Photochemische Primärprozesse von Xanthenfarbstoffen. II. Blitzlichtspektroskopische Untersuchungen zum Einfluß von anionischen Mizellen auf die photochemischen Primärprozesse von Selenopyronin

Photochemical Primary Processes of Xanthene Dyes. II. Investigations of the Influence of Anionic Micelles on the Primary Processes of Selenopyronine by Flash Excitation In aqueous solutions containing anionic micelles, the dye cations of selenopyronine are present at the micellar surface. If the concentration of the dye ions is much lower than the concentration of micelles, only monomolecular triplet decay (k₁^aM = 2 · 10⁻³s⁻¹) is observed. Under these conditions, the half-oxidized and half-reduced form of selenopyronin is not formed. If the concentration of the dye ions is much higher than the concentration of micelles, two or more dye ions are present at every micelle, and a fast bimolecular decay of the triplet state during the flash is observed. The quenching of the triplet state with p-benzoquinone (k₇^aM = 1,9 · 10⁹ l/mol s), DABCO (k₁₀^aM = 1,6 · 10⁷ l/mol s) and EDTA (k₁₁^aM = 1,3 · 10⁵ l/mol s) and the decay processes of the half-reduced and half-oxidized form in the micellar solution are investigated.     

Fotochemische Primärprozesse von Xanthenfarbstoffen. V. Untersuchungen zum Mizelleinfluß auf die fotochemischen Primärprozesse von Erythrosin

Photochemical Primary Processes of Xanthene Dyes. V. Investigations of the Influence of Micelles on the Photochemical Primary Processes of Erythrosine The triplet state of erythrosine decays in water solution mono- and bimolecularly (k₁ = 0,85 · 10⁴ s⁻¹; k_bi = 7,6 · 10⁸ l/mol s). As results of the bimolecular triplet decay a half-reduced and a half-oxidized form of the dye are observed. The dye ions are localized in the Stern layer of cationic micelles. The triplet state of those dye ions, which are localized individually at micelles, decays only monomolecularly (k = 2,1 · 10³ s⁻¹). If two or more dye ions are localized at a micelle, the bimolecular triplet decay takes place during the flash. Anionic micelles have no influence on the triplet decay processes of erythrosine.     

Fotochemische Primärprozesse von Xanthenfarbstoffen. VIII. Zum Einfluß von gemischten Mizellen auf die fotochemischen Primärprozesse von Selenopyronin und Erythrosin sowie die sensibilisierte Diazoniumsalzfotolyse

Photochemical Primary Processes of Xanthene Dyes. VIII. Influence of Mixed Micelles on the Photochemical Primary Processes of Selenopyronine and Erythrosine and the Sensitized Photolysis of Diazonium Salts The influence of the nonionic detergent dodecyltriglycol (DTG) on the escape rate of dye ions from cationic and anionic micelles is investigated. The rate constant of the escape of selenopyronine ions (Sp^⊕) from mixed micelles of sodium dodecylsulfate (NDS) and DTG (1:1) (k_A ≈︁ 3,2 · 10⁴ s⁻¹) is, as a result of the lower charge density, higher by the factor 10 than that from clean NDS-micelles (k_A ≈︁; 2,8 · 10³ s⁻¹). Erythrosine ions (Et^2⊖) are tightly fixed to cetyltrimethylammoniumbromide (CTAB)-micelles (k_A ≈︁; 0,25 · 10³ s⁻¹) and to mixed micelles of CTAB and DTG (1:1). This may be a result of the twofold negative charge of the erythrosine ions. Properties of the mixed micelles (polarity, average aggregation numbers) are determined by using the dyes and pyrene as probes. The sensitized photolysis of diazonium salts by electron transfer from photoexited selenopyronine under aerobic conditions is more effective by a factor of 3–5 in the presence of anionic micelles than when in a water solution.     

Photochemische Primärprozesse von Xanthenfarbstoffen. III. Blitzlichtspektroskopische Untersuchungen zum Einfluß von kationischen Mizellen auf die Photoredoxprozesse von Selenopyronin

Photochemical Primary Processes of Xanthene Dyes. III. Investigations of the Influence of Cationic Micelles on the Photoredox Processes of Selenopyronine by Flash Excitation Cationic micelles have no influence on the decay of the triplet state of selenopyronine (³F⁺). The products of photoredox reactions ³F⁺ + ³F⁺ (F⁺) → F^· + F and ³F⁺ + DABCO → F^· + DABCO live longer in the presence of the cationic micelles. The reason for the change of the lifetime is a separation of the photoredox products by micelles. F^. is stored in the interior of the micelles. The positively charged F and DABCO are repelled from the micelles and the electron back transfer is hindered.     

