Prunkl, Christa and Pichlmaier, Markus and Winter, Rainer and Kharlanov, Vladimir and Rettig, Wolfgang and Wagenknecht, Hans-Achim (2010) Optical, Redox, and DNA-Binding Properties of Phenanthridinium Chromophores: Elucidating the Role of the Phenyl Substituent for Fluorescence Enhancement of Ethidium in the Presence of DNA. CHEMISTRY-A EUROPEAN JOURNAL, 16 (11). pp. 3392-3402. ISSN 0947-6539,
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The phenanthridinium chromophores 5-ethyl-6-phenylphenanthridinium (1), 5-ethyl-6-methylphenanthridinium (2), 3,8-diamino-5-ethyl-6-methylphenanthridinium (3), and 3,8-diamino-5-ethyl-6-(4-N,N-diethylaminophenyl)phenanthridinium (4) were characterized by their optical and redox properties. All dyes were applied in titration experiments with a random-sequence 17mer DNA duplex and their binding affinities were determined. The results were compared to well-known ethidium bromide (E). In general, this set of data allows the influence of substituents in positions 3, 6, and 8 on the optical properties of E to be elucidated. Especially, compound 4 was used to compare the weak electron-donating character of the phenyl substituent at position 6 of E with the more electron-donating 4-N,N-diethylaminophenyl group. Analysis of all of the measurements revealed two pairs of chromophores. The first pair, consisting of 1 and 2, lacks the amino groups in positions 3 and 8, and, as a result, these dyes exhibit clearly altered optical and electrochemical properties compared with E. In the presence of DNA, a significant fluorescence quenching was observed. Their binding affinity to DNA is reduced by nearly one order of magnitude. The electronic effect of the phenyl group in position 6 on this type of dye is rather small. The properties of the second set, 3 and 4, are similar to E due to the presence of the two strongly electron-donating amino groups in positions 3 and 8. However, in contrast to 1 and 2, the electron-donating character of the substituent in position 6 of 3 and 4 is critical. The binding, as well as the fluorescence enhancement, is clearly related to the electron-donating effect of this substituent. Accordingly, compound 4 shows the strongest binding affinity and the strongest fluorescence enhancement. Quantum chemical calculations reveal a general mechanism related to the twisted intramolecular charge transfer (TICT) model. Accordingly, an increase of the twist angle between the phenyl ring in position 6 and the phenanthridinium core opens a nonradiative channel in the excited state that depends on the electron-donating character of the phenyl group. Access to this channel is hindered upon binding to DNA.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | PHOTOINDUCED ELECTRON-TRANSFER; DOUBLE-STRANDED DNA; NUCLEIC-ACIDS; CHARGE-TRANSFER; AQUEOUS-MEDIA; BIFUNCTIONAL INTERCALATORS; SACCHAROMYCES-CEREVISIAE; PHOTOAFFINITY LABELS; PROTEIN INTERACTIONS; COMPLEX-FORMATION; charge transfer; DNA; dyes/pigments; fluorescent probes; intercalations |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Anorganische Chemie > Alumni or Retired Professors > Arbeitskreis Prof. Dr. Rainer Winter Chemistry and Pharmacy > Institut für Organische Chemie > Alumni or Retired Professors > Arbeitskreis Prof. Dr. Hans-Achim Wagenknecht |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 12 Aug 2020 10:17 |
| Last Modified: | 12 Aug 2020 10:17 |
| URI: | https://pred.uni-regensburg.de/id/eprint/25395 |
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