Synthesis, electrochemistry and emission spectroscopy in fluid solution of four isomeric (α-diimine)Re(CO)3Hal complexes

Synthesis, spectroscopic and electrochemical studies of a series of transition metal complexes with amino- or bis(bromomethyl)-substituted dppz-ligands: Building blocks for fullerene-based donor–bridge–acceptor dyads

“…Extension of these shoulders into the red is observed for complexes that are easier to reduce. The lower intensity and higher energy of MLCT bands of complexes (a-diimine)ML n with M = Cu(I) and Re(I) is well established [29][30][31] (see Tables 4 and 5). …”

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

“…The corresponding potentials E 1/2 red (Figure 2, upper row)measures for the LUMO level -are lowered by 151-336 mV for complexes with asymmetric pyridyl-diazine ligands (32)(33)(34)(35), and by 315-616 mV for complexes with symmetric bidiazine ligands (36)(37)(38)(39) as compared to the bpy complex (31, Table 1). The degree of LUMO stabilisation in each series is most pronounced for the complexes bearing 4-pyrimidyl (pm) motives (33 and 37) and least pronounced for the 2-pyrimidyl (pym) motives (35 and 39).…”

“…Colours range from bright yellow (31) to dark red (37), the latter being rather unusual for [Re I X(N ∩ N)(CO) 3 ]-type complexes. Compared to the reference complex 31, the absorption spectra of the isothiocyanate compounds (32)(33)(34)(35)(36)(37)(38)(39) show charge-transfer band maxima at longer wavelengths ( Figure 3). Shifts are between 26 -28 nm for complexes of pypdz (32), pypm (33) and pypz (34), but only 6 nm for the pypym complex (35).…”

“…[34] Compared to representative Ru II -and Os II -polypyridyl complexes, fac-[Re(CO) 3 ] + -type complexes have rather large energy separations between the dπ(M) and π * (diimine) orbitals due to the stabilising effect of the CO ligands. [29,[35][36][37][38][39] A lot of work has been conducted to understand how electronic absorptions are influenced to design photoactive molecules with the desired excited state properties. [35] The vast majority of [ReX(N ∩ N)(CO) 3 ] 0/+ -type complexes, therefore, absorb at the blue edge of the solar spectrum and have a yellow to orange appearance.…”

“…The respective electrochemistry has been studied intensively in the last 50 years leading to a good understanding of the electronic processes. [38] In this work, the gap between bipyridine (bpy) and bidiazine (bdz) complexes is closed by introducing asymmetric pyridyl-diazine (pydz) ligands 12-15 (Scheme 1, right). The diimine ligands, as well as the axial ligands, were varied -for the former bipyridine (bpy) and phenanthroline (phen) derivatives or even larger polypyridyl ligands, for the latter various neutral, anionic as well as alkynyl ligands -and the effects on the photophysical properties were studied.…”