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Eastham K, Scattergood PA, Chu D, Boota RZ, Soupart A, Alary F, Dixon IM, Rice CR, Hardman SJO, Elliott PIP. Not All 3MC States Are the Same: The Role of 3MC cis States in the Photochemical N ∧N Ligand Release from [Ru(bpy) 2(N ∧N)] 2+ Complexes. Inorg Chem 2022; 61:19907-19924. [PMID: 36450138 DOI: 10.1021/acs.inorgchem.2c03146] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Ruthenium(II) complexes feature prominently in the development of agents for photoactivated chemotherapy; however, the excited-state mechanisms by which photochemical ligand release operates remain unclear. We report here a systematic experimental and computational study of a series of complexes [Ru(bpy)2(N∧N)]2+ (bpy = 2,2'-bipyridyl; N∧N = bpy (1), 6-methyl-2,2'-bipyridyl (2), 6,6'-dimethyl-2,2'-bipyridyl (3), 1-benzyl-4-(pyrid-2-yl)-1,2,3-triazole (4), 1-benzyl-4-(6-methylpyrid-2-yl)-1,2,3-triazole (5), 1,1'-dibenzyl-4,4'-bi-1,2,3-triazolyl (6)), in which we probe the contribution to the promotion of photochemical N∧N ligand release of the introduction of sterically encumbering methyl substituents and the electronic effect of replacement of pyridine by 1,2,3-triazole donors in the N∧N ligand. Complexes 2 to 6 all release the ligand N∧N on irradiation in acetonitrile solution to yield cis-[Ru(bpy)2(NCMe)2]2+, with resultant photorelease quantum yields that at first seem counter-intuitive and span a broad range. The data show that incorporation of a single sterically encumbering methyl substituent on the N∧N ligand (2 and 5) leads to a significantly enhanced rate of triplet metal-to-ligand charge-transfer (3MLCT) state deactivation but with little promotion of photoreactivity, whereas replacement of pyridine by triazole donors (4 and 6) leads to a similar rate of 3MLCT deactivation but with much greater photochemical reactivity. The data reported here, discussed in conjunction with previously reported data on related complexes, suggest that monomethylation in 2 and 5 sterically inhibits the formation of a 3MCcis state but promotes the population of 3MCtrans states which rapidly deactivate 3MLCT states and are prone to mediating ground-state recovery. On the other hand, increased photochemical reactivity in 4 and 6 seems to stem from the accessibility of 3MCcis states. The data provide important insights into the excited-state mechanism of photochemical ligand release by Ru(II) tris-bidentate complexes.
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Affiliation(s)
- Katie Eastham
- Department of Chemistry, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K
| | - Paul A Scattergood
- Department of Chemistry, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K.,Centre for Functional Materials, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K
| | - Danny Chu
- Department of Chemistry, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K
| | - Rayhaan Z Boota
- Department of Chemistry, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K.,Centre for Functional Materials, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K
| | - Adrien Soupart
- Laboratoire de Chimie et Physique Quantiques, UMR 5626 CNRS/Université Toulouse 3─Paul Sabatier, Université de Toulouse, 118 route de Narbonne, Toulouse 31062, France
| | - Fabienne Alary
- Laboratoire de Chimie et Physique Quantiques, UMR 5626 CNRS/Université Toulouse 3─Paul Sabatier, Université de Toulouse, 118 route de Narbonne, Toulouse 31062, France
| | - Isabelle M Dixon
- Laboratoire de Chimie et Physique Quantiques, UMR 5626 CNRS/Université Toulouse 3─Paul Sabatier, Université de Toulouse, 118 route de Narbonne, Toulouse 31062, France
| | - Craig R Rice
- Department of Chemistry, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K
| | - Samantha J O Hardman
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
| | - Paul I P Elliott
- Department of Chemistry, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K.,Centre for Functional Materials, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, U.K
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Findlay JA, Barnsley JE, Gordon KC, Crowley JD. Synthesis and Light-Induced Actuation of Photo-Labile 2-Pyridyl-1,2,3-Triazole Ru(bis-bipyridyl) Appended Ferrocene Rotors. Molecules 2018; 23:E2037. [PMID: 30110981 PMCID: PMC6222349 DOI: 10.3390/molecules23082037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Revised: 08/09/2018] [Accepted: 08/09/2018] [Indexed: 11/16/2022] Open
Abstract
