The Experts below are selected from a list of 6675 Experts worldwide ranked by ideXlab platform
Shunichi Fukuzumi - One of the best experts on this subject based on the ideXlab platform.
-
a two point bound zinc porphyrin zinc phthalocyanine fullerene supramolecular triad for sequential Energy and electron Transfer
Chemical Communications, 2013Co-Authors: Kei Ohkubo, Shunichi Fukuzumi, Paul A Karr, Francis DsouzaAbstract:A novel supramolecular triad composed of a zinc porphyrin–zinc phthalocyanine dyad and fullerenes has been assembled using a ‘two-point’ axial binding approach, and occurrence of efficient Photoinduced Energy Transfer followed by electron Transfer is demonstrated.
-
A ‘two-point’ bound zinc porphyrin–zinc phthalocyanine–fullerene supramolecular triad for sequential Energy and electron Transfer
Chemical communications (Cambridge England), 2013Co-Authors: Kei Ohkubo, Shunichi Fukuzumi, Paul A Karr, Francis D'souzaAbstract:A novel supramolecular triad composed of a zinc porphyrin–zinc phthalocyanine dyad and fullerenes has been assembled using a ‘two-point’ axial binding approach, and occurrence of efficient Photoinduced Energy Transfer followed by electron Transfer is demonstrated.
-
Charge separation in a novel artificial photosynthetic reaction center lives 380 ms.
Journal of the American Chemical Society, 2001Co-Authors: Hiroshi Imahori, Dirk M. Guldi, Yoshiteru Sakata, Koichi Tamaki, Yutaka Yoshida, Chuping Luo, Shunichi FukuzumiAbstract:An extremely long-lived charge-separated state has been achieved successfully using a ferrocene−zincporphyrin−freebaseporphyrin−fullerene tetrad which reveals a cascade of Photoinduced Energy Transfer and multistep electron Transfer within a molecule in frozen media as well as in solutions. The lifetime of the resulting charge-separated state (i.e., ferricenium ion−C60 radical anion pair) in a frozen benzonitrile is determined as 0.38 s, which is more than one order of magnitude longer than any other intramolecular charge recombination processes of synthetic systems, and is comparable to that observed for the bacterial photosynthetic reaction center. Such an extremely long lifetime of the tetrad system has been well correlated with the charge-separated lifetimes of two homologous series of porphyrin−fullerene dyad and triad systems.
-
Photoinduced Energy Transfer in mixed self-assembled monolayers of pyrene and porphyrin
Chemical Communications, 2000Co-Authors: Hiroshi Imahori, Yoshinobu Nishimura, Hiroyuki Norieda, Hironori Karita, Iwao Yamazaki, Yoshiteru Sakata, Shunichi FukuzumiAbstract:Mixed self-assembled monolayers of pyrene and porphyrin have been prepared to mimic efficient Energy Transfer in the photosynthetic antenna complex.
Michael D. Ward - One of the best experts on this subject based on the ideXlab platform.
