Intrinsically Switchable Electroactive Fluorophores Based on λ5 -Biphosphinines.

The synthesis and full characterization of a family of stable λ5 -biphosphinines connected in 4,4-position through a variety of π-conjugated bridges is reported. The impact of the π-bridge on the optical (absorption/emission) and redox properties was investigated using a joint experimental/theoretical approach. In contrast to the π-extended ones, the λ5 -biphosphinines directly connected through a C-C bond in 4,4-position display two easily accessible and reversible oxidations highlighting their multi-stage redox character. The in situ formed radical cations are studied by spectro-electrochemistry and electron paramagnetic resonance. Finally, electrochemical modulation of fluorescence (electrofluorochromism) was performed and revealed the potential of these intrinsically switchable electroactive fluorophores for further applications as switchable materials.

Artificial Molecular Ratchets: Tools Enabling Endergonic Processes.

Non-equilibrium chemical systems underpin multiple domains of contemporary interest, including supramolecular chemistry, molecular machines, systems chemistry, prebiotic chemistry, and energy transduction. Experimental chemists are now pioneering the realization of artificial systems that can harvest energy away from equilibrium. In this tutorial Review, we provide an overview of artificial molecular ratchets: the chemical mechanisms enabling energy absorption from the environment. By focusing on the mechanism type-rather than the application domain or energy source-we offer a unifying picture of seemingly disparate phenomena, which we hope will foster progress in this fascinating domain of science.

Tuning the Charge Transfer in λ5-Phosphinines with Amino Substituents.

We report the substitution of λ5-phosphinines (2,6-dicarbonitrile diphenyl-1-λ5-phosphinine) with an amino group. The impact of these modifications on both the optical and redox properties is investigated using a joint experimental/theoretical approach. In particular, we show that the choice of the donor diphenylamino group dramatically impacts the nature of the charge transfer. The use of di(methoxyphenyl)amine redshifts the optical properties and allows thermally activated delayed fluorescence in the solid state. Finally, we demonstrated that λ5-phosphinines with an amino group can be used as active emitters in an electroluminescent device.