TY - JOUR
T1 - Origin of strong synergism in weakly perturbed binary solvent system
T2 - A case study of primary alcohols and chlorinated methanes
AU - Gupta, Shradhey
AU - Rafiq, Shahnawaz
AU - Kundu, Mainak
AU - Sen, Pratik
PY - 2012/2/2
Y1 - 2012/2/2
N2 - 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-CHCl3 (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-CHCl3 binary mixture and hence suggested the maximum extent of hydrogen-bonding interactions prevailing at this proportion of mixture. The solvation behavior of MeOH-CHCl3 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-CHCl3 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-CHCl3 binary solvent mixture indicates the existence of MeOH-CHCl3 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-CHCl3 binary solvent mixture.
AB - 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-CHCl3 (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-CHCl3 binary mixture and hence suggested the maximum extent of hydrogen-bonding interactions prevailing at this proportion of mixture. The solvation behavior of MeOH-CHCl3 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-CHCl3 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-CHCl3 binary solvent mixture indicates the existence of MeOH-CHCl3 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-CHCl3 binary solvent mixture.
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U2 - 10.1021/jp207741h
DO - 10.1021/jp207741h
M3 - Article
AN - SCOPUS:84863069613
SN - 1520-6106
VL - 116
SP - 1345
EP - 1355
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 4
ER -