Vinylpolymerisation mit reduzierenden Übergangsmetallverbindungen. VII. Polymerisation von Methylmethacrylat in Gegenwart von Molybdän(III)-chlorid-Sulfoxid-Systemen

Vinyl Polymerization Initiated by Reducing Compounds of Transition Metals. VII. Polymerization of Methyl Methacrylate in the Presence of Molybdenum(III) Chloride/Sulfoxide Systems The polymerization of methyl methacrylate initiated by the molybdenum(III) chloride/dimethyl sulfoxide redox system was carried out at 70° in 1, 4-dioxane. The rate of polymerization can be described by the equation R_p = k · [MoCl₃]^0,5 · [DMSO]^0,5 · [MMA]^1,0. The overall activation energy was estimated to be 36.0 kJ/mol. It was found that diethyl, dipropyl, dibutyl, diphenyl and dibenzyl sulfoxides could also initiate the polymerization of methyl methacrylate in the presence of molybdenum(III) chloride, whereas vanadium(II) chloride, vanadium(III) chloride, titanium(III) chloride and chromium(II) acetate are inactive in combination with sulfoxides.     

Untersuchungen zur Spin-Trapping-Kinetik in Systemen von Radikalen unterschiedlicher Reaktivität. Die Photolyse von α-Phenylbenzoin in Gegenwart von Benzyliden-tert.-butylamin-N-oxid

Investigations on Spin-Trapping Kineties in Radical Systems with Different Reactivity. Photolyses of α-Phenylbenzoine in the Presence of Benzylideneter. -butylamine N-oxide As a model system to study the spin-trapping kinetics of systems forming two radicals of different reactivity α-phenylbenzoine (PhB) was chosen. The photolysis of PhB forms benzoyl (B·) and diphenylketylradikals (K·), respectively, which can be trapped by benzylidene-tert-butyl-amine N-oxide (PBN), as a spin trap. The rate constants of radical addition to PBN and their reactions with the spin adducts were determined by means of flash photolysis and kinetic calculations of the PBN concentration dependence. For B· and K· addtion rate constants to PBN of k₁ = 8,1 × 10⁵ M⁻¹s⁻¹, and k₂ = 5,8 · 10⁴ M⁻¹s⁻¹, respectively, were found. The rate constants for the reactions of B· and K· with the spin adducts are in the order of 10⁹…10¹⁰ M⁻¹s⁻¹.     

TPA‐PPEs – New alternating donor copolymers for potential application in photovoltaic devices

A series of phenyleneethynylene copolymers with triphenylamine units as hole‐transporting moieties (TPA‐PPEs) were synthesized by the palladium‐catalyzed cross‐coupling polycondensation of diethynyltriphenylamines and selected dihalogen comonomers, for instance substituted benzene, thiophene, benzothiadiazole, or anthracene. Incorporation of the electron‐rich amino group into the PPE backbone does not interrupt the main chain conjugation. Furthermore, it has a decreasing effect on the oxidation potential, thus makes these polymers interesting as hole‐injection/hole‐transporting materials. The chemical structure of the new alternating copolymers was confirmed by ¹H and ¹³C NMR spectroscopy and elemental analysis and gel‐permeation chromatography (GPC; THF, M_n ≈ 15,000–30,000 g/mol) was conducted. Furthermore, their optical properties were investigated by UV/vis spectroscopy. The TPA‐PPEs exhibit absorption maxima at around 400 nm (π‐π*), except anthracene containing copolymer 3f (λ_max = 514 nm in THF) and benzothiadiazole containing one 3g (λ_max = 503 nm in THF). The TPA copolymers have oxidation potentials about 1.1 V (Ag/AgCl). They are good photoconducting materials ( 3a : I_Photo = 4 × 10^?10 A at 425 nm (400 V), 3g : I_Photo = 1.3 × 10^?11 A at λ_max = 500 nm (20 V)) and show emission after excitation at around 450 nm (560 nm 3f ). Their application in nonoptimized polymer solar cells (bulk heterojunction) led to power conversion efficiencies of around 1–1.8% after illumination with 100 mW/cm² of AM1.5. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Struktur und elektrische Leitfähigkeit von polymeren organischen Halbleitern

