Phenolate based metallomacrocyclic xanthate complexes of Co(II)/Cu(II) and their exclusive deployment in [2 : 2] binuclear N,O-Schiff base macrocycle formation and in vitro anticancer studies.

Potassium salts of phenolate based polydentate xanthate ligands 4,4'-bis(2-dithiocarbonatobenzylideneamino)diphenyl ether () and 4,4'-bis(2-dithiocarbonatonaphthylmethylideneamino)diphenyl ether () have been synthesized and characterized, prior to use. The reaction of or with M(OAc)2 in Et3N affords access to a rare series of binuclear metallomacrocyclic xanthate complexes of the type [M2-µ(2)-bis-(κ(2)S,S-xan(1)/xan(2))] () which quickly forms [2 : 2] binuclear N,O-bidentate Schiff base macrocyclic complexes of the type [M2-µ(2)-bis-(κ(2)N,O-L(1)/L(2))] ( = 4,4'-bis(2-hydroxybenzylideneamino)diphenyl ether, = 4,4'-bis(2-hydroxynaphthylmethylidene-amino)diphenyl ether) via evolution of CS2 in solution. The compounds were characterized by microanalysis, relevant spectroscopy (FT-IR, UV-visible), mass spectrometry (ESI-MS), and powder and single crystal XRD techniques. In vitro anticancer activity of all the compounds was evaluated against HEP 3B (hepatoma) and IMR 32 (neuroblastoma) by the MTT assay. Remarkably, the binuclear copper(ii) xanthate complexes were found to be extremely active against both the cell lines (IC50: 8.1 ± 0.8 µM (), 8.8 ± 1.7 µM () against HEP 3B and 1.9 ± 0.3 µM () and 7.3 ± 0.6 µM () against IMR 32) and this projects them as good candidates for potent antitumor agents and the IC50 values confirm their better potency than the reference drug cisplatin. The flow-cytometric density plot illustrates the induction of apoptosis in HEP 3B and IMR 32 cells after treatment with , , , and .

Unusual crystal structure of N-substituted maleamic acid - very strong effect of intramolecular hydrogen bonds.

N-Carbamylmaleamic acid (malur) undergoes cyclodehydration under favourable conditions, as expected, to give N-carbamyl maleimide. N-(Carboxymethyl) maleamic acid (malgly), however, does not undergo a similar cyclization reaction. Strong π bonding between the C and N of the amide group as well as two intramolecular hydrogen bonds makes malgly a planar molecule, as revealed by single-crystal X-ray studies.

Design, synthesis and antimycobacterial activity of various 3-(4-(substitutedsulfonyl)piperazin-1-yl)benzo[d]isoxazole derivatives.

In this communication, we synthesized a series of twenty four novel 3-(4-(substitutedsulfonyl)piperazin-1-yl)benzo[d]isoxazole analogues, characterized using various spectroscopic techniques and evaluated for their in vitro anti-tubercular activity against Mycobacterium tuberculosis (MTB) H37Rv strain. The titled compounds exhibited Minimum inhibitory concentration (MIC) between 3.125 and >50 µg/mL. Among the tested compounds, 5c, 6a, 6j and 6p exhibited moderate activity (MIC = 12.5 µg/mL), while 5a and 6i exhibited good activity (MIC = 6.25 µg/mL) and 6b (MIC = 3.125 µg/mL) exhibited very good anti-tubercular activity. In addition, the analogues 5a, 5c, 6a, 6b, 6i, 6j and 6p were subjected to toxicity studies against mouse macrophage (RAW 264.7) cell lines to analyse the selectivity profile of the newly synthesized compounds and selectivity index of the most active compound was found to be >130 indicating suitability of the compound for further drug development. Structure of 6b was further substantiated through single crystal XRD.

Gold-catalysed cyclisation of N-propargylic ß-enaminones to form 3-methylene-1-pyrroline derivatives.

A gold(I) catalysed reaction between N-propargylic ß-enaminones and arynes was developed to access 3-methylene-1-pyrrolines. The title compounds were obtained in 57-78% yields. This reaction is useful for the generation of substituted 1-pyrrolines exhibiting significant molecular complexity.

Reinvestigation of growth of urea thiosemicarbazone monohydrate crystal.

The reaction of urea with thiosemicarbazide in 1:1 mole ratio in aqueous solution does not result in the formation of urea thiosemicarbazone monohydrate crystal, as reported by Hanumantharao, Kalainathan and Bhagavannarayana [Spectrochim. Acta A91 (2012) 345-351]. A reinvestigation of the reported reaction reveals that the crystal obtained is the starting material namely thiosemicarbazide, which has been unambiguously confirmed with the aid of infrared and (1)H NMR spectra and single crystal X-ray structure determination. Analysis of (1)H NMR spectrum reveals that thiosemicarbazide exhibits thione-thiol tautomerism in solution. In contrast, thiosemicarbazide exists as the thione tautomer in the solid state.

Synthesis, structure, DNA binding and cleavage properties of ternary amino acid Schiff base-phen/bipy Cu(II) complexes.

Ternary Cu(II) complexes [Cu(II)(saltrp)(B)] (1,2), (saltrp=salicylidene tryptophan, B=1,10 phenathroline (1) or 2,2' bipyridine (2)) were synthesized and characterized. Complex 2 was structurally characterized by single crystal X-ray crystallography. The molecular structure shows a distorted square pyramidal coordination geometry (CuN(3)O(2)) in which the ONO donor Schiff base is bonded to the Cu(II) in the basal plane. The N,N donor heterocyclic base displays an axial-equatorial binding mode. CT-DNA binding studies revealed that the complexes show good binding propensity (Intrinsic binding constant, K(b)=3.32×10(5) M(-1) for 1 and K(b)=3.10×10(5) M(-1) for 2). The catalytic role of these complexes in the oxidative and hydrolytic cleavage of DNA was studied in detail. Complex 1 binds and cleaves DNA more efficiently as compared to 2. From the kinetic experiments, rate constants for the hydrolysis of phosphodiester bond of DNA backbone were determined as 1.94 h(-1) and 1.05 h(-1) for 1 and 2 respectively. It amounts to (2.93-5.41)×10(7) fold rate enhancement compared to uncatalyzed double stranded DNA, which is impressive as compared to related Cu(II) Schiff base complexes.

Diastereoselective syntheses of 3-aryl-5-(arylalkyl)-6-methyl-1-(1-phenylethyl)thioxotetrahydropyrimidin-4(1H)-ones: a stereochemical perspective from endo and exocyclic chiral centres.

Diastereoselective syntheses of 3-aryl-(S/R)-6-methyl-1-[(S/R)-1-phenylethyl)]-2-thioxotetrahydro pyrimidin-4(1H)-ones were achieved in good yields by the condensation of aryl isothiocyanates with ethyl 3-(1-phenylethylamino)butanoate in a one-pot reaction. Benzylation of these substrates illustrated that the orientations of the exocylic and endocylic groups determine the stereochemical outcome of the product formed.

Sulfate anion helices formed by the assistance of a flip-flop water chain.

A flip-flop extended water structure assists the formation of sulfate anion helices (both left- and right-handed) in a crystalline hydrate of a simple organic-inorganic compound [C6H10N2]SO4. 1.5H2O (1).