Premium
Towards a homologous structural series of solvatochromic π* indicators
Author(s) -
Helburn R.,
Ullah N.,
Mansour G.,
Maxka J.
Publication year - 1997
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/(sici)1099-1395(199701)10:1<42::aid-poc856>3.0.co;2-h
Subject(s) - solvatochromism , chemistry , solvent , homologous series , nitroaniline , solvent polarity , ion , aqueous solution , alkyl , medicinal chemistry , organic chemistry
Two new π* indicators of solvent dipolarity and polarizability were synthesized and characterized with respect to their solvatochromic and acid‐base properties. The new dyes, N,N ‐dipropyl‐ p ‐nitroaniline and N,N ‐dibutyl‐ p ‐nitroaniline, are part of a homologous structural series of indicators with increasing lipophilic character, ranging from N,N ‐dimethyl‐ p ‐nitroaniline to N,N ‐dibutyl‐ p ‐nitroaniline. The new indicators are designed as specific polarity probes for the characterization of aqueous‐organic interfacial systems. Visible absorption spectra for N,N ‐dipropyl‐ p ‐nitroaniline and N,N ‐dibutyl‐ p ‐nitroaniline show solvent‐dependent bandshapes in a manner similar to that of the previously characterized diethyl species. Values of ‐ s decrease slightly from N,N ‐diethyl‐ p ‐nitroaniline to N,N ‐dipropyl‐ p ‐nitroaniline, leveling off with increasing alkyl chain length. The trend in p K BH +for the p ‐nitroanilinium ions over the range from N,N ‐dimethyl‐ to N,N ‐dibutyl‐ is consistent with known trends for the corresponding anilinium ions. © 1997 John Wiley & Sons, Ltd.