Short-conjugated zwitterionic cyanopyridinium chromophores: Synthesis, crystal structure, and linear/nonlinear optical properties

•A new class of zwitterionic cyanopyridinium chromophores was synthesized.•A simple and versatile synthetic method was developed.•The structure of new zwitterions was confirmed by X-ray crystallography.•Zwitterions show excellent film-forming ability, higher loading-levels in polymers.•Doped/grafted nonlinear optical polymers exhibit promising electro-optic properties.

A new class of short-conjugated zwitterionic cyanopyridinium chromophores with the absorption maxima less than 550 nm were designed and synthesized. These chromophores display a good solubility in organic solvents and exist in a charge-separated ground state, as confirmed by IR, X-ray crystallography, negative solvatochromism and fluorescence studies. They can be doped up to 10% by weight into poly(ether sulfone) and attached onto a methacrylate polymer by grafting. Without optimization of the poling conditions, a high electro-optic coefficient can be readily achieved using the chromophore-grafted nonlinear optical polymers.

Graphical abstractA series of short-conjugated zwitterionic cyanopyridinium chromophores were synthesized through a simple and versatile synthetic method. The charge-separated ground state of the zwitterions was confirmed by X-ray crystallography. Negative solvatochromism, fluorescence properties and nonlinear optical property of the new zwitterions were investigated.Figure optionsDownload full-size imageDownload as PowerPoint slide