Soonheum Park

Preparation of the palladium(II) dimethylamide Pd(2,6-(Ph2PCH2)2C6H3)(NMe2) at low temperatures and its ligand exchange with the dicyclohexylamide

Abstract The title complex Pd(2,6-(Ph2PCH2)2C6H3)(NMe2) (2) has been prepared from deprotonation of [Pd(2,6-(Ph2PCH2)2C6H3)(NHMe2)]OTf (1) by a stoichiometric amount of dicyclohexylamide anion at low temperatures. VT NMR experiments showed that 2 was stable below −10°C, and slowly underwent decomposition to give a couple of unidentified species at elevated temperatures. However, the reaction of 1 with an excess of lithium dicyclohexylamide (>ten equivalents) generated the monomeric palladium(II) hydride (2,6-(Ph2PCH2)2C6H3)PdH (3). The reaction of (Ph2PCH2)2C6H3)Pd(OTf) with an excess of lithium dicyclohexylamide also produced the hydride. A d8-THF solution of 3 was stable for 16 h at ambient temperature. However, an attempt to isolate 3 resulted in the formation of a small amount of the hydride-bridged dipalladium [(Pd(2,6-(Ph2PCH2)2C6H3))2(μ-H)]+ (4) and mostly decomposed species.

Synthesis, Anticancer and Antioxidant Activity of Novel Carbazole-based Thiazole Derivatives

GRAPHICAL ABSTRACT Abstract A series of carbazole-based thiazole derivatives were synthesized and characterized. The title compounds were evaluated for their cytotoxicity against three cancer cell lines A549, MCF-7, and HT29 by MTT assay. Among several thiazole derivatives, compounds 4-(4-bromophenyl)-2-(2-((9-ethyl-9H-carbazol-3-yl)methylene)hydrazinyl)thiazole (3f) and 2-(2-((9-ethyl-9H-carbazol-3-yl)methylene)hydrazinyl)-4-(4-nitrophenyl)thiazole (3g) are found to display significant cytotoxicity against three cancer cell lines. These compounds have also been tested for antioxidant activity and are found to exhibit higher antioxidant activity than that of the standard BHT.

Synthesis, Spectral Characterization, and In Vitro Cytotoxicity of N-2′-Hydroxyethyl-Substituted Azacholestanes Prepared from 6-Oxocholestanes by Modified Schmidt Reaction

The present paper reports the synthesis and spectroscopic characterization of few N-2′-hydroxyethyl-substituted azacholestanes using BF3-OEt2, TiCl4, SnCl4, and H2SO4 as catalysts in moderate yields by a modified version of Schmidt reaction. A notable feature is the passivity of SnCl4 in case of 3β-acetoxy-N-2′-hydroxyethyl-6-aza-B-homo-5α-cholestan-7-one and 3β-chloro-N-2′-hydroxyethyl-6-aza-B-homo-5α-cholestan-7-one. However, the reaction was unsuccessful in case of N-2′-Hydroxyethyl-6-aza-B-homo-5α-cholestan-7-one. Another striking aspect is the attainment of high yield in case of H2SO4 as catalyst. The semisolid compounds are characterized using various spectroscopic techniques such as FT-IR, 1H-NMR and mass spectra, and microanalytical data. A reaction mechanism has been proposed on the basis of previous studies. Moreover, the compounds have also been screened for their in vitro cytotoxicity against human colon carcinoma cell line, HCT116, and human liver hepatocellular carcinoma cell line, HepG2, using doxorubicin as standard. On the basis of IC50 values, 3β-chloro-N-2′-hydroxyethyl-6-aza-B-homo-5α-cholestan-7-one (5) was found to inhibit the cancer cells most effectively.

Synthesis and Bioactivity of Novel Phenothiazine-Based Thiazole Derivatives

GRAPHICAL ABSTRACT Abstract A series of phenothiazine-based thiazole derivatives were synthesized and evaluated for their cytotoxicity against three cancer cell lines A549, MCF-7, and HT29 by MTT assay. Among several thiazole derivatives, compound 3d against HT29 cells and 3g against MCF-7 cells are found to display good cytotoxicity. These compounds have also been tested for antifungal and antioxidant activity. Some of these compounds exhibited significant antifungal activity and compound 3j was found to exhibit almost equivalent antioxidant activity as that of BHT.

Protonolysis of a toluidinoalkyl platinum(II) complex derived from the insertion of the CC bond into the Pt–NHR (amido) bond: the role of amine in Pt-catalyzed hydroamination of acrylonitrile

The complex Pt{2,6-(R2PCH2)2C6H3}(OTf) [R = Ph (1a), Cy (1b)] catalyzes the hydroamination of acrylonitrile with p-toluidine to produce CH2(CN)CH2NH(Tol-p), exclusively. In the catalyzed reactions, platinum intermediates were detected by NMR spectroscopy. The p-tolylamido platinum complex Pt{2,6-(Ph2PCH2)2C6H3}{NH(Tol-p)} (4), containing the pincer ligand, was synthesized from the reaction of 1a and NaNH(Tol-p). Complex 4 reacted with acrylonitrile to yield the regiospecific insertion product Pt{2,6-(Ph2PCH2)2C6H3}{CH(CN)CH2NH(Tol-p)} (5), quantitatively. Reaction of 5 with HX (X = Cl, OTf) generated free acrylonitrile, p-toluidine and Pt{2,6-(Ph2PCH2)2C6H3}X. Reacting 5 with a proton source having a non-coordinating counter anion, [NH3(Tol-p)]BPh4, also produced free acrylonitrile along with a cationic amine complex [Pt{2,6-(Ph2PCH2)2C6H3}{NH2(Tol-p)}]+. On the other hand, reaction of 5 with [NH3(Tol-p)]BPh4 in the presence of excess p-toluidine (ca. 30 equiv.) generated the hydroaminated product CH2(CN)CH2NH(Tol-p), predominantly. Treatment of 5 with [NH2Me2]BPh4 in the absence of amine bases also released the hydroaminated product. These results apparently reveal that the amine substrate plays a critical role in driving the catalytic cycle.

