Substituted meta[n]Cycloparaphenylenes: Synthesis, Photophysical Properties and Host-guest Chemistry

Breaking the centrosymmetry of [n]cycloparaphenylenes ([n]CPPs) by one meta connection, leads to bright emission in the typically non-fluorescent smaller derivatives, conserving their size dependent emissive properties. Using the building block strategy for [n]CPPs, different nitrile substituted meta[n]CPPs (n=6, 8, 10) have been prepared. The nitrile substituent offers a convenient handle for functional group conversions (e.g., carboxylic acid, amide, aldehyde, as well as 1H-tetrazole). Besides the synthetic work, the photophysical properties of these novel m[n]CPP derivatives have been characterized. Additionally, the host-guest ability of cyano-m[10]CPP has been explored by studying its complexation with fullerene C-60. These insights open new applications of meta[n]CPPs as fluorophore in synthetic organic chemistry, material sciences as well as biomedical research.