysis, Fourier transform IR, UV, and fluorescence spectroscopy, X-ray diffraction, molar conductivity, and electrospray ionization mass spectrometry. X-ray structure analysis shows that both [Zn(phen)(dipico)(H(2)O)]·H(2)O (1) and [Zn(phen)(L-Thr)(H(2)O)Cl]·2H(2)O (2) have octahedral geometry about the Zn(II) atom. Both complexes can inhibit topoisomerase I, and have better anticancer activity than cisplatin against nasopharyngeal cancer cell lines, HK1 and HONE-1, with concentrations causing 50 % inhibition of cell proliferation (IC(50)) in the low micromolar range.

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The Lewis acidic pincer with a labile triflate ligand, viz. [Pd(OTf)(PCP)] (PCP = (-)CH(CH(2)CH(2)PPh(2))(2)) was prepared from [PdCl(PCP)] with AgOTf. It reacts readily with neutral bidentate ligands [L = 4,4'-bipyridine (4,4'-bpy) and 1,1'-bis(diphenylphosphino)ferrocene (dppf)] to give dinuclear PCP pincers [{Pd(PCP)}(2)(micro-L)][OTf](2) (L = 4,4'-bpy, 2; dppf,3).

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The cyclometallated Pd compound [upper bond 1 start]PdCl[PPh(2)CH(2)CH(2)C[upper bond 1 end]HCH(2)CH(2)PPh(2)], obtained from PdCl(2)(Ph(2)P(CH(2))(5)PPh(2)) in refluxing DMF (N,N-dimethylformamide), was characterized by NMR and X-ray single-crystal diffraction analysis. The cyclometallation of MCl(2)(Ph(2)P(CH(2))(5)PPh(2))(M = Pd, Pt) to give and its Pt(ii) analogue was probed using electrospray ionisation mass spectrometry (ESMS). The reactivity of towards neutral ligands such as phosphines and pyridines as well as basic metal complexes such as pyridine-thiolate compounds of Au(i), Hg(ii) and Pt(ii) in solution was also investigated.

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