Pyrene is a polycyclic
aromatic hydrocarbon and organic
dye that
can form superior bichromophoric systems when combined with a transition
metal-based chromophore. However, little is known about the effect
of the type of attachment (i.e., 1-vs2-pyrenyl) and the individual position of the pyrenyl substituents
at the ligand. Therefore, a systematic series of three novel diimine
ligands and their respective heteroleptic diimine-diphosphine copper(I)
complexes has been designed and extensively studied. Special attention
was given to two different substitution strategies: (i) attaching
pyreneviaits 1-position, which occurs most frequently
in the literature, orviaits 2-position and (ii)
targeting two contrasting substitution patterns at the 1,10-phenanthroline
ligand,i.e., the 5,6- and the 4,7-position. In the
applied spectroscopic, electrochemical, and theoretical methods (UV/vis,
emission, time-resolved luminescence and transient absorption, cyclic
voltammetry, density functional theory), it has been shown that the
precise choice of the derivatization sites is crucial. Substituting
the pyridine rings of phenanthroline in the 4,7-position with the
1-pyrenyl moiety has the strongest impact on the bichromophore. This
approach results in the most anodically shifted reduction potential
and a drastic increase in the excited state lifetime by more than
two orders of magnitude. In addition, it enables the highest singlet
oxygen quantum yield of 96% and the most beneficial activity in the
photocatalytic oxidation of 1,5-dihydroxy-naphthalene.