Synthesis of network polymer emitters: tunable detection of chemicals by geometric design

Conjugated network polymer emitters are potential materials for use as solid detectors of chemicals. We demonstrated the synthesis of fluorescent network polymers through a facile route. Solid-state fluorescent network polymer emitters were synthesized through the Knoevenagel polycondensation of an arylaldehyde (tris(p-formylphenyl)amine) with an arylacetonitrile (phenylenediacetonitrile) in good yields. The molecular structure based on the electron-donor triphenylamine and electron-acceptor cyano-substituted phenylene-vinylene showed a highly efficient solid-state fluorescence. The synthesized model small molecule showed a well-defined solvatofluorochromism: the dielectric constants were esol of approximately 0–50 at λfl of 480–560 nm. The response to solvent chemicals was also shown for the network polymers. Surprisingly, the network polymer linked with para-phenylene-vinylene was only responsive to the solvents with a low dielectric constant (esol ca.