4-Diphenylamino-phenyl substituted pyrazine: nonlinear optical switching by protonation

Through the integration of a 4-diphenylamino-phenyl unit with a pyrazine segment, a series of novel organic conjugated molecules with different spacers and shapes have been synthesized and fully characterized. These as-prepared compounds exhibit reversible acidochromism in response to protonation and deprotonation. The investigation of the nonlinear optical (NLO) properties reveals that the neutral forms of these structures display a reverse saturated absorption (RSA), while the protonated forms show a saturated absorption (SA).