title: 2,3-Diphenylbutadiene and donor-acceptor functionalized derivatives: exploring the competition between conjugation paths in branched pi-systems.
abstract: 2,3-Diphenylbutadiene and its donor-acceptor functionalized derivatives represent branched pi systems consisting of three overlapping linearly conjugated units, namely a 1,3-butadiene and two phenylethene subsystems. The evaluation of pi conjugation using a scheme based on the natural bond orbital analysis shows that the details of the structure of these compounds is governed by electron delocalization. The potential energy surface of 2,3-diphenylbutadiene shows two minima, each one representing a distinct combination of conjugation patterns. These minima are shown to be connected by a low-energy path with transition structures that have one conjugation path fully activated, while conjugation is completely disrupted along the other path. We will show that, in response to donor-accptor functionalization, the 2,3-diphenylbutadiene backbone will switch to other conformations, which come along with substantial changes in the electronic structure.
authors.affiliation: Laboratory of Physical Chemistry, Swiss Federal Institute of Technology, Wolfgang-Pauli-Str. 10, 8093 Zürich, Switzerland.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Limacher
authors.forename: Hans Peter
authors.initials: HP
authors.lastname: Lüthi