Kong Mun Lo

Homologous 1,3,5-triarylpyrazolines: synthesis, CH⋯π interactions guided self-assembly and effect of alkyloxy chain length on DNA binding properties

A series of new 2-pyrazoline derivatives (1c–12c) bearing one to twelve carbon homologous alkyloxy side chains have been synthesized in good to excellent yields via intramolecular cyclization reaction on treatment of chalcone intermediates (1a–12a) with phenyl hydrazine (1b) and characterized on the basis of their physical and spectral (IR, 1H & 13C NMR, GC-MS) data. The solid state structure of compound (2c) showed intriguing and unique 1D-supramolecular zigzag chain-like self-assembled structure, the driving force of which is only CH⋯π interactions. DNA interaction studies have also been carried out on selected compounds 1c, 3c, 5c, 6c, 9c and 12c of the series by UV-visible spectroscopy to evaluate their anticancer potential and the effect of alkyloxy chain length on DNA binding property. All the tested compounds showed strong DNA binding (105–106 M−1 binding constants) with hyperchromic effect. A slight increase in the DNA binding strength, observed on increasing the chain length of alkyloxy groups, was attributed to their conformational arrangements, leading to the best fit conformation of 1,3,5-triaryl moiety in the minor groove of DNA structure.

Organotin esters of 3-ureidopropionic acid. Crystal structure of triphenyltin(IV) 3-ureidopropionate, (C6H5)3SnOCO(CH2)2NHCONH2

Syntheses and spectroscopic (119mSn Mossbauer and infrared) data are reported for triorganotin derivatives of 3-ureidopropionic acid of the general formula, R3SnOCOCH2CH2NHCONH2 (R = Ph, nBu, cyclohexyl, and p-tolyl) and Ph2RSnOCOCH2CH2NHCONH2 (R = nBu, p-ClC6H4 and cyclopentyl). The crystal structure of triphenyltin 3-ureidopropionate has been determined. The compound adopts a trans-C3SnO2 trigonal bipyramidal geometry with the axial positions occupied by the ester oxygen and the ureido-oxygen of an adjacent molecule. The polymer units are held together by intermolecular hydrogen bonding between the group NH of the ureido fragment and the oxygen of the carboxylate carbonyl.

Synthesis and spectroscopic studies of thienyl triorganotin(IV) compounds. Crystal structures of [2-(4,4-dimethyl-2-oxazolinyl)-3-thienyl]dimethyltin N,N-dimethyldithiocarbamate and [2-(4,4-dimethyl-2-oxazolinyl)-3-thienyl]diphenyltin chloride

Abstract Two series of stannylated thiophenes of formula ( Z -C 4 H 2 SnR 2 X ( Z = 3-(2-pyridyl) and 2-(4,4-dimethyl-2-oxazolinyl); R = Me, n Bu, Ph, p -tolyl and c Hex; X = Cl, Br, I, OH, SC(S)NMe 2 , and 8-quinolinolyl) have been prepared and their structures established by 119 m Sn Mossbauer and NMR ( 13 C and 119 Sn) spectral analyses. A pronounced C , N -chelate bonding mode is inferred for the 3-(2-pyridyl)-2-thienyl ligand in the first series, the tin atoms thus being essentially five-coordinate with trans -C 3 SnNX trigonal bipyramidal geometries. Crystal structure determinations on two products in the second series, namely [2-(4,4-dimethyl-2-oxazolinyl)-3-thienyl]dimethyltin N , N -dimethyldithiocarbamate ( 1 ) and [2-(4, 4-dimethyl-2-oxazolinyl)-3-thienyl]diphenyltin chloride ( 2 ), confirmed the spectroscopic indications of pentacoordinate trigonal bipyramidal tin environments and revealed that the oxazolinyl nitrogen is the intramolecularly coordinated donor atom in each case and is located in an apical position with respect to the C 3 Sn trigonal girdle; the Sn-N bond length in 2 (2.580(8); 2.525(7) A) is relatively shorter than in 1 (2.720(3) A). The apical angle for 1 (162.12(7)°) shows the molecule to be more distorted than 2 (168.4(2) and 169.9(2)°).

Total synthesis, cytotoxic effects of damnacanthal, nordamnacanthal and related anthraquinone analogues.

