Synthesis,characterization, biological screening and molecular docking of Zn(II) and Cu(II) complexes of 3,5-dichlorosalicylaldehyde-N4-cyclohexylthiosemicarbazone

A 3,5-dichlorosalicylaldehyde-N⁴-cyclohexylthiosemicarbazone (C₁₄H₁₆Cl₂N₃OS) and its complexes [Zn(dsct)(phen)]·DMF ( 1 ), [Zn(dsct)(bipy)]·DMF ( 2 ), [Cu(dsct)(bipy)]·DMF ( 3 ) (phen = 1,10-phenathroline, bipy = 2,2’bipyridine) were synthesized and characterized by CHN analysis, FT-IR, UV–vis and NMR spectra. The molecular structure of the thiosemicarbazone (H₂dsct) and its complexes have been resolved using single crystal XRD studies. In the complexes, thiosemicarbazone exist in the thioiminolate form and acts as dideprotonated tridentate ligand coordinating through phenolic oxygen, thioiminolate sulfur and azomethine nitrogen. The antibacterial activity of the prepared compounds were screened against Escherichia coli, Salmonella typhi, Enterobacter aerogenes, Shigella dysentriae, Bacillus cereus, Staphylococcus aureus. All the complexes showed activity against bacterial strains E.coli and Salmonella typhi. The thiosemicarbazone showed activity against three bacterial strains such as E. coli, Enterobacter aerogenes and Shigella dysentriae. Complex 2 showed very good antibacterial activity as compared to standard drug (Ampicillin) against the bacterial strain, Salmonella typhi. Finally, the thiosemicarbazone and its complexes have been used to accomplish molecular docking studies against an Epidermal Growth Factor Receptor (EGFR) and breast cancer mutant 3hb5-oxidoreductase to determine the most preferred mode of interaction. The results confirm that the complex [Cu (dsct)(bipy)]·DMF( 3 ) showed the highest docking score as compared to other complexes under study. The [Cu(dsct)(bipy)]·DMF( 3 ) complex was evaluated for their anticancer activities against breast cancer cell line (MCF-7) and normal L929 (Mouse Fibroblast) cell line. It was found that the compound showed an LC₅₀ of 6.25 μg/mL against breast cancer cell line (MCF-7).     

Spectral studies and crystal structures of molybdenum(VI) complexes containing pyridine or picoline as auxiliary ligands: interaction energy calculations and free radical scavenging studies

Transition Metal Chemistry - Three cis-MoO2 complexes [MoO2(CAB)(py)] (1), [MoO2(CAB)(3-pic)] (2) and [MoO2(CAB)(4-pic)] (3) which vary in the nature of the heterocyclic bases in...     

Synthesis,structural insights and catalytic activity of a dioxidomolybdenum(VI) complex chelated with N4-(3-methoxyphenyl) thiosemicarbazone

Transition Metal Chemistry - A cis-dioxidomolybdenum(VI) complex of a thiosemicarbazone of the type [MoO2L(DMSO)], where H2L?=?3-ethoxysalicylaldehyde-N4-(3-methoxyphenyl)...     

Synthesis and Spectral Studies of Bisthiocarbohydrazone and Biscarbohydrazone of Quinoline-2-carbaldehyde: Crystal Structure of Bis(quinoline-2-aldehyde) Thiocarbohydrazone

Abstract Two new ligands, having flexible coordination ability, 1,5-bis(quinoline-2-carbaldehyde) thiocarbohydrazone and 1,5-bis(quinoline-2-carbaldehyde) carbohydrazone were synthesized and characterized by elemental analysis, IR, and UV spectral studies. The compounds exist in the thione/ketone tautomeric forms, as evidenced by IR spectral data. The structure of bis(quinoline-2-aldehyde) thiocarbohydrazone has been solved by single crystal XRD study. The compound C₂₁H₁₆N₆S crystallizes in triclinic form with two independent molecules in the asymmetric unit, space group , Z = 4, V = 1856.1(6) ?³ with unit cell parameters a = 11.331(2) ?, b = 11.714(2) ?, c = 15.116(3) ?, α = 100.369(4)°, β = 109.512(4)° and γ = 90.134(4)°. Both molecules exist in the thione forms and show a Z–Z configuration about both azomethine bonds, with quinoline nitrogens on opposite sides. The N–N, N–C and the C–S bond distances of the thiocarbohydrazide moiety suggest extensive electron delocalization of the whole thiocarbohydrazone moiety. Index Abstract Synthesis and spectral studies of bisthiocarbohydrazone and biscarbohydrazone of quinoline-2-carbaldehyde: Crystal structure of bis(quinoline-2-aldehyde) thiocarbohydrazone, E. Manoj, M. R. Prathapachandra Kurup, E. Suresh. Bis(quinoline-2-aldehyde) thiocarbohydrazone crystallizes in the tricliniccrystal system with two independent molecules in the asymmetric unit, and exists in the thione tautomeric form. Both molecules show a Z-Z configuration about both azomethinebonds, with quinoline nitrogens on opposite sides. The N–N, N–C and the C–S bond distances of the thiocarbohydrazide moiety suggest extensive electron delocalization of the whole thiocarbohydrazone moiety . Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Rheological representation of fractional order viscoelastic material models

