Time-Resolved, Step-Scan FTIR Spectroscopy of Excited States of Transition Metal Complexes

Schoonover, Jon R.; Strouse, Geoffrey F.; Omberg, Kristin M.; Dyer, R. Brian

doi:10.1080/02603599608032720

Cited by 68 publications

(99 citation statements)

References 60 publications

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“…As shown by the data in Table 1, the decrease in PMMA compared to CH 3 CN is 15-20 cm -1 for all three modes. These shifts are comparable to those observed by Turner and co-workers 13 between the fluid and frozen forms of 5:4 butyronitrile/propionitrile for fac-[Re I (bpy)(CO) 3 Cl] (-20, -18, and -23 cm -1 ).…”

Section: Discussionsupporting

confidence: 89%

“…For the MLCT excited state(s) of fac-[Re(bpy)(CO) 3 Cl], Turner and co-workers 13 reported a dramatic decrease in the ground-to-excited-state shift in ν(CO) at the fluid-to-glass transition in a 5:4 butyronitrile/propionitrile mixture. They attributed the decrease to enhanced mixing between the lowest MLCT excited state and low-lying bpy-based ππ* excited states in the rigid glass.…”

Section: Introductionmentioning

confidence: 99%

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Metal-to-Ligand Charge Transfer Excited-State ν(CO) Shifts in Rigid Media

Dattelbaum

Meyer

2002

J. Phys. Chem. A

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The results of ν(CO) infrared measurements on the ground and metal-to-ligand charge transfer (MLCT) excited states of fac-[Re I (4,4′-X 2 bpy)(CO) 3 (4-Etpy)] + (X ) H, CH 3 , and CO 2 Et; 4-Etpy is 4-ethylpyridine) in both CH 3 CN and poly(methyl methacrylate) (PMMA) films at 298 K are reported. In PMMA, the shifts in ν(CO) between the excited and ground states (+18 to +68 cm -1 ) are noticeably less than in solution (+33 to +88 cm -1 ). Our work was stimulated by the observation by Turner and co-workers (Chem. Commun. 1996, 1587-1588) that ν(CO) excited-to-ground-state shifts for fac-[Re(bpy)(CO) 3 Cl] are much less in a rigid butyronitrile/ propionitrile glass at 77 K than in CH 3 CN at 298 K. For the Re complexes, a single correlation exists between excited-state ν(CO) shifts and the MLCT ground-to-excited-state energy gap (E 0 ) regardless of whether the energy gap is changed by varying the substituent X or the medium. The substituent and rigid medium effects appear to have a common orbital origin arising from π*(4,4′-X 2 bpy •-)-π*(CO) mixing. This provides the orbital basis for mixing higher lying dπ(Re)-π*(CO) MLCT states with the emitting dπ(Re)-π*(4,4′-X 2 -bpy •-) MLCT excited state(s).

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Section: Discussionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Metal-to-Ligand Charge Transfer Excited-State ν(CO) Shifts in Rigid Media

Dattelbaum

Meyer

2002

J. Phys. Chem. A

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“…This type of π* SCN back-bonding has been successfully used by a number of researchers as a spectroscopic tag for TRIR (time-resolved infrared) experiments involving electronic excitation of transition metal complexes. [19][20][21][22][23][24][25][26][27] Similarly, we can analyze the frequency changes in the ground and excited states to investigate the electron transition during the excitation. The frequencies were calculated based on the optimized geometries in the ground and the lowest-lying excited states, respectively.…”

Section: Molecular Orbital Analysismentioning

confidence: 99%

Theoretical Investigation on the Absorption and Emission Properties of the Three Isomers of Bis(thiocyanato)(2,2′‐bipyridyl)platinum(II)

Hu¹,

Liu²,

Feng³

2007

Chin. J. Chem.

