Solvatochromic study of 1,2-dihydroxyanthraquinone in neat and binary solvent mixtures.

Study of preferential solvation of 2,6-diaminoanthraquinone in binary mixtures by absorption and fluorescence studies.

The solvation structure of copper(II) ion in N,N-dimethylformamide (DMF) and N,N-dimethylformamide–acetonitrile (AN) mixtures has been investigated by means of X-ray diffraction at 25 °C. The X-ray scattering data for the copper(II) perchlorate DMF solution were well-interpreted in terms of the presence of the axially elongated octahedral [Cu(dmf)6]2+ ion in DMF. Among the six DMF molecules, four of them are at the distance of 203(3) pm at the equatorial position and the other two are at 243(5) pm at the axial one. On the other hand, in copper(II) perchlorate DMF–AN solutions with the Cdmf⁄CCu mole ratios of 5.308 and 7.435, where Ci denotes the total concentrations of species i, the copper(II) ion is coordinated with four DMF molecules within the square-plane and with no solvent molecule along the axis of the plane. The equatorial Cu–O bond length is 200(1) pm and practically the same as that within the [Cu(dmf)6]2+ ion in DMF. In copper(II) nitrate DMF solutions (1.086 and 1.500 mol dm−3), a nitrate ion...

Solvation structure of copper(II) ion in N,N-dimethylformamide and N,N-dimethylformamide-acetonitrile mixtures determined by the X-ray diffraction method.

Dielectric absorption studies of H-bonded complexes of N , N -dimethyl formamide and N , N -dimethyl acetamide with p -cresol, p -chlorophenol, 2,4-dichlorophenol and p -nitrophenol in benzene have been made at 308 K using 9.37 GHz dielectric relaxation set up. The validity of the single frequency equation of Higasi et al. for multiple relaxation time τ (1) is found to be function of the hydrogen bonding strength of the phenolic hydrogen, whereas the group rotation relaxation time τ (2) is a function of the steric interactions of the proton donor. The relaxation time is maximum at 50:50 mol% ratio.

Dielectric relaxation studies of N,N-dimethyl formamide and N,N-dimethyl acetamide on complexation with phenols

The values of dielectric constant for N,N-dimethylformamide(DMF)–water mixtures in entire mixing range have been determined in the frequency range 100 MHz–20 GHz at 298 K using the dielectric relaxation spectroscopy (DRS) method The dielectric spectra of DMF–water mixture with an asymmetric shape are observed The mixture behavior is described according to the Cole–Davidson model using four parameters ( e ∞ , e 0 , τ and β ) The number of hydrogen bonds between the water–water and DMF–water pairs is estimated from the values of the static dielectric constant by using the Luzar model The model provides a satisfactory explanation of the experimental results related to the static dielectric constant The hydrogen bond binding energies for water–water (pair 11) and DMF–water (pair 12) are estimated to be 1301 and 1310 kJ/mol, we report a new strategy to parameterize effective DMF–water cluster interactions to provide valuable insights into the underlying mechanism of the relaxation acts

The hydrogen bonding dynamics and cooperative interactions in aqueous N,N-dimethyl formamide solution studied by dielectric relaxation spectroscopy

Using a standing wave X-band microwave technique, the dielectric constant ( epsilon ") and dielectric loss ( epsilon ') of dilute solutions of N,N-dimethylformamide (DMF), acetronitrile (AN) and four binary mixtures of DMF and AN have been measured. Measurements were carried out in benzene solution at 9.885 GHz and 15 degrees C. Similar measurements have also been made on a (DMF+AN) mixture containing 50 mol.% AN at 15, 20, 25 and 30 degrees C. Following the single-frequency concentration variational method, the dielectric relaxation times ( tau ) for all these systems have been evaluated. The variation of relaxation time as a function of AN molar fraction in (DMF+AN) mixtures shows a solute-solute type of molecular association between DMF and AN at all compositions. The energy parameters ( Delta Fepsilon , Delta Hepsilon , Delta Sepsilon ) for the dielectric relaxation of the 50:50 mol.% mixture at various temperatures have been found to be in fairly good agreement with the corresponding energy parameters for the viscous flow. The entropy of activation for the relaxation process and for the viscous flow has been found to be negative.

https://iopscience.iop.org/article/10.1088/0022-3727/18/6/022/pdf

D S Gill

Papers

Molecular association between N,N-dimethylformamide and acetonitrile using dielectric relaxation measurements in the microwave region