Transient FTIR spectroscopy after one- and two-colour excitation on a highly luminescent chromium(iii) complex

Abstract

<p>Depending on the energy of the near-IR photon, the lowest emissive state of the molecular ruby is depopulated or populated.</p>

Autoren

Pit Boden
Patrick Di Martino-Fumo
Gereon Niedner-Schatteburg
Wolfram Seidel
Katja Heinze
Markus Gerhards

DOI

10.1039/d1cp01077h

eISSN

1463-9084

ISSN

1463-9076

Ausgabe der Veröffentlichung

25

Zeitschrift

Physical Chemistry Chemical Physics

Sprache

en

Online publication date

2021

Paginierung

13808 - 13818

Status

Published online

Herausgeber

Royal Society of Chemistry (RSC)

Herausgeber URL

http://dx.doi.org/10.1039/d1cp01077h

Datum der Datenerfassung

2024

Titel

Transient FTIR spectroscopy after one- and two-colour excitation on a highly luminescent chromium(<scp>iii</scp>) complex

Ausgabe der Zeitschrift

23

Data source: Crossref

Abstract

The development of photoactive transition metal complexes with Earth-abundant metals is a rapidly growing research field, where a deeper understanding of the underlying photophysical processes is of great importance. A multitude of potential applications in the fields of photosensitizing, optical sensing, photoluminescence and photoredox catalysis motivates demanding spectroscopic studies. We applied a series of high-level spectroscopic methods on the previously reported highly luminescent chromium(iii) complex [Cr(ddpd)2](BF4)3 (ddpd = N,N'-dimethyl-N,N'-dipyridine-2-ylpyridine-2,6-diamine) possessing two near-IR emissive doublet states with microsecond lifetimes. Luminescence measurements were performed at temperatures down to about 10 K, showing a remarkable rise of the integrated emission intensity by more than a factor of three. The emissive doublet states were structurally characterized by transient FTIR spectroscopy at 290 K and 20 K, supplemented by ground state FTIR and Raman spectroscopy in combination with density functional theory. According to emission and step-scan FT-IR spectroscopy, the stronger luminescence at lower temperature arises from decreased non-radiative decay via energy transfer to CH vibrational overtones and increased radiative decay based on lowered symmetry. Pump/pump/probe (FTIR) and pump/dump/probe (FTIR) schemes were developed to modulate the excited doublet state populations at 290 and 20 K as a function of specific near-IR pump vs. dump wavelengths. The effect of the second near-IR pulse can be explained by combinations of excited state absorption, ground state absorption and stimulated emission. The successful establishment of these two-colour step-scan FTIR experiments is an important step towards profound studies on further transition metal complexes with energetically close-lying excited states in the near future.

Addresses

Department of Chemistry and Research Center OPTIMAS, TU Kaiserslautern, Erwin-Schrödinger-Straße 52, 67663 Kaiserslautern, Germany.

Autoren

Pit Boden
Patrick Di Martino-Fumo
Gereon Niedner-Schatteburg
Wolfram Seidel
Katja Heinze
Markus Gerhards

DOI

10.1039/d1cp01077h

eISSN

1463-9084

Externe Identifier

PubMed Identifier: 34139001

Funding acknowledgements

Deutsche Forschungsgemeinschaft: GE 961/10-01
Deutsche Forschungsgemeinschaft: HE 2778/15-1

Open access

false

ISSN

1463-9076

Ausgabe der Veröffentlichung

25

Zeitschrift

Physical chemistry chemical physics : PCCP

Sprache

eng

Medium

Print

Paginierung

13808 - 13818

Datum der Veröffentlichung

2021

Status

Published

Datum der Datenerfassung

2021

Titel

Transient FTIR spectroscopy after one- and two-colour excitation on a highly luminescent chromium(III) complex.

Sub types

Journal Article

Ausgabe der Zeitschrift

23

Data source: Europe PubMed Central

Abstract

The development of photoactive transition metal complexes with Earth-abundant metals is a rapidly growing research field, where a deeper understanding of the underlying photophysical processes is of great importance. A multitude of potential applications in the fields of photosensitizing, optical sensing, photoluminescence and photoredox catalysis motivates demanding spectroscopic studies. We applied a series of high-level spectroscopic methods on the previously reported highly luminescent chromium(iii) complex [Cr(ddpd)2](BF4)3 (ddpd = N,N'-dimethyl-N,N'-dipyridine-2-ylpyridine-2,6-diamine) possessing two near-IR emissive doublet states with microsecond lifetimes. Luminescence measurements were performed at temperatures down to about 10 K, showing a remarkable rise of the integrated emission intensity by more than a factor of three. The emissive doublet states were structurally characterized by transient FTIR spectroscopy at 290 K and 20 K, supplemented by ground state FTIR and Raman spectroscopy in combination with density functional theory. According to emission and step-scan FT-IR spectroscopy, the stronger luminescence at lower temperature arises from decreased non-radiative decay via energy transfer to CH vibrational overtones and increased radiative decay based on lowered symmetry. Pump/pump/probe (FTIR) and pump/dump/probe (FTIR) schemes were developed to modulate the excited doublet state populations at 290 and 20 K as a function of specific near-IR pump vs. dump wavelengths. The effect of the second near-IR pulse can be explained by combinations of excited state absorption, ground state absorption and stimulated emission. The successful establishment of these two-colour step-scan FTIR experiments is an important step towards profound studies on further transition metal complexes with energetically close-lying excited states in the near future.

Autoren

Pit Boden
Patrick Di Martino-Fumo
Gereon Niedner-Schatteburg
Wolfram Seidel
Katja Heinze
Markus Gerhards

Autoren-URL

https://www.ncbi.nlm.nih.gov/pubmed/34139001

DOI

10.1039/d1cp01077h

eISSN

1463-9084

Ausgabe der Veröffentlichung

25

Zeitschrift

Phys Chem Chem Phys

Sprache

eng

Country

England

Paginierung

13808 - 13818

Datum der Veröffentlichung

2021

Status

Published

Titel

Transient FTIR spectroscopy after one- and two-colour excitation on a highly luminescent chromium(III) complex.

Sub types

Journal Article

Ausgabe der Zeitschrift

23

Data source: PubMed

Transient FTIR spectroscopy after one- and two-colour excitation on a highly luminescent chromium(iii) complex

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