Alternating furanylene-meta-phenylene oligomers: synthesis and photophysics

A range of alternating furanylene-meta-phenylene oligoaryls of different chain lengths is synthesized by a convergent/divergent protocol from the annulation of a propargylic dithioacetal and an aldehyde with a propargylic dithioacetal moiety as a substituent. The emission properties of these oligomers showed chain-length dependent in poor solvent such as cyclohexane. Time resolved fluorescence spectroscopic analyses indicate that there might be intramolecular interaction between the chromophores in 2c-e and such interaction became more prominent as the chain-lengths increased from 9 to 21. Since oligomers 2 have meta-phenylene and 2,5-furnaylene linkages, the oligomers 2e, may likely be folded to enable intrachain chromophore-chromophore interactions. In addition, these oligomers are electrochemically active and the first oxidation potentials are chain-length dependent.