Intramolecular charge transfer in π -conjugated oligomers: a theoretical study on the effect of temperature and oxidation state

Massimiliano Aschi¹ , Maira D’Alessandro², Monica Pellegrino³, Alfredo Di Nola², Marco D’Abramo^{2, 4} and Andrea Amadei⁵ 

(1)  Dipartimento di Chimica, Ingegneria Chimica e Materiali Universita’ di L’Aquila, Via Vetoio (Coppito), 67010 L’Aquila, Italia
(2)  Dipartimento di Chimica, Universita’ di Roma ‘La Sapienza’, P.le A. Moro 5, 00185 Roma, Italia
(3)  Dipartimento di Ingegneria Elettronica, Universita’ di Roma‘La Sapienza’, Via Eudossiana 18, 00184 Roma, Italia
(4)  Barcelona Supercomputing Center, Torre Girona, c/ Jordi Girona, 31, 08034 Barcelona, Spain
(5)  Dipartimento di Scienze e Tecnologie Chimiche, Universita’ di Roma ‘Tor Vergata’, Via della Ricerca Scientifica 1, 00133 Roma, Italy

Received: 15 October 2007  Accepted: 20 December 2007  Published online: 11 January 2008

FULL TEXT

Abstract  Intramolecular charge transfer (ICT) of gaseous π-conjugated oligo-phenyleneethynylenes (OPE) induced by a homogeneous applied electric field has been theoretically investigated using a combined approach integrating molecular dynamics (MD) simulations and Perturbed Matrix Method calculations. In line with recent investigations, our results indicate the peculiar role of conformational transitions on OPE electronic properties which reflects on a strong temperature effect on ICT. Electron transfer reactions inducing chemical alteration on OPE, also taken into account in this study, revealed extremely important for explaining non-linear ICT effects and probably plays a central role in the mechanisms underlying molecular transport junctions. Our study further points out the necessity of using MD-based approach for modelling molecular electronics, even when relatively rigid molecular systems are concerned.

Keywords  Molecular electronics - Intramolecular charge transfer - Molecular dynamics - Quantum chemistry