-
Synthesis and photophysical properties of Ir(III)/Re(I) dyads: control of Ir→Re Photoinduced Energy Transfer
Dalton transactions (Cambridge England : 2003), 2016Co-Authors: Suad T. Saad, Alexander J. Metherell, Elizabeth Baggaley, Michael D. WardAbstract:A series of dinuclear Ir(III)/Re(I) complexes has been prepared based on a family of symmetrical bridging ligands containing two bidentate N,N′-chelating pyrazolyl–pyridine termini, connected by a central aromatic or aliphatic spacer. The Ir(III) termini are based on {Ir(F2ppy)2}+ units (where F2ppy is the cyclometallating anion of a fluorinated phenylpyridine) and the Re(I) termini are based on {Re(CO)3Cl} units. Both types of terminus are luminescent, with the Ir-based unit showing characteristic strong, structured phosphorescence in the blue region (maximum 452 nm) with a triplet excited state Energy of 22 200 cm−1 and the Re-based unit showing much weaker and lower-Energy phosphorescence (maximum 530 nm) with a triplet excited state Energy of 21 300 cm−1. The Energy gradient between the two excited states allows for partial Ir→Re Photoinduced Energy-Transfer, with substantial (but incomplete) quenching of the higher-Energy Ir-based emission component and sensitised emission – evidenced by an obvious grow-in component – on the lower-Energy Re-based emission. The Ir→Re Energy-Transfer rate constants vary over the range 1–8 × 107 s−1 depending on the bridging ligand: there is no simple correlation between bridging ligand structure and Energy-Transfer rate, possibly because this will depend substantially on the conformation of these flexible molecules in solution. To test the role of ligand conformation further, we investigated a complex in which the bridging chain is a (CH2CH2O)6 unit whose conformation is known to be solvent-polarity dependent, with such chains adopting an open, elongated conformation in water and more compact, folded conformations in organic solvents. There was a clear link between the rate and extent of Ir→Re Energy-Transfer which reduced in polar solvents as the chain became elongated and the Ir/Re separation was larger; and increased in less polar solvents as the chain adopted a more compact conformation and the Ir/Re separation was reduced.
-
A new ligand skeleton for imaging applications with d–f complexes: combined lifetime imaging and high relaxivity in an Ir/Gd dyad
Chemical communications (Cambridge England), 2015Co-Authors: Atanu Jana, Elizabeth Baggaley, Angelo James Amoroso, Michael D. WardAbstract:A new rigid and conjugated ligand structure connecting phenanthroline and poly(amino-carboxylate) binding sites provides d–f complexes which show high potential for use in dual (luminescence + magnetic resonance) imaging and for optimisation of d → f Photoinduced Energy-Transfer.
-
Luminescence and time-resolved infrared study of dyads containing (Diimine)Ru(4,4 '-diethylamido-2,2 '-bipyridine)(2) and (Diimine)Ru(CN)(4) moieties: solvent-induced reversal of the direction of Photoinduced Energy-Transfer
Inorganic chemistry, 2009Co-Authors: Timothy L. Easun, Michael D. Ward, Wassim Z. Alsindi, Michael Towrie, Kate L. Ronayne, Xue-zhong Sun, Nina Deppermann, Michael W. GeorgeAbstract:The exploitation of the dramatic negative solvatochromism of the [Ru(bipy)(CN)(4)] moiety (bipy = 2,2'-bipyridine) allows a change in solvent to reverse the direction of Photoinduced Energy Transfer (PEnT) in two related dinuclear complexes. Both dyads consist of a [Ru(bpyam)(2)L(n)](2+) (Ru-bpyam) unit (bpyam = 4,4'-diethylamido-2,2'-bipyridine; L(n) = bis-bipyridyl-based bridging ligand) and a [Ru(L(n))(CN)(4)](2-) (Ru-CN) unit. Both termini have IR-active spectroscopic handles (amide carbonyl or cyanide, respectively) allowing the excited-state dynamics to be studied by time-resolved IR (TRIR) spectroscopy. One dyad (1) contains a relatively rigid exoditopic macrocyclic bis-bipyridyl bridging ligand (L(1)) and the other (2) contains a more flexible bis-bipyridyl bridging ligand with only one covalent linkage between the two bipyridyl binding sites (L(2)). The conformational effects on PEnT rates in these dyads are probed using a combination of luminescence and TRIR studies. In both 1 and 2 in D(2)O it is demonstrated that Ru-CN --> Ru-bpyam PEnT occurs (PEnT time scales were in the range 10 ps-3 ns) because the (3)MLCT Energy of the Ru-CN terminus is higher than that of the Ru-bpyam terminus. Changing the solvent from D(2)O to CH(3)CN results in lowering the (3)MLCT Energy of the Ru-CN unit below that of the Ru-bpyam unit such that in both dyads a reversal in the direction of PEnT to Ru-bpyam --> Ru-CN (time scales of 10 ps-2 ns) occurs. Complex kinetic behavior results from the presence of a dark (3)MLCT excited state formulated as {(bpyam)(2)Ru(3+)(L(n*-))} and by the presence of multiple conformers in solution which have different Ru...Ru separations giving rise to different Energy Transfer rates.
