10309-95-2Relevant articles and documents
A Pulse Radiolysis Study of the Leucocyanide of Malachite Green Dye in Organic Solvents
Bobrowski, K.,Dzierkowska, G.,Grodkowski, J.,Stuglik, Z.,Zagorski, Z. P.,McLaughlin, W. L.
, p. 4358 - 4366 (1985)
Microsecond pulse radiolysis studies have been carried out on the leucocyanide of malachite gree dye (MGCN) dissolved in either 1,2-dichloroethane, chloroform, carbon tetrachloride, acetone, cyclohexane, benzene, toluene, dimethyl sulfoxide, N,N-dimethylformamide, methanol, 2-propanol, tetrahydrofuran, dioxane, benzonitrile, or acetonitrile.The transient absorption spectra obtained in argon-saturated solutions, and with various added electron scavengers (N2O, O2, or CCl4), indicate that there are everal intermediate species and radiolytic products.We suggest that one product is the carbonium ion (MG+) of malachite green dye (wavelength of the absorption maximum, λmax = 620 nm) and the other 4,4'-bis(dimethylamino)-triphenylmethyl radical (MG radical, λmax = 400 nm).There is evidence for the formation of an intermediate primary radical cation (MGCN+) and a triplet excited state of malachite green cyanide.In oxygen-depleted solutions the absorbing species with λmax at 620 nm is formed in a fast process completed within the time of the 5,5-μs pulse.However, only in 1,2-dichloroethane solution is this absorption stable during the observation time, whereas in all the other solvents it is unstable and decays within tenths of microseconds, the decay time depending of the solvent.In polar solvents such as Me2SO, DMF, alcohols, and acetonitrile, in the presence of oxygen, formation of the 620-nm absorption takes place in two kinetically distict processes.The first is very fast (much shorter than the 5,5-μs pulse) and the second much slower (lasting tens of microseconds after the pulse).Possible mechanisms for the fast and slow components of radiolytic dye formation are postulated.
Ionic Photodissociation and Picosecond Solvation Dynamics of Contact Ion Pairs
Spears, Kenneth G.,Gray, Timothy H.,Huang, De-yin
, p. 779 - 790 (1986)
We report picosecond spectroscopic studies of the ionic photodissociation dynamics of malachite green leucocyanide (MGCN).The photoexcitation of MGCN in polar solvents forms malachite green (MG(1+)) carbonium ion and cyanide (CN(1-)).The lowest excited state of MGCN has ionic dissociation lifetimes of 0.1-5 ns which are controlled by solvation of an ionic transition state.Classical dielectric solvation models give reasonable transition state parameters for low-viscosity aprotic solvents and alcohol solvents.A higher energy excited state of MGCN rapidly dissociates into ions after radiationless conversion.The recombination yields of the vibrationally excited contact ion pair depend on dielectric constant and are related to vibrational relaxation and longitudinal dielectric relaxation.The initial contact ion pair has MG(1+) in a tetrahedral geometry which subsequently reorganizes to form planar MG(1+) with a delocalized charge.The times of this conversion are observed by transient absorption spectroscopy, and in aprotic solvents they increase with increasing dielectric constant from 6 to 13 ps.This rate behavior in aprotic solvents is characteristic of an activation energy defined by the solvent energetics.However, charge reorganization rates in alcohol solvents are determined by alcohol monomer reorientation times.This is an unusual solvent effect in which a specific solvent motion controls a transition state barrier crossing.The individual steps of ionic dissociation yield an experimental model for solvent effects in nucleophilic reactions.We give a brief, critical review of solvent dielectric relaxation and its application to charge reorganization phenomena.
Mechanism of hydride transfer reaction from 4-(dimethylamino)phenyl methane derivatives to 2,3-dichloro-5,6-dicyano-p-benzoquinone
Yamamoto, Shunzo,Sakurai, Tetsuo,Yingjin, Liu,Sueishi, Yoshimi
, p. 833 - 837 (2007/10/03)
The kinetics of the hydride-transfer reactions from bis[4- (dimethylamino)phenyl] methane (MH2), bis[4(dimethylamino)phenyl] methoxy methane (MHOMe), Leuco Malachite Green (MGH) and Leuco Crystal Violet (CVH) to 2,3-dichloro-5,6-dicyano-p-benzo
