孙立成
光体系Ⅱ的化学模拟,氢化酶的化学模拟,超分子化学及光化学,新型太阳能电池,纳米半导体材料的表面修饰,光致电子转移及能量传递,电致化学发光材料。
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- 姓名:孙立成
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学术头衔:
博士生导师
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学科领域:
物理化学
- 研究兴趣:光体系Ⅱ的化学模拟,氢化酶的化学模拟,超分子化学及光化学,新型太阳能电池,纳米半导体材料的表面修饰,光致电子转移及能量传递,电致化学发光材料。
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孙立成
,-0001,():
-1年11月30日
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【期刊论文】A Biomimetic Model System for the Water Oxidizing Triad in Photosystem II
孙立成, Ann Magnuson, †, Yves Frapart, Malin Abrahamsson, ‡, Olivier Horner, §, ┴, Björn Åkermark, ||, Licheng Sun, Jean-Jacques Girerd, Leif Hammarström, *, and Stenbjörn Styring*
J. Am. Chem. Soc. 1999, 121, 89-96,-0001,():
-1年11月30日
In plants, solar energy is used to extract electrons from water, producing atmospheric oxygen. This is conducted by Photosystem II, where a redox "triad" consisting of chlorophyll, a tyrosine, and a manganese cluster, governs an essential part of the process. Photooxidation of the chlorophylls produces electron transfer from the tyrosine, which forms a radical. The radical and the manganese cluster together extract electrons from water, providing the biosphere with an unlimited electron source. As a partial model for this system we constructed a ruthenium (II) complex with a covalently attached tyrosine, where the photooxidized ruthenium was rereduced by the tyrosine. In this study we show that the tyrosyl radical, which gives a transient EPR signal under illumination, can oxidize a manganese complex. The dinuclear manganese complex, which initially is in the Mn (III)/(III) state, is oxidized by the photogenerated tyrosyl radical to the Mn (III)/(IV) state. The redox potentials in our system are comparable to those in Photosystem II. Thus, our synthetic redox "triad" mimics important elements in the electron donor "triad" in Photosystem II, significantly advancing the development of systems for artificial photosynthesis based on ruthenium-manganese complexes.
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孙立成, Licheng Sun, *, †, Mark Burkitt, ‡, Markus Tamm, Mary Katherine Raymond, §, Malin Abrahamsson, Denis LeGourriérec, Yves Frapart, Ann Magnuson, Ping Huang Kenéz, Peter Brandt, Anh Tran, Leif Hammarstrom, Stenbjorn Styring, and Björn Ǻkermark*, ||
J. Am. Chem. Soc. 1999, 121, 6834-6842,-0001,():
-1年11月30日
ents as well as by chemical oxidation. Flash photolysis and EPR measurements on 4 in the presence of an electron acceptor (methylviologen, MV2+, or cobalt pentaminechloride, Co3+) showed that an intermolecular electron transfer from the excited state of Ru (II) in 4 to the electron acceptor took place, forming Ru (III) and the methylviologen radical MV+·or Co2+. This was followed by intramolecular electron transfer from the substituted tyrosine moiety to the photogenerated Ru (III), regenerating Ru (II) and forming a tyrosyl radical. In water, the radical has a g value of 2.0044, indicative of a deprotonated tyrosyl radical. In acetonitrile, a radical with a g value of 2.0029 was formed, which can be assigned to the tyrosine radical cation. In both solvents the electron transfer is intramolecular with a rate constant kET>1×107 s-1. This is 2 orders of magnitude greater than the one for a similar compound 3, in which no dpa arm is attached to the tyrosine unit. Therefore the hydrogen bonding between the substituted tyrosine and the dpa arms in 4 is proposed to be responsible for the fast electron transfer. This interaction mimics the proposed His 190 and tyrosineZ interaction in the donor side of PS II.
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孙立成, Martin Sjodin, †, Stenbjorn Styring, ‡, Bjorn Åkermark, §, Licheng Sun, and Leif Hammarstrom*
J. Am. Chem. Soc. 2000, 122, 3932-3936,-0001,():
-1年11月30日
The pH- and the temperature dependence of the rate constant for electron transfer from tyrosine to ruthenium in Ru (II) (bpy)2 (4-Me-4'CONH-L-tyrosine etyl ester-2,2'-bpy) 2PF6 was investigated using flash photolysis. At a pH below the tyrosine pKa≈10 the rate constant increased monotonically with pH. This increase was consistent with a concerted electron transfer/deprotonation mechanism. Also indicative of a concerted reaction was the unusually high reorganization energy, 2eV, extracted from temperature-dependent measurements. Deprotonation of the tyrosine group, at pH>pKa, resulted in a 100-fold increase in rate constant due to a decreased reorganization energy, λ=0.9eV. Also, the rate constant became independent of pH. In Mn-depleted photosystem II a similar pH dependence has been found for electron transfer from tyrosinez (Tyrz) to the oxidized primary donor P680+. On the basis of the kinetic similarities we propose that the mechanisms in the two systems are the same, that is, the electron transfer occurs as a concerted protoncoupled electron-transfer reaction, and at pH<7 the Tyrz proton is released directly to the bulk water.