DFT/TD-DFT calculations, spectroscopic characterizations (FTIR, NMR, UV–vis), molecular docking and enzyme inhibition study of 7-benzoyloxycoumarin

The quantum chemical study, spectroscopic characterization and biological activity of the pharmaceutically active 7-benzoyloxycoumarin (2) molecule have been presented. Potential energy surface (PES) scanning has been performed to search for the most stable molecular geometry of the present compound. The stable geometry in the ground state, IR, UV-Vis absorption and NMR (13C, 1H) spectra of the title compound were theoretically obtained and compared with the experimental one. Various theoretical molecular parameters like molecular energy, atomic charges, dipole moment, thermodynamic parameters, donor-acceptor natural bond orbital (NBO) hyperconjugative interaction energies, frontier molecular orbitals energies, HOMO-LUMO gap, molecular electrostatic potential, chemical reactivity descriptors, molecular polarizability and non-linear optical (NLO) properties are presented. Moreover, the 3D Hirshfeld surfaces and the associated 2D fingerprint plots have been explored. The percentages of various non-covalent interactions are studied and pictorialized by fingerprint plots of Hirshfeld surface. 7-Benzoyloxycoumarin has shown promising inhibitory activity against butrylcholinesterase (BuChE) as compared to the reference drug, galantamine. Molecular docking is carried to introduce compound into the X-ray crystal structures of butrylcholinesterase at the active site to find out the probable binding mode. The results of molecular docking indicated that 7-benzoyloxy derivative of coumarin may show enzyme inhibitor activity.

Effect of Anodic Gas Compositions on the Overpotential in a Molten Carbonate Fuel Cell

Anodic overpotential has been investigated with gas composition changes in a class molten carbonate fuel cell. The overpotential was measured with steady state polarization, reactant gas addition (RA), inert gas step addition (ISA), and electrochemical impedance spectroscopy (EIS) methods at different anodic inlet gas compositions, i.e.,

SYNTHESIS AND SOLUTION NMR-STUDIES OF THE TRIS(3,5-DIMETHYLPYRAZOL-1-YL) HYDROBORATOPALLADIUM(II) COMPLEX, Pd{(pz*)3BH}(PPh3)CI

H_2:CO_2:H_2O

Synthesis, characterization, and cytotoxicity of N-2′-hydroxyethyl-substituted azastigmastanes

Abstract The sterically hindered tris(3, 5-dimethylpyrazol-l-yl)hydroborate complex of palladium, Pd{(pz*)3BH}(PPh3)Cl (1) has been prepared by the stepwise reaction of (CH3CN)2PdCl2 with K{(pz*)3BH}, and then PPh3. The complex 1 has been fully characterized by microanalysis and various spectroscopic methods. A solution NMR study of 1 revealed that two pz* groups of the {(pz*)3BH} ligand coordinate to palladium in cis positions, while the remaining group is not coordinated. VT NMR experiments have been performed to determine that signal broadening of the phenyl proton resonances in the 1H-NMR spectrum is likely attributed to restricted rotation of the coordinated PPh3 within the congested complex on the NMR time scale. Complex 1 was metastable in solution towards reaction with water to decompose into several uncharacterized species, in which a facile hydrolytic cleavage of the B-H bond proceeded as judged by IR and 1H-NMR spectra of the products. Reaction of 1 with PPh3 in CDCl3 exclusively yielded cis-PdCl2(PPh3)2, implicating a chlorine abstraction from the solvent.

Synthesis, Structural Characterization and Antimicrobial Activity of Cu(II) and Fe(III) Complexes Incorporating Azo-Azomethine Ligand

Abstract The in vitro cytotoxicity of N-2′-hydroxyethyl-substituted azastigmastanes and its precursor steroidal ketones against cancer cell lines: MCF-7, HepG2, and HCT 116; has been carried out using MTT assay. The N-2′-hydroxyethyl-substituted azastigmastanes were synthesized by bespoke version of Schmidt reaction using common Lewis acids like BF3–OEt2, SnCl4 and H2SO4 as catalysts in substantial yields. Sulphuric acid was found to be the most suitable catalyst in terms of reaction yield and time, while SnCl4 was found to be the weakest in case of 3β-acetoxy-N-2′-hydroxyethyl-6-aza-B-homo-5α-stigmastan-7-one and 3β-chloro-N-2′-hydroxyethyl-6-aza-B-homo-5α-stigmastan-7-one and almost inactive in case of N-2′-hydroxyethyl-6-aza-B-homo-5α-stigmastan-7-one. The products were obtained in semi-solid state and characterized by spectroscopic techniques and microanalytical data. Moreover, on the basis of IC50, compound 5 was found to inhibit the cancer cells most effectively in conformity with our previous findings.