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.