Heteroatom Chemistry最新文献

Structure and bonding of hybrid group 13/14 pyramidal molecules ClE[$$R₄] (E = B–Ga, E′ = C–Ge, R = SiMe₃, SiMe^tBu₂) were studied by DFT calculations. Six pyramidal structures are suggested for their potential synthetic realization.

A new domino reaction between thioaurones and malononitrile has been reported. This reaction allows efficient access to benzothiophene-fused pyran derivatives in good yields under mild reaction conditions. The substrate scope is broad; a series of benzothiophene-fused pyran derivatives have been synthesized.

The host-guest complexation of six amine boranes (R₃NBH₃) by the macrocyclic host molecule cucurbit[7]uril (CB[7]) in aqueous solution has been investigated using ¹H and ¹¹B NMR spectroscopy. The limiting complexation-induced ¹H and ¹¹B chemical shift changes indicate that the amine boranes are included in the hydrophobic cavity of the host molecule. The host-guest stability constants for neutral { R₃NBH₃∙CB[7] } complexes (in the range of 10⁵-10⁷M^-1) have been determined by ¹H NMR competition experiments and are compared with the corresponding values for the isoelectronic/isostructural { R₃NCH₃∙CB[7] }⁺ complexes. Ammonia borane (H₃NBH₃) does not form a host-guest complex with CB[7]. The trends in the host-guest stability constant with the guest molar volume are examined, and the stability is ascribed to the hydrophobic effect (packing coefficient) and quadrupole-dipole interactions.

Phosphole P(V) derivatives are interesting building blocks for various applications from ligand synthesis to material sciences. We herein describe the preparation and characterisation of new 2,4-disubstituted oxo-, thiooxo-, and selenooxophospholes. The nature of the substituents on the phosphole ring determines the reactivity of these compounds towards homodimerization reactions. Aryl and trimethylsilyl substituted oxophospholes undergo selective [4+2] dimerization, whereas, for thiooxo- and selenooxophospholes, light-induced, selective [2+2] head-to-head dimerization occurs in the case of aryl substituents. DFT calculations provide some insights on these differences in reactivity.

Methylthioanilines, a series of sulfur-nitrogen donor ligands substituted with OCH₃, CH₃, Cl, and Br, and their copper(II) complexes have been synthesized and characterized by ¹H and ¹³C NMR, elemental analysis, FTIR, UV-Vis and EPR spectra, molar conductance, and magnetic susceptibility measurements. The NMR spectra of the ligands revealed that the para/ortho protons and para carbon were sensitive to the electronic effect of substituents. The CHNS analysis presented CuLCl₂ (L = OCH₃, CH₃, Cl) and CuL₂Cl₂ (L = Br) stoichiometries for the copper complexes. FTIR spectra showed that the bidentate ligands were coordinated to the copper ion through their nitrogen and sulfur atoms. The electronic spectra have suggested square planar and octahedral geometries for these complexes. The EPR spectra demonstrated that the solid state copper(II) complexes possess $$ orbital ground state and g_∥ > g_⊥ > 2.0023 in a tetragonal environment. The compounds were evaluated for in vitro antimicrobial activity against S. aureus, B. subtilis, E. coli, and C. albicans. The copper complexes showed higher activity than the parent ligands against S. aureus and B. subtilis; the electron-donating OCH₃ and CH₃ derivatives were more active than the withdrawing Br- and Cl-substituted compounds.

To understand the stability, chelation behaviour, and biological activity of 4-Formylpyridinethiosemicarbazone (H4FPT), it is important to recognize its interactive geometry. Hence, computational studies on geometrically optimized structures of thione and thiol forms of H4FPT were performed. Binary metal complexes of the ligand, H4FPT (L) with the Ni(II) and Cu(II) metal ions (M), were synthesized and characterized by various spectroanalytical techniques as elemental analysis, molar conductance, magnetic susceptibility measurements, LC-MS, TGA, IR, UV-Visible, ESR, and powder XRD. Elemental analysis, LC-MS, and TGA studies indicate 1:2 (ML₂) composition for mononuclear Ni(II) complex and 1:1 (ML) composition for dinuclear Cu(II) complex. Electronic absorption titrations, fluorescence quenching studies, and viscosity measurements suggest intercalative mode of binding of the complexes with calf thymus DNA (CT-DNA). These complexes also promote hydrolytic cleavage of plasmid pBR322. The ligand (H4FPT) and its complexes showed moderate-to-good activity against Gram-positive and Gram-negative bacterial strains. The DPPH radical scavenging studies showed antioxidant nature of both complexes.

Diaryl(iodo)bismuthanes possessing a hypervalent C=O•••Bi–I bond were conveniently synthesized in a one-pot reaction by using arylzinc reagents generated from o-carbonyl iodobenzenes and zinc powder under ultrasonication. This method is superior to the conventional organolithium and Grignard methods because it has a wide functional group tolerance, requires no protecting group manipulations, and proceeds under mild reaction conditions that do not need low temperature control. Furthermore, no intermediate triarylbismuthane precursor for the hypervalent iodobismuthane is necessary.

N-tert-Butyl-1,2-diaminoethane was shown to react rapidly with atmospheric carbon dioxide to generate the zwitterionic ammonium carbamate salt CO₂N(H)C₂H₄N$$Bu (1). Reaction of N-tert-butyl-1,2-diaminoethane with triethylorthoformate gave 1-tert-butyl-2-imidazoline (2) in 24% yield after fractional distillation, and the hydroxyalkyl-tethered imidazolinium salt [HOC(Me)₂CH₂NC₂H₄N(CH)^tBu][Cl] (3) was synthesised from the sequential reaction of N-tert-butyl-1,2-diaminoethane with isobutylene epoxide, HCl, and triethylorthoformate.

In this study we are going to present thiazole based carbohydrazide in search of potent antidiabetic agent as α-amylase inhibitors. Thiazole based carbohydrazide derivatives 1-25 have been synthesized, characterized by ¹HNMR, ¹³CNMR, and EI-MS, and evaluated for α-amylase inhibition. Except compound 11 all analogs showed α-amylase inhibitory activity with IC₅₀ values from 1.709 ± 0.12 to 3.049 ± 0.25 μM against the standard acarbose (IC₅₀ = 1.637 ± 0.153 μM). Compounds 1, 10, 14, and 20 exhibited outstanding inhibitory potential with IC₅₀ value 1.763 ± 0.03, 1.747 ± 0.20, 1.709 ± 0.12, and 1.948 ± 0.23 μM, respectively, compared with the standard acarbose. Structure activity relationships have been established for the active compounds. To get an idea about the binding interaction of the compounds, molecular docking studies were done.

Detailed NMR spectral analysis of DMSO-d₆ solutions of the series of substituted 2-phenacylbenzimidazoles (ketimine form, K) reveals two from three tautomeric forms. Integrals of the ¹H NMR signals are used in establishing the molar ratio of tautomers. The experimental analyses are supported by quantum-chemical calculations, which satisfactorily reproduced the experimental trends. Although the reported semiempirical quantum-chemical calculations show that enaminone E, i.e., 2-(1,3-dihydro-2H-benzo[d]imidazol-2-ylidene)-1-phenylethan-1-one, was thermodynamically most stable, the results of MP2 ab initio calculations reveal the following order of stability: ketimine > enolimine > enaminone (substituents do not affect this sequence). ¹³C CPMAS NMR spectral data reveal that in the crystalline state the enolimine tautomer O is predominant in the p-CH₃ and p-NO₂ substituted congeners.