Control of electron transfer and its utilization

Sakata, Yoshiteru; Imahori, Hiroshi; Tsue, Hirohito; Higashida, Suguru; Akiyama, Tsuyoshi; Yoshizawa, Eiichi; Aoki, Masanori; Yamada, Koji; Hagiwara, Keisuke; Taniguchi, Seiji; Okada, Tadashi

doi:10.1351/pac199769091951

Cited by 66 publications

(45 citation statements)

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“…[1][2][3][4][5][6][7][8][9][10][11] Natural photosynthetic reaction centers constitute remarkable molecular-level photovoltaic devices which utilize incident photons to initiate a complex series of electronic transitions to achieve a high-energy charge separated state. 5,7 The understanding of the fundamental photosynthetic electronic transition pathways, which include singlet-singlet energy transfer, triplet-triplet energy transfer, and photo-initiated electron transfer, has provided a firm platform for the development of chemical systems which duplicate such efficient energy conversion processes.…”

Section: Introductionmentioning

confidence: 99%

The effect of structural changes on charge transfer states in a light-harvesting carotenoid-diaryl-porphyrin-C60 molecular triad

Olguin

Basurto

Zope

et al. 2014

The Journal of Chemical Physics

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We present a detailed study of charge transfer (CT) excited states for a large number of structural conformations in a light-harvesting Carotenoid-diaryl-Porphyrin-C 60 (CPC 60 ) molecular triad. The molecular triad undergoes a photoinduced charge transfer process exhibiting a large excited state dipole moment, making it suitable for application to molecular-scale opto-electronic devices. An important consideration is that the conformational flexibility of the CPC 60 triad impacts its dynamics in solvents. Since experimentally measured dipole moments for the triad of ~110 Debye (D) and ~160 Debye strongly indicate a range in conformational variability for the triad in the excited state, studying the effect of conformational changes on the CT excited state energetics furthers the understanding of its charge transfer states. We have calculated the lowest CT excited state energies for a series of 14 triad conformers, where the structural conformations were generated by incrementally scanning a 360 degree torsional (dihedral) twist at the C 60 -porhyrin linkage and the porphyrin-carotenoid linkage. Additionally, five different CPC 60 conformations were studied to determine the effect of pi-conjugation and particle-hole Coulombic attraction on the CT excitation energies. Our calculations show that structural conformational changes in the triad show a variation of ~0.4 eV in CT excited state energies in the gas-phase. The corresponding calculated excited state dipoles show a range of 88 D -188 D.

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Section: Introductionmentioning

confidence: 99%

The effect of structural changes on charge transfer states in a light-harvesting carotenoid-diaryl-porphyrin-C60 molecular triad

Olguin

Basurto

Zope

et al. 2014

The Journal of Chemical Physics

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“…4 The complexity of this process has prompted numerous studies of pairing donor-acceptor molecules to mimic the photosynthetic system. These molecules have been joined through covalent alkyl chains, 5 peptide bond, hydrogen bond, 6 rigid spacers, 7 self-assembled via metal-ligands, 8 or more recently, through ion pairing formed by association of molecules grafted with oppositely charged substituents. 9,10 Synthetic macrocycles such as porphyrins, and structurally similar phthalocyanines share many of the characteristics of the naturally occurring porphyrin-like systems.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of new cationic metalloporphyrins and heterodimer formation with anionic metallophthalocyanines

