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Shakirova JR, Nayeri S, Jamali S, Porsev VV, Gurzhiy VV, Levin OV, Koshevoy IO, Tunik SP. Targeted Synthesis of NIR Luminescent Rhenium Diimine cis,trans-[Re( N N )(CO) 2 (L) 2 ] n+ Complexes Containing N-Donor Axial Ligands: Photophysical, Electrochemical, and Theoretical Studies. Chempluschem 2020; 85:2518-2527. [PMID: 33226192 DOI: 10.1002/cplu.202000597] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 11/05/2020] [Indexed: 11/09/2022]
Abstract
The combined action of ultraviolet irradiation and microwave heating onto acetonitrile solution of [Re( N N )(CO)3 (NCMe)]OTf ( N N =phenantroline and neocuproine) afforded cis,trans-Re( N N )(CO)2 (NCMe)2 ]+ acetonitrile derivatives. Substitution of relatively labile NCMe with a series of aromatic N-donor ligands (pyridine, pyrazine, 4,4'-bipyridine, N-methyl-4,4'-bipyridine) gave a novel family of the diimine cis,trans-[Re( N N )(CO)2 (L)2 ]+ complexes. Photophysical studies of the obtained compounds in solution revealed unusually high absorption across the visible region and NIR phosphorescence with emission band maxima ranging from 711 to 805 nm. The nature of emissive excited states was studied using DFT calculations to show dominant contribution of 3 MLCT (dπ(Re)→π*( N N )) character. Electrochemical (CV and DPV) studies of the monocationic diimine complexes revealed one reduction and one oxidation wave assigned to reduction of the diimine moiety and oxidation of the rhenium center, respectively.
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Affiliation(s)
- J R Shakirova
- Department of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russia
| | - S Nayeri
- Department of Chemistry, Sharif University of Technology, P.O. Box, 11155-3516, Tehran, Iran
| | - S Jamali
- Department of Chemistry, Sharif University of Technology, P.O. Box, 11155-3516, Tehran, Iran
| | - Vitaly V Porsev
- Department of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russia
| | - Vladislav V Gurzhiy
- Department of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russia
| | - Oleg V Levin
- Department of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russia
| | - I O Koshevoy
- Department of Chemistry, University of Eastern Finland, 80101, Joensuu, Finland
| | - S P Tunik
- Department of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504, St. Petersburg, Russia
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Paz Y. Transient IR spectroscopy as a tool for studying photocatalytic materials. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:503004. [PMID: 31469092 DOI: 10.1088/1361-648x/ab3eda] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Over the years, a considerable amount of attention has been given to the thermodynamics of photocatalysts, i.e. to the location of their valence and conduction bands on the energy scale. The kinetics of the photoinduced charge carriers at short times (i.e. prior to their surface redox reactions) is no less important. While significant work on the transient electronic spectra of photocatalysts has been performed, the transient vibrational spectra of this class of materials was hardly studied. This manuscript aims to increase the scientific awareness to the potential of transient IR spectroscopy (TRIR) as a complementary tool for understanding the first, crucial, steps of photocatalytic processes in solid photocatalysts. This was done herein first by describing the various techniques currently in use for measuring transient IR signals of photo-excited systems and discussing their pros and cons. Then, a variety of examples is given, representing different types of photocatalysts such as oxides (TiO2, NaTaO3, BiOCl, BiVO4), photosensitized oxides (dye-sensitized TiO2), organic polymers (graphitic carbon nitride) and organo-metalic photocatalysts (rhenium bipyridyl complexes). These examples span from materials with no IR fingerprint signals (TiO2) to materials having a distinct spectrum showing well-defined, localized, relatively narrow, vibrational bands (carbon nitride). In choosing the given-above examples, care was made to represent the several pump & probe techniques that are applied when studying transient IR spectroscopy, namely dispersive, transient 2D-IR spectroscopy and step-scan IR spectroscopy. It is hoped that this short review will contribute to expanding the use of TRIR as a viable and important technique among the arsenal of tools struggling to solve the mysteries behind photocatalysis.
