Photophysics of a Ruthenium 4H‐Imidazole Panchromatic Dye in Interaction with Titanium Dioxide

The photophysics of bis(4,4′‐di‐tert‐butyl‐2,2′‐bipyridine‐κ²N,N′)[2‐(4‐carboxyphenyl)‐4,5‐bis(p‐tolylimino‐κN)imidazolato]ruthenium(II) hexafluorophosphate is investigated, both in solution and attached to a nanocrystalline TiO₂ film. The studied substitution pattern of the 4H‐imidazole ligand is observed to block a photoinduced structural reorganization pathway within the 4H‐imidazole ligand that has been previously investigated. Protonation at the 4H‐imidazole ring decreases the excited‐state lifetime in solution. When the unprotonated dye is anchored to TiO₂, photoinduced electron injection occurs from thermally nonrelaxed triplet metal‐to‐ligand charge transfer (³MLCT) states with a characteristic time constant of 0.5 ps and an injection efficiency of roughly 25 %. Electron injection from the subsequently populated thermalized ³MLCT state of the dye does not take place. The energy of this state seems to be lower than the conduction band edge of TiO₂.     

The kinetics of the nitrate radical self-reaction

This article describes the first direct determination of the rate coefficient for the self-reaction between two NO₃ radicals. A laser photolysis technique was used to generate NO₃, and time-resolved decays of NO₃ were followed after stopping the photolysis. The products of the reaction are inferred to be NO₂ and O₂. The derived rate coefficient at room temperature for the self-reaction of (2.3 ± 0.8) ×10^?16 cm³ molecule^?1s^?1 is in excellent agreement with the only other data, which were obtained in an indirect study. Consideration is given to the magnitude and influence of secondary chemistry and to the participation of FO in the chemistry of the NO₃ buildup phase. The studies were conducted over a pressure range of 8 to 100 torr in helium. No clear pressure dependence was observed, and some tentative inferences are drawn both from this result and from the absolute magnitude of the rate coefficient about the mechanism of the reaction. There is apparently no role for the reaction in the chemistry of the atmosphere. © 1993 John Wiley & Sons, Inc.     

Minimization of the acetate interference of calcium-selective carrier-PVC-membrane electrodes for process-controlled haemodialysis

Summary Up to now calcium-selective electrodes with carrier-PVC-membranes have shown a need for correction during their application in controlling the process at an artificial kidney, for the presence of acetate anions leads to immense differences of measurements because of the anion interference. On the basis of experimental research the membrane characteristics could be changed in such a way that there is no need to correct the measurements when the electrodes are used during bicarbonate haemodialyses with 2 mmol/1 acetate. This was achieved by optimizing the ratio of the concentration of synthetic, electrically neutral carrier and lipophilic anion and by using plasticizer effects. A special membrane was developed in the same way for an application in dialysis solutions with 35 mmol/l acetate.     

Die photochemische Anlagerung von Nitrosaminen an Inden

The 1-oximino-2-amino-indane derivatives IV-a and IV-b are formed by the photoaddition reaction of N-nitrosomorpholine and N-nitrosopiperidine with indene. Reduction with LiAlH₄ led to the corresponding amines V-a and V-b supposed to have trans-configuration. Substitution of secondary bases to the chlorine atom in the bis-nitrosochloride II produced compounds of type III which are isomers of IV. The constitution of II was confirmed by conversion to 2-amino-indane (VI).