25128-26-1

Upstream product

• 26985-31-9 methyl viologen cation radical 
• 114987-36-9 C₄₂H₇₀O₃₅*C₁₂H₁₄N₂ 
• 553-26-4 4,4'-bipyridine 
• 74-83-9 methyl bromide 
• 11121-48-5 2,4,5,7-tetraiodo-3',4',5',6'-tetrachlorofluorescein dianion 
• 299-36-5 ascorbate 
• 4685-14-7 1,1'-dimethyl-4,4'-dipyridylium radical cation 
• 714905-09-6 1,1'-Dimethyl-1',4'-dihydro-[4,4']bipyridinyl-1-ium 
• 99352-43-9 [ruthenium(II)(2,2'-bipyridine)2(1,1'-dipyrido[3,2-a:2',3'-c]phenazine)]⁽¹⁺⁾ 
• 71-47-6 formate 

Downstream Products

• 22541-53-3 cobalt(II) 
• 50-00-0 formaldehyd 
• 124-38-9 carbon dioxide 
• 688-57-3 ethylenediamine-N,N,N'-triacetic acid 
• 26985-31-9 methyl viologen cation radical 
• 1081-34-1 2,2':5',2''-terthiophene radical cation 
• 492-97-7 cation radical of 2,2'-bithiophene 
• 11121-48-5 2,4,5,7-tetraiodo-3',4',5',6'-tetrachlorofluorescein dianion 
• 505-73-7 disulfanediyldiacetic acid 
• 4685-14-7 methyl viologen radical cation 
• 4685-14-7 1,1'-dimethyl-4,4'-dipyridylium radical cation 
• 18983-82-9 CO⁽¹⁸⁾O 
• 4685-14-7 Paraquat 
• 55086-02-7 6-hydroxy-5-azatricyclo<4.3.1.1^3,8>undecane 

Relevant academic research and scientific papers

Solvent Effect on the Monomer-Dimer Equilibrium and Dimerization of the 1-Methyl-2-methoxycarbonylpyridinyl Radical

Solvent effects on the hyperfine splitting constants, monomer-dimer equilibrium, and kinetic parameters of the dimerization of the 1-methyl-2-methoxycarbonylpyridinyl radical have been examined in detail, using methylcyclohexane, toluene, 2-methyltetrahydrofuran, acetone, and acetonitrile as the solvents.A comparatively large activation energy for the fast step in the two-step dimerization mechanism suggests strongly that the dimeric intermediate is the 2,2'-dimer of the radical, which subsequently rearranges to the stable 4,4'-dimer.

Electron-Transfer Reactions of Chlorophyll a and Porphyrin Triplets with Radicals in Aqueous Micellar Solutions

The reactivity of the photoexcited triplet states of chlorophyll a (Chla), ZnTPP, and MgTPP (PT) with radicals was studied in neutral micelles by pulse radiolysis and photolysis (PRAP) spectroscopy.Steady-state triplet concentration was produced by a 2-ms light pulse, and the system was then subjected to a 10-ns electron pulse to form the radicals (CH3)2.COH, Br2-., and MV+. from the proper solutes.The triplet states were found to undergo one-electron reduction by (CH3)2.COH and oxidation by Br2-. with second-order rate constants approaching the diffusion-controlled limit and significantly more rapidly than the reactions of the ground states.The reaction of the triplet states (PT) with MV+. radicals was found to result in an overall recovery of the ground-state P from PT.The mechanism of this process is discussed in terms of two steps of electron transfer: PT + MV+. -> P-. + MV2+ -> P + MV+..

Quantitative Electrochemical Kinetics Studies of "Microelectrodes": Catalytic Water Reduction By Methyl Viologen/Colloidal Platinum

The reduction of water by methyl viologen, catalyzed by colloidal platinum, has been extensively studied as a function of pH, radical concentration, and platinum concentration by several independent techniques.The data present a comparative test of a homogeneous kinetic approach and a novel electrochemical approach.Two techiniques were used to monitor the platinum-catalyzed oxidation of methyl viologen radical: conventional and stopped flow mixing experiments, and a novel application of electrocatalytic cyclic voltammetry.Conventional kinetic analysis for homogeneous reactions provides conditional rate constants which are great than first order in platinum.At = 10-6 M and pH 3.0, the conditional rate constant is k = 1.2*104 L mol-1 s-1.In addition, steady state catalysis of hydrogen production analogous to photochemical systems was monitored in a nonphotochemical system, using electrochemically reduced mediators.The methods are critically compared as mechanistic tools.Only data obtained with use of steady state techniques can be quantitatively analyzed by using simple electrochemical theory.The principle findings include the following: (1) a surprising apparent second order rate dependence on colloid concentration is accounted for by electrochemical theory, but not by homogeneous theory; (2) the electrochemical model quantitatively acounts for the shift in pH1/2 with mediator concentration; and (3) with use of electrogenerated mediator an experimental value for log jH20 = -3.4 is obtained for colloidal platinum, in good agreement with the bulk electrode.

