Determination of a solvent hydrogen-bond acidity scale by means of the solvatochromism of pyridinium-N-phenolate betaine dye 30 and PCM-TD-DFT calculations.
Empirical parameters of solvents describing their hydrogen-bond (HB) acidity (e.g., the Kamlet-Taft α parameter) are often difficult to determine for new solvents because they are not directly related to a single definition process. Here, we propose a simple method based on one probe, the betaine dye 30, and one reference process, the solvatochromism of this dye, measured by its first electronic transition energy, ET(30). These ET(30) values are calculated within the time-dependent density functional theory framework, using a polarizable continuum solvent model (PCM). The part of ET(30) values that is not included in the PCM calculation is taken as the HB component of the measured ET(30) values, allowing us to deduce a solvent HB acidity parameter α1. The validity of this simple model is assessed by good linear correlations between α1 and a variety of solute properties mainly depending on the solvent's HB acidity. The quality of fit observed with α1 is at least comparable with that obtained by previous solvent HB acidity scales. The simplicity of our method is illustrated by the determination of α1 and of its companion, the electrostatic solvent parameter ES, for some new green solvents derived from glycerol.
Laboratoire CEISAM, UMR CNRS 6230, Université de Nantes , 2, rue de la Houssinière, 44322 Nantes, France.
José P
JP
Cerón-Carrasco
Denis
D
Jacquemin
Christian
C
Laurence
Aurélien
A
Planchat
Christian
C
Reichardt
Khadija
K
Sraïdi
D001622:Betaine / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry*; D005990:Glycerol / Q000737:chemistry; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D011726:Pyridinium Compounds / Q000737:chemistry*; D011789:Quantum Theory; D012997:Solvents / Q000737:chemistry*
D004396:Coloring Agents; D011726:Pyridinium Compounds; D012997:Solvents; D001622:Betaine; D005990:Glycerol