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This paper presents a Density Functional or Time Dependent Density Functional (DFT/TDDFT) study of the molecular and electronic structures, optical absorption and emission spectra of three linkage isomers: bis(isothiocyanato-S)(2,2'-bipyridyl) platinum(II) ([Pt(SCN) 2 (bpy)]), (isothiocyanato-S)(thiocyanato-N)-(2,2'-bipyridyl) platinum(II) ([Pt(SCN)(NCS)(bpy)]), and bis(thiocyanato-N)(2,2')-bipyridyl)platinum(II) ([Pt(NCS) 2 (bpy)]), in which different coordination ligands based on the N-and S-coordination of the thiocyanato ligands control the luminescent color. The electronic structures were studied using the B3LYP functional. Optimized geometries were compared to the experimentally observed structures. TDDFT calculation was carried out to investigate the excited singlet and triplet states. Calculations have been performed both in vacuo and in solvents, using a polarized continuum model (PCM) to account for solute-solvent interactions. Inclusion of the solvent led to a significant energy change, and as a consequence, the computed spectrum calculated in the presence of the solvent was in good agreement with the experimental determinations. The first two absorptions were found to originate from mixed platinum-SCN (or NSC) to bipyridyl-π* transitions rather than pure metal-to-ligand-charge-transfer (MLCT) transitions, whereas the higher-energy bands arose from intraligand π→π* transitions. The stretching frequencies of C≡N have been calculated both in the ground and excited states, which are relative to the charge transition during the excitation. In addition, different sizes of basis sets were also discussed in this paper.

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“…[49] Furthermore,t pe could be susceptible to ligand-based redox chemistry (ligand non-innocence) similar to t bpy,tpy or Me PDP 2À , [1,2] contrasting ddpd as aredox-innocent spectator ligand. [6] In this study,wee xploit the complex [Cr(tpe) 2 ] 3+ with an Earth-abundant metal ion as ap otential substitute for the classical, precious metal containing chromophore [Ru-(bpy) 3 ] 2+ in luminescence,a sw ell as in photoinduced energy and electron transfer reactions.S ingle crystal X-ray diffraction, [50][51][52][53][54] NIR luminescence quantum yields [55] and lifetimes, variable temperature luminescence and step-scan FT-IR spectroscopy, [56][57][58] electrochemistry and spectroelectrochemistry,S tern-Volmer analyses as well as quantum chemical calculations [59][60][61][62][63][64][65][66][67][68][69] confirm the proposed design guidelines.…”

Section: Introductionmentioning

confidence: 62%

“…Thei ncrease in emission intensity is compatible with the proposed diminished k nr (surface) at lower temperature of the "pseudo-Stokes shifted" 2 X g (D 3d ) state (Figure 3). [79] To gain more insight into the geometries of the long-lived excited states,w es ubjected KBr disks of [Cr(tpe) 2 ][BF 4 ] 3 to time-resolved step-scan FTIR spectroscopy [56][57][58]80] in the energy range of 1750 to 1200 cm À1 at 290 and 20 K ( Figure 5a). Thenegative bands in the difference spectra indicate depopulation of the ground state while positive bands belong to the electronically excited state(s).…”

Section: Excited State Propertiesmentioning

confidence: 99%

Luminescence and Light‐Driven Energy and Electron Transfer from an Exceptionally Long‐Lived Excited State of a Non‐Innocent Chromium(III) Complex

et al. 2019

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Photoactive metal complexes employing Earthabundant metal ions are ak ey to sustainable photophysical and photochemical applications.W ee xploit the effects of an inversion center and ligand non-innocence to tune the luminescence and photochemistry of the excited state of the [CrN 6 ] chromophore [Cr(tpe) 2 ] 3+ with close to octahedral symmetry (tpe = 1,1,1-tris(pyrid-2-yl)ethane). [Cr(tpe) 2 ] 3+ exhibits the longest luminescence lifetime (t = 4500 ms) reported up to date for am olecular polypyridyl chromium(III) complex together with av ery high luminescence quantum yield of F = 8.2 %a t room temperature in fluid solution. Furthermore,t he tpe ligands in [Cr(tpe) 2 ] 3+ are redox non-innocent, leading to reversible reductive chemistry.The excited state redoxpotential and lifetime of [Cr(tpe) 2 ] 3+ surpass those of the classical photosensitizer [Ru(bpy) 3 ] 2+ (bpy = 2,2'-bipyridine) enabling energy transfer (to oxygen) and photoredox processes (with azulene and tri(n-butyl)amine).Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.org/10.

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Time-Resolved, Step-Scan FTIR Spectroscopy of Excited States of Transition Metal Complexes

Cited by 68 publications

References 60 publications

Metal-to-Ligand Charge Transfer Excited-State ν(CO) Shifts in Rigid Media

Metal-to-Ligand Charge Transfer Excited-State ν(CO) Shifts in Rigid Media

Theoretical Investigation on the Absorption and Emission Properties of the Three Isomers of Bis(thiocyanato)(2,2′‐bipyridyl)platinum(II)

Luminescence and Light‐Driven Energy and Electron Transfer from an Exceptionally Long‐Lived Excited State of a Non‐Innocent Chromium(III) Complex

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