Influence of Hetero‐Biaryl Ligands on the Photo‐Electrochemical Properties of [Re^INCS(N^∩N)(CO)₃]‐Type Photosensitizers

Abstract

A complete set of the symmetrical bidiazine (bdz) and asymmetrical pyridyldiazine (pydz) ligands, along with the known 2,2′-bipyridyl (bpy) ligand, and their respective rhenium(I)-tricarbonyl-bromo and -thiocyonato complexes are presented. A bathochromic shift is observed with an increasing number of nitrogen atoms, caused by a stabilization of the diimine based LUMO. As expected from the energy gap law, this results in an increase in the non-radiative decay constant (k nr ) [a]

Flexible to rigid: IR spectroscopic investigation of a rhenium-tricarbonyl-complex at a buried interface

“…The final product in this reaction is the isothiocyanate (NCS À ). [39][40][41] Fig. 4 (dashed lines) exhibits a NCS À stretching band (the C-N stretching mode of the isothiocyanate ligand) at 0 and 10 ALD cycles, but not for thicker ALD layers.…”

Red Light Absorption of [ReI(CO)3(α-diimine)Cl] Complexes through Extension of the 4,4′-Bipyrimidine Ligand’s π-System

“…When comparing several [Re(CO) 3 (NN)Cl] complexes with different isomers of the bidentate bidiazine ligands, the 4,4′-bipyrimidine ( bpm ) ligand has the lowest-lying π* energy levels [ 28 ], making it a very promising ligand for red-shifted MLCT energies (see compound 1 in Scheme 1 ). The properties of [Re(CO) 3 ( bpm )Cl] ( 1 ) have been reported [ 29 , 35 , 36 ], and we took it as a starting point to further extend the π-system of the bpm ligand. The introduction of some typical aromatic substituents into the 6,6′-position of the bpm (dpb = 6,6′-diphenyl-, dmpb = 6,6′- p- methoxyphenyl-, dnb = 6,6′-(1-naphythyl)-4,4′-bipyrimdine) was reported to yield only minor effects on the photophysical properties [ 35 ]; thus, we decided to introduce fused rings to the bpm ligand to yield 4,4′-biquinazoline ( bqz , compound 2 in Scheme 1 ), as this ligand was reported to significantly red-shift the MLCT absorption of respective Ru(II) complexes [ 37 , 38 ].…”

Synthesis and Photophysical Evaluation of 3,3’‐Nitrogen Bis‐Substituted fac‐[Re(CO)3(Diimine)Br] Complexes

“…The diimine ligands are typically bipyridine (bpy) derivatives due to the favorable photo‐ and electrochemical properties of fac ‐[Re(CO) 3 (bpy)Br] complexes. Namely, these complexes are strongly absorbing in the lower visible range of the solar spectrum with phosphorescence emissions in the orange to red part [1–5] . Excited states are long‐lived [6] showing no loss of carbonyl or diimine ligands [7–10] .…”

“…Generally, fac ‐[Re(CO) 3 (diimine)X] complexes rely on three main derivatization strategies for system optimization. Modification of the diimine ligand allows tailoring of the photophysical behavior of the complex, since the LUMO is largely located on the diimine ligand [4,17,18] . The HOMO, on the other hand, is generally impacted by the rhenium d‐orbitals and the carbonyl ligands.…”