Structural, Optical and Magnetic Properties of Zn1-xCoxO Nanoparticles

Zn_1-xCo_xO nanoparticles with three different values of 'x' (x = 0.05, 0.10, 0.15) were prepared by chemical co-precipitation process without any further heat treatment. The X-ray diffraction studies confirmed the wurtzite hexagonal crystal structure for synthesized Zn_1-xCo_xO nanoparticles. The dislocation density results reveal that there is an increase in the concentration of lattice imperfections with increasing the concentration of Co ions. The true values of lattice constants were calculated by using Nelson-Riley Function (NRF). Further, the average bond length (BL) were also calculated and presented. The optical and magnetic properties of Zn_1-xCo_xO nanoparticles were examined by room-temperature photoluminescence (PL) spectroscopy and vibrating sample magnetometer (VSM), respectively. The calculated values of magnetic susceptibility for Zn_1-xCo_xO nanoparticles with x = 0.05, 0.10, 0.15 were found to be 9.883×10^-4, 2.29×10^-2 and 2.37×10^-2, respectively.

Hydrogen bond interactions in the binary solutions of formamide with methanol: FTIR spectroscopic and theoretical studies

FTIR spectroscopic studies on the binary solutions of formamide with methanol reveal the presence of "free" O - H in methanol. These "free" O - H groups are found in methanol tetramers which is confirmed from the DFT calculations. DFT calculations on the formamide dimers of five different geometries encompassing one or more of the N - H⋯O, C - H⋯O and N - H⋯N hydrogen bonds tell that N - H⋯N bonds are the strongest. Dissociation of the. N - H⋯N bonds of formamide in the binary solutions with methanol has a major impact on the NH₂ symmetric stretching mode of formamide in the FTIR spectra. In these solutions the formation of 1:4 (formamide:methanol), 1:5 and 2:4 complexes are possible. These complexes are more stable than the formamide dimers, methanol tetramer and pentamer investigated in the present work. Methanol methyl group plays no role in either the self-association or heterointeraction with formamide.

FTIR studies, DFT calculations and time domain reflectometry studies on tetrahydrofuran - methanol binary solutions

FTIR signature of neat tetrahydrofuran (THF), methanol (MeOH) and their binary solutions at various molefractions (0.8:0.2 (THF:MeOH), 0.6:0.4, 0.4:0.6 and 0.2:0.8) have been recorded. Density Functional Theory (DFT) calculations have also been carried out on THF, MeOH multimers and possible THF-MeOH complex molecules. The results of FTIR studies and DFT calculations confirm the formation of 1:3 (THF:MeOH) and 1:4 complex structures with (MeOH)O - H⋯O(THF), (MeOH methyl)C - H⋯O(THF) and (THF methylene)C - H⋯O(MeOH) H-bond interactions. (MeOH)O - H⋯O(MeOH) homointeractions among the MeOH trimers and tetramers are stronger than the THF-MeOH heterointeractions in complexes. But, the stability of 1:4 complexes is more than that of the trimers and tetramers as inferred from the interaction energy values obtained by DFT calculations. Time Domain Reflectometry (TDR) study has also been carried out on the THF-MeOH binary solutions in the frequency range 10 MHz-30 GHz at 298 K. The results of dielectric studies have been correlated with that of FTIR studies and DFT calculations.

Molecular interactions in ethyl acetate-chlorobenzene binary solution: Dielectric, spectroscopic studies and quantum chemical calculations

Dielectric studies using Time Domain Reflectometry method has been carried out on the binary solution of Ethyl acetate (EA) with Chlorobenzene (CBZ) over the entire composition range. Spectroscopic (FTIR and ¹³C NMR) signatures of neat EA, CBZ and their equimolar binary solution have also been recorded. The results of the spectroscopic studies favour the presence of (CBZ) CH⋯OC (EA), (EA) methylene CH⋯π electrons (CBZ) and (EA) methyl CH⋯Cl (CBZ) contacts which have been validated using quantum chemical calculations. Dimerization of CBZ has been identified. Presence of β-clusters has been identified in all the solutions. Although EA and CBZ molecules have nearly equal molar volumes, CBZ molecules experience larger hindrance for the rotation than EA molecules. Very small excess dielectric constant (ε^E) values may be correlated with weak heteromolecular forces and/or closed heteromolecular association.

A probe on the intermolecular forces in diisopropyl ether-n-butyric acid mixture by dielectric, FTIR studies and quantum chemical calculations

The results of FTIR spectral measurement on equimolar diisopropyl ether-butyric acid binary mixture and quantum chemical calculations on the complex molecule have been presented. Dielectric studies have been carried out on the binary mixture over the entire composition range and at four different temperatures 303 K, 308 K, 313 K and 318 K. n-Butyric acid seems to prefer less polar ether to interact with it. It appears that the usual interpretation of variation of static dielectric constant and positive deviation of excess permittivity from ideal mixture behavior needs to be relooked.

Molecular interaction study of the diisopropyl ether-propionic acid mixture by spectroscopic and dielectric studies

FTIR and 13C NMR spectral studies have been carried out on diisopropyl ether-propionic acid binary mixture to probe the molecular interactions and stoichiometry of complexation. Density functional theory (DFT) calculations of vibrational frequencies of pure acid and ether-acid binary mixtures have also been performed. In addition, Kirkwood-correlation factors, excess permittivity and excess free energy of mixing have been obtained at various concentrations and at four different temperatures from the dielectric measurements. Excess permittivity is found to have positive deviation and excess free energy deviates negatively from ideal behaviour.

Solute-solvent interactions of acid-1,4-dioxane mixtures-By dielectric, FTIR, UV-vis and 13C NMR spectrometric methods

Results of the dielectric studies carried out on the binary mixture of n-butyric and caprylic acids with 1,4-dioxane over the entire composition range and at temperatures 303K, 308K, 313K and 318K, and FTIR, UV-vis and 13C NMR spectral studies are presented in this paper. The excess permittivity and excess free energy were fitted with the Redlich-Kister polynomial. The variation of Kirkwood correlation factors, excess permittivity and excess free energy of mixing with the concentration and temperature has been investigated in view of understanding the ordering of dipoles of solute and solvent molecules. The FTIR, UV-vis and 13C NMR spectral analysis reveals the formation of complex between solute and solvent molecules. The parallel alignment of electric dipoles of the complex predicted by dielectric studies is well supported by UV-vis spectral analysis. The structure of the complex molecule present in the clusters has been deduced.