In this review article we want to give information about low molecular and polymer organic semiconductors, which were recently synthesized in our institute. Specific electric conductivities up to σ_298°K = 9.0 · 10^?5Ω^?1 · cm^?1 and thermic activation energies of E = 0.30 eV of polyenearylenes, respectively -heteroarylenes were measured. Polyazomethines have a maximum σ_298°K = 3.3 · 10^?9Ω^?1 · cm^?1 and E = 0.35 eV. Polymers with indophenine units have conductivities up to σ_298°K = 1.1 · 10^?4Ω^?1 · cm^?1 and E = 0.39 eV. A maximum of σ_298°K = 5.0 · 10^?2Ω^?1 · cm^?1 and E = 0.05 eV was found for bis-(1.2-dicyanoethylenedithiolo)-metal salts. Polymers with a phthalocyanine- or hemiporphyrazine-like structure achieve a conductivity of σ_298°K = 2.3 · 10^?2Ω^?1 · cm^?1 and E = 0.15eV. Coordination polymers of dimercaptomaleic acid, respectively their monoamide show a maximum of σ_298°K = 3.2 · l0^?lΩ^?l · cm^?1 and E = 0.20 ev. Polymers with σ_298°K ≤1.5 · 10^?5 Ω^?l · cm^?l and E ≥ 0.5 eV were obtained by the polymerization of succinonitrile. All the investigated substances show an electronic conductivity. The existence of an ionic conductivity could, in all cases, be excluded by using direct current measurements over a long period of time.     

Photopolymerization of methyl methacrylate with the triethylamine-bromine charge transfer complex as photoinitiator

The triethylamine-bromine (TEA-Br₂) charge transfer complex was employed as photoinitiator in the photopolymerization of methyl methacrylate under light of 440 nm. The initial rate of conversion was 0.418%/min with an induction period of 56 min. The initiator and monomer exponents were 0.5 and 1.0, respectively. The polymerization was inhibited in the presence of hydroquinone but oxygen had a very little inhibitory effect. The value of k/k_t was 5.13 · 10^?2 l/mol · s and the activation energy was 19.18 kJ/mol. The rate constant for the decomposition of the charge transfer complex (k_ε) was 4.61 · 10^?6 1/s. Kinetic data and other evidence indicate that the overall polymerization takes place by a radical mechanism.     

Photocatalytic degradation of 2,2‐bis(4‐hydroxy‐3‐methylphenyl) propane (BPP) based on molecular recognition interaction

BACKGROUND: Endocrine disruptors in the aquatic environment and their potential adverse effects are currently issues of concern. One of these endocrine disruptors is 2,2‐bis(4‐hydroxy‐3‐methylphenyl)propane (BPP). In this work the molecular recognition interaction of BPP with β‐cyclodextrin (β‐CD) was studied using IR spectroscopy and steady state fluorescence spectroscopy, and the photocatalytic degradation behaviour of BPP based on molecular recognition interaction was investigated in a TiO₂/UV–visible (λ_max = 365 nm) system. This might provide a new method for the treatment of some organic pollutants in wastewater. RESULTS: β‐CD reacts with BPP to form a 1:1 inclusion complex, the formation constant of which is 4.94 × 10³ L mol^?1. The photodegradation rate constant of BPP after molecular recognition by β‐CD showed a 1.42‐fold increase in the TiO₂/UV–visible (λ_max = 365 nm) system. The photodegradation of BPP depended on the concentration of β‐CD, the pH value, the gaseous medium and the initial concentration of BPP. The photodegradation efficiency of BPP with molecular recognition was higher than that without molecular recognition. After 100 min of irradiation the mineralisation efficiency of BPP after molecular recognition by β‐CD reached 94.8%, whereas the mineralisation efficiency of BPP before molecular recognition by β‐CD was only 40.6%. CONCLUSION: The photocatalytic degradation of BPP after molecular recognition by β‐CD can be enhanced in the TiO₂/UV‐visible (λ_max = 365 nm) system. This enhancement is dependent on the enhancement of the adsorption of BPP, the moderate inclusion depth of BPP in the β‐CD cavity and the increase in the frontier electron density of BPP after molecular recognition. Copyright © 2008 Society of Chemical Industry     

