18099-04-2Relevant academic research and scientific papers
A Proton NMR Study of the Reactions with Acid of meso-Tetraphenylporphyrins with Various Numbers of 4-Dimethylamino Groups
Walter, Robert I.,Ojadi, Emmanuel C. A.,Linschitz, Henry
, p. 13308 - 13312 (1993)
Proton NMR spectroscopy has been used to study the protonation of meso-tetraphenylporphyrins with zero, one, or four para dimethylamino substituents.Changes in the spectra are similar for corresponding protons through this series of compounds.We give the
Direct spectrophotometric measurement of demetalation kinetics of 5,10,15,20-tetraphenylporphyrinatozinc(II) at the liquid-liquid interface by a centrifugal liquid membrane method
Nagatani, Hirohisa,Watarai, Hitoshi
, p. 2860 - 2865 (1998)
The equilibrium and kinetics of the protonation of 5,10, 15,20-tetraphenylporphyrin (H2TPP) and the demetalation of 5,10,15,20-tetraphenylporphyrinatozinc(II) (ZnTPP) at a dodecane-aqueous acid interface were investigated by means of a new in situ spectrophotometric method, the centrifugal liquid membrane method, which can provide the ultrathin two-phase liquid membrane system in a rotating glass cell. The consumption of H2-TPP in the bulk dodecane phase and the production of the diprotonated aggregate, (H4TPP2+)n, adsorbed at the liquid-liquid interface were directly measured from the spectral change. The equilibrium constants of the interfacial aggregation of H4TPP2+ and the demetalation of ZnTPP were determined as log(Ke1/dm6 mol-2) = 2.14 ± 0.07 and log(Ke2/dm9 mol-3) = -6.05 ± 0.04 at 298 K, respectively. The observed rate constant of the demetalation of ZnTPP depended upon the first order of the acidity function, and it was suggested that the rate-determining step is the formation of the monoprotonated intermediate, [ZnTPPH]+, at the liquid-liquid interface. The demetalation rate constant of ZnTPP was determined as k1 = (8.6 ± 1.3) × 10-5 dm3 mol-1 s-1 at 298 K. In the aggregation of H4TPP2+, the rate-determining step was controlled by molecular diffusion of H2TPP in the bulk dodecane phase.
Two-phase stopped-flow measurement of the protonation of tetraphenylporphyrin at the liquid - Liquid interface
Nagatani, Hirohlsa,Watarai, Hitoshi
, p. 1250 - 1253 (1996)
The formation rate of the protonated form of tetraphenylporphyrin (TPP) in a dispersed two-phase system composed of dodecane and aqueous trichloroacetic acid (TCA) was studied by means of a stopped-flow method. The protonation reaction took place at the l