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【期刊论文】Towards artificial photosynthesis: ruthenium-manganese chemistry for energy production
孙立成, Licheng Sun, a Leif Hammarstr
Chem. Soc. Rev., 2001, 30, 36-49,-0001,():
-1年11月30日
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【期刊论文】Modified Phthalocyanines for Efficient Near-IR Sensitization of Nanostructured TiO2 Electrode
孙立成, Jianjun He, †, Gábor Benkö, Ferenc Korodi, ‡, Tomás Polívka, Reiner Lomoth, §, Björn Åkermark, Licheng Sun, *, Anders Hagfeldt, and Villy Sundström*
J. AM. CHEM. SOC. 2002, 124, 4922-4932,-0001,():
-1年11月30日
A zinc phthalocyanine with tyrosine substituents (ZnPcTyr), modified for efficient far-red/near- IR performance in dye-sensitized nanostructured TiO2 solar cells, and its reference, glycine-substituted zinc phthalocyanine (ZnPcGly), were synthesized and characterized. The compounds were studied spectroscopically, electrochemically, and photoelectrochemically. Incorporating tyrosine groups into phthalocyanine makes the dye ethanol-soluble and reduces surface aggregation as a result of steric effects. The performance of a solar cell based on ZnPcTyr is much better than that based on ZnPcGly. Addition of 3α,7α-dihydroxy-5β-cholic acid (cheno) and 4-tert-butylpyridine (TBP) to the dye solution when preparing a dye-sensitized TiO2 electrode diminishes significantly the surface aggregation and, therefore, improves the performance of solar cells based on these phthalocyanines. The highest monochromatic incident phototo-current conversion efficiency (IPCE) of ~24% at 690nm and an overall conversion efficiency (ŋ) of 0.54% were achieved for a cell based on a ZnPcTyr-sensitized TiO2 electrode. Addition of TBP in the electrolyte decreases the IPCE and ŋ considerably, although it increases the open-circuit photovoltage. Time-resolved transient absorption measurements of interfacial electron-transfer kinetics in a ZnPcTyr-sensitized nanostructured TiO2 thin film show that electron injection from the excited state of the dye into the conduction band of TiO2 is completed in ~500fs and that more than half of the injected electrons recombines with the oxidized dye molecules in ~300ps. In addition to surface aggregation, the very fast electron recombination is most likely responsible for the low performance of the solar cell based on ZnPcTyr.
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孙立成, Raed Ghanem, †, Yunhua Xu, ‡, Jie Pan, Tobias Hobias Hoffmann, Johan Andersson, Tomáš Polvka, Torbjörn Pascher, Stenbjörn Styring, §, Licheng Sun, *, and Villy Sundström*
Iong. Chem. 2002, 41, 6258-6266,-0001,():
-1年11月30日
radical is formed in less than 5μs with a yield of 15%. This rather low yield is a result of a fast back electron transfer reaction from the nanocrystalline TiO2 to the photogenerated Ru (III).
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【期刊论文】Photoinduced Electron Transfer between a Carotenoid and TiO2 Nanoparticle
孙立成, Jie Pan, †, ‡, Gábor Benkö, Yunhua Xu, §, Torbjörn Pascher, Licheng Sun, Villy Sundström, and Tomáš Polívka*
1395 J. AM. CHEM. SOC. VOL. 124, No.46, 2002,-0001,():
-1年11月30日
The dynamics of photoinduced electron injection and recombination between all-trans-8'-apo-β-caroten-8'-oic acid (ACOA) and a TiO2 colloidal nanoparticle have been studied by means of transient absorption spectroscopy. We observed an ultrafast (~360fs) electron injection from the initially excited S2 state of ACOA into the TiO2 conduction band with a quantum yield of ~40%. As a result, the ACOA·+ radical cation was formed, as demonstrated by its intense absorption band centered at 840nm. Because of the competing S2-S1 internal conversion, ~60% of the S2-state population relaxes to the S1 state. Although the S1 state is thermodynamically favorable to donate electrons to the TiO2, no evidence was found for electron injection from the ACOA S1 state, most likely as a result of a complicated electronic nature of the S1 state, which decays with a ~18ps time constant to the ground state. The charge recombination between the injected electrons and the ACOA·+ was found to be a highly nonexponential process extending from picoseconds to microseconds. Besides the usual pathway of charge recombination forming the ACOA ground state, about half of the ACOA·+ recombines via the ACOA triplet state, which was monitored by its absorption band at 530nm. This second channel of recombination proceeds on the nanosecond time scale, and the formed triplet state decays to the ground state with a lifetime of ~7.3 μs. By examination of the process of photoinduced electron transfer in a carotenoid-semiconductor system, the results provide an insight into the photophysical properties of carotenoids, as well as evidence that the interfacial electron injection occurs from the initially populated excited state prior to electronic and nuclear relaxation of the carotenoid molecule.