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Affiliation(s)
- Yaron Paz
- Department of Chemical Engineering, Technion, Haifa, Israel
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Kamatsuka T, Shinokubo H, Miyake Y. Design and Synthesis of Tunable Ligands with 4,4′-Bipyridyl as an Electron-Accepting Unit and Their Rhenium Complexes. Organometallics 2017. [DOI: 10.1021/acs.organomet.7b00611] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Takuto Kamatsuka
- Department of Molecular and
Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
| | - Hiroshi Shinokubo
- Department of Molecular and
Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
| | - Yoshihiro Miyake
- Department of Molecular and
Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
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Huff GS, Lo WKC, Horvath R, Turner JO, Sun XZ, Weal GR, Davidson HJ, Kennedy ADW, McAdam CJ, Crowley JD, George MW, Gordon KC. Excited States of Triphenylamine-Substituted 2-Pyridyl-1,2,3-triazole Complexes. Inorg Chem 2016; 55:12238-12253. [DOI: 10.1021/acs.inorgchem.6b01959] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Gregory S. Huff
- Department of Chemistry, University of Otago, Dunedin 9054, New Zealand
| | - Warrick K. C. Lo
- Department of Chemistry, University of Otago, Dunedin 9054, New Zealand
| | - Raphael Horvath
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, U.K
| | - Jack O. Turner
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, U.K
| | - Xue-Zhong Sun
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, U.K
| | - Geoffrey R. Weal
- Department of Chemistry, University of Otago, Dunedin 9054, New Zealand
| | | | | | - C. John McAdam
- Department of Chemistry, University of Otago, Dunedin 9054, New Zealand
| | - James D. Crowley
- Department of Chemistry, University of Otago, Dunedin 9054, New Zealand
| | - Michael W. George
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, U.K
- Department of Chemical and Environmental
Engineering, University of Nottingham Ningbo China, 199 Taikang East
Road, Ningbo 315100, China
| | - Keith C. Gordon
- Department of Chemistry, University of Otago, Dunedin 9054, New Zealand
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Miyake Y, Nakajima K, Higuchi Y, Nishibayashi Y. Synthesis and Redox Properties of PNP Pincer Complexes Based onN-Methyl-4,4′-bipyridinium. Eur J Inorg Chem 2014. [DOI: 10.1002/ejic.201402349] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Huang YH, Chen JD, Hsu KH, Chu LK, Lee YP. Transient Infrared Absorption Spectra of Reaction Intermediates Detected with a Step-scan Fourier-transform Infrared Spectrometer. J CHIN CHEM SOC-TAIP 2013. [DOI: 10.1002/jccs.201300415] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Chirdon DN, McCusker CE, Castellano FN, Bernhard S. Tracking of Tuning Effects in Bis-Cyclometalated Iridium Complexes: A Combined Time Resolved Infrared Spectroscopy, Electrochemical, and Computational Study. Inorg Chem 2013; 52:8795-804. [DOI: 10.1021/ic401009q] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Danielle N. Chirdon
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Catherine E. McCusker
- Department of Chemistry and Center for Photochemical
Sciences, Bowling Green State University, Bowling Green, Ohio 43403, United States
| | - Felix N. Castellano
- Department of Chemistry and Center for Photochemical
Sciences, Bowling Green State University, Bowling Green, Ohio 43403, United States
| | - Stefan Bernhard
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
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Prusakova V, McCusker CE, Castellano FN. Ligand-Localized Triplet-State Photophysics in a Platinum(II) Terpyridyl Perylenediimideacetylide. Inorg Chem 2012; 51:8589-98. [DOI: 10.1021/ic301169t] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Valentina Prusakova
- Department of Chemistry
and Center for Photochemical
Sciences, Bowling Green State University, Bowling Green, Ohio 43403, United States
| | - Catherine E. McCusker
- Department of Chemistry
and Center for Photochemical
Sciences, Bowling Green State University, Bowling Green, Ohio 43403, United States
| | - Felix N. Castellano
- Department of Chemistry
and Center for Photochemical
Sciences, Bowling Green State University, Bowling Green, Ohio 43403, United States
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Alberding BG, Brown-Xu SE, Chisholm MH, Gustafson TL, Reed CR, Naseri V. Photophysical properties of MM quadruply bonded complexes (M = Mo, W) supported by carboxylate ligands: charge delocalization and dynamics in S1 and T1 states. Dalton Trans 2012; 41:13097-104. [DOI: 10.1039/c2dt30490b] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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10
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Glik EA, Kinayyigit S, Ronayne KL, Towrie M, Sazanovich IV, Weinstein JA, Castellano FN. Ultrafast Excited State Dynamics of Pt(II) Chromophores Bearing Multiple Infrared Absorbers. Inorg Chem 2008; 47:6974-83. [DOI: 10.1021/ic800578h] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Elena A. Glik
- Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio, 43403, Laser for Science Facility, Photon Science Department, Rutherford Appleton Laboratory, Science and Technology Facilities Council, Chilton, OX11 0QX, U.K., and Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Solen Kinayyigit
- Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio, 43403, Laser for Science Facility, Photon Science Department, Rutherford Appleton Laboratory, Science and Technology Facilities Council, Chilton, OX11 0QX, U.K., and Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Kate L. Ronayne
- Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio, 43403, Laser for Science Facility, Photon Science Department, Rutherford Appleton Laboratory, Science and Technology Facilities Council, Chilton, OX11 0QX, U.K., and Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Michael Towrie
- Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio, 43403, Laser for Science Facility, Photon Science Department, Rutherford Appleton Laboratory, Science and Technology Facilities Council, Chilton, OX11 0QX, U.K., and Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Igor V. Sazanovich
- Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio, 43403, Laser for Science Facility, Photon Science Department, Rutherford Appleton Laboratory, Science and Technology Facilities Council, Chilton, OX11 0QX, U.K., and Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Julia A. Weinstein
- Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio, 43403, Laser for Science Facility, Photon Science Department, Rutherford Appleton Laboratory, Science and Technology Facilities Council, Chilton, OX11 0QX, U.K., and Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
| | - Felix N. Castellano
- Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio, 43403, Laser for Science Facility, Photon Science Department, Rutherford Appleton Laboratory, Science and Technology Facilities Council, Chilton, OX11 0QX, U.K., and Department of Chemistry, University of Sheffield, Sheffield S3 7HF, U.K
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Organometallic Chemistry of Polypyridine Ligands II. ADVANCES IN HETEROCYCLIC CHEMISTRY 2007. [DOI: 10.1016/s0065-2725(06)94002-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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12
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Merzlikine AG, Voskresensky SV, Danilov EO, Neckers DC, Fedorov AV. Analysis of the time-resolved FTIR spectra produced by the photolysis of alkyl phenylglyoxylates. Photochem Photobiol Sci 2007; 6:608-13. [PMID: 17549261 DOI: 10.1039/b614792e] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The photochemistry of alkyl phenylglyoxylates (APG) was further investigated using time-resolved infrared spectroscopy. The primary focus was on the analysis of weak transient bands around 1828 and 1730 cm(-1) in the time-resolved FTIR spectra of glyoxylates. The observed transients were assigned to benzoyl and alkyl mandelate ester radicals, respectively. The formation of benzoyl radical was fast and attributed to the Norrish Type I process. In addition, the intensities of the strong FTIR bands around 1680 and 2100 cm(-1) were used to analyze the yields of the triplet state and ketene, respectively. These new and previous data on APG photochemistry are discussed in relation to the acrylate polymerization photoinitiation by alkyl phenylglyoxylates.
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Affiliation(s)
- Alexei G Merzlikine
- Center for Photochemical Sciences, Bowling Green State University, Bowling Green, OH 43403, USA
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Kuimova MK, Sun XZ, Matousek P, Grills DC, Parker AW, Towrie M, George MW. Probing intraligand and charge transfer excited states of fac-[Re(R)(CO)3(CO2Et-dppz)]+ (R = py, 4-Me2N-py; CO2Et-dppz = dipyrido[3,2a:2′,3′c]phenazine-11-carboxylic ethyl ester) using time-resolved infrared spectroscopy. Photochem Photobiol Sci 2007; 6:1158-63. [DOI: 10.1039/b705002j] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Howell SL, Gordon KC. Vibrational Spectroscopy of Reduced Re(I) Complexes of 1,10-Phenanthroline and Substituted Analogues. J Phys Chem A 2006; 110:4880-7. [PMID: 16599458 DOI: 10.1021/jp056614d] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
IR spectroscopy in concert with DFT calculations and resonance Raman spectroelectrochemistry has been used to identify the molecular orbital nature of the singly occupied molecular orbital (SOMO) in reduced [Re(CO)(3)Cl(L)] and [Re(CO)(3)(4-Mepy)(L)](+) complexes, where L = 1,10-phenanthroline and its 4,7-diphenyl- and 3,4,7,8-tetramethyl-substituted analogues. The SOMO of each reduced species considered was found to be of b(1) symmetry, rather than the close lying orbital of a(2) symmetry (within a C(2)(v)() symmetry description of the phenanthroline moiety). This was deduced in a number of ways. First, the average carbonyl band force constants (Deltak(av) = k(av){reduced complex} - k(av){parent complex}) range from -57 to -41 N m(-1) for the series of compounds studied. The value of Deltak(av) relates to the extent of orbital overlap between the ligand MO and the metal dpi MO. These values are consistent with population of a b(1) MO because the wave function amplitude at the chelating nitrogens for this MO is significantly greater than that for a(2) MO. Second, calculations on singly reduced [Re(CO)(3)(4-Mepy)(phen)](+) and [Re(CO)(3)(4-Mepy)(tem)](+) predict population of a b(2) SOMO. The spectra predicted for these species are in close agreement with the vibrational spectroscopic data; for the IR data the shifts in the CO bands are predicted to 6 cm(-1) and the mean absolute deviation between calculated and measured Raman bands was found to be 10 cm(-1).
