Photophysical Processes in Rhenium(I) Diiminetricarbonyl Arylisocyanides Featuring Three Interacting Triplet Excited States
Abstract
We present here a series of four transition-metal complexes based on the rhenium(I) tricarbonyl 1,10-phenanthroline (phen) template, with a lone ancillary arylisocyanide (CNAr) ligand to yield metal–organic chromophores of the generic molecular formula [Re(phen)(CO)3(CNAr)]+ [CNAr = 2,6-diisopropylphenyl isocyanide (1), 4-phenyl-2,6-diisopropylphenyl isocyanide (2), 4-phenylethynyl-2,6-diisopropylphenyl isocyanide (3), and 4-biphenyl-2,6-diisopropylphenyl isocyanide (4)]. This particular series features varied degrees of π-conjugation length in the CNAr moiety, resulting in significant modulation in the resultant photophysical properties. All molecules possess long-lived [8–700 μs at room temperature (RT)], strongly blue-green photoluminescent and highly energetic excited states (λmax,em = 500–518 nm; Φ = 14–64%). Each of these chromophores has been photophysically investigated using static and dynamic spectroscopic techniques, the latter probed from ultrafast to supra-nanosecond time scales using transient absorption and photoluminescence (PL). Time-resolved PL intensity decays recorded as a function of the temperature were consistent with the presence of at least two emissive states lying closely spaced in energy with a third nonemissive state lying much higher in energy and likely ligand-field in character. The combined experimental evidence, along with the aid of electronic structure calculations (density functional theory and time-dependent density functional theory performed at the M06/Def2-SVP/SDD level), illustrates that the CNAr ligand is actively engagedmore »
- Publication Date:
- Research Org.:
- North Carolina State University, Raleigh, NC (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Contributing Org.:
- Air Force Institute of Technology (AFIT)
- OSTI Identifier:
- 1633637
- Grant/Contract Number:
- SC0011979
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Inorganic Chemistry
- Additional Journal Information:
- Journal Volume: 58; Journal Issue: 13; Journal ID: ISSN 0020-1669
- Publisher:
- American Chemical Society (ACS)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 14 SOLAR ENERGY
Citation Formats
Favale, Joseph M., Danilov, Evgeny O., Yarnell, James E., and Castellano, Felix N. Photophysical Processes in Rhenium(I) Diiminetricarbonyl Arylisocyanides Featuring Three Interacting Triplet Excited States. United States: N. p., 2019.
Web. doi:10.1021/acs.inorgchem.9b01155.
Favale, Joseph M., Danilov, Evgeny O., Yarnell, James E., & Castellano, Felix N. Photophysical Processes in Rhenium(I) Diiminetricarbonyl Arylisocyanides Featuring Three Interacting Triplet Excited States. United States. https://doi.org/10.1021/acs.inorgchem.9b01155
Favale, Joseph M., Danilov, Evgeny O., Yarnell, James E., and Castellano, Felix N. Wed .
"Photophysical Processes in Rhenium(I) Diiminetricarbonyl Arylisocyanides Featuring Three Interacting Triplet Excited States". United States. https://doi.org/10.1021/acs.inorgchem.9b01155. https://www.osti.gov/servlets/purl/1633637.
@article{osti_1633637,
title = {Photophysical Processes in Rhenium(I) Diiminetricarbonyl Arylisocyanides Featuring Three Interacting Triplet Excited States},
author = {Favale, Joseph M. and Danilov, Evgeny O. and Yarnell, James E. and Castellano, Felix N.},
abstractNote = {We present here a series of four transition-metal complexes based on the rhenium(I) tricarbonyl 1,10-phenanthroline (phen) template, with a lone ancillary arylisocyanide (CNAr) ligand to yield metal–organic chromophores of the generic molecular formula [Re(phen)(CO)3(CNAr)]+ [CNAr = 2,6-diisopropylphenyl isocyanide (1), 4-phenyl-2,6-diisopropylphenyl isocyanide (2), 4-phenylethynyl-2,6-diisopropylphenyl isocyanide (3), and 4-biphenyl-2,6-diisopropylphenyl isocyanide (4)]. This particular series features varied degrees of π-conjugation length in the CNAr moiety, resulting in significant modulation in the resultant photophysical properties. All molecules possess long-lived [8–700 μs at room temperature (RT)], strongly blue-green photoluminescent and highly energetic excited states (λmax,em = 500–518 nm; Φ = 14–64%). Each of these chromophores has been photophysically investigated using static and dynamic spectroscopic techniques, the latter probed from ultrafast to supra-nanosecond time scales using transient absorption and photoluminescence (PL). Time-resolved PL intensity decays recorded as a function of the temperature were consistent with the presence of at least two emissive states lying closely spaced in energy with a third nonemissive state lying much higher in energy and likely ligand-field in character. The combined experimental evidence, along with the aid of electronic structure calculations (density functional theory and time-dependent density functional theory performed at the M06/Def2-SVP/SDD level), illustrates that the CNAr ligand is actively engaged in manipulating the excited-state decay in three of these molecules (2–4), wherein the triplet metal-to-ligand charge-transfer (3MLCT) state along with two distinct triplet ligand-centered (3LC) excited-state configurations (phen and CNAr) conspire to produce the resultant photophysical properties. Because the π conjugation within the CNAr ligand was extended, an interesting shift in the dominant photophysical processes was observed. When the CNAr conjugation length is short, as in 1, the phenanthroline 3LC state dominates, resulting in a configurationally mixed triplet excited state of both LC and MLCT character. With more extended π conjugation in the CNAr subunit (2–4), the initially generated 3LC(phen)/3MLCT excited state ultimately migrates to the CNAr 3LC state on the order of tens of picoseconds. Molecules 3 and 4 in this series also feature unique examples of inorganic excimer formation, as demonstrated by dynamic self-quenching in the corresponding PL intensity decays accompanied by the observation of a short-lived low-energy emission feature.},
doi = {10.1021/acs.inorgchem.9b01155},
journal = {Inorganic Chemistry},
number = 13,
volume = 58,
place = {United States},
year = {Wed Jun 19 00:00:00 EDT 2019},
month = {Wed Jun 19 00:00:00 EDT 2019}
}
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Figures / Tables:
Scheme 1: General Synthetic Pathway and Molecular Structures of the $fac$-Rhenium(I) Complexes 1−4