On the photolysis of hydroxy alkylphenones and o-substituted derivatives. Laser flash photolysis and photocuring studies

1-Phenyl-2-acetoxy-2-methyl-propanone-1 (III) and 1-phenyl-2-methoxy-2-methyl-propanone-1 (IV) were irradiated at room temperature with 15 or 25 ns flashes of 265 nm or 347 nm light in Ar-saturated cyclohexane or benzene solution. Transient absorptions and emissions were recorded as a function of time between 300 and 550 nm. Triplet lifetimes of III in cyclohexane and benzene and of IV in p-dioxane were determined as ca. 2 μs. In contrast to the photolysis of 1-phenyl-2-hydroxy-2-methyl-propanone-1 (compound I) and of 1-[4-(2-propyl)-phenyl]-2-hydroxy-2-methyl-propanone-1 (compound II), α-cleavage occurs upon UV irradiation of III and IV to a minor or negligible extent. Triplets of III were found to react effectively with N-methyldiethanol amine, but a reaction with cyclohexane did not become noticeable. They react with O₂ with k(T + O₂) = 1.6 · 10⁹ l/mol s. Triplets of IV react with cyclohexane with k(T + CH) = 8.6 · 10⁵ l/mol s and with O₂ with k(T + O₂) = 1.1 · 10⁹ l/mol s. They are inert towards p-dioxane. Photocuring of a transparent acrylate coating system yielded the following results on the basis of pendulum hardness measurements: I and II exhibit excellent initiator effectivity, III and IV are not capable of initiating curing if applied without coinitiator, e.g. N-methyldiethanol amine. In the presence of the latter III and IV exhibit satisfactory curing capability. In conclusion: the high curing effectivity of I and II is due to the high yield and the high rate of α-cleavage. III and IV do not undergo α-cleavage and therefore do not initiate curing. The curing capability of III and IV in the presence of a coinitiator is due to the formation of ketyl radicals by a hydrogen transfer mechanism.     

Optical properties of bis-(2,4,6-trimethylpyridine)iodine(I) cation: absorption and emission

With regard to its electronic structure, the cation Icoll₂⁺ (coll = collidine or 2,4,6-trimethylpyridine) is viewed as a coordination compound of iodine(I) with a p⁴ electron configuration. The lowest-energy excited state of Icoll₂⁺ is suggested to be a ππ^* collidine intraligand (IL) triplet which appears in absorption (λ_max=332 nm, ε=250) and emission (λ_max=405 nm, φ=0.001, τ∼90 ns). Owing to the heavy-atom effect of iodine this phosphorescence occurs at r.t. The longest-wavelength pp absorption is apparently obscured by the intense spin-allowed IL band at λ_max=268 nm.     

Flash photolysis investigation on primary processes of the sensitized polymerization of vinylmonomers. III. Photoreactions of benzoin compounds and stationary polymerization experiments

Benzoin (B), benzoinacetate (BA), benzoinmethylether (BME) and benzoinisopropylether (BIPE) were irradiated at room temperature in benzene solution in the presence of styrene (St), methyl methacrylate (MMA), vinylacetate (VAc) or acrylonitrile (AN). Flash photolysis experiments at λ=347 nm yielded (a) rate constants k_q (in 1 mol^-1s^-1) of the reaction between excited sensitizers and monomers: 8·10⁹ (B/St), 5·10⁸ (B/MMA), 5·10⁹ (BA/St), 8·10⁸ (BA/MMA); (b) rate constants K^R.+M (in 1mol^-1 s^-1) of the reaction between sensitizer radicals and monomers: about 1.5·10⁵ (BME/St, BME/VAc, BA/VAc, B/VAc), 9· 10⁴ (BME/MMA), 2·10⁴ (BME/AN). The reaction R·+M caused in certain cases (B/St, B/VAc, BME/St) the formation of an additional optical absorption after the flash. Stationary irradiations at λ>320 nm of monomer solutions (5mol/1) showed that BA is least effective. Rates of polymerization increased in the series BA<B<BIPE<BME. For the systems containing St or MMA it was found that ?_i=_i+0.6α_R (?_i=quantum yield for the initiation of kinetic chains, α_R =fraction of triplets converted to radicals). The fraction of radicals starting kinetic chains is ca. 0.3 in these cases.     

