Increasingly twisted push–pull oligothiophenes and their planarization in confined space
A series of systematically deplanarized push–pull oligothiophenes is designed and synthesized to determine the perfect twist for maximal spectroscopic response to their planarization within lipid bilayer membranes. Weak deplanarization naturally gives weak shifts, but strong deplanarization also gives weak shifts because planarization becomes impossible. Intermediate deplanarization turns out to be ideal. The shifts found in response to chromophore planarization are not as dramatic as with lobsters during cooking but sufficient to discriminate solid-ordered and liquid-disordered membranes with the naked eye.