Metal-Centered Photoinduced Electron Transfer Reduction of a Gold(III) Porphyrin Cation Linked with a Zinc Porphyrin to Produce a Long-Lived Charge-Separated State in Nonpolar Solvents

Fukuzumi, Shunichi; Ohkubo, Kei; Ou, Zhonghong; Shao, Jianguo; Km, Kadish; Hutchison, James A.; Kp, Ghiggino; Pj, Sintic; Crossley, Maxwell J.

doi:10.1021/ja037214b

Cited by 107 publications

(75 citation statements)

References 24 publications

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“…The kinetics of the oxidation of glycolaldehyde [9], a few alkanols [10], aryl alcohols [10] and a-hydroxy acids [11] by Au(III) have already been reported. There are recent reports on redox and ligand exchange reactions of potential gold(I) and gold(III)-cyanide metabolites under biomimetic conditions [12], as well as reports of a metal-centered photoinduced electron transfer reduction of a Au(III)-porphyrin cation in non-polar solvents [13]. A recent study [14] in the reactions of a few Au(III) complexes with serum albumin revealed the presence of both weak and strong metal-protein interactions and adduct formation for such gold(III) complexes through coordination at the level of surface histidines has been proposed.…”

Section: Introductionmentioning

confidence: 99%

Kinetics and mechanism of the reduction of gold(III) by glycine in acetate buffer

Sen

Gani

Midya

et al. 2007

Transition Met Chem

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The kinetics of reduction of tetrachloroaurate(III) by glycine has been spectrophotometrically studied in NaOAc-AcOH buffer in the pH range 3.73-4.77. The reaction is first order with respect to both Au(III) and glycine. Both H + and Cl -ions have inhibiting effects on the reaction rate. The rate decreases with a decrease in the dielectric constant of the medium. AuCl 4 -and AuCl 3 (OH) -are presumed to be the predominant oxidizing species under the conditions of the experiment. The reaction of gold(III) and zwitterionic species of glycine proceeds with the intermediate formation of gold(I) and iminic cation and the latter subsequently hydrolyses in a fast step to produce formaldehyde and ammonium ion. Formaldehyde was identified as the only organic product by 1 H NMR spectroscopy.

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Section: Introductionmentioning

confidence: 99%

Kinetics and mechanism of the reduction of gold(III) by glycine in acetate buffer

Sen

Gani

Midya

et al. 2007

Transition Met Chem

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“…[3] In these cases, not only the selection of the building block matters, [4] but also the distance, [5] the electronic coupling mediated by the connecting unit, [6] the solvent polarity, [7] and the aggregation status [8] can play an important role. Over the years, we have been working with different electron-poor moieties, [9] especially with perylenebisimide (PBI), owing to its strong absorption in the 450-600 nm region, its chemical and thermal stabilities, and its ease of chemical modification.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Photophysics of Silicon Phthalocyanine–Perylenebisimide Triads Connected through Rigid and Flexible Bridges

Céspedes-Guirao

Martín‐Gomis

Ohkubo

et al. 2011

Chemistry A European J

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Three new bisperylenebisimide-silicon phthalocyanine triads [(PBI)(2)-SiPcs 1, 2, and 3] connected with either rigid or flexible bridges were synthesized and characterized. A new synthetic approach to connect SiPc and PBI moieties through click chemistry produced triad 3 with an 80% yield. In (PBI)(2)-SiPc 1, PBI and SiPc are orthogonal and were connected with a rigid connector; triads 2 and 3 bear flexible aliphatic bridges, resulting in a tilted (2) or nearly parallel arrangement (3) of PBI and SiPc. Photoinduced intramolecular processes in these (PBI)(2)-SiPcs were studied and the results are compared with those of the reference compounds SiPc-ref and PBI-ref. The occurrence of electron-transfer processes between the SiPc and PBI units was confirmed by time-resolved emission and transient absorption techniques. Charge-separated (CS) states with lifetimes of 0.91, 1.3 and 2.0 ns for triads 1, 2, and 3, respectively, were detected using femtosecond laser flash photolysis. Upon the addition of Mg(ClO(4))(2), an increase in the lifetime of the CS states to 59, 110 and 200 μs was observed for triads (PBI)(2)-SiPcs 1, 2, and 3, respectively. The energy of the CS state (SiPc(·+)-PDI(·-)/Mg(2+)) is lower than the energy of both silicon phthalocyanine ((3)SiPc*-PDI) and perylenebisimide (SiPc-(3)PDI*) triplet excited states, which decelerates the metal ion-decoupled electron-transfer process for charge recombination to the ground state, thus increasing the lifetime of the CS state. The photophysics of the three triads demonstrate the importance of the rigidity of the spacer and the orientation between donor and acceptor units.

