Preferential solvation of p-nitroaniline in a binary mixture of chloroform and hydrogen bond acceptor solvents: the role of specific solute–solvent hydrogen bonding

2020 ◽  
Vol 22 (6) ◽  
pp. 3545-3562 ◽  
Author(s):  
Prakash Kumar Malik ◽  
Madhusmita Tripathy ◽  
Aravind Babu Kajjam ◽  
Sabita Patel
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Binary Mixture ◽  
Preferential Solvation ◽  
Binary Solvent ◽  
Local Concentration ◽  
Solvent Mixtures ◽  
Hydrogen Bond Acceptor ◽  
Binary Solvent Mixtures

Solute–solvent H-bonding in binary solvent mixtures may increase the local concentration at specific sites resulting in location specific preferential solvation.

scholarly journals Solvation in pure and mixed solvents: Some recent developments

2007 ◽  
Vol 79 (6) ◽  
pp. 1135-1151 ◽  
Author(s):  
Omar A. El Seoud
Keyword(s):  
Hydrogen Bonding ◽  
Hydrophobic Interactions ◽  
Preferential Solvation ◽  
Mixed Solvents ◽  
Effect Of Temperature ◽  
Binary Solvent ◽  
Solvent Mixtures ◽  
Dispersion Interactions ◽  
Binary Solvent Mixtures ◽  
Recent Developments

The effect of solvents on the spectra, absorption, or emission of substances is called solvatochromism; it is due to solute/solvent nonspecific and specific interactions, including dipole/dipole, dipole-induced/dipole, dispersion interactions, and hydrogen bonding. Thermo-solvatochromism refers to the effect of temperature on solvatochromism. The molecular structure of certain substances, polarity probes, make them particularly sensitive to these interactions; their solutions in different solvents have distinct and vivid colors. The study of both phenomena sheds light on the relative importance of the solvation mechanisms. This account focuses on recent developments in solvation in pure and binary solvent mixtures. The former has been quantitatively analyzed in terms of a multiparameter equation, modified to include the lipophilicity of the solvent. Solvation in binary solvent mixtures is complex because of the phenomenon of "preferential solvation" of the probe by one component of the mixture. A recently introduced solvent exchange model allows calculation of the composition of the probe solvation shell, relative to that of bulk medium. This model is based on the presence of the organic solvent (S), water (W), and a 1:1 hydrogen-bonded species (S-W). Solvation by the latter is more efficient than by its precursor solvents, due to probe/solvent hydrogen-bonding and hydrophobic interactions. Dimethylsulfoxide (DMSO) is an exception, because the strong DMSO/W interactions probably deactivate the latter species toward solvation. The relevance of the results obtained to kinetics of reactions is briefly discussed by addressing temperature-induced desolvation of the species involved (reactants and activated complexes) and the complex dependence of kinetic data (observed rate constants and activation parameters) in binary solvent mixtures on medium composition.

Dielectric enrichment in binary solvent mixtures. The intramolecular hydrogen bond in N-alkyl-substituted o-nitroanilines. Substituent effects

1992 ◽  
Vol 70 (10) ◽  
pp. 2677-2682 ◽  
Author(s):  
Rosa Cattana ◽  
Juana J. Silber ◽  
Jorge Anunziata
Keyword(s):  
Hydrogen Bond ◽  
Intramolecular Hydrogen Bond ◽  
Preferential Solvation ◽  
Substituent Effects ◽  
Solvent Mixture ◽  
Binary Solvent ◽  
Solvent Mixtures ◽  
Hydrogen Bond Acceptor ◽  
Intramolecular Hydrogen ◽  
Strong Intramolecular Hydrogen Bond

In this work we report solvatochromism studies on o-nitroaniline and several N-alkyl-o-nitroaniline derivatives used as solutes in solvent mixtures of an "inert" nonpolar cosolvent, cyclohexane, and THF as a solvent with hydrogen bond acceptor ability. These studies allowed us to establish the competition between inter- and intramolecular hydrogen bond in solutes. This was done by comparing the magnitude of the local inhomogeneity induced by the solute-in-solvent mixture, that is, "preferential solvation," using Suppan's dielectric enrichment model as modified by us to be applied to electronic transitions. Since preferential solvation accounts for dielectric as well as specific interactions while dielectric enrichment only for the former, it was shown by comparison that it is possible to separate both effects and even quantify them. It was deduced that N-alkyl-o-nitroanilines form a strong intramolecular hydrogen bond, which remains unbroken even in polar solvents and hydrogen bond acceptors such as dimethyl sulfoxide. This was also confirmed by solvatochromic studies in pure solvents. On the other hand, a symmetrical dependence of the effects of alkyl substituents and solvents on the shifts of the absorption spectra was observed.

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