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孙立成, Magnus Borgstrom, †, Olof Johansson, ‡, Reiner Lomoth, Helena Berglund Baudin, Staffan Wallin, Licheng Sun, *, Björn Åkermark, and Leif Hammarström
Inorg. Chem. 2003, 42, 5173-5184,-0001,():
-1年11月30日
Two electron donor-acceptor triads based on a benzoquinone acceptor linked to a light absorbing [Ru(bpy)3]2+ complex have been synthesized. In triad 6 (denoted Ru II-BQ-Co III), a [Co(bpy)3]3+ complex, a potential secondary acceptor, was linked to the quinone. In the other triad, 8 (denoted PTZ-Ru II-BQ), a phenothiazine donor was linked to the ruthenium moiety. The corresponding dyads Ru II-BQ (4) and PTZ-Ru II (9) were prepared for comparison. Upon light excitation in the visible band of the ruthenium moiety, electron transfer to the quinone occurred with a rate constant Kf=5×109 S-1 (τf=200ps) in all the quinone containing complexes. Recombination to the ground state followed, with a rate constant kb~4.5×108 S-1 (τb~2.2ns), for both Ru II-BQ and Ru II-BQ-Co III with no indication of a charge shift to generate the reduced Co II moiety. In the PTZ-Ru II-BQ triad, however, the initial charge separation was followed by a rapid (k>5×109 S-1) electron transfer from the phenothiazine moiety to give the fairly long-lived PTZ·+-Ru II-BQ·- state (τ=80ns) in unusually high yield for a [Ru(bpy)3]2+-based triad (>90%), that lies at △G°=1.32 eV relative to the ground state. Unfortunately, this triad turned out to be rather photolabile. Interestingly, coupling between the oxidized PTZ·+ and the BQ·- moieties seemed to occur. This discouraged further extension to incorporate more redox active units. Finally, in the dyad PTZ-Ru II a reversible, near isoergonic electron transfer was observed on excitation. Thus, a quasiequilibrium was established with an observed time constant of 7ns, with ca. 82% of the population in the PTZ-*Ru II state and 18% in the PTZ·+-Ru II (bpy·-) state. These states decayed in parallel with an observed lifetime of 90ns. The initial electron transfer to form the PTZ·+-Ru II(bpy·-) state was thus faster than what would have been inferred from the *Ru II emission decay (τ=90ns). This result suggests that reports for related PTZ-Ru II and PTZ-Ru II-acceptor complexes in the literature might need to be reconsidered.
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孙立成, Sascha Ott, †, Magnus Borgstrom, ‡, Mikael Kritikos, §, Reiner Lomoth, Jonas Bergquist, ‖, Björn Åkermark, *, Leif Hammarström, and Licheng Sun*
Inorg. Chem. 2004, 43, 4683-4692,-0001,():
-1年11月30日
A model of the iron hydrogenase active site with the structure [(μ-ADT)Fe2(CO)6] (ADT =azadithiolate (S-CH2-NR-CH2-S), (2: R =4-bromophenyl, 3: R=4-iodophenyl)) has been assembled and covalently linked to a [Ru(terpy)2]2+photosensitizer. This trinuclear complex 1 represents one synthetic step toward the realization of our concept of light-driven proton reduction. A rigid phenylacetylene tether has been incorporated as the linking unit in 1 in order to prolong the lifetime of the otherwise short-lived [Ru(terpy)2]2+ excited state. The success of this strategy is demonstrated by comparison of the photophysical properties of 1 and of two related ruthenium complexes bearing acetylenic terpyridine ligands, with those of [Ru(terpy)2]2+. IR and electrochemical studies reveal that the nitrogen heteroatom of the ADT bridge has a marked influence on the electronic properties of the [Fe2(CO)6] core. Using the Rehm-Weller equation, the driving force for an electron transfer from the photoexcited *[Ru(terpy)2]2+ to the diiron site in 1 was calculated to be uphill by 0.59 eV. During the construction of the trinuclear complex 1, n-propylamine has been identified as a decarbonylation agent on the [(μ-ADT)Fe2(CO)6] portion of the supermolecule. Following this procedure, the first azadithiolate-bridged dinuclear iron complex coordinated by a phosphine ligand [(μ-ADT)Fe2(CO)5PPh3] (4, R =4-bromophenyl) was synthesized.
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