Photooxidation von Leukofarbstoffen. VIII. Kurzzeitspektroskopische Untersuchungen zum Mechanismus der Photooxidation von Leukokristallviolett

Photooxidation of Leuco Dyes. VIII. Time Resolved Investigations of the Mechanism of the Photooxidation of Leucocrystal Violet The photooxidation of leucocrystal violet has been reexamined by means of conventional and laser flash photolysis as well as spin trap experiments. Three radical transients have been observed and assigned to the cation radical (λ_max ≈ 490, 530 nm), the neutral radical with one NCH₃ CH₂ moiety (λ_max ≈ 480 nm) and the triphenyl methyl radical derivative (λmax ≈ 400 nm).     

Die Wahl des optimalen Verfahrens für die Bestimmung des Primärradikalabbruchs aus Geschwindigkeitsdaten

The various plots for estimating the ratio of rate constants characteristic for primary radical termination, k₅/k₁k₂, have been examined systematically. Apart from the special case d ≡ k₃k₆/k₅² = 1 there is no exact linear relationship between the general quantity \documentclass{article}\pagestyle{empty}\begin{document}${\rm Y \equiv (\sqrt {c_S} c_{M}/v_{Br})^{n}}$\end{document} and the general variable \documentclass{article}\pagestyle{empty}\begin{document}${\rm X \equiv (\sqrt {c_S} /c_M)^{s} (v_{Br}/c_M^{2} )^{1 - s}}$\end{document}. In any case, however, Y can he expressed as a power series of X. Therefore the best way to obtain the most favourable linear representation of Y as a function of X is to choose s and n according to the condition that the coefficient of the term quadratic in X has to disappear (n ? 2 s + d = 0) and the coefficient of the X³-term also equals 0 or is at least close to 0. Under these conditions even those data can be represented in an almost perfect linear form which show variations of the quantity \documentclass{article}\pagestyle{empty}\begin{document}$({\rm \sqrt{c_{s}}c_{M}/v_{Br})}$\end{document} by a factor of \documentclass{article}\pagestyle{empty}\begin{document}$\sqrt{2}$\end{document} or more for different initiator concentrations c_s. If additionally allowance is made for the consumption of monomer by the initiation process the desired ratio of rate constants, k_s/k₁k₂, is obtained from the plot of Y vs. X according to the equation The application of this method is illustrated using an example from literature.     

On the primary processes of sensitized photopolymerization of vinylmonomers. Laser flash photolysis studies and stationary polymerization experiments

The absorption spectra of the triplets of aromatic ketones used as photosensitizers for the polymerization of unsaturated compounds — benzophenone (BP), 3,3′,4,4′-tetramethoxycarbonylbenzophenone (TMCB) and 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) — were recorded after irradiation of benzene or acetone solutions of the ketones with 25 ns flashes from a frequency doubled ruby laser (λ = 347,1 nm) at room temperature. Furthermore, the spectra of the respective ketyl radicals were measured. Rate constants of the reaction of triplets with various monomers were measured. Very high rate constants (> 10⁹ 1 · mol^?1 s^?1) were found for styrene (St) and N-vinylpyrrolidone (VP). The triplet energy E_T of these monomers is smaller than E_T of the sensitizers, except the case BP/VP. Other monomers — vinylacetate (VAc), methylmethacrylate (MMA), acrylonitrile (AN) — react relatively slowly with sensitizer triplets (5 × 10⁶ to 1.4 × 10⁸ l · mol^?1 s^?1). It is assumed that these monomers have E_T values higher than the E_T values of the sensitizers. The rate of polymerization v was determined in tetrahydrofuran solutions containing monomer (5 mol/1) and sensitizer (6–7 × 10⁴ mol/1) from stationary experiments with irradiation of light with λ > 320 nm. The probabilities, α_R, for the initiation of polymerization derived from the rate constants of triplet quenching by the monomers were correlated with the measured rates of polymerization. In accordance with expectation it was found that St and VP did not polymerize and that in the cases of VAc, MMA and AN a significant polymerization takes place (in the absence of sensitizer the rates v were negligibly small). For MMA v is proportional to α.     

