Solvatochromism in pure and binary solvent mixtures: effects of the molecular structure of the zwitterionic probe
Tada, EB; Novaki, LP; El Seoud, OA
| HERO ID | 1171611 |
|---|---|
| In Press | No |
| Year | 2000 |
| Title | Solvatochromism in pure and binary solvent mixtures: effects of the molecular structure of the zwitterionic probe |
| Authors | Tada, EB; Novaki, LP; El Seoud, OA |
| Journal | Journal of Physical Organic Chemistry |
| Volume | 13 |
| Issue | 11 |
| Page Numbers | 679-687 |
| Abstract | The solvatochromic behavior of 2,6-dichloro-4-(2,4,6-triphenyl-1-pyridinio)phenolate (WB) was studied by UV-visible spectrophotometry in 32 pure solvents, in binary mixtures of l-butanol-cyclohexane (BuOH-Cyhx), and of water with methanol, ethanol, I-propanol, 2-butoxyethanol (2-BE), acetonitrile, 1,4-dioxane and THF. The solvent polarity, E-T(33) in kcal mol(-1), was calculated from the position of the longest-wavelength intramolecular charge-transfer absorption band of WE and the results were compared with those for 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridinio)phenolate [RB, E-T(30)] add of 1-methyl-8-oxyquinolinium betaine [QB, E-T(QB)]. For pure solvents, ET(33) is a linear function of ET(30), with a slope of practically unity. Steric crowding from the two ortho phenyl rings of RE hinders the formation of H-bonds with solvents, which results in similar susceptibilities of WE and RE to solvent acidity. For binary solvent mixtures, all plots of ET versus the mole fraction of l-butanol or water are nonlinear owing to preferential solvation of the probe by one component of the mixed solvent and, when applicable, to solvent micro-heterogeneity. Preferential solvation due to non-specific and specific probe-solvent interactions was calculated for BuOH-Cyhx and water-acetonitrile. Both solvation mechanisms contribute to the non-ideal behavior in the former binary mixture, whereas probe-solvent specific interactions dominate the solvatochromic behavior in the latter. The composition of the probe solvation shell was calculated. In aqueous alcohols, preferential solvation is by the alcohol. In water-aprotic solvent mixtures, preferential solvation of RE and WE is by the solvent which is present in lower concentration, whereas QB seems to form its own, water-rich solvation shell over a wide range of water concentration. Copyright (C) 2000 John Wiley & Sons, Ltd.< |
| Doi | 10.1002/1099-1395(200011)13:11<679::AID-POC299>3.0.CO;2-R |
| Wosid | WOS:000165198900002 |
| Is Certified Translation | No |
| Dupe Override | No |
| Comments | Source: Web of Science 000165198900002Scopus URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-0000307251&doi=10.1002%2f1099-1395%28200011%2913%3a11%3c679%3a%3aAID-POC299%3e3.0.CO%3b2-R&partnerID=40&md5=d5a48a47a65397985fa714a5a1e3475b |
| Is Public | Yes |
| Language Text | English |
| Keyword | solvatochromism; preferential solvation; binary mixtures; polarity |
| Is Qa | No |