-
Photoinduced Energy Transfer in a conformationally flexible re i ru ii dyad probed by time resolved infrared spectroscopy effects of conformation and spatial localization of excited states
Inorganic Chemistry, 2008Co-Authors: Timothy L. Easun, Michael D. Ward, Wassim Z. Alsindi, Michael Towrie, Kate L. Ronayne, Xue-zhong Sun, Michael W. GeorgeAbstract:The dyad RuLRe contains {Re(bpy)(CO)3Cl} and {Ru(bpy)(bpyam)2}2+ termini (bpy = 2,2′-bipyridine; bpyam = 4,4′-diethylamido-2,2′-bipyridine) separated by a flexible ethylene spacer. Luminescence studies reveal the expected Re → Ru Photoinduced Energy Transfer, with partial quenching of ReI-based triplet metal-to-ligand charge-Transfer (3MLCT) luminescence and consequent sensitization of the RuII-based 3MLCT luminescence, which has a component with a grow-in lifetime of 0.76 (±0.2) ns. The presence of IR-active spectroscopic handles on both termini [CO ligands directly attached to ReI and amide carbonyl substituents on the bpy ligands coordinated to RuII] allowed the excited-state dynamics to be studied by time-resolved IR (TRIR) spectroscopy in much more detail than allowed by luminescence methods. A combination of picosecond- and nanosecond-time-scale TRIR studies revealed the presence of at least three distinct Re → Ru Energy-Transfer processes, with lifetimes of ca. 20 ps and 1 and 13 ns. This complex b...
-
Photoinduced Energy Transfer in a conformationally flexible Re(I)/Ru(II) dyad probed by time-resolved infrared spectroscopy: effects of conformation and spatial localization of excited states.
Inorganic chemistry, 2008Co-Authors: Timothy L. Easun, Michael D. Ward, Wassim Z. Alsindi, Michael Towrie, Kate L. Ronayne, Xue-zhong Sun, Michael W. GeorgeAbstract:The dyad RuLRe contains {Re(bpy)(CO)3Cl} and {Ru(bpy)(bpyam)2}2+ termini (bpy = 2,2′-bipyridine; bpyam = 4,4′-diethylamido-2,2′-bipyridine) separated by a flexible ethylene spacer. Luminescence studies reveal the expected Re → Ru Photoinduced Energy Transfer, with partial quenching of ReI-based triplet metal-to-ligand charge-Transfer (3MLCT) luminescence and consequent sensitization of the RuII-based 3MLCT luminescence, which has a component with a grow-in lifetime of 0.76 (±0.2) ns. The presence of IR-active spectroscopic handles on both termini [CO ligands directly attached to ReI and amide carbonyl substituents on the bpy ligands coordinated to RuII] allowed the excited-state dynamics to be studied by time-resolved IR (TRIR) spectroscopy in much more detail than allowed by luminescence methods. A combination of picosecond- and nanosecond-time-scale TRIR studies revealed the presence of at least three distinct Re → Ru Energy-Transfer processes, with lifetimes of ca. 20 ps and 1 and 13 ns. This complex b...
Raymond Ziessel - One of the best experts on this subject based on the ideXlab platform.
-
Photoinduced Energy Transfer processes in hybrid organic-inorganic multichromophoric arrays arranged on a truxene-based platform.