Energetics of Pseudomonas cepacia G4 growth in a chemostat with phenol limitation

Analysis of the growth of Pseudomonas cepacia G4 on phenol in continuous culture has been carried out. The data were checked for consistency using both available electron and carbon balances. Coupled with the covariate adjustment estimation technique, the best estimates for true biomass energetic yield, η_max and maintenance, m_e, were obtained when the carbon dioxide measurements were excluded. However, upon making corrections to the gas measurements, the best estimates were the maximum likelihood estimates (MLE) based on the complete data. The method therefore allows discrimination to be made between data. Also, similar estimates were obtained using Pirt's model based on the Monod approach and a modified form based on substrate uptake rate being the limiting factor. For the aerobic growth of P. cepacia G4 on phenol, η_max = 0·417 and m_e = 0·0513 h^?1 were obtained when the CO₂ data were excluded. When corrections were made to the gas measurements to take into account the dissolved CO₂ and the effect of operating temperature, η_max = 0·432 and m_e = 0·0684 h^?1 were obtained. From the 95% confidence intervals, a maximum of about 38–47·5% of the energy contained in phenol is incorporated into the biomass while the balance (52·5–62%) is evolved as heat with only a little energy needed for the maintenance of the organism.     

Absorption and emission spectrum of bis-(triphenylphosphine)-dicarbonylnickel(0)

The complex Ni⁰(PPh₃)₂(CO)₂ shows a red photoluminescence (λ_max=650 nm) at r.t. It is suggested that this emission originates from a Ni⁰→PPh₃ metal-to-ligand charge transfer triplet.     

Factors affecting catalytic performance in yadh-catalyzed reductions in non-conventional media

The effects of parameters including water content, the amount of celite and the co-factor regeneration system on reduction of benzaldehyde to benzyl alcohol by yeast alcohol dehydrogenase (YADH) immobilized on celite in non-conventional media were investigated. Kinetic parameters (apparent) such as V_max, K_m, and k_car for different organic solvents used (butyl acetate, hexane, heptane and i-octane) were determined. K_m values for benzaldehyde increased as the solvent was varied in the following manner: butyl acetate < hexane < i-octane < heptane. The highest K_m value (20.26 mmol/L) was noted in heptane and the lowest (3.24 mmol/L) in butyl acetate. The V_max value in heptane was more than an order of magnitude higher than that in butyl acetate. Catalytic efficiencies (as expressed by k_car/K_m) ranged from 0.703 × 10^?4 L/mol · s for hexane to 0.171 × 10^?4 L/mol · s for butyl acetate. In general, linear relationships were observed between k_car/K_m and the following solvent physico-chemical constants: dielectric constant logarithm of the saturated molar solubility of water in the organic solvents, log S_w/o, logarithm of partition coefficient of organic solvent in water/octanol two-phase system, log P, Hildebrand solubility parameter, δ, and solvatochromism of pyridinium-N-phenoxide betaine dye, ET(30).     

Reactions of Photoexcited Triplet States of Zinc Porphyrin with Transient Radicals in Aqueous Solutions

The technique of simultaneous pulse radiolysis and photolysis, PRAP, has been utilized to study the reactions of various radicals with ground state ZnTPPS and the triplet state ZnTPPS^T in aqueous solutions. The radicals H and OH add to both states with k ∼ 1 × 10¹⁰ M⁻¹ s⁻¹. The CH₂C(CH₃)₂OH radical from t-BuOH is relatively inert toward ZnTPPS but reacts rapidly (k = 1.8 × 10⁹ M⁻¹ s⁻¹) with ZnTPPS^T to form an adduct. Electron transfer reactions are found to be about an order of magnitude faster with the triplet than with the ground state. The (CH₃)₂COH radical reduces both ZnTPPS (k = 1 × 10⁸ M⁻¹ s⁻¹) and ZnTPPS^T (k = 3 × 10⁹ M⁻¹ s⁻¹) to the anion radical (ZnTPPS)⁻. The radical Br⁻₂ oxidizes both states to the cation radical (ZnTPPS)⁺ with k = 8 × 10⁸ M⁻¹ s⁻¹ for the ground state and 5 × 10⁹ M⁻¹ s⁻¹ for the triplet. The transient cation Cd⁺ reduces both states with a diffusion-controlled rate (k = 1 × 10¹⁰ M⁻¹ s⁻¹) to produce the anion radical. The above mechanisms of radical addition and electron transfer are also supported by the product spectra.