Naturally occurring anthraquinones, damnacanthal (1) and nordamnacanthal (2) were synthesized with modified reaction steps and investigated for their cytotoxicity against the MCF-7 and K-562 cancer cell lines, respectively. Intermediate analogues 2-bromomethyl-1,3-dimethoxyanthraquinone (5, IC50 = 5.70 ± 0.21 and 8.50 ± 1.18 μg/mL), 2-hydroxymethyl-1,3-dimethoxyanthraquinone (6, IC50 = 12.10 ± 0.14 and 14.00 ± 2.13), 2-formyl-1,3-dimethoxyantharquinone (7, IC50 = 13.10 ± 1.02 and 14.80 ± 0.74), 1,3-dimethoxy-2-methylanthraquinone (4, IC50 = 9.40 ± 3.51 and 28.40 ± 2.33), and 1,3-dihydroxy-2-methylanthraquinone (3, IC50 = 25.60 ± 0.42 and 28.40 ± 0.79) also exhibited moderate cytotoxicity against MCF-7 and K-562 cancer cell lines, respectively. Other structurally related compounds like 1,3-dihydroxyanthraquinone (13a, IC50 = 19.70 ± 0.35 and 14.50 ± 1.28), 1,3-dimethoxyanthraquinone (13b, IC50 = 6.50 ± 0.66 and 5.90 ± 0.95) were also showed good cytotoxicity. The target compound damnacanthal (1) was found to be the most cytotoxic against the MCF-7 and K-562 cancer cell lines, with IC50 values of 3.80 ± 0.57 and 5.50 ± 1.26, respectively. The structures of all compounds were elucidated with the help of detailed spectroscopic techniques.

Synthesis, characterization and biological evaluation of cationic hydrazone copper complexes with diverse diimine co-ligands

Four new copper(II) complexes containing triphenylphosphonium conjugated salicylaldehyde-(4-fluorobenzhydrazone), (L) with the formulation [CuL]Cl(1), [Cu(phen)L]Cl(2), [Cu(bpy)L]Cl(3), [Cu(dmbpy)L]Cl(4), (where L = doubly deprotonated hydrazone; phen = 1,10′-phenanthroline; bpy = 2,2′-bipyridine; dmbpy = 5,5′-dimethyl-2,2′-bipyridine) have been synthesized. The compounds were characterized by spectroscopic methods and, in the case of crystalline products, by X-ray crystallography. The topoisomerase I (topo I) inhibition, DNA binding and cleavage activities and cytotoxicity of the compounds were studied. A DNA relaxation study demonstrated that all the copper complexes successfully inhibit topo I enzyme by binding to topo I as the preferred pathway. Complex 1 is the most active with starting inhibitory concentration ≈20 μM. The planarity of the tridentate hydrazone Schiff base ligand and the diimine co-ligands increase the binding affinity to DNA. The presence of the 1,10′-phenanthroline co-ligand in complex 2 induces plasmid DNA (pBR322) cleavage without exogenous agents. It is noteworthy that the addition of diimine co-ligands to the copper(II) complex enhanced the cytotoxicity of the compounds, especially against the human prostate adenocarcinoma cell line (PC-3). Complex 2 exhibits the highest activity against PC-3 with the IC50 value of 2.47 ± 0.37 μM. Annexin V/propidium iodide analysis showed that compound 1 induces apoptotic and necrotic cell death, whereas compound 2–4 work mainly through apoptosis.

The effect of terminal substituents on crystal structure, mesophase behaviour and optical property of azo-ester linked materials

ABSTRACT A series of azo-ester linked mesogen containing liquid crystalline acrylate compounds C1-C6 having different terminal groups (–F, –Cl, –Br, –OCH3, –OC2H5 and –OC3H7) were successfully synthesised and characterised. The chemical structure, purity, thermal stability, mesophase behaviour and optical property of the synthesised compounds were investigated by different instrumental techniques. X-ray crystal structure showed that compounds C1, C4 and C5 exhibited more stable E configuration with two bulky group in the opposite side of the N=N double bond motifs. The fluoro-substituted derivative (C1) is connected by the R12(5) type of C–H…O hydrogen bond motifs whereas the molecules of C4, and C5 are connected to each other by means cyclic R22(8) type of C–H…O hydrogen bond motifs. Thermogravimetric study revealed that the investigated compounds exhibited excellent thermal stability. All the compounds showed enantiotropic liquid crystal (LC) phase behaviour and the mesophase formation was greatly influenced by the terminal substituents. Alkoxy (–OCH3, –OC2H5 and –OC3H7) substituted compounds exhibited greater mesophase stability than those of halogen (–F, –Cl and –Br) terminated derivatives. UV-vis spectroscopic study revealed that the investigated compounds exhibited a broad absorption band around 300–420 nm with absorption maximum (λmax) of nearly 370 nm. GRAPHICAL ABSTRACT

Synthesis and structural characterization of (2-oxazolinylthienyl)tetraorganotin(IV) compounds

