Dynamic proton-induced emission switching in donor-functionalized dehydrobenzopyrid[15]annulenes.

An isomeric pair of 15-membered dehydrobenzopyridannulenes functionalized with -NBu(2) groups as pi-electron donors was prepared and their steady-state spectroscopic parameters investigated. The property differences arising from placement of the pyridine nitrogen relative to the macrocycle, as well as the differential effects of stepwise protonation of the acceptor and donor nitrogens, were examined. The macrocycles exhibited dynamic shifting in the emission spectra, which is believed to correlate to induced changes in the frontier molecular orbitals of the molecules.