To realise useful control over molecular motion in the future an extensive toolbox of both actionable molecules and stimuli-responsive units must be developed. Previously, our laboratory has reported 1,1'-disubstituted ferrocene (Fc) rotor units which assume a contracted/π-stacked conformation until complexation of cationic metal ions causes rotation about the Ferrocene (Fc) molecular 'ball-bearing'. Herein, we explore the potential of using the photochemical ejection of [Ru(2,2'-bipyridyl)₂]2+ units as a stimulus for the rotational contraction of new ferrocene rotor units. Fc rotors with both 'regular' and 'inverse' 2-pyridyl-1,2,3-triazole binding pockets and their corresponding [Ru(2,2'-bipyridyl)₂]2+ complexes were synthesised. The rotors and complexes were characterised using nuclear magnetic resonance (NMR) and ultraviolet (UV)-visible spectroscopies, Electro-Spray Ionisation Mass Spectrometry (ESI⁻MS), and electrochemistry. The 1,1'-disubstituted Fc ligands were shown to π-stack both in solution and solid state. Density Functional Theory (DFT) calculations (CAM-B3LYP/6-31G(d)) support the notion that complexation to [Ru(2,2'-bipyridyl)₂]2+ caused a rotation from the syn- to the anti-conformation. Upon photo-irradiation with UV light (254 nm), photo-ejection of the [Ru(2,2'-bipyridyl)₂(CH₃CN)₂]2+ units in acetonitrile was observed. The re-complexation of the [Ru(2,2'-bipyridyl)₂]2+ units could be achieved using acetone as the reaction solvent. However, the process was exceedingly slowly. Additionally, the Fc ligands slowly decomposed when exposed to UV irradiation meaning that only one extension and contraction cycle could be completed.
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Affiliation(s)
- James A Findlay
- Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, Otago, New Zealand.
| | - Jonathan E Barnsley
- Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, Otago, New Zealand.
| | - Keith C Gordon
- Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, Otago, New Zealand.
| | - James D Crowley
- Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, Otago, New Zealand.
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Rabbani R, Masson E. Probing Interactions between Hydrocarbons and Auxiliary Guests inside Cucurbit[8]uril. Org Lett 2017; 19:4303-4306. [DOI: 10.1021/acs.orglett.7b01966] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Ramin Rabbani
- Department of Chemistry and
Biochemistry, Ohio University, Athens, Ohio 45701, United States
| | - Eric Masson
- Department of Chemistry and
Biochemistry, Ohio University, Athens, Ohio 45701, United States
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Welby CE, Armitage GK, Bartley H, Wilkinson A, Sinopoli A, Uppal BS, Rice CR, Elliott PIP. Photochemistry of RuII 4,4'-bi-1,2,3-triazolyl (btz) complexes: crystallographic characterization of the photoreactive ligand-loss intermediate trans-[Ru(bpy)(κ2-btz)(κ1-btz)(NCMe)]2+. Chemistry 2014; 20:8467-76. [PMID: 24889966 PMCID: PMC4506527 DOI: 10.1002/chem.201402354] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Indexed: 12/03/2022]
Abstract
We report the unprecedented observation and unequivocal crystallographic characterization of the meta-stable ligand loss intermediate solvento complex trans-[Ru(bpy)(κ2-btz)(κ1-btz)(NCMe)]2+ (1 a) that contains a monodentate chelate ligand. This and analogous complexes can be observed during the photolysis reactions of a family of complexes of the form [Ru()(btz)2]2+ (1 a–d: btz=1,1′-dibenzyl-4,4′-bi-1,2,3-triazolyl; =a) 2,2′-bipyridyl (bpy), b) 4,4′-dimethyl-2,2′-bipyridyl (dmbpy), c) 4,4′-dimethoxy-2,2′-bipyridyl (dmeobpy), d) 1,10-phenanthroline (phen)). In acetonitrile solutions, 1 a–d eventually convert to the bis-solvento complexes trans-[Ru()(btz)(NCMe)2]2+ (3 a–d) along with one equivalent of free btz, in a process in which the remaining coordinated bidentate ligands undergo a new rearrangement such that they become coplanar. X-ray crystal structure of 3 a and 3 d confirmed the co-planar arrangement of the and btz ligands and the trans coordination of two solvent molecules. These conversions proceed via the observed intermediate complexes 2 a–d, which are formed quantitatively from 1 a–d in a matter of minutes and to which they slowly revert back on being left to stand in the dark over several days. The remarkably long lifetime of the intermediate complexes (>12 h at 40 °C) allowed the isolation of 2 a in the solid state, and the complex to be crystallographically characterized. Similarly to the structures adopted by complexes 3 a and d, the bpy and κ2-btz ligands in 2 a coordinate in a square-planar fashion with the second monodentate btz ligand coordinated trans to an acetonitrile ligand.