Ribeiro

Azzellini

2003

J. Braz. Chem. Soc.

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Existe grande interesse no estudo de heterodímeros constituídos por metaloporfirinas e ftalocianinas de carga oposta, uma vez que estes sistemas são modelos do special pair da fotossíntese e dispositivos moleculares promissores para a transferência de elétrons unidirecional. Neste trabalho foram sintetizadas novas metaloporfirinas catiônicas, e investigada a formação de heteroagregados com metaloftalocianinas aniônicas em DMSO. Estes novos derivados porfirínicos catiônicos apresentam grupos benzílicos ligados aos nitrogênios piridínicos da tetra-(piridil)porfirina (H 2 TPyP), resultando em compostos que são mais hidrofóbicos e que apresentam sistemas π adicionais em relação aos ligantes tetra-(metilpiridínio)porfirina (H 2 TMPyP) e tetra-(trimetilaminofenil)porfirina (H 2 TAPP). Observou-se que a estequiometria dos agregados formados e os valores de constante de associação entre as porfirinas catiônicas e as ftalocianinas aniônicas são dependentes do metal coordenado a ambos os macrociclos. As Zn(II)porfirinas formam em solução preferencialmente o agregado de estequiometria 1:1 (porfirina:ftalocianina) no meio reacional, enquanto que no caso das Pd(II)porfirinas pode ocorrer a formação de agregados 1:1 ou 1:2 (porfirina:ftalocianina). Os valores de K PI , por sua vez, são sempre maiores para os agregados formados com as ftalocianinas de Cu(II), sendo este comportamento relacionado com a menor distorção para fora do plano da ligação Cu-N comparada com a ligação Ni-N em decorrência da ligação axial de uma molécula de DMSO ao íon metálico coordenado à ftalocianina. Os valores de K PI também são menores para os heterodímeros formados com as porfirinas que apresentam os meso-susbtituintes benzílicos mais volumosos, em função da disposição angular dos mesmos em relação ao plano do anel porfirínico que provoca um maior impedimento estérico. Estes resultados demonstram que a associação entre macrociclos tetrapirrólicos pode ser controlada através de vários fatores estruturais. Estes fatores também podem conduzir a diferentes propriedades fotofísicas destes heteroagregados; estudos neste sentido estão em andamento.There is great interest in the investigation of heterodimers formed by metalloporphyrins and metallophthalocyanines grafted with oppositely charged substituents, since these systems are models of the photosynthetic special pair and promising unidirectional electron transfer molecular devices. In the present study new cationic metalloporphyrin derivatives were synthesized and their association with anionic metallophthalocyanines forming heteroaggregates, investigated. These new cationic porphyrins derivatives show benzylic groups bound to the pyridyl nitrogen atoms of tetra-(pyridyl)porphyrin (TPyP), resulting in additional π systems and more hydrophobic compounds if compared with tetra-(methylpiridinium)porphyrin (H 2 TMPyP) and tetra-(trimethylaminophenyl)porphyrin (H 2 TAPP) ligands. It could be observed that both stoichiometry and association constants between cationic porphyrins and anionic phthalocyanines ...

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“…[1] This result is relevant to the problem of designing and synthesizing materials for artificial photosynthetic models and photovoltaic devices. [2] In particular, there is great current interest on blends of oligo-and polythiophenes with fullerene and fullerene derivatives as model systems for photovoltaic devices. [3 -5] Blends of unsubstituted sexithiophene (T6) and fullerene C 60 have been recently shown to display interesting photovoltaic properties, which, however, depend critically on the morphology of the blend itself.…”

Section: Introductionmentioning

confidence: 99%

Thermal Characterization of Sexithiophenes Regioselectively Functionalized with Electron Donor Methylsulfanyl Groups

Scandola¹,

Finelli

Bongini

et al. 2001

Macromol. Chem. Phys.

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Control of electron transfer and its utilization

Abstract: Abstract

Cited by 66 publications

References 1 publication

The effect of structural changes on charge transfer states in a light-harvesting carotenoid-diaryl-porphyrin-C60 molecular triad

The effect of structural changes on charge transfer states in a light-harvesting carotenoid-diaryl-porphyrin-C60 molecular triad

Synthesis of new cationic metalloporphyrins and heterodimer formation with anionic metallophthalocyanines

Thermal Characterization of Sexithiophenes Regioselectively Functionalized with Electron Donor Methylsulfanyl Groups

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