Photoinduced Aryl Transfer from Imidazolyl-Quinoline π-Conjugated Systems.

Aryl transfer between heteroatoms was photochemically available through radical initiation followed by a bimolecular reaction. However, such an excited-state reaction has rarely been reported through a photoinduced intramolecular pathway in the π-conjugated systems. Herein, we found, for the first time, a clean photoinduced intramolecular aryl shift for imidazolyl-quinoline derivatives (imidazophenanthrene) and (imidazophenanthroline), of which the photoproducts are thermally reversible.

Energy Counterbalance to Harness Photoinduced Structural Planarization of Dibenzo[]azepines toward Thermal Reversibility.

In sharp contrast to most photoinduced structural planarization (PISP) phenomena, which are highly exergonic and irreversible processes, we report here a series of a new class of PISP molecules, 9-phenyl-9-tribenzo[]azepine () and its derivatives, where PISP is within the thermally reversible regime. The underlying foundation is the energy counterbalance along PISP, where upon electronic excitation the azepine core chromophore undergoes planarization to gain stabilization from a cyclic 4 π conjugation ( is an integer; Baird's rule). Concurrently, the C═C fused benzene ring is prone to gain aromaticity, which conversely decreases the 4 π-electron resonance stabilization of the 9-tribenzo[]azepine, hindering a full planarization.

How an Eight-Membered Ring Alters the Rhodamine Chromophore.

Readily available phenylene-1,3-diamines can be converted into unprecedented analogues of rhodamine and malachite green possessing a central eight-membered ring in three steps. The overall process couples a cyanine chromophore with a urea bridge giving rise to new dyes possessing distinct spectral characteristics: absorption of orange light combined with a weak emission of red light both in solution and in the crystalline state. Their photophysics is governed by the twist of lateral phenyl rings and intramolecular and intermolecular CT transitions.