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Affiliation(s)
- Sarah L Howell
- Department of Chemistry, MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, Union Place, Dunedin, New Zealand
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Walsh PJ, Gordon KC, Lundin NJ, Blackman AG. Photoexcitation in Cu(I) and Re(I) Complexes Containing Substituted Dipyrido[3,2-a:2‘,3‘-c]phenazine: A Spectroscopic and Density Functional Theoretical Study. J Phys Chem A 2005; 109:5933-42. [PMID: 16833927 DOI: 10.1021/jp051009w] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Copper(I) and rhenium(I) complexes [Cu(PPh(3))(2)(dppz-11-COOEt)]BF(4), [Cu(PPh(3))(2)(dppz-11-Br)]BF(4), [Re(CO)(3)Cl(dppz-11-COOEt)] and [Re(CO)(3)Cl(dppz-11-Br)] (dppz-11-COOEt = dipyrido-[3,2a:2',3'c]phenazine-11-carboxylic ethyl ester, dppz-11-Br = 11-bromo-dipyrido[3,2a:2',3'c]-phenazine) have been studied using Raman, resonance Raman, and transient resonance Raman (TR(2)) spectroscopy, in conjunction with computational chemistry. DFT (B3LYP) frequency calculations with a 6-31G(d) basis set for the ligands and copper(I) centers and an effective core potential (LANL2DZ) for rhenium in the rhenium(I) complexes show close agreement with the experimental nonresonance Raman spectra. Modes that are phenazine-based, phenanthroline-based, and delocalized across the entire ligand structure were identified. The nature of the absorbing chromophores at 356 nm for ligands and complexes was established using resonance Raman spectroscopy in concert with vibrational assignments from calculations. This analysis reveals that the dominant chromophore for the complexes measured at 356 nm is ligand-centered (LC), except for [Re(CO)(3)Cl(dppz-11-Br)], which appears to have additional chromophores at this wavelength. Calculations on the reduced complexes, undertaken to model the metal-to-ligand charge transfer (MLCT) excited state, show that the reducing electron occupies a ligand MO that is delocalized across the ligand structure. Resonance Raman spectra (lambda(exc) = 514.5 nm) of the reduced rhenium complexes show a similar spectral pattern to that observed in [Re(CO)(3)Cl(dppz)](*-); the measured bands are therefore attributed to ligand radical anion modes. These bands lie at 1583-1593 cm(-1) for [Re(CO)(3)Cl(dppz-11-COOEt)] and 1611 cm(-1) for [Re(CO)(3)Cl(dppz-11-Br)]. The thermally equilibrated excited states are examined using nanosecond-TR(2) spectroscopy (lambda(exc) = 354.7 nm). The TR(2) spectra of the ligands provide spectral signatures for the (3)LC state. A band at 1382 cm(-1) is identified as a marker for the (3)LC states of both ligands. TR(2) spectra of the copper and rhenium complexes of dppz-11-Br show this (3)LC band, but it is not prominent in the spectra of [Cu(PPh(3))(2)(dppz-11-COOEt)](+) and [Re(CO)(3)Cl(dppz-11-COOEt)]. Calculations suggest that the lowest triplet states of both of the rhenium(I) complexes and [Cu(PPh(3))(2)(dppz-11-Br)](+) are metal-to-ligand charge transfer in nature, but the lowest triplet state of [Cu(PPh(3))(2)(dppz-11-COOEt)](+) appears to be LC in character.