Dalton transactions (Cambridge England : 2003), 2012Co-Authors: Stephane Diring, Andrea Barbieri, Barbara Ventura, Raymond ZiesselAbstract:The synthesis, photophysical characterization and Energy-Transfer features of a series of hybrid truxene derivatives peripherally decorated with inorganic Os-containing polypyridine units and organic Bodipy dyes are reported. The photoactive terminal units are coupled to the central truxene scaffold by rigid ethynyl linkers in a star-shaped arrangement. The absorption range widely covers the UV-Vis spectrum and the Os 3MLCT or the Bodipy triplet act as final collectors of the absorbed Energy.
-
Photoinduced Energy Transfer dynamics in multichromophoric arrays containing transition metal complexes and organic modules
Coordination Chemistry Reviews, 2012Co-Authors: Andrea Barbieri, Barbara Ventura, Raymond ZiesselAbstract:Abstract Transfer of excitation Energy in natural systems is a fundamental process for light harvesting and propagation of information. The deep understanding of the Energy Transfer mechanisms and of the strategies for governing the directionality of the Energy flow in artificial multichromophoric arrays is at the basis of their use in demanding fields such as solar Energy conversion and optoelectronic applications. This review describes the recent activity of the authors in the synthesis and photophysical characterization of supramolecular arrays containing transition metal polypyridine complexes and organic units, with attention on the mechanisms and the pathways of the Energy Transfer processes that occur in the arrays. A topic of interest has been the exploitation of antenna effects as well as Energy conduction in molecular wires. The design of the systems took into consideration several aspects that need to be balanced in the construction of efficient and useful arrays, in particular the spatial displacement of the units, their Energy content distribution and the nature of the linkers that connect them. The latter point was of great relevance and the most recent studies afforded the preparation and the analysis of systems where the ligand is a large aromatic unit, that can both provide a structural role, a suitable electronic communication between the chromophores and an additional photoactive partnership.
-
Photoinduced Energy-Transfer dynamics in multichromophoric arrays containing transition metal complexes and organic modules ☆
Coordination Chemistry Reviews, 2012Co-Authors: Andrea Barbieri, Barbara Ventura, Raymond ZiesselAbstract:Abstract Transfer of excitation Energy in natural systems is a fundamental process for light harvesting and propagation of information. The deep understanding of the Energy Transfer mechanisms and of the strategies for governing the directionality of the Energy flow in artificial multichromophoric arrays is at the basis of their use in demanding fields such as solar Energy conversion and optoelectronic applications. This review describes the recent activity of the authors in the synthesis and photophysical characterization of supramolecular arrays containing transition metal polypyridine complexes and organic units, with attention on the mechanisms and the pathways of the Energy Transfer processes that occur in the arrays. A topic of interest has been the exploitation of antenna effects as well as Energy conduction in molecular wires. The design of the systems took into consideration several aspects that need to be balanced in the construction of efficient and useful arrays, in particular the spatial displacement of the units, their Energy content distribution and the nature of the linkers that connect them. The latter point was of great relevance and the most recent studies afforded the preparation and the analysis of systems where the ligand is a large aromatic unit, that can both provide a structural role, a suitable electronic communication between the chromophores and an additional photoactive partnership.
-
a pre organised truxene platform for phosphorescent ru bpy 2 and os bpy 2 metal centres a clear cut switch from forster to dexter type Energy Transfer mechanism
Chemistry: A European Journal, 2010Co-Authors: Stephane Diring, Francesco Barigelletti, Andrea Barbieri, Raymond Ziessel, Barbara VenturaAbstract:: We report on the synthesis, optical properties and Energy-Transfer features of a series of transition-metal-containing complexes and dyads, based on a pre-organised truxene scaffold. In this series, the [Ru(bpy)(3)](2+) and [Os(bpy)(3)](2+) photoactive terminals are coupled to the bridging aromatic truxene core through rigid ethynyl linkers. The Photoinduced Energy-Transfer processes taking place from the Ru- to the Os-based levels, and from the truxene bridging ligand to the terminal-metal chromophores are studied and the pathways and mechanisms are discussed. The Photoinduced Energy-Transfer process observed in the dyad proceeds rapidly through: i) an efficient (1)L-->(1)Os direct Energy Transfer followed by intersystem crossing to (3)Os, and ii) a fast (1)L-->(1)Ru Energy-Transfer step and subsequent intersystem crossing to (3)Ru followed by a (3)Ru-->(3)Os Energy-Transfer process. The first (1)L-->(1)Os and (1)L-->(1)Ru steps are controlled by a dipole-dipole interaction (Forster mechanism), whereas the subsequent (3)Ru-->(3)Os step proceeds by means of a long-range (approximately 24 A) through-bond mediated Dexter mechanism, facilitated by the conjugation along the bpy-truxene-bpy molecular axis.
