pKa-Werte von Ethidiumbromid und 7-Amino-9-phenyl-10- äthyl-phenanthridinium-bromid / pKa-Values of Ethidiumbromide and 7-Amino-9-phenyl-10-ethyl-phenanthridinium- bromide
Open Access
- 1 December 1976
- journal article
- research article
- Published by Walter de Gruyter GmbH in Zeitschrift für Naturforschung C
- Vol. 31 (11-12) , 656-660
- https://doi.org/10.1515/znc-1976-11-1205
Abstract
Ethidium bromide (1) has 2 amino groups in 2- and 7-position which are protonated in acidic water solution. Both pKa-values of 1 are determined at 20.degree. C by the pH-dependence of the electronic spectra using a iterative calculating procedure, pKa1 = 0.713, pKa2 = 2.43. Acetylation of 1 and quantum mechanical calculations lead to the conclusion that the electronic density at the 7-amino group is greater than in 2-position. Therefore with decreasing pH preferably the 7-amino group is protonated (pKa2), followed by the protonation of the 2-amino group (pKa1). The pKa of 7-amino-9-phenyl-10-ethyl-phenanthridinium-bromide in H2O solution at 20.degree. C is determined to pKa = 1.25.Keywords
This publication has 1 reference indexed in Scilit:
- Structural considerations in the interaction of DNA and acridinesJournal of Molecular Biology, 1961