Vibrational and electronic studies on interactions of Cu (II) with protic amides: Structural aspects of biological importance

Raman, IR and UV–Vis–NIR experiments of formamide (FA), N-methylformamide (NMF) and their solutions with copper perchlorate at different compositions were carried out. The downshift of the ν_CO mode and the upshift of the νCN vibration have been observed for both amides and suggest that an ionic structure is stabilized by Cu (II). The quantitative Raman study at the νCN region reveals that six FA molecules are coordinated to Cu (II) while four NMF molecules are around the metal ion. The data are complemented by information at the region characteristic of the metal–ligand vibrations, which evidences coordination through the O atom. The spectral changes observed at the ν_CN region have been then combined to the electronic data and show that [Cu(FA)₆]²⁺ and [Cu(NMF)₄]²⁺ are described as distorted octahedral and square planar complexes.     

Synthesis of Trinorditerpenoid Derivatives and Evaluation of Antimicrobial and Cytotoxic Activity

The synthesis of optically active trinorditerpenes was carried out, and their antimicrobial and antitumor activity was tested. The synthetic derivative 12-hydroxypodocarpa-8,11,13-triene (7) showed GI₅₀ at 6.6 µM against breast cancer MDA-MB-435 (LC₅₀ = 50.9 µM and log10 GI₅₀ = −5.18). The 12-acetyloxypodocarpa-8,11,13-triene (8) showed GI₅₀ at 12.1 µM against leukemia RPMI-8226 (LC₅₀ = 76.1 µM and log₁₀GI₅₀ = −4.92).__________Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 255–259, May–June, 2005.     

Growth,geometrical analysis,FMO, MEP UV–vis,nonlinear optical and antibacterial properties of pure and 2-furoic acid doped Guanidinium carbonate single crystal

In the presence of distilled water, the adaption of the slow evaporation solution growth approach resulted in the successful development of single crystals of Pure and doped GC (FAGC). The cell characteristics of the produced FAGC crystals were investigated using single-crystal X-ray diffraction analysis. The theoretical analysis was carried out using the DFT method, and the HOMO-LUMO energy band difference was estimated. The Molecular optimized geometry, MEP and HOMO-LUMO energy distance were computed using the B3LYP level of theory using a 6-31G (d,p) basis set. The FT-IR spectrum probes the modes of vibration of various functional groups in pure and doped GC (FAGC) crystals. According to UV–visible NIR transmittance experiments, the formed crystal exhibits a high transmittance in the whole visible range. The relative SHG efficiency of pure and doped crystals (FAGC) was carried out by the Kurtz perry technique. The Antibacterial activity demonstrates that both the pure and the dopant have antibacterial action against dangerous microorganisms.     

Isolation and Spectroscopic Characterization of New Endohedral Fullerenes in the Size Gap of C74 to C76

New alkaline earth metal endohedral fullerenes Sr@C₇₄, Sr@C₇₆‐I, II and Ca@C₇₄, prepared by means of the RF‐method, have been isolated using multistep HPLC. The purity was ascertained by anionic LDI TOF mass spectroscopy, considering the isotopic patterns of the compounds. The influence of the incorporated metal on the electronic structure has been studied by VIS‐NIR and Raman spectroscopy. Photoexcited triplet‐state EPR spectroscopy was used to investigate the structure of these otherwise EPR‐silent fullerenes. Displaying the frequency of the cage vs. encapsulated metal vibrational modes as a function of the square root of the reciprocal masses of the metals clearly separates the M³⁺@C_n^3— and the M²⁺@C_n^2— families. This seems to be a generally applicable tool for monitoring the metal to fullerene charge transfer.     

Comprehensive quantum chemical calculations and molecular docking analysis of uracil mustard by first principle

Uracil mustard belongs to the nitrogen mustard family and is primarily used in anticancer drugs. The research that follows, investigates many quantum chemical features such as the computation of global minimum energies with no negative wavenumber values using the Density Functional Theory (DFT) with Becke three functional and 6-311G (d, p)/6–311++G (d, p) basis sets. All the vibrational modes have been calibrated and justified in comparison to their experimental counterparts. Mustard's polarizability and hyperpolarizability components, Natural Bond Analysis (NBO), electronic properties, Fukui function analysis, various global parameters, Quantum Theory of Atoms In Molecule (QTAIM) analysis, ADMET analysis, and docking analysis have all been investigated using the same theory and basis sets, indicating its biochemical significance. The biological activity of the molecule is reported by using PASS software. The Full fitness score and binding affinity parameters are utilized to determine the binding strength with 6cq3 protein. The acidity of the title molecule is calculated in water solvent by polarizable continuum model (PCM) solvent effects (estimated in water). The HOMO, LUMO, and MESP plots are used to explore the nature of binding and surfaces. The Fukui functions are computed using Mulliken atomic charges for neutral atoms, cations, and anions. The Ultraviolet–visible (UV–vis) of the molecule is computed employing the TD-DFT method.     

Characterisation of Nanohybrids of Porphyrins with Metallic and Semiconducting Carbon Nanotubes by EPR and Optical Spectroscopy

Single‐walled carbon nanotubes (SWCNTs) are noncovalently functionalised with octaethylporphyrins (OEPs) and the resulting nanohybrids are isolated from the free OEPs. Electron paramagnetic resonance (EPR) spectroscopy of cobalt(II)OEP, adsorbed on the nanotube walls by π–π‐stacking, demonstrates that the CNTs act as electron acceptors. EPR is shown to be very effective in resolving the different interactions for metallic and semiconducting tubes. Moreover, molecular oxygen is shown to bind selectively to nanohybrids with semiconducting tubes. Water solubilisation of the porphyrin/CNT nanohybrids using bile salts, after applying a thorough washing procedure, yields solutions in which at least 99 % of the porphyrins are interacting with the CNTs. Due to this purification, we observe, for the first time, the isolated absorption spectrum of the interacting porphyrins, which is strongly red‐shifted compared to the free porphyrin absorption. In addition a quasi‐complete quenching of the porphyrin fluorescence is also observed.     

The reaction mechanism of p-toluenediamine anodic oxidation: an in situ ESR-UV/Vis/NIR spectroelectrochemical study.

In situ ESR-UV/Vis spectroelectrochemistry is applied to obtain new insights into the intermediates and reaction products of the anodic oxidation of p-toluenediamine in aqueous solution at different pH values. A strong pH dependence of the stability of the cation radical is found. While the absence of a stable radical was proved by ESR spectroscopy at pH 2 and 10, this radical is detected at medium pH values and assigned to the semiquinonediimine structure. The UV/Vis absorption of the radical is observed at these pH values as well. The p-toluenediimine intermediate and the trimeric reaction product were followed during the electrode reaction by UV/Vis spectroscopy at all pH values.     

金属氮化物包合物Tb3N@C80的分离和表征

在利用电弧放电法合成铽的富勒烯笼内金属包合物时,首次观察到Tb₃N@C₈₀的存在,并用两步HPLC法将其分离和提纯.进一步的实验结果表明,氮气的加入是导致Tb₃N@C₈₀生成的原因.并用MALDI-TOF-MS和UV-Vis-NIR光谱对其进行了表征.