-
A Pre‐organised Truxene Platform for Phosphorescent [Ru(bpy)2] and [Os(bpy)2] Metal Centres: A Clear‐Cut Switch from Förster‐ to Dexter‐Type Energy‐Transfer Mechanism
Chemistry (Weinheim an der Bergstrasse Germany), 2010Co-Authors: Stephane Diring, Francesco Barigelletti, Andrea Barbieri, Raymond Ziessel, Barbara VenturaAbstract:We report on the synthesis, optical properties and Energy-Transfer features of a series of transition-metal-containing complexes and dyads, based on a pre-organised truxene scaffold. In this series, the [Ru(bpy)(3)](2+) and [Os(bpy)(3)](2+) photoactive terminals are coupled to the bridging aromatic truxene core through rigid ethynyl linkers. The Photoinduced Energy-Transfer processes taking place from the Ru- to the Os-based levels, and from the truxene bridging ligand to the terminal-metal chromophores are studied and the pathways and mechanisms are discussed. The Photoinduced Energy-Transfer process observed in the dyad proceeds rapidly through: i) an efficient (1)L-->(1)Os direct Energy Transfer followed by intersystem crossing to (3)Os, and ii) a fast (1)L-->(1)Ru Energy-Transfer step and subsequent intersystem crossing to (3)Ru followed by a (3)Ru-->(3)Os Energy-Transfer process. The first (1)L-->(1)Os and (1)L-->(1)Ru steps are controlled by a dipole-dipole interaction (Forster mechanism), whereas the subsequent (3)Ru-->(3)Os step proceeds by means of a long-range (approximately 24 A) through-bond mediated Dexter mechanism, facilitated by the conjugation along the bpy-truxene-bpy molecular axis.
Leif Hammarström - One of the best experts on this subject based on the ideXlab platform.
-
Photoinduced Energy Transfer coupled to charge separation in a Ru(II)-Ru(II)-acceptor triad.
Inorganic chemistry, 2006Co-Authors: Magnus Borgström, Sascha Ott, Reiner Lomoth, Jonas Bergquist, Leif Hammarström, Olof JohanssonAbstract:Photoinduced Energy Transfer coupled to charge separation in a Ru(II)-Ru(II)-acceptor triad.
-
Distance-independent Photoinduced Energy Transfer over 1.1 to 2.3 nm in ruthenium trisbipyridine–fullerene assemblies
New Journal of Chemistry, 2005Co-Authors: Frédérique Chaignon, J Torroba, Magnus Borgström, Errol Blart, Leif Hammarström, Fabrice OdobelAbstract:Ruthenium trisbipyridine C60 dyads linked viapara-phenyleneethynylene units have been prepared. They displayed a rapid Energy Transfer from Ru to C60 with a rate that was independent of distance, from 1.1 to 2.3 nm. The results are explained by a hopping mechanism involving a bridge-localized excited-state. In fact, for the longest bridge this state was lower in Energy than the Ru-based MLCT state, as evidenced by the spectroscopic data.