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Affiliation(s)
- Christine E Welby
- Department of Chemistry, University of Huddersfield, Queensgate, Huddersfield, HD1 3DH (UK)
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Welby CE, Armitage GK, Bartley H, Sinopoli A, Uppal BS, Elliott PIP. Photochemical ligand ejection from non-sterically promoted Ru(ii)bis(diimine) 4,4′-bi-1,2,3-triazolyl complexes. Photochem Photobiol Sci 2014; 13:735-8. [DOI: 10.1039/c3pp50437a] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Complexes of the form [Ru(diimine)2(btz)]2+ (btz = 1,1′-dibenzyl-4,4′-bi-1,2,3-triazolyl) are observed to undergo photochemical ejection of the btz ligand in the absence of any promotion through steric congestion.
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Affiliation(s)
| | | | - Harry Bartley
- Department of Chemistry
- University of Huddersfield
- Huddersfield, UK
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Welby CE, Rice CR, Elliott PIP. Unambiguous Characterization of a Photoreactive Ligand-Loss Intermediate. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201304219] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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7
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Welby CE, Rice CR, Elliott PIP. Unambiguous Characterization of a Photoreactive Ligand-Loss Intermediate. Angew Chem Int Ed Engl 2013; 52:10826-9. [DOI: 10.1002/anie.201304219] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Indexed: 11/07/2022]
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Onishi M, Tashiro Y, Arikawa Y, Nagaoka J, Umakoshi K, Sunada Y, Nozaki K. Chiral Bis(oxazoline) Ruthenium Complexes with Bipyridyl-Type N-Heteroaromatics: Comparative Stereochemical and Photochemical Characterization of their Λ- and Δ-Diastereomeric Geminate Isomers. Chem Asian J 2011; 6:1405-15. [DOI: 10.1002/asia.201000738] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2010] [Indexed: 11/11/2022]
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9
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Sakuda E, Ando Y, Ito A, Kitamura N. Long-Lived and Temperature-Independent Emission from a Novel Ruthenium(II) Complex Having an Arylborane Charge-Transfer Unit. Inorg Chem 2011; 50:1603-13. [DOI: 10.1021/ic1020669] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Eri Sakuda
- Department of Chemistry, Faculty of Science,
| | - Yuki Ando
- Department of Chemistry, Faculty of Science,
| | - Akitaka Ito
- Department of Chemistry, Faculty of Science,
| | - Noboru Kitamura
- Department of Chemistry, Faculty of Science,
- Department of Chemical Sciences and Engineering, Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan
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Abrahamsson M, Becker HC, Hammarström L, Bonnefous C, Chamchoumis C, Thummel RP. Six-Membered Ring Chelate Complexes of Ru(II): Structural and Photophysical Effects. Inorg Chem 2007; 46:10354-64. [DOI: 10.1021/ic7011827] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Maria Abrahamsson
- Chemical Physics, Department of Photochemistry and Molecular Science, The Ångström Laboratories, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden, Department of Chemistry, University of Houston, Houston, Texas 77204-5003
| | - Hans-Christian Becker
- Chemical Physics, Department of Photochemistry and Molecular Science, The Ångström Laboratories, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden, Department of Chemistry, University of Houston, Houston, Texas 77204-5003
| | - Leif Hammarström
- Chemical Physics, Department of Photochemistry and Molecular Science, The Ångström Laboratories, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden, Department of Chemistry, University of Houston, Houston, Texas 77204-5003
| | - Celine Bonnefous
- Chemical Physics, Department of Photochemistry and Molecular Science, The Ångström Laboratories, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden, Department of Chemistry, University of Houston, Houston, Texas 77204-5003
| | - Charles Chamchoumis
