Origin of Strong Synergism in Weakly Perturbed Binary Solvent System: A Case Study of Primary Alcohols and Chlorinated Methanes

Abstract

A strong synergistic solvation was observed for the mixtures of hydrogen bond donating and accepting solvent pairs. The nature of the interactions between two solvent pairs was investigated with different dye molecules viz. coumarin 480, coumarin 153, 4-aminophthalimide, and p-nitroaniline. Coumarin 480 in differenet alcohols-CHCl(3) (alcohols: MeOH, EtOH, BuOH) binary mixture shows a strong synergism, which is explained in the backdrop of solvent-solvent interactions. Fluorescence quenching of C480 by 1,2-phenylenediamine in the binary solvent mixture exhibited the maximum deviation in quenching constant corresponding to ~0.45 mol fraction of MeOH in MeOH-CHCl(3) binary mixture and hence suggested the maximum extent of hydrogen-bonding interactions prevailing at this proportion of mixture. The solvation behavior of MeOH-CHCl(3) mixture shows strong probe dependence with no synergism observed in p-nitroaniline, which is ascribed to its higher ground state dipole moment (8.8 D) relative to C480 (6.3 D). Interestingly, the strong synergistic signature observed through spectrophotometric measurement of C480 in alcohol-CHCl(3) binary mixture is absent when studied by fluorescence measurement. The higher excited state dipole moment of coumarin 480 (13.1 D) is considered to be the driving force for the absence of synergism in the excited state. In such strongly perturbed systems (due to high dipole moment values) the dominant phenomenon is preferential solvation. Analysis of proton NMR of MeOH-CHCl(3) binary solvent mixture indicates the existence of MeOH-CHCl(3) clusters in the stoichiometric ratio of 1:2.15. Refractive index measurement also infers the existence of hydrogen bonded network structure between MeOH and CHCl(3). A modified Bosch solvent exchange model has been used to determine the feasibility of synergistic behavior and polarity parameter of the mixed solvent structure of MeOH-CHCl(3) binary solvent mixture.

Role of Hydrogen Bond in the Solvation Behavior of the Binary Mixtures Containing Fluorocarbon Alcohol Molecules and Chloroform: An Experimental and Theoretical Study

“…In case of ETH‐CHCl 3 binary mixture, the δ value of the proton of CHCl 3 shifts towards upfield with increasing χ CHCl3 and at the same time, the δ value of the OH proton of ETH shifts towards downfield with increasing χ ETH (black line in Figures a and b respectively). This observation is consistent with the earlier NMR study for the CHCl 3 binary mixture with methanol . The trend of the δ values of CHCl 3 proton and alcoholic OH proton for the MFE‐CHCl 3 binary mixture is similar to ETH‐CHCl 3 except that the change in the δ value of CHCl 3 proton is less in the case of MFE‐CHCl 3 .…”

“…In other cases, both constituents of the solvent mixture can solvate a probe molecule as a different entity which provides a completely different solvation environment around the solute molecule causing to show a significant change of a particular property (solvation in the present study) from its bulk counterparts and this effect is known as synergetic effect . The experimental and theoretical tools have been used in a great deal to understand the preferential solvation as well as synergetic behavior of the solvent mixtures . Several different spectroscopic techniques such as UV‐Vis, NMR, vibrational spectroscopy, solvation dynamics, two dimensional infrared techniques have been used to understand the behavior of solvent mixtures as these techniques have the capability to provide the quantitative information about the solute‐solvent interaction as well as hydrogen bond network present in solvent mixtures.…”

“…The experimental and theoretical tools have been used in a great deal to understand the preferential solvation as well as synergetic behavior of the solvent mixtures . Several different spectroscopic techniques such as UV‐Vis, NMR, vibrational spectroscopy, solvation dynamics, two dimensional infrared techniques have been used to understand the behavior of solvent mixtures as these techniques have the capability to provide the quantitative information about the solute‐solvent interaction as well as hydrogen bond network present in solvent mixtures. Molecular dynamics simulations (MD) have further enlightened the understanding of the various reasons responsible for the non‐ideal behavior of the solvent mixtures …”

Picosecond Solvation and Rotational Dynamics: An Attempt to Reinvestigate the Mystery of Alcohol–Water Binary Mixtures

“…C480 is extensively used as a solvation probe due to the dramatic increase in dipole moment upon photoexcitation (Δμ ≈ 7 D). 101 Additionally, due to its rigid structure, the other nonradiative pathway like intramolecular charge transfer (ICT) is inhibited compared to its other analogues. 102 Figure 5 represents the variation of solvation time of C480 in TBA− water (Figure 5a respectively.…”

Investigations of absorption and emission spectral data in mixed liquid media. A short review of recent literature

“…Spectroscopic methods have been recently used most to rationalize the nature and the extent of intermolecular interactions from the heterogeneous media (liquid mixtures) [3][4][5][6][7][8]. Table 1 lists several recent studies about spectroscopic behavior of the different solvatochromic probes in various binary solvent mixtures.…”