-
Photoinduced Electron Transfer from a Higher Excited State of a Porphyrin in a Zinc Porphyrin−Ruthenium(II) tris-Bipyridine Dyad
The Journal of Physical Chemistry A, 1999Co-Authors: Denise Legourriérec, Mikael Andersson, Jan Davidsson, Emad Mukhtar, Licheng Sun, Leif HammarströmAbstract:Photoinduced Energy Transfer from a higher excited state of a porphyrin in a Zinc Potphyrin-Ruthenium(II) tris-Bipyridine Dyad
-
Photoinduced Electron Transfer Reactions in a Porphyrin−Viologen Complex: Observation of S2 to S1 Relaxation and Electron Transfer from the S2 State
The Journal of Physical Chemistry B, 1999Co-Authors: Mikael Andersson, Leif Hammarström, Jan Davidsson, Jouko Korppi-tommola, Timo PeltolaAbstract:Photoinduced Energy Transfer Reactions in a Porphyrin-Viologen Complex: Observation of S2 to S1 Relaxation and Electron Transfer from the S2 state
Francesco Barigelletti - One of the best experts on this subject based on the ideXlab platform.
-
a pre organised truxene platform for phosphorescent ru bpy 2 and os bpy 2 metal centres a clear cut switch from forster to dexter type Energy Transfer mechanism
Chemistry: A European Journal, 2010Co-Authors: Stephane Diring, Francesco Barigelletti, Andrea Barbieri, Raymond Ziessel, Barbara VenturaAbstract:: We report on the synthesis, optical properties and Energy-Transfer features of a series of transition-metal-containing complexes and dyads, based on a pre-organised truxene scaffold. In this series, the [Ru(bpy)(3)](2+) and [Os(bpy)(3)](2+) photoactive terminals are coupled to the bridging aromatic truxene core through rigid ethynyl linkers. The Photoinduced Energy-Transfer processes taking place from the Ru- to the Os-based levels, and from the truxene bridging ligand to the terminal-metal chromophores are studied and the pathways and mechanisms are discussed. The Photoinduced Energy-Transfer process observed in the dyad proceeds rapidly through: i) an efficient (1)L-->(1)Os direct Energy Transfer followed by intersystem crossing to (3)Os, and ii) a fast (1)L-->(1)Ru Energy-Transfer step and subsequent intersystem crossing to (3)Ru followed by a (3)Ru-->(3)Os Energy-Transfer process. The first (1)L-->(1)Os and (1)L-->(1)Ru steps are controlled by a dipole-dipole interaction (Forster mechanism), whereas the subsequent (3)Ru-->(3)Os step proceeds by means of a long-range (approximately 24 A) through-bond mediated Dexter mechanism, facilitated by the conjugation along the bpy-truxene-bpy molecular axis.
-
A Pre‐organised Truxene Platform for Phosphorescent [Ru(bpy)2] and [Os(bpy)2] Metal Centres: A Clear‐Cut Switch from Förster‐ to Dexter‐Type Energy‐Transfer Mechanism
Chemistry (Weinheim an der Bergstrasse Germany), 2010Co-Authors: Stephane Diring, Francesco Barigelletti, Andrea Barbieri, Raymond Ziessel, Barbara VenturaAbstract:We report on the synthesis, optical properties and Energy-Transfer features of a series of transition-metal-containing complexes and dyads, based on a pre-organised truxene scaffold. In this series, the [Ru(bpy)(3)](2+) and [Os(bpy)(3)](2+) photoactive terminals are coupled to the bridging aromatic truxene core through rigid ethynyl linkers. The Photoinduced Energy-Transfer processes taking place from the Ru- to the Os-based levels, and from the truxene bridging ligand to the terminal-metal chromophores are studied and the pathways and mechanisms are discussed. The Photoinduced Energy-Transfer process observed in the dyad proceeds rapidly through: i) an efficient (1)L-->(1)Os direct Energy Transfer followed by intersystem crossing to (3)Os, and ii) a fast (1)L-->(1)Ru Energy-Transfer step and subsequent intersystem crossing to (3)Ru followed by a (3)Ru-->(3)Os Energy-Transfer process. The first (1)L-->(1)Os and (1)L-->(1)Ru steps are controlled by a dipole-dipole interaction (Forster mechanism), whereas the subsequent (3)Ru-->(3)Os step proceeds by means of a long-range (approximately 24 A) through-bond mediated Dexter mechanism, facilitated by the conjugation along the bpy-truxene-bpy molecular axis.
