title: Comprehensive analysis of fragment orbital interactions to build highly π-conjugated thienylene-substituted phenylene oligomers.
abstract: π-Conjugated thienylene-phenylene oligomers with fluorinated and dialkoxylated phenylene fragments have been designed and prepared to understand the interactions in fragment orbitals, the influence of the substituents (F, OMe) on the HOMO-LUMO gap, and the role of intramolecular non-covalent cumulative interactions in the construction of π-conjugated nanostructures. Their strong conjugation was also evidenced in the gas phase by UV photoelectron spectroscopy and theoretical calculations. These results can be explained by the crucial role of the relative energetic positions of the π orbitals of the dimethoxyphenylene, which was used to model the dialkoxyphenylene entity, in determining the π/π(*) orbital levels of the fluorinated phenylene entity. Dialkoxyphenylenes raise the HOMO orbitals, whereas fluorinated phenylenes lower the LUMO orbitals in the oligomers. In addition, the presence of S⋅⋅⋅F and H⋅⋅⋅F interactions in the fluorinated phenylene-thienylene compounds add to the S⋅⋅⋅O interactions in the mixed targets and contribute to the full conjugation in the oligomer, inducing weak inter-ring angles between the involved aromatic cycles. These results, which showed extended conjugation of the π system, were corroborated by a narrow HOMO-LUMO gap (according to DFT calculations) and by a relatively strong maximum wavelength (as obtained by TD-DFT calculations and experimental UV/Vis measurements). The crystallographic data of two mixed thienylene-(fluorinated and dialkoxylated phenylene) five-ring oligomers agree with the above results and show the formation of quasi-planar conformations with non-covalent S⋅⋅⋅O, H⋅⋅⋅F, and S⋅⋅⋅F interactions. These studies in the solid and gas phases show the relevance of associating dialkoxyphenylene and fluorinated phenylene fragments with thiophene to lead to oligomers with improved electronic delocalization for electronic or optoelectronic devices.
authors.affiliation: Institut Charles Gerhardt, UMR 5253 CNRS, Equipe AM2N, Ecole Nationale Supérieure de Chimie de Montpellier, 8, rue de l'Ecole Normale, 34296 Montpellier Cedex 05, France.
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Florès
authors.forename: Marie-Agnès
authors.initials: MA
authors.lastname: Lacour
authors.forename: Xavier
authors.initials: X
authors.lastname: Sallenave
authors.forename: Françoise
authors.initials: F
authors.lastname: Serein-Spirau
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Lère-Porte
authors.forename: Joël J E
authors.initials: JJ
authors.lastname: Moreau
authors.forename: Karinne
authors.initials: K
authors.lastname: Miqueu
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Sotiropoulos
authors.forename: David
authors.initials: D
authors.lastname: Flot
mesh_terms: D003516:Cycloparaffins / Q000737:chemistry*; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D056951:Photoelectron Spectroscopy; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D003516:Cycloparaffins; D006845:Hydrocarbons, Fluorinated; D013876:Thiophenes