Ruthenium complexes with 1,4,5,8-tetraazaphenanthrene. Unusual photophysical behavior of the tris-homoleptic compound

Oligonucleotide Duplexes with Tethered Photoreactive Ruthenium(II) Complexes: Influence of the Ligands and Their Linker on the Photoinduced Electron Transfer and Crosslinking Processes of the Two Strands

“…The conjugates were dissolved in CH 3 The concentrations of the metallated oligonucleotides were determined optically by using the absorption coefficient value ε given in the literature for the free complexes. [22,29] The concentration of the complementary strands was determined by using the absorption coefficient value ε at 260 nm (complementary strand to sequence 0 and 1, ε = 205600  -1 cm -1 and 199300  -1 cm -1 , respectively). The duplex solutions were prepared from equimolar single-strand solutions in aqueous buffer (50 m NaCl, 10 m Tris, pH 7).…”

“…Indeed, whereas [Ru(tap) 2 2+ it was shown that as a result of its high percentage of thermal activation from the 3 MLCT to the 3 MC state, it can undergo loss of one of the ligands, which results in photosubstitution. [22] This process can be monitored by recording UV/Vis absorption spectra in which the MLCT band at 400 nm is bleached upon irradiation and is replaced by a new band around 500 nm, with a characteristic isosbestic point at 450 nm. Absorption in the 500 nm region is typical of [Ru II (tap) 2 XY] n+ (X and Y are H 2 O or Cl -).…”

“…Absorption in the 500 nm region is typical of [Ru II (tap) 2 XY] n+ (X and Y are H 2 O or Cl -). [22] To check whether the functionalization of the complex could modify this photodechelation process, the changes in the UV/Vis spectra of [Ru(tap) 2 under irradiation were monitored (see Figure S1 in the Supporting Information, A and B, respectively). It turned out that no effect of the derivatization was observed, as [Ru-(tap) 2 tap"] 2+ photodechelates like its non-derivatized counterpart (isosbestic point at 450 nm), whereas [Ru(tap) 2 -phen"] 2+ was insensitive to light irradiation.…”

Photoadducts of Metallic Compounds with Nucleic Acids − Role Played by the Photoelectron Transfer Process and by the TAP and HAT Ligands in the RuII Complexes

“…It has been demonstrated (see later) that the 3 MLCT (metal to ligand charge-transfer) state of this complex is efficiently thermally activated to a 3 MC (metalcentred) state, which produces a rather high quantum yield of photodechelation (loss of a ligand under illumination). [26] Therefore, [Ru(TAP) 3 ] 2ϩ exhibits, under illumination, a higher probability of substitution of one of its TAP ligands by a DNA base than complexes with lower photodechelation quantum yields. The photoreactivity of this complex in the presence of AMP has been studied by UV/Vis absorbance and laser flash photolysis, [25] and it indicates the formation of [Ru(TAP) 2 …”

Laser Induced Electrical Transients at Semiconductor Electrodes

“…This occurs in a variety of systems: 1. photoemission of electrons from a metal electrode into an electrolyte [1,2], 2. charge carrier injection from the electronic excited state of an adsorbed molecule into the depletion layer of a wide band gap semiconductor [3,4], and 3. into the surface layer of an organic insulating crystal such as anthracene [5,6], 4. electron-hole pair generation in the surface layer of a semiconductor with subsequent discharge of the minority carriers into the electrolyte [6,7], 5. generation of excitons in the surface layer of an organic crystal with subsequent charge transfer at the interface [8], 6. lightdriven electron-hole pair separation in a functionalized membrane in contact with an electrolyte [9,10].…”