Iridium terpyridine complexes as functional assembling units in arrays for the conversion of light energy

被引:158
作者
Flamigni, Lucia [1 ]
Collin, Jean-Paul [2 ]
Sauvage, Jean-Pierre [2 ]
机构
[1] Ist ISOF CNR, I-40129 Bologna, Italy
[2] Univ Strasbourg, Lab Chim Organo Minerale, Inst Bel, CNRS,UMR 7177, F-67070 Strasbourg, France
关键词
D O I
10.1021/ar700282n
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
In photosynthesis, sunlight energy is converted into a chemical potential by an electron transfer sequence that is started by an excited state and ultimately yields a long-lived charge-separated state. This process can be reproduced by carefully designed multicomponent artificial arrays of three or more components, and the stored energy can be used to oxidize or reduce molecules in solution, to inject electrons or holes, or to create an electron flow. Therefore, the process is important both for artificial-photosynthesis research and for photovoltaic and optoelectronic applications. Molecular arrays for photoinduced charge separation often use chromophores that resemble the natural ones. However, new synthetic components, including transition metal complexes, have had some success. This Account discusses the use of bis-terpyridine (tpy) metal complexes as assembling and functional units of such multicomponent arrays. M(tpy)(2)(n+) complexes have the advantage of yielding linear rrays with unambiguous geometry. Originally, Ru(tpy)(2)(2+) and Os(tpy)(2)(2+) were used as photosensitizers in triads containing typical organic donors and acceptors. However, it soon became evident that the relatively low excited state of these complexes could act as,an energy drain of the excited state of the photosensitizer and, thus, seriously compete with charge separation. A new metal complex that preserved the favorable tpy geometry and yet had a higher energy level Was needed. We identified Ir(tpy)(2)(3+), which displayed a higher energy level, a more facile reduction that favored charge separation, a longer excited-state lifetime, and strong spectroscopic features that were useful for the identification of intermediates. Ir(tpy)(2)(3+) was used in arrays with electron-donating gold porphyrin and electron-accepting free-base porphyrins. A judicious change of the free-base porphyrin photosensitizer with zinc porphyrin allowed us to shape the photoreactivity and led to charge separation with unity yield and a lifetime on the order of a microsecond. In a subsequent approach, an Ir(tpy)(2)(3+) derivative was connected to an amine electron donor and a bisimide electron acceptor in an array 5 nm long. In this case, the complex acted as photosensitizer, and long-lived charge separation over the extremities (> 100 mu s, nearly independent of the presence of oxygen) was achieved. The efficiency of the charge separation was modest, but it was improved later, after a modification aiming at decoupling the donor and photosensitizer components. This study represents an example of how the performances of an artificial photofunctional array can be modeled by a judicious design assisted by a detailed knowledge of the systems.
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页码:857 / 871
页数:15
相关论文
共 27 条
[1]   Chemical approaches to artificial photosynthesis. 2 [J].
Alstrum-Acevedo, JH ;
Brennaman, MK ;
Meyer, TJ .
INORGANIC CHEMISTRY, 2005, 44 (20) :6802-6827
[2]   SYNTHESIS, LUMINESCENCE, AND EXCITED-STATE COMPLEXES OF THE TRIS(1,10-PHENANTHROLINE)IRIDIUM(III) AND BIS(TERPYRIDINE)IRIDIUM(III) CATIONS [J].
AYALA, NP ;
FLYNN, CM ;
SACKSTEDER, L ;
DEMAS, JN ;
DEGRAFF, BA .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1990, 112 (10) :3837-3844
[3]   Autonomous artificial nanomotor powered by sunlight [J].
Balzani, V ;
Clemente-León, M ;
Credi, A ;
Ferrer, B ;
Venturi, M ;
Flood, AH ;
Stoddart, JF .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2006, 103 (05) :1178-1183
[4]   Dyads containing iridium(III) bis-terpyridine as photoactive center: Synthesis and electron transfer study [J].
Baranoff, E ;
Dixon, IM ;
Collin, JP ;
Sauvage, JP ;
Ventura, B ;
Flamigni, L .
INORGANIC CHEMISTRY, 2004, 43 (10) :3057-3066
[5]   Light induced manganese oxidation and long-lived charge separation in a Mn2II,II-RuII (bpy)3-acceptor triad [J].
Borgström, M ;
Shaikh, N ;
Johansson, O ;
Anderlund, MF ;
Styring, S ;
Åkermark, B ;
Magnuson, A ;
Hammarström, L .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2005, 127 (49) :17504-17515
[6]   Platinum chromophore-based systems for photoinduced charge separation: A molecular design approach for artificial photosynthesis [J].
Chakraborty, S ;
Wadas, TJ ;
Hester, H ;
Schmehl, R ;
Eisenberg, R .
INORGANIC CHEMISTRY, 2005, 44 (20) :6865-6878
[7]   Synthesis and photophysical properties of iridium(III) bisterpyridine and its homologues: a family of complexes with a long-lived excited state [J].
Collin, JP ;
Dixon, IM ;
Sauvage, JP ;
Williams, JAG ;
Barigelletti, F ;
Flamigni, L .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1999, 121 (21) :5009-5016
[8]   PHOTOINDUCED PROCESSES IN DYADS AND TRIADS CONTAINING A RUTHENIUM(II) BIS(TERPYRIDINE) PHOTOSENSITIZER COVALENTLY LINKED TO ELECTRON-DONOR AND ACCEPTOR GROUPS [J].
COLLIN, JP ;
GUILLEREZ, S ;
SAUVAGE, JP ;
BARIGELLETTI, F ;
DECOLA, L ;
FLAMIGNI, L ;
BALZANI, V .
INORGANIC CHEMISTRY, 1991, 30 (22) :4230-4238
[9]   PHOTOINDUCED PROCESSES IN DYADS AND TRIADS - AN OSMIUM(II)-BIS(TERPYRIDINE) PHOTOSENSITIZER COVALENTLY LINKED TO ELECTRON-DONOR AND ACCEPTOR GROUPS [J].
COLLIN, JP ;
GUILLEREZ, S ;
SAUVAGE, JP ;
BARIGELLETTI, F ;
DECOLA, L ;
FLAMIGNI, L ;
BALZANI, V .
INORGANIC CHEMISTRY, 1992, 31 (20) :4112-4117
[10]   PHOTOCHEMICALLY INDUCED CHARGE SEPARATION AT THE MOLECULAR-LEVEL - A CHROMOPHORE QUENCHER COMPLEX CONTAINING BOTH AN ELECTRON-TRANSFER DONOR AND AN ACCEPTOR [J].
DANIELSON, E ;
ELLIOTT, CM ;
MERKERT, JW ;
MEYER, TJ .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1987, 109 (08) :2519-2520