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Your search keyword '"Urner, Lorenz M."' showing total 3 results
Start Over Author "Urner, Lorenz M." Topic photochemistry
3 results on '"Urner, Lorenz M."'

1. Porphyrin Donor and Tunable Push-Pull Acceptor Conjugates-Experimental Investigation of Marcus Theory.

Author

Reekie, Tristan A., Sekita, Michael, Urner, Lorenz M., Bauroth, Stefan, Ruhlmann, Laurent, Gisselbrecht, Jean ‐ Paul, Boudon, Corinne, Trapp, Nils, Clark, Timothy, Guldi, Dirk M., and Diederich, François

Subjects
PORPHYRINS, MARCUS equation, ELECTRON donor-acceptor complexes, ZINC compounds, CHROMOPHORES, ELECTROCHEMISTRY
Abstract

We report on a series of electron donor-acceptor conjugates incorporating a ZnII-porphyrin-based electron donor and a variety of non-conjugated rigid linkers connecting to push-pull chromophores as electron acceptors. The electron acceptors comprize multicyanobutadienes or extended tetracyanoquinodimethane analogues with first reduction potentials ranging from −1.67 to −0.23 V vs. Fc+/Fc in CH2Cl2, which are accessible through a final-step cycloaddition-retroelectrocyclization (CA-RE) reaction. Characterization of the conjugates includes electrochemistry, spectroelectrochemistry, DFT calculations, and photophysical measurements in a range of solvents. The collected data allows for the construction of multiple Marcus curves that consider electron-acceptor strength, linker length, and solvent, with data points extending well into the inverted region. The enhancement of electron-vibration couplings, resulting from the rigid spacers and, in particular, multicyano-groups in the conformationally highly fixed push-pull acceptor chromophores affects the charge-recombination kinetics in the inverted region drastically. [ABSTRACT FROM AUTHOR]

Published
2017
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2. Systematic Variation of Cyanobuta-1,3-dienes and Expanded Tetracyanoquinodimethane Analogues as Electron Acceptors in Photoactive, Rigid Porphyrin Conjugates.

Author

Urner, Lorenz M., Sekita, Michael, Trapp, Nils, Schweizer, W. Bernd, Wörle, Michael, Gisselbrecht, Jean‐Paul, Boudon, Corinne, Guldi, Dirk M., and Diederich, François

Subjects
*TETRACYANOQUINODIMETHANE, *DIOLEFINS, *ELECTROPHILES, *PORPHYRINS, *ELECTRON donor-acceptor complexes, *RING formation (Chemistry), *ATOMIC displacements
Abstract

We report on a homologous series of nine electron donor-acceptor systems featuring push-pull chromophores as electron acceptors, which are accessible by a cycloaddition-retroelectrocyclization (CA-RE) reaction. The conjugates comprise a ZnII porphyrin as electron donor, which is connected through either a rigid phenylene-ethynylene-phenylene (PEP)-bicyclo[2.2.2]octane or a PEP- trans-decahydroquinoline spacer to different anilino-substituted multicyanobutadienes or extended tetracyanoquinodimethane analogues with first reduction potentials ranging from -1.78 to -0.58 V vs. Fc+/Fc. Characterization of the conjugates includes X-ray crystallography, electrochemistry, DFT calculations, and fluorescence spectroscopy. The extent of ZnII porphyrin fluorescence quenching correlates with the strength of the electron acceptor. Overall, we demonstrate the synthetic feasibility of rationally modulating the acceptor strength by means of the CA-RE reaction in geometrically well-defined electron donor-acceptor conjugates. [ABSTRACT FROM AUTHOR]

Published
2015
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3. Cyanobuta-1,3-dienes as Novel Electron Acceptors for Photoactive Multicomponent Systems

Author

Francesca Tancini, Kara Howes, W. Bernd Schweizer, Andrea Listorti, Jean-Paul Gisselbrecht, José Lorenzo Alonso-Gómez, Abdelhalim Belbakra, Corinne Boudon, Filippo Monti, Claudio Chiorboli, François Diederich, Philippe Reutenauer, Nicola Armaroli, Lorenz M. Urner, Tancini, Francesca, Monti, Filippo, Howes, Kara, Belbakra, Abdelhalim, Listorti, Andrea, Schweizer, W. Bernd, Reutenauer, Philippe, Alonso Gómez, José Lorenzo, Chiorboli, Claudio, Urner, Lorenz M, Gisselbrecht, Jean Paul, Boudon, Corinne, Armaroli, Nicola, and Diederich, François

Subjects
chemistry.chemical_classification, electron acceptors, Chemistry, cyanobuta-1, Organic Chemistry, General Chemistry, Electron acceptor, porphyrins, Photochemistry, 7. Clean energy, Acceptor, Porphyrin, Catalysis, Photoinduced electron transfer, photoinduced electron transfer, Electron transfer, chemistry.chemical_compound, Benzonitrile, photoinduced energy transfer, singlet oxygen luminescence, Photoinduced charge separation, Intramolecular force, 3-dienes
Abstract

The synthesis, electrochemical, and photophysical properties of five multicomponent systems featuring a Zn(II) porphyrin (ZnP) linked to one or two anilino donor-substituted pentacyano- (PCBD) or tetracyanobuta-1,3-dienes (TCBD), with and without an interchromophoric bridging spacer (S), are reported: ZnP-S-PCBD (1), ZnP-S-TCBD (2), ZnP-TCBD (3), ZnP-(S-PCBD)2 (4), and ZnP-(S-TCBD)2 (5). By means of steady-state and time-resolved absorption and luminescence spectroscopy (RT and 77 K), photoinduced intramolecular energy and electron transfer processes are evidenced, upon excitation of the porphyrin unit. In systems equipped with the strongest acceptor PCBD and the spacer (1, 4), no evidence of electron transfer is found in toluene, suggesting ZnP→PCBD energy transfer, followed by ultrafast (

Published
2013

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