Abstract The synthesis and spectroscopic characterization ( 119 m Sn Mossbauer and 13 C/ 119 Sn NMR) of a series of thienyl tetraorganotin compounds, L n SnR 4- n , (L  [2-(4,4-dimethyl-2-oxazolinyl)-3-thienyl]; R  CH 3 , n-C 4 H 9 , c -C 6 H 11 , C 6 H 5 , p -CH 3 C 6 H 4 and p -ClC 6 H 4 ; n = 1, 2) are described. The compounds are essentially four-coordinate structures in the solid state and in solution. An X-ray crystal structure analysis of [2-(4,4-dimethyl-2-oxazolinyl)-3-thienyl]tri( p -tolyl)tin confirms the tetrahedral geometry at tin. The oxazolinyl substituent on the thienyl ring is oriented in such a way that the oxygen atom rather than the nitrogen points towards tin at a non-bonded contact of 2.977(3) A, thus inducing a slight distortion of the tetrahedral geometry. This finding contrasts with those for LSnPh 2 Cl and LSnMe 2 (S 2 CNMe 2 ), in which the oxazolinyl nitrogen is intramolecularly coordinated to tin.

Synthesis, structural characterization, and anticancer activity of a monobenzyltin compound against MCF-7 breast cancer cells

A new monoorganotin Schiff base compound, [N-(3,5-dichloro-2-oxidobenzylidene)-4-chlorobenzyhydrazidato](o-methylbenzyl)aquatin(IV) chloride, (compound C1), was synthesized, and its structural features were investigated by spectroscopic techniques and single-crystal X-ray diffractometry. Compound C1 was exposed to several human cancer cell lines, including breast adenocarcinoma cell lines MCF-7 and MDA-MB-231, ovarian adenocarcinoma cell lines Skov3 and Caov3, and prostate cancer cell line PC3, in order to examine its cytotoxic effect for different forms of cancer. Human hepatic cell line WRL-68 was used as a normal cell line. We concentrated on the MCF-7 cell line to detect possible underlying mechanism involvement of compound C1. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay revealed the strongest cytotoxicity of compound C1 against MCF-7 cells, with a half maximal inhibitory concentration (IC50) value of 2.5±0.50 μg/mL after 48 hours treatment. The IC50 value was >30 μg/mL in WRL-68 cells. Induced antiproliferative activity of compound C1 for MCF-7 cells was further confirmed by lactate dehydrogenase, reactive oxygen species, acridine orange/propidium iodide staining, and DNA fragmentation assays. A significant increase of lactate dehydrogenase release in treated cells was observed via fluorescence analysis. Luminescent analysis showed significant growth in intracellular reactive oxygen species production after treatment. Morphological changes of necrosis and early and late apoptosis stages were observed in treated cells after staining with acridine orange/propidium iodide. DNA fragmentation was observed as a characteristic of apoptosis in treated cells. Results of the present study obviously reveal potential cytotoxic effects of compound C1 against human breast cancer MCF-7 cells.

4-Hydr­oxy-N′-(4-hydroxy­benzo­yl)benzo­hydrazide

In the molecule of the title compound, C14H12N2O4, the two benzene rings make a dihedral angle of 84.53 (8)°. O—H⋯O and N—H⋯O hydrogen bonds link adjacent molecules into a layer structure.

MOLECULAR RECOGNITION OF AN ORGANIC MOLECULE THROUGH A TWO DIMENSIONAL SQUARE NETWORK INCLUSION COMPLEX. SYNTHESIS AND CRYSTAL STRUCTURE OF [Cd(4,4′-bpy)2(H2O)2] (BF4)2 · 2(4,4′-bpy) · (C6H6N2O2) · 2H2O

Abstract The 2D square network complex [Cd(4,4′-bpy)2(H2O)2] (BF4)2 · 2(4,4′-bpy) · (C6H6N2O2) · 2H2O (1) (where 4,4′-bpy = 4,4′-bipyridine and C6H6N2O2 = o-nitrobenzenamine) has been prepared by reaction of Cd(BF4)2 · 6H2O and 4,4′-bpy in the presence of o-nitrobenzenamine. High shape selectivity was observed in this self-assembly process. Single crystal X-ray analysis revealed that 1 possesses a 2D square network of [Cd(4,4′-bpy)2(H2O)2] cations, which are made up of layers stacked upon each other. The o-nitrobenzenamine molecule is 2-fold disordered over a centre of inversion in the same plane as the cationic network. Uncoordinated 4,4′-bpy molecules as well as uncoordinated water molecules and BF4 − counter anions are intercalated between the cationic network layers. Extensive hydrogen-bonding is observed to stabilize this crystal packing.