Synthesis and characterization of cross-conjugated cruciforms with varied functional groups

A series of novel oligo(p-phenylenes) (OPPs) derivatives with bisdiene side-chains are synthesized and fully characterized. These cruciforms are soluble in common organic solvents and show good thermal stability. Absorption and emission spectra are recorded to study the effect of different electron-withdrawing and electron-donating groups on photophysical properties. Powder XRD shows crystalline structures for all the cruciforms. Single crystal XRD studies show tight-packing along the planar bisdiene axis but significant twisting along phenylene units, which correlate the role of functionalization along the bisdiene axis in tuning the band gaps of the cruciforms.