Consequences of the One-Electron Reduction and Photoexcitation of Unsymmetric Bis-imidazolium Salts

Abstract

AbstractCoupling of uronium salts with in situ generated N‐heterocyclic carbenes provides straightforward access to symmetrical [4]2+ and unsymmetrical bis‐imidazolium salts [6]2+ and [9]2+. As indicated by cyclic and square‐wave voltammetry, [6]2+ and [9]2+ can be (irreversibly) reduced by one electron. The initially formed radicals [6].+ and [9].+ undergo further reactions, which were probed by EPR spectroscopy and density functional calculations. The final products of the two‐electron reduction are the two carbenes. Upon irradiation with UV light both [6]2+ and [9]2+ emit at room temperature in solution but with dramatically different characteristics. The different fluorescence behavior is analyzed by emission spectroscopy and interpreted by using time‐dependent density functional calculations as largely due to different excited‐state dynamics of [6]2+ and [9]2+. The geometries of both radicals [6].+ and [9].+ and excited states {[6]2+}* and {[9]2+}* are substantially different from those of the parent ground‐state molecules.

Autoren

Verena Gierz
Jascha Melomedov
Christoph Förster
Christine Deißler
Frank Rominger
Doris Kunz
Katja Heinze

DOI

10.1002/chem.201200323

eISSN

1521-3765

ISSN

0947-6539

Ausgabe der Veröffentlichung

34

Zeitschrift

Chemistry – A European Journal

Sprache

en

Online publication date

2012

Paginierung

10677 - 10688

Datum der Veröffentlichung

2012

Status

Published

Herausgeber

Wiley

Herausgeber URL

http://dx.doi.org/10.1002/chem.201200323

Datum der Datenerfassung

2023

Titel

Consequences of the One‐Electron Reduction and Photoexcitation of Unsymmetric Bis‐imidazolium Salts

Ausgabe der Zeitschrift

18

Datenquelle: Crossref

Abstract

Coupling of uronium salts with in situ generated N-heterocyclic carbenes provides straightforward access to symmetrical [4](2+) and unsymmetrical bis-imidazolium salts [6](2+) and [9](2+) . As indicated by cyclic and square-wave voltammetry, [6](2+) and [9](2+) can be (irreversibly) reduced by one electron. The initially formed radicals [6](.+) and [9](.+) undergo further reactions, which were probed by EPR spectroscopy and density functional calculations. The final products of the two-electron reduction are the two carbenes. Upon irradiation with UV light both [6](2+) and [9](2+) emit at room temperature in solution but with dramatically different characteristics. The different fluorescence behavior is analyzed by emission spectroscopy and interpreted by using time-dependent density functional calculations as largely due to different excited-state dynamics of [6](2+) and [9](2+) . The geometries of both radicals [6](.+) and [9](.+) and excited states {[6](2+) }* and {[9](2+) }* are substantially different from those of the parent ground-state molecules.

Addresses

Institute of Inorganic Chemistry, Eberhard Karls-University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany.

Autoren

Verena Gierz
Jascha Melomedov
Christoph Förster
Christine Deissler
Frank Rominger
Doris Kunz
Katja Heinze

DOI

10.1002/chem.201200323

eISSN

1521-3765

Externe Identifier

PubMed Identifier: 22791514

Open access

false

ISSN

0947-6539

Ausgabe der Veröffentlichung

34

Zeitschrift

Chemistry (Weinheim an der Bergstrasse, Germany)

Sprache

eng

Medium

Print-Electronic

Online publication date

2012

Paginierung

10677 - 10688

Datum der Veröffentlichung

2012

Status

Published

Datum der Datenerfassung

2012

Titel

Consequences of the one-electron reduction and photoexcitation of unsymmetric bis-imidazolium salts.

Sub types

Journal Article

Ausgabe der Zeitschrift

18

Datenquelle: Europe PubMed Central

Abstract

Coupling of uronium salts with in situ generated N-heterocyclic carbenes provides straightforward access to symmetrical [4](2+) and unsymmetrical bis-imidazolium salts [6](2+) and [9](2+) . As indicated by cyclic and square-wave voltammetry, [6](2+) and [9](2+) can be (irreversibly) reduced by one electron. The initially formed radicals [6](.+) and [9](.+) undergo further reactions, which were probed by EPR spectroscopy and density functional calculations. The final products of the two-electron reduction are the two carbenes. Upon irradiation with UV light both [6](2+) and [9](2+) emit at room temperature in solution but with dramatically different characteristics. The different fluorescence behavior is analyzed by emission spectroscopy and interpreted by using time-dependent density functional calculations as largely due to different excited-state dynamics of [6](2+) and [9](2+) . The geometries of both radicals [6](.+) and [9](.+) and excited states {[6](2+) }* and {[9](2+) }* are substantially different from those of the parent ground-state molecules.

Autoren

Verena Gierz
Jascha Melomedov
Christoph Förster
Christine Deissler
Frank Rominger
Doris Kunz
Katja Heinze

Autoren-URL

https://www.ncbi.nlm.nih.gov/pubmed/22791514

DOI

10.1002/chem.201200323

eISSN

1521-3765

Ausgabe der Veröffentlichung

34

Zeitschrift

Chemistry

Sprache

eng

Country

Germany

Paginierung

10677 - 10688

Datum der Veröffentlichung

2012

Status

Published

Datum, an dem der Datensatz öffentlich gemacht wurde

2012

Titel

Consequences of the one-electron reduction and photoexcitation of unsymmetric bis-imidazolium salts.

Sub types

Journal Article

Ausgabe der Zeitschrift

18

Datenquelle: PubMed

Consequences of the One-Electron Reduction and Photoexcitation of Unsymmetric Bis-imidazolium Salts

Werkzeuge