We develop rheological representations, i.e., discrete spectrum models, for the fractional derivative viscoelastic element (fractional dashpot or springpot). Our representations are generalized Maxwell models or series of Kelvin-Voigt units, which, however, maintain the number of parameters of the corresponding fractional order model. Accordingly, the number of parameters of the rheological representation is independent of the number of rheological units. We prove that the representations converge to the corresponding fractional model in the limit as the number of units tends to infinity. The representations extend to compound fractional derivative models such as the fractional Maxwell model, fractional Kelvin-Voigt model, and fractional standard linear solid. Computational experiments show that the rheological representations are accurate approximations of the fractional order models even for a small number of units.     

A new approach to variable selection in least squares problems

The title Lasso has been suggested by Tibshirani (1996) as acolourful name for a technique of variable selection which requiresthe minimization of a sum of squares subject to an l₁ bound on the solution. This forces zero components in the minimizingsolution for small values of . Thus this bound can functionas a selection parameter. This paper makes two contributionsto computational problems associated with implementing the Lasso:(1) a compact descent method for solving the constrained problemfor a particular value of is formulated, and (2) a homotopymethod, in which the constraint bound becomes the homotopyparameter, is developed to completely describe the possibleselection regimes. Both algorithms have a finite terminationproperty. It is suggested that modified Gram-Schmidt orthogonalizationapplied to an augmented design matrix provides an effectivebasis for implementing the algorithms.     

Spectral characterization and crystal structure of 2-benzoylpyridine nicotinoyl hydrazone

The synthesis, spectral characterization and crystal structure of 2-benzoylpyridine nicotinoyl hydrazone (HL) is reported. Spectral techniques employed include 1H NMR, COSY homonuclear, HSQC heteronuclear correlation techniques, electronic and IR. The infrared spectrum suggests the existence of the compound in keto form in solid state, which is further established by the single crystal X-ray analysis. The compound crystallizes into a triclinic lattice with P-1 symmetry with two molecules per unit cell.     

Synthesis,spectral characterization and crystal structure of copper(II) complexes of 2-hydroxyacetophenone-N(4)-phenyl semicarbazone

Six new copper(II) complexes of 2-hydroxyacetophenone-N(4)-phenyl semicarbazone have been synthesized and physico-chemically characterized. The tridentate character of the semicarbazone is inferred from IR spectra. Based on EPR studies, the spin Hamiltonian and bonding parameters have been calculated. The g   values, calculated for all the complexes in frozen DMF, indicate the presence of the unpaired electron in the d_x2-y2${\text{d}}_{x^2-y^2}$ orbital. The metal–ligand bonding parameters evaluated showed strong in-plane σ and in-plane π-bonding. The structure of the compound, CuLphen has been resolved using single crystal X-ray diffraction studies. The crystal structure revealed a monoclinic lattice with space group symmetry P2₁/c. The compound adopts a distorted square pyramidal geometry with a N₂O₂ core as the base.     

Synthesis,spectroscopic studies and crystal structures of two new vanadium complexes of 2-benzoylpyridine containing hydrazone ligands

The reaction of VO(acac)₂ with 2-benzoylpyridine substituted aroylhydrazones is studied. Oxovanadium(IV) and (V) complexes are obtained, indicating the binding of ligands to the metal ion through the imine nitrogen, enolate oxygen and pyridyl nitrogen. The oxovanadium(IV) compound [VOL¹(OCH₃)] · 0.14H₂O (1a) gets oxidized to dioxovanadium(V) species [VO₂L¹] (1b) upon crystal formation. The crystal structures of the ligand and the two vanadium complexes are reported. Single crystal X-ray diffraction studies of the compound [VO(HL²)(μ₂-O)]₂ (2) revealed a centrosymmetric dimer.     

Zinc(II) complexes derived from di-2-pyridyl ketone N-phenyl-3-semicarbazone: Crystal structures and spectral studies

Six zinc(II) complexes, Zn(HL)Br₂ (1), Zn(HL)Cl₂ (2), ZnL(OAc) (3), ZnLN₃ (4), ZnL₂ (5) and ZnL₂ · H₂O (6), have been synthesized and characterized by different physicochemical techniques. Complex 1 is five coordinated and has a distorted square pyramidal geometry. Complexes 5 and 6 are six coordinated and have distorted octahedral geometries. In complexes 1 and 2, the ligand moieties are coordinated in the neutral form (HL), and in the other complexes they are monoanionic (L⁻).