Push-Pull Derivatives Based on 2,4'-Biphenylene Linker with Quinoxaline, [1,2,5]Oxadiazolo[3,4-]Pyrazine and [1,2,5]Thiadiazolo[3,4-]Pyrazine Electron Withdrawing Parts.

A series of novel V-shaped quinoxaline, [1,2,5]oxadiazolo[3,4-]pyrazine and [1,2,5]thiadiazolo[3,4-]pyrazine push-pull derivatives with 2,4'-biphenylene linker were designed and their electrochemical, photophysical and nonlinear optical properties were investigated. [1,2,5]Oxadiazolo[3,4-]pyrazine is the stronger electron-withdrawing fragment as shown by electrochemical, and photophysical data. All compounds are emissive in a solid-state (from the cyan to red region of the spectrum) and quinoxaline derivatives are emissions in DCM solution. It has been found that quinoxaline derivatives demonstrate important solvatochromism and extra-large Stokes shifts, characteristic of twisted intramolecular charge transfer excited state as well as aggregation induced emission. The experimental conclusions have been justified by theoretical (TD-)DFT calculations.