Zinc chlorin

Zinc chloride cell Zinc-chlorine cell Zinc chromate... 

Stabilization Mechanism. Zinc and cadmium salts react with defect sites on PVC to displace the labHe chloride atoms (32). This reaction ultimately leads to the formation of the respective chloride salts which can be very damaging to the polymer. The role of the calcium and/or barium carboxylate is to react with the newly formed zinc—chlorine or cadmium—chlorine bonds by exchanging ligands (33). In effect, this regenerates the active zinc or cadmium stabilizer and delays the formation of significant concentrations of strong Lewis acids. 

Other alkaline primary cells couple zinc with oxides of mercury or silver and some even use atmospheric oxygen (zinc—air cell). Frequendy, zinc powder is used in the fabrication of batteries because of its high surface area. Secondary (rechargeable) cells with zinc anodes under development are the alkaline zinc—nickel oxide and zinc—chlorine (see Batteries). 

Environment Internal pH 8.2-7.8, phosphate-zinc, chlorine, 65-100°F (18-38°C), calcium, hardness 300-600 ppm, total alkalinity 45-60 ppm... 

Chlorins, e.g. 14, form adducts with osmium(VIII) oxide, which can be hydrolyzed in aqueous sodium sulfide to bacteriochlorindiols, e g. 2, or isobacteriochlorindiols, e.g. 3. Thus, similar to diimide reductions of chlorins, metal-free tetraphenylchlorin 14 (M = 2H) is selectively oxidized to a corresponding bacteriochlorin 2 whereas the zinc chlorin gives an isobac-teriochlorin 3 on oxidation with osmium(VIII) oxide.40 With less symmetrical chlorins, very complex mixtures of constitutional isomers and stereoisomers are formed by /i-bishydroxyla-tion.17... 

While the zinc/chlorine battery is preferred for utility load-leveling applications [49], the zinc/bromine system is the more promising one for electric vehicle requirements [50, 51]. 

Fig. 9.20 Comb-type bipolar electrodes for zinc-chlorine batteries (a) bipolar stack (b) unit cell...

Other flow batteries investigated for both electric vehicle applications and utility load leveling include zinc-chlorine. Zn-CL, and zinc-bromine, Zn-Br2, batteries. 

It is immediately apparent that the Daniell cell differs from the zinc-chlorine battery in that the electrode materials (i.e., zinc and copper) of the former are both metals that normally exhibit a tendency to lose electrons. If the Daniell cell is to function as a battery, both metals cannot lose electrons—one must lose and the other must gain electrons. In this particular case, the issue can be decided, qualitatively at least, in terms of the order of activity of the metals. From Table 11.1, it should be recalled that zinc is much more active chemically than copper hence zinc might be expected to lose electrons more readily than copper if the metals are in contact with solutions of their ions at the same concentration. It may be inferred correctly that the reactions that occur when the Daniell cell serves as a source of electrical energy are as follows ... 

Any consideration of the requirements to be fulfilled in the construction of battery cells should recognize first that the substances used as electrodes may be, but need not be, produced by electrolysis. In the earlier discussion of the zinc-chlorine battery, both of the substances involved at the two terminals were considered to be the products of a previously conducted electrolysis. However, the zinc-chlorine battery could just as well have been constructed by the use of zinc and chlorine produced by entirely nonelectrolytic methods. You should recall that, in connection with the description of the Daniell cell, no specifications were made with regard to the origin of any of the chemicals involved. This freedom to select suitable materials regardless of their origin or past history follows from the fact that the changes that occur during... 

Roger C, Muller MG, Lysetska M, Miloslavina Y, Holzwarth AR, Wurthner F. Efficient energy transfer from peripheral chromophores to the self-assembled zinc chlorin rod antenna a bioinspired light-harvesting system to bridge the green gap . J Am Chem Soc 2006 128 6542-3. 

Ohkubo K, Kotani H, Shao J, et al. Production of an ultra-long-lived charge-separated state in a zinc chlorin-C(photoinduced electron transfer. Angew Chem Int Ed Eng 2004 43 853-6. 

Figure 4 shows the driving force dependence of the CS rate constants (log / et) and the CR rate constants (log / bet) for a series of free base and zinc chlorin... 

The elemental composition is useful for characterisation of inorganic pigments and organic dyes. However, a database is needed for their identification. In all ballpoint pen inks, sulfur, copper, silicon and phosphorus are present in the elemental composition. Some samples also contain zinc, chlorine, bromine and calcium. In black inks, chromium and lead are additionally found. Samples differ with respect to the elemental composition quantitatively rather than the qualitatively. A greater variability in elemental content is observed for gel inks. 

Zinc chlorins are more easily oxidized than their free base counterparts, and this fact has been used in the design of some chlorin-porphyrin-imide triads that demonstrate multistep electron transfer [16]. For example, triad 47 consists of a zinc chlorin linked to a free base porphyrin that also bears a pyromellitimide acceptor moiety. Phenyl linkers join all active constituents. Excitation of the zinc chlorin moiety of 47 in tetrahydrofuran gives CZ-P-Im, which decays with a 20-ps time constant to yield CZ +-P -Im. This initial charge-separated state evolves into CZ +-P-Im with a lifetime of 120 ps. The CZ -P-Im " state is formed with an overall quantum yield of 0.90 and decays biphasically with time constants of 110 ns and 400 ns. 

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