Tetranuclear Palladacycles of 3-Acetyl-7-methoxy-2 H-chromen-2-one Derived Schiff Bases: Efficient Catalysts for Suzuki-Miyaura Coupling in an Aqueous Medium.

Tetranuclear organopalladium(II) complexes 1-3 and mononuclear complex 4 have been synthesized by the complexation of 3-acetyl-7-methoxy-2 H-chromen-2-one derived Schiff bases with potassium tetrachloropalladate K2[PdCl4]. Structural confirmation for the complexes (1-3) has been achieved by single-crystal X-ray diffraction analysis. The ligands are found to bind with the palladium ion through its azomethine nitrogen, thiolate sulfur, and C4 carbon atom of the coumarin moiety subsequent to C-H activation. The monomeric nature of complex 4 was confirmed from its mass spectroscopic data. In complex 4, coordination occurred via the lactone oxygen, azomethine nitrogen, and thiolate sulfur atoms. Computational study has been used to determine the optimized molecular structures of the complexes. An explanation on the energies of their highest occupied and lowest unoccupied molecular orbital levels and their electronic spectra has also been provided on the basis of the theoretical calculations. A systematic study of the application of these complexes as catalysts in Suzuki-Miyaura coupling (SMC) has been done with different aryl halides and phenyl boronic acid in an aqueous medium. Optimization of the reaction indicated that complex 2 exhibits greater efficiency than other complexes. An appreciable yield of the coupled products was observed with the minimum use of catalyst (µmol), and the C-C coupling has been confirmed by GC/GC-MS. An interesting result of our catalyst is the coupling of four different chloroquinolines with phenyl boronic acid to afford the coupled products in good yields.

Multifaceted Chiral Probe 2,3-Dihydro-4-hydroxy-chromene Schiff Base in Detecting Cu2+ Ions, l-Histidine, and Indazole: Spectroscopic Investigation and Confocal and Live Cell Imaging.

2,3-Dihydro-4-hydroxy-chromene-4(N)-ethyl thiosemicarbazone (probe F4) is used as a chemosensor, and it selectively detected Cu2+ ions among the metal ions by showing fluorescence "TURN ON" behavior. The stoichiometric binding of the probe with Cu2+ (CF4) was confirmed by Job's plot and mass spectroscopy. Further, CF4 was used as a sensor for the detection of l-amino acids and N-heterocyclic compounds. Among them, CF4 selectively detected l-histidine by showing fluorescence "TURN-OFF" behavior and selectively detected indazole by showing fluorescence "TURN-ON" behavior. These behaviors were further confirmed by in vivo live cell imaging studies by using Caenorhabditis elegans as a model. In vitro cytotoxicity was assayed for probe F4, complex CF4, and CF4 with l-histidine and indazole. The IC50 concentration was used for confocal imaging studies by using the MDA-MB-231 cell line (breast cancer cell line).

Copper ion mediated selective cleavage of C-S bond in ferrocenylthiosemicarbazone forming mixed geometrical [(PPh3)Cu(µ-S)2Cu(PPh3)2] having Cu2S2 core: toward a new avenue in copper-sulfur chemistry.

Unprecedented selective cleavage of the carbon-sulfur bond of the ferrocenylthiosemicarbazone moiety has been observed for the first time, resulting in the formation of mixed geometrical binuclear copper complex [(PPh(3))Cu(µ-S)(2)Cu(PPh(3))(2)]. Upon trying direct synthesis of the title complex, an unusual tetranuclear [Cu(4)(µ(3)-Cl)(4)(PPh(3))(4)] cubane resulted.

Synthesis, X-ray crystal structure, DNA binding, antioxidant and cytotoxicity studies of Ni(ii) and Pd(ii) thiosemicarbazone complexes.

New complexes, [Ni(HL)(PPh(3))]Cl (1), [Pd(L)(PPh(3))](2), and [Pd(L)(AsPh(3))](3), were synthesized from the reactions of 4-chloro-5-methyl-salicylaldehyde thiosemicarbazone [H(2)L] with [NiCl(2)(PPh(3))(2)], [PdCl(2)(PPh(3))(2)] and [PdCl(2)(AsPh(3))(2)]. They were characterized by IR, electronic, (1)H-NMR spectral data. Further, the structures of the complexes have been determined by single crystal X-ray diffraction. While the thiosemicarbazone coordinated as binegative tridentate (ONS) in complexes 2 and 3, it is coordinated as mono negative tridentate (ONS) in 1. The interactions of the new complexes with calf thymus DNA was examined by absorption and emission spectra, and viscosity measurements. Moreover, the antioxidant properties of the new complexes have also been tested against DPPH radical in which complex 1 exhibited better activity than that of the other two complexes 2 and 3. The in vitro cytotoxicity of complexes 1-3 against A549 and HepG2 cell lines was assayed, and the new complexes exhibited higher cytotoxic activity with lower IC(50) values indicating their efficiency in killing the cancer cells even at very low concentrations.

Evaluation of DNA binding, antioxidant and cytotoxic activity of mononuclear Co(III) complexes of 2-oxo-1,2-dihydrobenzo[h]quinoline-3-carbaldehyde thiosemicarbazones.

Four new 2-oxo-1,2-dihydrobenzo[h]quinoline-3-carbaldehyde N-substituted thiosemicarbazone ligands (H(2)-LR, where R = H, Me, Et or Ph) and their corresponding new cobalt(III) complexes have been synthesized and characterized. The structures of the complexes 2 and 3 were determined by single crystal X-ray diffraction analysis. The interactions of the new complexes with DNA were investigated by absorption, emission and viscosity studies which indicated that the complexes bind to DNA via intercalation. Antioxidant studies of the new complexes showed that the significant antioxidant activity against DPPH radical. In addition, the in vitro cytotoxicity of complexes 1-4 against A549 cell line was assayed which showed higher cytotoxic activity with lower IC(50) values indicating their efficiency in killing the cancer cells even at very low concentrations.