10309-95-2Relevant academic research and scientific papers
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.
Synthesis and characterization of N-demethylated metabolites of malachite green and leucomalachite green
Cho, Bongsup P.,Yang, Tianle,Blankenship, Lonnie R.,Moody, Joanna D.,Churchwell, Mona,Beland, Frederick A.,Culp, Sandra J.
, p. 285 - 294 (2007/10/03)
Malachite green (MG), a triphenylmethane dye used to treat fungal and protozoan infections in fish, undergoes sequential oxidation to produce various N-demethylated derivatives (monodes-, dides(sym)-, dides(unsym)-, trides-, and tetrades-) both before and after reduction to leucomalachite green (LMG). The close structure resemblance of the metabolites with aromatic amine carcinogens implicates a potential genotoxicity from exposure to MG. The availability of the synthetic standards is important for metabolic and DNA adduct studies of MG. This paper describes a simple and versatile method for the synthesis of MG, LMG, and their N-demethylated metabolites. The synthesis involves a coupling of 4-(dimethylamino)-benzophenone or 4-nitrobenzophenone with the aryllithium reagents derived from appropriately substituted 4-bromoaniline derivatives, followed by treatment with HCl in methanol. The resulting cationic MG and their leuco analogues showed systematic UV/vis spectral and tandem mass fragmentation patterns consistent with sequential N-demethylation. The extensive 1H and 13C spectral assignments of the metabolites were aided by the availability of 13C7-labeled MG and LMG. The results indicate the existence of a resonance structure with the cationic charge located in the central methane carbon (C7). The synthetic procedure is general in scope so that it can be extended to the preparation of N-demethylated metabolites of other structurally related N-methylated triphenylmethane dyes.
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
The Relative Electrophilic Reactivities of Tropylium Cation and its (OC)3M ?-Complexes: Kinetic Studies of Alkoxide Transfer and Reversible Nucleophilic Addition
Lal, Kasturi,Leckey, Nigel T.,Watts, William, E.,Bunton, Clifford A.,Mhala, Marutirao M.,Moffatt, John R.
, p. 1091 - 1098 (2007/10/02)
?-Complexation of the tropylium cation (Tr)(1+) with an (OC)3Cr group increases thermodynamic stability (ΔpKR+ ca. 4.3 in methanol) and reduces reactivity towards abstraction of methoxide ion from Malachite Green methyl ether (MG)OMe (krel. ca. 110) in MeNO2 - MeCOEt (40:60 v/v) and nucleophilic exoaddition of methanol (krel. ca. 2100) in methanol.The organometallic cation (1a) is stable in aqueous solutions of pH(1+), (1+), and (1+) in MeNO2-MeCOEt (40:60 v/v) are 1:10:6, respectively.The rates of transfer to (Tr)(1+) of alkoxide ion from (η-7-exo-alkoxycycloheptatriene)Cr(CO)3 complexes (2a-d) in MeCN decrease through the series: alkoxy=methoxy>ethoxy>isopropoxy>t-butoxy, but the overall rate change is only about five-fold.In methanol, the 7-exo-methoxycycloheptatriene complex (2a) is about ten times more reactive towards acid heterolysis than is methyl tropyl ether.This conversion is general acid-catalysed.In aqueous solutions of pH>ca. 6, the rate of spontaneous heterolysis of the ether (2a) is substantially faster than that of consumption of the resulting cation (1a) which increases with increasing pH.The 7-endo-methoxy stereoisomer (3) is inert to acid heterolysis in aqueous solutions to give cation (1a), but undergoes decomplexation to give (Tr)(1+).
