Abstract
π-Conjugated thienylene[n.63743]phenylene oligomers with fluorinated and dialkoxylated phenylene fragments have been designed and prepd. to understand the interactions in fragment orbitals, the influence of the substituents (F, OMe) on the HOMO-LUMO gap, and the role of intramol. non-covalent cumulative interactions in the construction of π-conjugated nanostructures. Their strong conjugation was also evidenced in the gas phase by UPS and theor. calcns. 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 detg. 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 addn., the presence of S[n.8901][n.8901][n.8901]F and H[n.8901][n.8901][n.8901]F interactions in the fluorinated phenylene[n.63743]thienylene compds. add to the S[n.8901][n.8901][n.8901]O interactions in the mixed targets and contribute to the full conjugation in the oligomer, inducing weak inter-ring angles between the involved arom. cycles. These results, which showed extended conjugation of the π system, were corroborated by a narrow HOMO-LUMO gap (according to DFT calcns.) and by a relatively strong max. wavelength (as obtained by TD-DFT calcns. and exptl. UV/Vis measurements). The crystallog. data of two mixed thienylene[n.63743](fluorinated and dialkoxylated phenylene) five-ring oligomers agree with the above results and show the formation of quasi-planar conformations with non-covalent S[n.8901][n.8901][n.8901]O, H[n.8901][n.8901][n.8901]F, and S[n.8901][n.8901][n.8901]F interactions. These studies in the solid and gas phases show the relevance of assocg. dialkoxyphenylene and fluorinated phenylene fragments with thiophene to lead to oligomers with improved electronic delocalization for electronic or optoelectronic devices.