Bicyclic-Ammonium-Incorporated Ylidic Nitrogen Groups for Strong π‑Electron Donation in Push–Pull Benzene π‑Conjugated Systems

Ylidic nitrogen-based π-electron-donating groups, (quinuclidinio)­amidyl (QA) and (1-azanorbornanio)­amidyl (ANA) groups, were developed to shift the absorption of push–pull benzenes toward longer wavelengths. Changing the pyrrolidinyl group to the QA or ANA group achieved a bathochromic shift of 45–100 nm in the maximum absorption wavelength, depending on the push–pull π-conjugated system investigated (p-nitrobenzene, 1,8-naphthalimide, and an azo dye).