Solvation Dynamics in Mixtures of Polar and Nonpolar Solvents

Abstract

Time-resolved Stokes shift measurements and steady-state absorption and fluorescence measurements of Coumarin 153 (C153) at different temperatures were used to explore the solvation dynamics of binary mixtures of alcohols and alkanes at various alcohol concentrations. These solvent mixtures show even at alcohol concentrations as low as 0.3% a strong Stokes shift of about 1200 cm -1 . Depending on alcohol concentration, this Stokes shift takes place on a time scale ranging from 300 ps up to several nanoseconds. These characteristic times are 2 orders of magnitude longer than the relaxation times typically found in alcohols, which is attributed to rotational reorientation of the solvent molecules. A monoexponential temporal behavior of the Stokes shift and a linear dependence of the time constants on the alkane viscosity are observed. These results and temperature dependent static fluorescence measurements strongly support a diffusion-controlled process of solvation in these mixtures.

Exploration of the Dynamical Evolution and the Associated Energetics of Water Nanoclusters Formed in a Hydrophobic Solvent

“…[39][40][41] This slow component might have its genesis in the translational diffusion of water into the solvation shell displacing the nonpolar solvent molecules in the cluster. 41,56,57 Also the decrease in τ slow with increasing water content is associated with the increasing average mutual diffusion coefficient (〈D m 〉) as the increase in water content in a water-DX mixture increases the number of hydrogen bonds per oxygen atom and also the relaxation rate.…”

Time‐dependent density functional theory study on the absorption spectrum of Coumarin 102 and its hydrogen‐bonded complexes

“…25,[60][61][62][63][64][65] The type B HB of Coumarin 153 and 102 has been detected by several experimental groups. 15,18,[66][67][68] However, there is still no direct observation of the type A HB between C102 and a solvent molecule. Our calculated absorption wavelengths of the C102 complexes with two HB of type B are in very good agreement with experimental measurements, but the errors increase when the type A HB involved in the calculation.…”

Influence of Solvent Polarity and Hydrogen Bonding on the Electronic Transition of Coumarin 120: A TDDFT Study

“…Experimental and theoretical investigations have shown the presence of the type B and C HBs for Coumarin 151 with the water and methanol molecules in the gas phase. [33,[61][62][63][64][65][66] The type B HBs of Coumarins 153 and 102 have been studied by several experimental groups, [18,[22][23][24][25] and since these two coumarins contain no hydrogen-bond donating group, the type C HB does not exist. However, there is still no direct observation of a type A HB between a 7-aminocoumarin and a solvent molecule.…”

“…[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] The effect of a specific HB on the solvation electrostatics and dynamics has also been investigated. [21][22][23][24][25] To better understand the effects of both polarity and H-bonding of the solvent on the electronic spectrum of a given solute, a multiparameter equation that independently quantifies these various influences has been developed by Kamlet, Taft et al, [30,31] various aspects of solvent effects on the spectra of numerous solutes are parametrized in this multiterm solvatochromism equation, which has been widely used in recent years. [14][15][16][17]30] The general form of the Kamlet-Taft equation describing the transition energy is given by Equation (1)…”