Thermo-optical properties of polar dielectric laser dye solvents

This work is devoted to study the thermo-optical properties of three important pure polar dielectric laser dye solvents (aniline, pyridine and ethyl ether). Experimental measurements of the refractive index n and its thermo-optic coefficient dn/dT are carried out using dual laser Mach–Zehnder interferometric technique. The determined values of n and dn/dT are used to extract new data concerning the mentioned laser dye solvents. Applying the empirical relationship of Cauchy between the refractive index and the wavelength, the optical dispersion dn/dλ and dn/dT, as a function of wavelength are calculated and represented. Additionally, Cauchy's constants as a function of temperature has been calculated and a comparison between the studied solvents are considered.     

水杨酸钠在极性溶剂中的荧光和激光特性的研究

采用XeCl激光作为泵浦源,首次系统研究了水杨酸钠在水、甲醇、乙醇以及水醇混合物等极性溶剂中的荧光和激光特性.探明它有很强的激发态自吸收作用.从分子结构的角度分析了水杨酸钠荧光积分强度的温度特性.     

Study of the complexation and solvation of polar molecules in binary solvents by differential spectroscopy

A method of application of differential absorption spectroscopy for determining the absorption spectra of primary 1: 1 solvated complexes between polar molecules of an organic dye and the active component of a binary solvent whose neutral component is a nonpolar liquid is proposed. The method was tested on diluted solutions of 4-dimethylaminochalcone (4-DMC) (which is one of the most efficient spectral-luminescent probes used in present-day medical and biological investigations) in mixtures of n-hexane with acetone at extremely small concentrations of the polar component. It is shown that the experimentally found absolute shift of the long-wavelength absorption band of 4-DMC is in satisfactory quantitative agreement with the analogous value obtained independently on the basis of the theory describing the joint effect of nonlinear (complexation) and linear (solvation) dipole-dipole interactions on the spectral band positions.     

Dielectric relaxation of polar molecules in mixtures of non-polar solvents.

The relaxation times of some rigid polar molecules are studied in very diluted mixtures of heptane-carbontetrachloride and heptanedecaline, Exponential relation between relaxation time and a characteristic length of the polar solute (r_eff) is found. The structure factor of the mixture which contains the contributions of both solvents cannot be composed by adding the features of each component only. Furthermore, the measured collision times seem not to follow a simple sum rule.     

Fluorescence of 3-monomethylamino-N-methylphthalamide in mixtures of polar and nonpolar solvents

Modifications occurring in the fluorescence and excitation spectra of 3-monoethylamino-N-methylphthalimide (3 MANP) dissolved in nonpolar solvents (-hexane and methylcyclohexane) as a function of added n-butanol and n-propanol between -90 and 90°C were measured. The modifications were due to the presence of two types of centres resulting from the interaction of the solvent molecules with the nonpolar solvent on the one hand, and with the polar solvent on the other. The mixed complex character of the fluorescence band was not affected by the concentration of the solution in the range 10^-7?5 x 10^-4 mol/l. An attempt was made to establish a relationship between the emission due to the centres resulting from the interaction with the alcohol molecules and the association degree of the respective molecules.     

Effect of polar aprotic solvents on hydroxyethyl cellulose-based gel polymer electrolyte

Quasi-solid bioelectrolytes based on hydroxyethyl cellulose (HEC) and sodium iodide (NaI) in three different polar aprotic solvent systems, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and dimethylacetamide (DMA), were fabricated and characterized. FTIR studies revealed active solvent-ion interactions in DMF-based electrolytes in comparison to DMA and DMSO. The effect of the solvent system on the crystallinity of HEC gel electrolytes was more significant at low NaI concentration. In each solvent system, the highest ionic conductivity was achieved at 70 wt% NaI and generally DMF-based electrolytes showed higher conductivity than the other solvents. The availability of multiple complexation sites present in DMF is ascribed to improvement in ion mobility and hence conductivity. Rheological analysis was carried out to elucidate the mechanical properties of the gels. Generally, the mechanical strength of the polymer gels was unaffected by the type of solvent.     

Association of bi-cyanine dyes with rigidly linked chromophores in polar solvents

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 50, No. 2, pp. 237–243, February, 1989.     

Study of electron solvation in polar solvents using path integral calculations

A path-integral Monte Carlo algorithm for the simulation of electrons solvated in polar liquids is briefly outlined, and results are presented for the electron solvated in liquid water.     

Binary mixture of p‐methylbenzaldehyde with polar and nonpolar solvents

In this work, a combined theoretical and experimental study of binary mixture of liquid p‐methylbenzaldehyde (PMBz) is reported using ab initio calculations as well as Raman and IR spectroscopies. The purpose of this study was twofold: firstly, to describe the interaction of PMBz in terms of bonding energies and preferred geometries; and secondly, to characterize the spectroscopic effects on the vibrational modes of PMBz in the binary mixture of different polar and nonpolar solvents. The three vibrational modes, namely, carbonyl stretching, ν(C CH₃) and aldehydic (C H) vibrations have been analyzed in all the three solvents in different concentrations. The dependence of Raman linewidth on the concentration of PMBz of these modes was also taken into account. By analyzing the peak position and linewidth of these modes, it is seen that the solute–solvent interaction is stronger in BuOH and 1,2 dichloroethane (DCE) because of the hydrogen‐bonding interaction between these molecules. The formation of C H···O hydrogen bonds in liquid p‐methylbenzaldehyde is also investigated by Gaussian fitting. The ab initio calculations suggest several possible dimer configurations. Copyright © 2008 John Wiley & Sons, Ltd.     

Anomalous fluorescence properties of 4-N,N-dimethylaminobenzoic acid in polar solvents

4-N,N-Dimethylaminobenzoic acid exhibits anomalous fluorescence in polar and hydrogen-bonding solvents. The fluorescence spectra and kinetics suggest that this arises due to the formation of a ground-state dimer or higher polymer. Preliminary measurements in hexane containing small amounts of polar acetonitrile do not rule out the possibility of exciplex formation also occurring.