-
Photoinduced Energy Transfer in multichromophores based on planar Pt–bipyridine–acetylide and octahedral Ru–bipyridine centres
Dalton transactions (Cambridge England : 2003), 2008Co-Authors: Raymond Ziessel, Andrea Barbieri, Barbara Ventura, Julie Batcha Seneclauze, Francesco BarigellettiAbstract:In bi- and trimetallic Pt-bipyridine-acetylide/Ru-bipyridine complexes the intermetallic Pt-Ru distance is approximately 9 e, and complete Pt-->Ru Energy Transfer is observed with sensitization of the Ru-based luminescence.
-
Photoinduced Energy Transfer between Re(I) and Ru(II) termini connected through a new exo-ditopic bis-phenanthroline ligand fused to a central macrocycle spacer: Synthesis, structure, and electrochemical and photophysical properties of a heterodinucl
Inorganica Chimica Acta, 2007Co-Authors: Theodore Lazarides, Francesco Barigelletti, Harry Adams, Andrea Barbieri, Cristiana Sabatini, Michael D. WardAbstract:Abstract A new ligand L 1 has been prepared in which two 1,10-phenanthroline fragments are separated by an 18-crown-6 macrocyclic spacer. This was used to prepare the heterodinuclear complex [(bipy) 2 Ru(μ-L 1 )Re(CO) 3 Cl][PF 6 ] 2 [ Ru ( L 1 ) Re ] in which the {Ru(bipy) 2 (phen)} 2+ and {Re(CO)Cl(phen)} chromophores are separated by a saturated and fairly flexible crown-ether fragment. On the basis of photophysical studies on Ru ( L 1 ) Re and associated mononuclear Ru(II) and Re(I) complexes, Re → Ru Photoinduced Energy-Transfer occurs with a rate constant of 1.9 × 10 8 s −1 in solution room temperature leading to near-complete quenching of the Re(I)-based luminescence. At 77 K the Re(I)-based luminescence component is completely quenched. Calculations on the efficiency of both Forster and Dexter Energy-Transfer as a function of Re⋯Ru distance in this system suggest that a folded conformation of the complex, in which the Re⋯Ru separation is much shorter than that implied by the extended conformation detected crystallographically, is responsible for the Energy-Transfer, since neither Forster nor Dexter Re → Ru Energy-Transfer should be possible with the complex in an extended conformation. Addition of K + or Ba 2+ salts to solutions of Ru ( L 1 ) Re had no effect on the photophysical properties, probably because the association constants are too low to give significant metal-ion binding in the macrocycle at the low concentrations employed.
-
Modulation of Photoinduced Energy-Transfer between Ru(II) and Os(II) termini in a dinuclear complex by a conformational change induced by Ba2+ binding at a central macrocyclic site
Inorganic Chemistry Communications, 2003Co-Authors: Rowena L. Paul, Michael D. Ward, Angeles Farran Morales, Gianluca Accorsi, Thomas A. Miller, Francesco BarigellettiAbstract:Abstract In a dinuclear complex containing {Ru(bpy)3}2+ and {Os(bpy)3}2+ termini separated by a flexible diaza-18-crown-6 macrocyclic spacer, binding of a Ba2+ ion at the central macrocycle results in an increase in the Ru⋯Os separation for electrostatic reasons, and hence a decrease in the efficiency of Ru→Os Photoinduced Energy-Transfer.