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

作者：Urner Lorenz M; Sekita Michael; Trapp Nils; Schweizer W Bernd; Woerle Michael; Gisselbrecht Jean Paul; Boudon Corinne; Guldi Dirk M^*; Diederich Francois

来源：European Journal of Organic Chemistry, 2015, 2015(1): 91-108.

DOI：10.1002/ejoc.201403252

• Energy conversion
• Photochemistry
• Donor-acceptor systems
• Electron transfer
• Porphyrinoids

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 Zn-II 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 Zn-II 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.

• 出版日期2015-1