Premium
Syntheses and UV/Vis‐Spectroscopic Properties of Hydrophilic 2‐, 3‐, and 4‐Pyridyl‐Substituted Solvatochromic and Halochromic Pyridinium N ‐Phenolate Betaine Dyes as New Empirical Solvent Polarity Indicators
Author(s) -
Reichardt Christian,
Che Daqing,
Heckenkemper Guido,
Schäfer Gerhard
Publication year - 2001
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200106)2001:12<2343::aid-ejoc2343>3.0.co;2-i
Subject(s) - solvatochromism , betaine , chemistry , aqueous solution , solvent , pyridinium , polarity (international relations) , solvent polarity , organic chemistry , solvent effects , solubility , photochemistry , biochemistry , cell
Syntheses and negative solvatochromism of nine new hydrophilic 2‐, 3‐, and 4‐pyridyl‐substituted pyridinium N ‐phenolate betaine dyes 3 − 11 are described. These were produced in order to obtain zwitterionic dyes better soluble in water and other aqueous media (such as binary water/solvent mixtures, aqueous ionophore solutions) than the rather hydrophobic standard betaine dyes 1 and 2 , which have been used to establish an empirical scale of solvent polarity, called the E T ( 30 ) scale. Betaine dye 8 , in which three of the peripheral phenyl groups of 1 are replaced by two 3‐pyridyl rings and one 4‐pyridyl ring, proved to be particularly suitable for the determination of E T ( 30 ) values in aqueous media.