Kinetics and Mechanism of the Forward and Reverse Reactions between N,N'-Dimethyl-4,4'-bipyrydinium and Hexacyanoferrate(11)

The kinetics of the hexacyanoferrate(III)-N,N'-dimethyl-4,4'-bipyridinium radical (MV+) reaction was studied by a laser flash photolysis technique.The radical was generated, in the presence of Fe(CN)63-, by quenching the excited state *Ru(bpy)32+ with MV2+.The second-order rate constant for the Fe(CN)63--MV+ reaction is (7.6+/-0.5)x109 M-1s-1 at 23 deg C and ionic strength 0.10 M.Comparison with the rate constants calculated for the diffusion-controlled reaction (4.7x109 M1-s1-) and the activation-controlled reaction (5.2x1012 M1-s1-, on the basis of self-exchange rate constants of 8.0x105 M1-s1- and 1.9x104 M1-s1- for the MV2+/+ and Fe(CN)63-/4- couples, respectively) leads to the conclusion that the Fe(CN)63--MV+ reaction is diffusion controlled.The rate constant for the Fe(CN)64--MV2+ reaction, calculated from the rate constant for the Fe(CN)63--MV+ reaction and the appropriate equilibrium constant, is 2.4x10-5 M-1s-1 at 23 deg C and ionic strength 0.10 M.Microscopic reversibility considerations require that the Fe(CN)64--MV2+ reaction be controlled by the dissociation of the successor complex Fe(CN)63-/MV+.The thermal and optical electron transfers in the ion pair Fe-(CN)64-/MV2+ and in related systems are analyzed and discussed.

Rose Bengal Radicals and their Reactivity

The one-electron oxidised (radical cation) and one-electron reduced (radical anion) forms of the photosensitiser rose bengal have absorption maxima at 470 nm (molar absorption coefficient 21100 dm3 mol-1cm-1) and 420 nm (molar absorption coefficient 37600 dm3mol-1cm1-), respectively.The radical anion (RB.-) undergoes electron-transfer reactions both with oxygen (k=1.5E8 dm3mol-1s-1) and iron(III) complexed with ethylenediamineteteraacetic acid (EDTA) (k=4.5E8 dm3mol1-s1-) and diethylenetriaminepentaacetic acid (DTPA) (k=8.6E8 dm3mol-1s-1).Rose bengal reacts both with solvated electron and semireduced nicotinamide adenine dinucleotide radical (NAD.) to give RB.- with the second-order rate constants of 3.1E10 and 9.6E8 dm3mol1-s1-.The one electron-reduction potential E21 for rose bengal, measured vis pluse radiolysis, was found to be -511 mV.

DESolution of CD and CB Macrocycles

Supramolecular chemistry utilizing the macrocyclic hosts cyclodextrins (CDs) and cucurbit[n]urils (CB[n]s) is traditionally performed in aqueous media; however, their solubility is typically poor, especially for the family of CB[n]s. Through derivatization of these macrocycles their solubility can be augmented to enable enhanced solubility in water and in some organic solvents. The increase in solubility of these derivatized macrocycles allows for their use in a wider range of chemical environments and giving rise to myriad potential applications. The dissolution of parent CDs (α-, β- and γ-) and CB[n]s (n=6–8) in deep eutectic solvents (DES) is reported, showing dramatic enhanced solubility of the larger species in both families, CB[7] and CB[8] as well as β- and γ-CD, respectively. Furthermore, the host–guest properties are maintained in this new solvation medium.

Charge effects in photoinduced electron-transfer reactions between [Ru(bpy)3]2+ and viologen derivatives

Photoexcited *[Ru(bpy)3]2+ is oxidatively quenched by methylviologen (MV2+) and 1,1′-bis(2-carboxyethyl)-4,4′-bipyridinium (BCEBP2+) with a similar rate constant at pH 2.2; kqbs = 1.48×109 and 1.58×109 mol-1 dm3 s-1 (30 °C) for MV2+ and BCEBP2+, respectively. However, *[Ru(bpy)3]2+ is much more slowly quenched by MV2+ than by BCEBP0 at pH 5.0, where the superscript "0" represents that BCEBP is neutral; kqbs = 1.01 × 109 and 1.74×109 mol-1 dm3 s-1 for MV2+ and BCEBP0, respectively. The reverse electron-transfer reaction between [Ru(bpy)3]3+ and one-electron-reduced ·BCEBP+ (krevobs = 3.33×109 mol-1 dm3 s-1) proceeds slightly more rapidly than the reaction between [Ru(bpy)3]3+ and ·MV+ (krevobs = 2.80×109 mol-1 dm3 s-1) at pH 2.2 (30 °C), while the former reaction (krevobs = 5.85×109 mol-1 dm3 s-1) proceeds 2-times as rapidly as the latter reaction (krevobs = 2.74×109 mol-1 dm3 s-1) at pH 5.0. These differences at pH 5.0 between MV2+ and BCEBP0 are interpreted in terms of charge effects on the diffusion and diffusional dissociation of an exciplex and an encounter complex. The electron-transfer reactions in the exciplex and the encounter complex have been analyzed according to Marcus theory. The difference in an electronic coupling matrix element (Hrp) between MV2+ and BCEBP2+ or 0 is discussed in terms of the charge effects and steric effects.

