Rydberg-Valence Interactions in Monoolefins: Dispersing Electronic Properties in 1,1'-Bicyclohexylidene

摘要

Functionalized oligo(cyclohexylidene)s form an attractive class of molecular building blocks for the development of organic materials for (opto)electronic applications because of their longrange electron transfer properties over several molecular units. The compounds are built from 1,4-linked cyclohexylidene units bridging an electron donating and accepting moiety via an alternating σ-π-σ orbital topology. The photoinduced electron transfer process in oligo (cyclohexylidene)s in relation to their orbital topology has been the subject of various studies. He photoelectron spectroscopy (PES), ab initio calculations, and natural bond orbital (NBO) analysis on the basic unit of this class of compounds, 1,1'-bicyclohexylidene (BCH), and of its end-functionalized derivatives have shown that through-bond interactions between the π-system of the exocyclic carbon-carbon bond and the σ-orbitals of the sp~3-hybridized carbon atoms, of appropriate energy and symmetry, in the cyclohexyl rings are the driving force for the charge separation. Time-resolved measurements of photoinduced currents in a system of self-assembled monolayers of the α,ω-bisulfide derivative of BCH on a gold surfaces and CdSe quantum dots corroborate this conclusion: Strong coupling between the two interfaces is provided by the organic spacer bisulfides.