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Leong TX, Collins BK, Dey Baksi S, Mackin RT, Sribnyi A, Burin AL, Gladysz JA, Rubtsov IV. Tracking Energy Transfer across a Platinum Center. J Phys Chem A 2022; 126:4915-4930. [PMID: 35881911 PMCID: PMC9358659 DOI: 10.1021/acs.jpca.2c02017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
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Rigid, conjugated alkyne bridges serve as important components
in various transition-metal complexes used for energy conversion,
charge separation, sensing, and molecular electronics. Alkyne stretching
modes have potential for modulating charge separation in donor–bridge–acceptor
compounds. Understanding the rules of energy relaxation and energy
transfer across the metal center in such compounds can help optimize
their electron transfer switching properties. We used relaxation-assisted
two-dimensional infrared spectroscopy to track energy transfer across
metal centers in platinum complexes featuring a triazole-terminated
alkyne ligand of two or six carbons, a perfluorophenyl ligand, and
two tri(p-tolyl)phosphine ligands. Comprehensive
analyses of waiting-time dynamics for numerous cross and diagonal
peaks were performed, focusing on coherent oscillation, energy transfer,
and cooling parameters. These observables augmented with density functional
theory computations of vibrational frequencies and anharmonic force
constants enabled identification of different functional groups of
the compounds. Computations of vibrational relaxation pathways and
mode couplings were performed, and two regimes of intramolecular energy
redistribution are described. One involves energy transfer between
ligands via high-frequency modes; the transfer is efficient only if
the modes involved are delocalized over both ligands. The energy transport
pathways between the ligands are identified. Another regime involves
redistribution via low-frequency delocalized modes, which does not
lead to interligand energy transport.
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Affiliation(s)
- Tammy X Leong
- Department of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
| | - Brenna K Collins
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - Sourajit Dey Baksi
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - Robert T Mackin
- Department of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
| | - Artem Sribnyi
- Department of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
| | - Alexander L Burin
- Department of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
| | - John A Gladysz
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - Igor V Rubtsov
- Department of Chemistry, Tulane University, New Orleans, Louisiana 70118, United States
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Crum VF, Kiefer LM, Kubarych KJ. Ultrafast vibrational dynamics of a solute correlates with dynamics of the solvent. J Chem Phys 2021; 155:134502. [PMID: 34624983 DOI: 10.1063/5.0061770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Two-dimensional infrared (2D-IR) spectroscopy is used to measure the spectral dynamics of the metal carbonyl complex cyclopentadienyl manganese tricarbonyl (CMT) in a series of linear alkyl nitriles. 2D-IR spectroscopy provides direct readout of solvation dynamics through spectral diffusion, probing the decay of frequency correlation induced by fluctuations of the solvent environment. 2D-IR simultaneously monitors intramolecular vibrational energy redistribution (IVR) among excited vibrations, which can also be influenced by the solvent through the spectral density rather than the dynamical friction underlying solvation. Here, we report that the CMT vibrational probe reveals solvent dependences in both the spectral diffusion and the IVR time scales, where each slows with increased alkyl chain length. In order to assess the degree to which solute-solvent interactions can be correlated with bulk solvent properties, we compared our results with low-frequency dynamics obtained from optical Kerr effect (OKE) spectroscopy-performed by others-on the same nitrile solvent series. We find excellent correlation between our spectral diffusion results and the orientational dynamics time scales from OKE. We also find a correlation between our IVR time scales and the amplitudes of the low-frequency spectral densities evaluated at the 90-cm-1 energy difference, corresponding to the gap between the two strong vibrational modes of the carbonyl probe. 2D-IR and OKE provide complementary perspectives on condensed phase dynamics, and these findings provide experimental evidence that at least at the level of dynamical correlations, some aspects of a solute vibrational dynamics can be inferred from properties of the solvent.
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Affiliation(s)
- Vivian F Crum
- Department of Chemistry, University of Michigan, 930 N. University Ave., Ann Arbor, Michigan 48109, USA
| | - Laura M Kiefer
- Department of Chemistry, University of Michigan, 930 N. University Ave., Ann Arbor, Michigan 48109, USA
| | - Kevin J Kubarych
- Department of Chemistry, University of Michigan, 930 N. University Ave., Ann Arbor, Michigan 48109, USA
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