- Chemical Physics, Department of Photochemistry and Molecular Science, The Ångström Laboratories, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden, Department of Chemistry, University of Houston, Houston, Texas 77204-5003
| | - Randolph P. Thummel
- Chemical Physics, Department of Photochemistry and Molecular Science, The Ångström Laboratories, Uppsala University, Box 523, SE-751 20 Uppsala, Sweden, Department of Chemistry, University of Houston, Houston, Texas 77204-5003
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11
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Atom transfer radical polymerization of N-(ω′-alkylcarbazolyl)methacrylates via the use of novel heteroleptic Ru(II) polypyridyl initiator. Inorganica Chim Acta 2004. [DOI: 10.1016/j.ica.2004.03.059] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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12
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Potvin PG, Luyen PU, Bräckow J. Electrostatic bubbles and supramolecular assistance of photosensitization by carboxylated Ru(II) complexes. J Am Chem Soc 2003; 125:4894-906. [PMID: 12696909 DOI: 10.1021/ja028671f] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The paper examines the supramolecular effects at play during photosensitization by carboxylated Ru(II) sensitizers, both by experiment and by modeling. Experimentally, twelve Ru(II) complexes of pyrazolylpyridine and polypyridine ligands, including two benchmark complexes and two new species, were assessed as photosensitizers by measurement of the kinetics of methyl viologen cation radical (MV(*)(+)) generation through an oxidative, photoinduced electron transfer (PET) to methyl viologen (MV(2+)) under continuous irradiation in the presence of a sacrificial reductant. All complexes, luminescent or not, produced measurable amounts of MV(*)(+) in CH(3)CN. The assessment protocol was found to be useful with sensitizers of widely varying excited-state lifetimes (tau) as well as being easier and faster than conventional approaches. The seven sensitizers bearing peripheral COOH groups were found to be significantly more active than their non-carboxylated analogues, which is consistent with ionization of the COOH groups and electrostatic promotion of PET. Only the luminescent complexes were active in aqueous solvents, where tau appears to be the dominant effector. The benefits are exemplified by the singly carboxylated [Ru(H1)(bpy)(2)](2+) (H1 is 1-(4-carboxyphenyl)-3-(2-pyridyl)-4,5,6,7-tetrahydroindazole), a weakly luminescent sensitizer that was less active in aqueous solvents than [Ru(bpy)(3)](2+) (bpy is 2,2'-bipyridine), but which became the better sensitizer in CH(3)CN. Computationally, electrostatic field and dissociation energy calculations demonstrated that even a single peripheral COO(-) substituent suffices to provide supramolecular assistance: it defines a spheric "bubble" of electrostatically attractive space that is sufficiently large to allow the supramolecular preassociation of MV(2+), which provides an entropic advantage to PET that reduces the importance of tau in organic solvent. Calculations also show that the PET is electrostatically favored over its reverse (BET) even with cationic sensitizers because the "bubble" contracts after PET while the bulk medium becomes more repulsive, and favorable cation exchanges can occur to effect post-PET dissociation. Two peripheral COO(-) groups can define a two-point binding site for MV(2+) in an attractive sector of space that contracts to a kidney-shaped "bubble" after PET. This enables unimolecular PET while the reverse reaction remains bimolecular. The resultant benefits are illustrated with [Ru(Na1)(2)(bpy)](2+), a very weakly luminescent sensitizer that was totally inactive in H(2)O but appreciably active in CH(3)CN, despite the need to displace Na(+) in order to derive any electrostatic benefit. The Marcus free energies of activation for PET and BET corroborate the benefits of carboxylation, solvent, and other factors and correlated with the experimental rate constants.