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“…These results are qualitatively in agreement with a charge-recombination processes occurring in the normal region of the Marcus plot. [29][30][31] The femtosecond transient absorption measurements of the self-assembled tetrad 2 in nonpolar toluene showed the absorption of TPA-ZnPC + in the visible region between 650 and 800 nm, together with the near-IR absorption of C 60 ImC À with a maximum at l = 1000 nm, confirming the formation of the radical ion pair SubPc-TPA-ZnPC + :C 60 C À . The timeprofile of C 60 ImC À in the NIR region ( Figure 7, inset) shows a fast rise, from which the rate of the charge-separation process (k CS S ) from the singlet ZnP to C 60 Im was calculated as 8.…”

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Supramolecular Tetrad of Subphthalocyanine–Triphenylamine–Zinc Porphyrin Coordinated to Fullerene as an “Antenna‐Reaction‐Center” Mimic: Formation of a Long‐Lived Charge‐Separated State in Nonpolar Solvent

El‐Khouly

Kay

et al. 2010

Chemistry A European J

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We report here the formation of a long-lived charge-separated state of a self-assembled donor-acceptor tetrad, formed by axial coordination of a fulleropyrrolidine appended with an imidazole coordinating ligand (C(60)Im) to the zinc center of a subphthalocyanine-triphenylamine-zinc porphyrin (SubPc-TPA-ZnP), as a charge-stabilizing antenna reaction center mimic in toluene. The subphthalocyanine and triphenylamine entities, with their high-energy singlet states, act as an energy-transferring antenna unit to produce a singlet zinc porphyrin. The formation constant for the self-assembled tetrad was determined to be 1.0 x 10(4) M(-1), suggesting a moderately stable complex formation. The geometric and electronic structures of the covalently linked SubPc-TPA-ZnP triad and self-assembled SubPc-TPA-ZnP:C(60)Im tetrad were examined by using an ab initio B3LYP/6-31G method. The majority of the highest occupied frontier molecular orbital was found over the ZnP and TPA entities, whereas the lowest unoccupied molecular orbital was located over the fullerene entity, suggesting the formation of the radical-ion pair (SubPc-TPA-ZnP(*+):C(60)Im(*-)). The redox measurements revealed that the energy level of the radical-ion pair in toluene is located lower than that of the singlet and triplet states of the zinc porphyrin and fullerene entities. The femtosecond transient absorption measurements revealed fast charge separation from the singlet porphyrin to the coordinated C(60)Im with a lifetime of 1.1 ns. Interestingly, slow charge recombination (1.6 x 10(5) s(-1)) and the long lifetime of the charge-separated state (6.6 micros) were obtained in toluene by utilizing the nanosecond transient measurements.

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Metal-Centered Photoinduced Electron Transfer Reduction of a Gold(III) Porphyrin Cation Linked with a Zinc Porphyrin to Produce a Long-Lived Charge-Separated State in Nonpolar Solvents

Cited by 107 publications

References 24 publications

Kinetics and mechanism of the reduction of gold(III) by glycine in acetate buffer

Kinetics and mechanism of the reduction of gold(III) by glycine in acetate buffer

Synthesis and Photophysics of Silicon Phthalocyanine–Perylenebisimide Triads Connected through Rigid and Flexible Bridges

Supramolecular Tetrad of Subphthalocyanine–Triphenylamine–Zinc Porphyrin Coordinated to Fullerene as an “Antenna‐Reaction‐Center” Mimic: Formation of a Long‐Lived Charge‐Separated State in Nonpolar Solvent

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