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Affiliation(s)
- Penny J Walsh
- Department of Chemistry, University of Otago, Dunedin, New Zealand
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Demadis KD, Hartshorn CM, Meyer TJ. The localized-to-delocalized transition in mixed-valence chemistry. Chem Rev 2001; 101:2655-86. [PMID: 11749392 DOI: 10.1021/cr990413m] [Citation(s) in RCA: 852] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- K D Demadis
- Department of Chemistry, Venable and Kenan Laboratories, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3290, USA
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Smith GD, Maxwell KA, DeSimone JM, Meyer TJ, Palmer RA. Step-scan FTIR time-resolved spectroscopy study of excited-state dipole orientation in soluble metallopolymers. Inorg Chem 2000; 39:893-8. [PMID: 12526366 DOI: 10.1021/ic990819h] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Step-scan FTIR time-resolved spectroscopy (S2FTIR TRS) in acetonitrile-d3 has been used to probe the acceptor ligand in metal-to-ligand charge transfer (MLCT) excited states of amide-substituted polypyridyl complexes of RuII and in analogues appended to polystyrene. On the basis of ground-to-excited state shifts in v(C = O) of -31 cm-1 for the amide group in [RuII(bpy)2(bpyCONHEt')]2+ (bpyCONHEt' = 4'-methyl-2,2'-bipyridine-4-carboxamide-Et'; Et' = -CH2CH2BzCH2CH3) (1) and in the derivatized polystyrene abbreviated [PS-[CH2-CH2NHCObpy-RuII(bpy)2]20]40+ (3), the excited-state dipole is directed toward the amide-containing pyridyl group in the polymer side chain. Smaller shifts in v(C = O) of -17 cm-1 in [RuII(4,4'-(CONEt2)2bpy)2-(bpyCONHEt')]2+ (2) and in the derivatized polystyrene abbreviated [PS-[CH2CH2NHCObpy-RuII(4,4'-(CONEt2)2bpy)2]20]40+ (4) indicate that the excited-state dipole is directed toward one of the diamide bpy ligands. The nearly identical results for 1 and 3 and for 2 and 4 show that the molecular and electronic structures of the monomer excited states are largely retained in the polymer samples. These conclusions about dipole orientation in the polymers are potentially of importance in understanding intrastrand energy transfer dynamics. The excited-state dipole in 3 is oriented in the direction of the covalent link to the polymer backbone, and toward nearest neighbors. In 4, it is oriented away from the backbone.
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Affiliation(s)
- G D Smith
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
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Omberg KM, Smith GD, Kavaliunas DA, Chen P, Treadway JA, Schoonover JR, Palmer RA, Meyer TJ. Excited-State Electronic Structure in Polypyridyl Complexes Containing Unsymmetrical Ligands. Inorg Chem 1999; 38:951-956. [PMID: 11670867 DOI: 10.1021/ic981338l] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Step-scan Fourier transform infrared absorption difference time-resolved (S(2)FTIR DeltaA TRS) and time-resolved resonance Raman (TR(3)) spectroscopies have been applied to a series of questions related to excited-state structure in the metal-to-ligand charge transfer (MLCT) excited states of [Ru(bpy)(2)(4,4'-(CO(2)Et)(2)bpy)](2+), [Ru(bpy)(2)(4-CO(2)Et-4'-CH(3)bpy)](2+), [Ru(bpy)(4,4'-(CO(2)Et)(2)bpy)(2)](2+), [Ru(4,4'-(CO(2)Et)(2)bpy)(3)](2+), [Ru(bpy)(2)(4,4'-(CONEt(2))(2)bpy)](2+), [Ru(bpy)(2)(4-CONEt(2)-4'-CH(3)bpy)](2+), and [Ru(4-CONEt(2)-4'-CH(3)bpy)(3)](2+) (bpy is 2,2'-bipyridine). These complexes contain bpy ligands which are either symmetrically or unsymmetrically derivatized with electron-withdrawing ester or amide substituents. Analysis of the vibrational data, largely based on the magnitudes of the nu(CO) shifts of the amide and ester substituents (Deltanu(CO)), reveals that the ester- or amide-derivatized ligands are the ultimate acceptors and that the excited electron is localized on one acceptor ligand on the nanosecond time scale. In the unsymmetrically substituted acceptor ligands, the excited electron is largely polarized toward the ester- or amide-derivatized pyridine rings. In the MLCT excited states of [Ru(bpy)(2)(4,4'-(CO(2)Et)(2)bpy)](2+) and [Ru(bpy)(2)(4,4'-(CONEt(2))(2)bpy)](2+), Deltanu(CO) is only 60-70% of that observed upon complete ligand reduction due to a strong polarization interaction in the excited state between the dpi(5) Ru(III) core and the excited electron.
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Affiliation(s)
- Kristin M. Omberg
- Department of Chemistry, CB#3290, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, and Department of Chemistry, Duke University, P.O. Box 90346, Durham, North Carolina 27708-0346
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