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Affiliation(s)
- Pierre G Potvin
- Department of Chemistry, York University, 4700 Keele Street, Toronto, ON, Canada M3J 1P3
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Functionalised 2,2′-bipyridine ligands for the preparation of metallostars; X-ray structures of free ligands and preparation of copper(I) and silver(I) complexes. Polyhedron 2003. [DOI: 10.1016/s0277-5387(02)01310-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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14
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Photophysical behavior of molecular dyads and triad comprising tris(bipyrazine)rutheniumII, bis(bipyridine)chlororutheniumII and pentacyanoferrateII complexes. J Photochem Photobiol A Chem 2002. [DOI: 10.1016/s1010-6030(02)00150-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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15
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Farah AA, Pietro WJ. Cis-dichloro-bis-2-(2-pyridyl)-4-(methylcarboxy)quinoline ruthenium (II): a novel ruthenium (II) tris-chelated building precursor. INORG CHEM COMMUN 2001. [DOI: 10.1016/s1387-7003(01)00169-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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16
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Brandt P, Norrby T, Åkermark B, Norrby PO. Molecular Mechanics (MM3) Parameters for Ruthenium(II)-Polypyridyl Complexes. Inorg Chem 1998; 37:4120-4127. [PMID: 11670532 DOI: 10.1021/ic980021i] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have developed molecular mechanics parameters for Ru(II)-polypyridyl coordination compounds with the MM3 force field in MacroModel. X-ray structures, together with a B3LYP frequency calculation on a model system, have been utilized in the parametrization. The performance of the force field and the quality of each parameter is analyzed. A clear qualitative correlation have been found between coordination geometry and emission properties for the ruthenium polypyridyl complexes examined in this paper.
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Affiliation(s)
- Peter Brandt
- Department of Medicinal Chemistry, Royal Danish School of Pharmacy, Universitetsparken 2, DK 2100 Copenhagen, Denmark
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Norrby T, Börje A, Åkermark B, Hammarström L, Alsins J, Lashgari K, Norrestam R, Mårtensson J, Stenhagen G. Synthesis, Structure, and Photophysical Properties of Novel Ruthenium(II) Carboxypyridine Type Complexes. Inorg Chem 1997; 36:5850-5858. [PMID: 11670208 DOI: 10.1021/ic9705812] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A series of Ru(II) compounds and salts have been synthesized: [Ru(6-carboxylato-bpy)(2)] (5), [Ru(6-carboxylato-bpy)(tpy)]PF(6) (9), [Ru(tpy)(2)](PF(6))(2) (8), and [Ru(bpy)(2)(Pic)]PF(6) (11), where 6-carboxy-bpy (1) = 6-carboxy-2,2'-bipyridine, tpy (2) = 2,2':6',2"-terpyridine, and Pic = 2-carboxylatopyridine. The compounds have been characterized by NMR, electrospray mass spectrometry (ESI-MS), cyclic voltammetry, absorption and emission spectroscopy (at 100, 140, and 298 K), and single-crystal X-ray diffraction (complex 5). Complex 5 crystallizes in the monoclinic system, space group P2(1)/n, formula RuC(22)H(14)N(4)O(4).C(2)H(5)OH, with a = 11.088(3) Å, b = 11.226(3) Å, c = 35.283(9) Å, beta = 91.41(2) degrees, and Z = 8. A linear dependence on the number of coordinated carboxylato groups and the electrochemical redox potentials was found, ca. 0.4 V lower reduction potential for the oxidation step (Ru(II/III)) per carboxylate group. Also, to the best of our knowledge, these are the first examples (9, 11) of mononuclear Ru(II) complexes containing a carboxypyridine-ruthenium moiety displaying any luminescence emission.
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Affiliation(s)
- Thomas Norrby
- Department of Organic Chemistry, Chalmers University of Technology, S-412 96 Göteborg, Sweden
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