Comparison of the Infrared Spectra (4000–70 cm−1) of Several Hydrated and Anhydrous Salts of Transition Metals

Accurate prediction of terahertz spectra of molecular crystals of fentanyl and its analogs

Fentanyl is a potent synthetic opioid pain reliever with a high bioavailability that can be used as prescription anesthetic. Rapid identification via non-contact methods of both known and emerging opioid substances in the fentanyl family help identify the substances and enable rapid medical attention. We apply PBEh-3c method to identify vibrational normal modes from 0.01 to 3 THz in solid fentanyl and its selected analogs. The molecular structure of each fentanyl analog and unique arrangement of H-bonds and dispersion interactions significantly change crystal packing and is subsequently reflected in the THz spectrum. Further, the study of THz spectra of a series of stereoisomers shows that small changes in molecular structure results in distinct crystal packing and significantly alters THz spectra as well. We discuss spectral features of synthetic opioids with higher potency than conventional fentanyl such as ohmefentanyl and sufentanil and discover the pattern of THz spectra of fentanyl analogs.

A study of the structural changes in a chitosan matrix produced by the adsorption of copper and chromium ions

A study of the structural changes at micro- and nano-scale in a chitosan matrix after the adsorption of different metal ions is presented. Toward this aim, samples of chitosan films soaked in different concentrations of copper(II) and chromium(VI) aqueous solutions were prepared. Cu and Cr ions were selected as sorbates since they have different ionic properties. The effect of the adsorbed metal ions on the microstructure of the chitosan matrices were studied using Fourier transformed infrared spectroscopy, UV-vis spectroscopy, differential scanning calorimetry and thermogravimetric analysis. To go further into the study of the samples at the molecular level, the nuclear technique positron annihilation lifetime spectroscopy was used. Results are discussed in terms of the interaction between the metal ions and the chitosan functional groups.

Interaction of vanadium (IV) solvates (L) with second-generation fluoroquinolone antibacterial drug ciprofloxacin: spectroscopic, structure, thermal analyses, kinetics and biological evaluation (L=An, DMF, Py and Et3N)

The preparation and characterization of the new solid complexes [VO(CIP)2L]SO4⋅nH2O, where L=aniline (An), dimethylformamide (DMF), pyridine (Py) and triethylamine (Et3N) in the reaction of ciprofloxacin (CIP) with VO(SO4)2·2H2O in ethanol. The isolated complexes have been characterized with their melting points, elemental analysis, IR spectroscopy, magnetic properties, conductance measurements, UV-Vis. and (1)H NMR spectroscopic methods and thermal analyses. The results supported the formation of the complexes and indicated that ciprofloxacin reacts as a bidentate ligand bound to the vanadium ion through the pyridone oxygen and one carboxylato oxygen. The activation energies, E(*); entropies, ΔS(*); enthalpies, ΔH(*); Gibbs free energies, ΔG(*), of the thermal decomposition reactions have been derived from thermo gravimetric (TGA) and differential thermo gravimetric (DTG) curves, using Coats-Redfern and Horowitz-Metzeger methods. The lowest energy model structure of each complex has been proposed by using the density functional theory (DFT) at the B3LYP/CEP-31G level of theory. The ligand and their metal complexes were also evaluated for their antibacterial activity against several bacterial species, such as Bacillus Subtilis (B. Subtilis), Staphylococcus aureus (S. aureus), Nesseria Gonorrhoeae (N. Gonorrhoeae), Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli).

Synthesis, characterization and antimicrobial investigation of some moxifloxacin metal complexes

The new complexes of moxifloxacin (MOX), with Ti(IV), Y(III), Pd(II) and Ce(IV) have been synthesized. These complexes were then characterized by melting point, magnetic studies and spectroscopic techniques involving infrared spectra (IR), UV-Vis, (1)H NMR. C, H, N and halogen elemental analysis and thermal behavior of complexes also investigated. The results suggested that the molar ratio for all complexes is M: MOX=1:2 where moxifloxacin acts as a bidentate via one of the oxygen atoms of the carboxylate group and through the ring carbonyl group and the complexes have the following formula [Ti(MOX)(2)](SO(4))(2)·7H(2)O, [Y(MOX)(2)Cl(2)]Cl·12H(2)O, [Pd(MOX)(2)(H(2)O)(2)]Cl(2)·6H(2)O and [Ce(MOX)(2)](SO(4))(2)·2H(2)O. The activation energies, E*, enthalpies, ΔH*, entropies, ΔS* and Gibbs free energies, ΔG*, of the thermal decomposition reactions have been derived from thermogravimetric (TGA) and differential thermogravimetric (DrTG) curves, using Coats-Redfern (CR) and Horowitz-Metzger (HM) methods. The antimicrobial activity of these complexes has been evaluated against three Gram-positive and three Gram-negative bacteria and compared with the reference drug moxifloxacin. The antibacterial activity of Ti(IV) complex is significant for E. coli K32 and highly significant for S. aureus K1, B. subtilis K22, Br. otitidis K76, P. aeruginosa SW1 and K. oxytoca K42 compared with free moxifloxacin.

DFT calculation of the chromyl nitrate, CrO2(NO3)2 The molecular force field

We have carried out a structural and vibrational theoretical study for chromyl nitrate. The density functional theory has been used to study its structure and vibrational properties. The geometries were fully optimised at the B3LYP/Lanl2DZ, B3LYP/6-31G* and B3LYP/6-311++G levels of theory and the harmonic vibrational frequencies were evaluated at the same levels. The calculated harmonic vibrational frequencies for chromyl nitrate are consistent with the experimental IR and Raman spectra in the solid and liquid phases. These calculations gave us a precise knowledge of the normal modes of vibration taking into account the type of coordination adopted by nitrate groups of this compound as monodentate and bidentate. We have also made the assignment of all the observed bands in the vibrational spectra for chromyl nitrate. The nature of the Cr-O and Cr<--O bonds in the compound were quantitatively investigated by means of Natural Bond Order (NBO) analysis. The topological properties of electronic charge density are analysed employing Bader's Atoms in Molecules theory (AIM).

Micro-Raman studies of hydrous ferrous sulfates and jarosites

Ferrous sulfates of various hydration states (FeSO(4) X xH(2)O; x=7, 4, 1) and jarosites (MFe(3)(SO(4))(2)(OH)(6); M=Na or K) were synthesized and studied by micro-Raman spectroscopy between 295 and 8K. Spectral analyses of the sulfate and water/hydroxyl vibrational modes are presented. Fingerprint regions attributed to the symmetric (nu(1)) and antisymmetric (nu(3)) stretching vibrations of the sulfate group are found to vary with the degree of hydration in hydrous ferrous sulfate. In jarosites, the Raman shift of the OH stretching mode is related to the type of alkali metal present between the tetrahedral and octahedral layers. The Raman technique can thus unambiguously identify ferrous sulfate of various hydration states and jarosites bearing different alkali metal ions.

On coordination modes of adenine in cadmium(II) complexes

Complexes of cadmium(II) derivatives with adenine from water or by simulation of physiological conditions are obtained. The complexes have been studied by spectroscopic, conductometric, 1H-NMR, and by TG and DSC measurements. Possible coordination modes of the ligand are proposed.