Reductive Quenching of the Luminescent Excited State of Tris(2,2'-bipyrazine)ruthenium(2+) Ion in Aqueous Solution

The photodynamics of aqueous solutions containing Ru(bpz)32+ (bpz=2,2'bipyrazine) and reductive quenchers (D=EDTA (ethylenediaminetetraacetic acid), C2O42-, TEOA (triethanolamine), ascorbate ion, and thiols (RS-), e.g. cysteine and glutathione) in the presence and absence of MV2+ (methylviologen) have been evaluated by the use of time-resolved spectrofluorimetry and pulsed laser flash photolysis as a function of pH, , and 2+>; as well, we have determined Φ(MV.+) from the continuus photolyses of these systems.Values of kq are dependent on pH due to the acid-base properties of the quenchers and range from ca. 3E9 M-1 s-1 for ascorbate ion and deprotonated thiols to ca. 1E7 M-1 s-1 for C2O42-.The oxidized radicals (Dox.) of EDTA, C2O42-, and TEOA may undergo irreversible transformation into reducing radicals (Dred.) within the quenchig solvent cage in competition with geminate-pair back electron transfer; the efficiencies of escape of the redox products (Ru(bzp)3+ and Dred.) into the bulk solution (νce) for these sacrifical quenchers are very high (>0.5).Thiols are semisacrifical quenchers; their oxidized radical (RS.) must escape from the quenching cage before conversion to Dred. (RSSR.-)can occur; νce+ in bulk solution.In the absence of MV2+, Dred. from sacrifical and semisacrifical quenchers reacts rapidly (k>E9 M-1 s-1) with Ru(bzp)32+, generating a second equivalent of the reduced complex.In the presence of MV2+, both Ru(bzp)32+ and Dred. produce MV2.+ rapidly (k=E8-E9 M-1 s-1).Ru(bzp)3+ engages in an acid-base equilibrium (pKa=7.1); the conjugate acid is a poorer reducing agent by ca.0.2 V than is the basic form and is unable to reduce MV2+.As a result, the generation of MV.+ in acidic solution is pH- and 2+>-dependent.The values of Φ(MV.+) from the continuous photolysis correlate very well with the rate constants and efficiencies of the various steps in the mechanism according to the following expression: Φ(MV.+)=ν.*νq*νce*(νred+νred'), where ν. is the efficiency of population of Ru(bzp)32+, νq is the efficiency of quenching of Ru(bzp)32+, and νred and νred' are the efficiencies of the reactions of Ru(bzp)3+ and Dred. with MV2+, respectively.Values of Φ(MV.+) as high as 1.2 have been obtained at pH 4.5 in solutions containing 0.10 M MV2+ and 0.26 M C2O42-.

Rates and Mechanism for Oxidation of Paraquat and Diquat Radical Cations by Several Peroxides

The rates of oxidation of the free radicals MV(+)-radicals and DQ(+)-radicals derived from herbicides Paraquat and Diquat by hydrogen peroxide, peroxodiphosphate species, and peroxodisulfate have been investigated.Where consistent data were obtainable, the reactions are first order each in peroxide and radical.Results for H2O2 and MV(+)-radical are k = 2.0 (M*s)-1 at 25 deg C, ΔH(excit.) = 92 kJ*mol-1, and ΔS(excit.) = 73 J*(mol*K)-1; similar results were found with H2O2 and DQ(+)-radical.Although hydroxyl radicals are likely intermediates, the predicted inhibition when methanol is present did not materialize; a mechanistic rationalization is presented.The rates with peroxodiphosphate were pH dependent and could be interpreted as different contributions from H2P2O8(2-), HP2O8(3-), and P2O8(4-) in the same order as found for peroxodiphosphate and unstable radicals.The rate with S2O8(2-) is fastest, but complications prevented the evaluation of a rate constant.

Tuning radical interactions in trisradical tricationic complexes by varying host-cavity sizes

Although host-guest pairing interactions between bisradical dicationic cyclobis(paraquat-p-phenylene) (BB2(+)) and the bipyridinium radical cation (BIPY+) have been studied extensively, host molecules other than BB2(+) are few and far between. Herein, four bisradical dicationic cyclophanes with tunable cavity sizes are investigated as new bisradical dicationic hosts for accommodating the methyl viologen radical cation (MV+) to form trisradical tricationic complexes. The structure-property relationships between cavity sizes and binding affinities have been established by comprehensive solution and solid-state characterizations as well as DFT calculations. The association constants of the four new trisradical tricationic complexes are found to range between 7400 and 170?000 M-1, with the strongest one being 4.3 times higher than that for [MV?BB]3(+). The facile accessibility and tunable stability of these new trisradical tricationic complexes make them attractive redox-controlled recognition motifs for further use in supramolecular chemistry and mechanostereochemistry.