Bulky and Stable Copper(I)-Phenanthroline Complex: Impact of Steric Strain and Symmetry on the Excited-State Properties.

The steric strain around copper(I) in typical [Cu(NN)] complexes, where NN is a diimine ligand substituted in α-positions of the nitrogen atoms by R, is known to strongly impact the excited-state properties. Generally speaking, the larger the R, the longer the emission lifetime and the higher the quantum yield. However, the stability of the coordination scaffold can be at stake if the steric strain imposed by R is too large.

Copper(I) Bis(diimine) Complexes with High Photooxidation Power: Reductive Quenching of the Excited State with a Benzimidazoline Sacrificial Donor.

The reductive quenching of photoexcited photosensitizers is a very efficient way to achieve challenging reduction reactions. In this process, the excited photosensitizer is reduced by a sacrificial electron donor. This mechanism is rarely observed with copper(I) bis(diimine) complexes, which are nevertheless acknowledged as very promising photosensitizers.

Non-Symmetrical Sterically Challenged Phenanthroline Ligands and Their Homoleptic Copper(I) Complexes with Improved Excited-State Properties.

A strategy is presented to improve the excited state reactivity of homoleptic copper-bis(diimine) complexes CuL by increasing the steric bulk around Cu whereas preserving their stability. Substituting the phenanthroline at the 2-position by a phenyl group allows the implementation of stabilizing intramolecular π stacking within the copper complex, whereas tethering a branched alkyl chain at the 9-position provides enough steric bulk to rise the excited state energy E . Two novel complexes are studied and compared to symmetrical models.

Intriguing Effects of Halogen Substitution on the Photophysical Properties of 2,9-(Bis)halo-Substituted Phenanthrolinecopper(I) Complexes.

Three new copper(I) complexes [Cu(L)](PF) (where L stands for 2,9-dihalo-1,10-phenanthroline and X = Cl, Br, and I) have been synthesized in order to study the impact of halogen substituents tethered in the α position of the chelating nitrogen atoms on their physical properties. The photophysical properties of these new complexes (hereafter named Cu-X) were characterized in both their ground and excited states. Femtosecond ultrafast spectroscopy revealed that early photoinduced processes are faster for Cu-I than for Cu-Cl or Cu-Br, both showing similar behaviors.