Organophosphonates systems

Zubieta J., Clusters and solid phases of the oxovanadium-phosphate and -organophosphonate systems, Comments Inorg. Chem. 16 (1994) pp. 153-183. 

The contemporary interest in metal organophosphonate coordination chemistry has received considerable impetus from the applications of such materials as sorbents, catalysts and catalyst supports. The structural chemistry of the metal organophosphonate system is extremely rich " and is represented by mononuclear coordination complexes, molecular clusters, " one-dimensional materials, and layered phases. Extensive investigations have been reported on layered phosphonates of divalent, " trivalent, tetravalent, " and recently hexavalent elements. Several examples of three dimensional metal organophosphonate frameworks have also been described since the first report by Bujoli. " ... 

Salta, J. Chen, Q. Chang, Y.-D. Zubieta, J., The Oxovanadium-Organophosphonate System - Complex... 

Moreover organophosphoric acid esters have found application as insecticides (e.g. Parathion). Some derivatives are highly toxic to man (e.g. Sarin, Soman). The organophosphonates act as inhibitors of the enzyme cholinesterase by phosphorylating it. This enzyme is involved in the proper function of the parasympathetic nervous system. A concentration of 5 x 10 g/L in the air can already cause strong toxic effects to man. 

DF and its precursor, DC are organophosphonic acids. They will react with alcohols to form crude lethal nerve agents, such as crude GB. High overexposure may cause inhibition of cholinesterase activity. Although much less toxic than GB, DF and DC are toxic and corrosive materials. Because DF and DC are relatively volatile compounds, the primary route of exposure is expected to be the respiratory system. However, ingestion also results from inhalation exposures in animals and could occur in humans. DF and DC vapors have a pungent odor and may cause severe and painful irritation of the eyes, nose, throat, and lungs. Data provided is for DF only, DC has similar properties. 

Studies for the organophosphonates include the effects of solution pH on their adsorption onto the anodized aluminum substrates. Mechanisms are discussed for the respective interactions of the lonizable phosphonate and neutral silane compounds with two different polymeric epoxy systems. 

Rosset et al. (2013) reported biodiesel production by esterification of oleic acid with aliphatic alcohols using immobilized Candida antarctica lipase, showing high yields of biodiesel (above 90%) in less than 24 h with ethanol, n-propanol and n-butanol whereas with methanol, the enzyme was inactive after ten ( cles of reaction. In another report, Yin et al. (2013) studied an efficient bifimctional catalyst lipase/organophosphonic acid-functionalized silica (SG-T-P-LS) for biodiesel synthesis by esterification of oleic acid with ethanol. In this system, the process had a conversion ratio reaching 89.94 0.42% under the conditions that the ethanol/acid molar ratio was 1.05 1 and the SG-T-P-LS to free fatty acid weight ratio was 14.9 wt.% at 28.6 C (Yin et al., 2013). 

In 1988, Mallouk and coworkers showed that multilayer films could be prepared simply by sequential complexation of Zr" + and a, >-fe/sphosphonic acid [30]. The technique has been extended to the complexation of organophosphonates with a variety of other metals [31,32], and even to completely different metal-ligand systems [33-38]. The multilayers grown by this technique are well ordered, robust, and relatively easy to prepare. Substrates of any size or shape can be covered, and even noncentrosymmetric multilayers may be obtained [39]. Based on very specific interactions, the technique is, however, restricted to a narrow class of chemical compounds. 

When chemical specificity is called for, a highly selective thin film is one solution. For analytes of major concern— Hg, trichloroethylene, Cr and certain organophosphonates— it may be worthwhile to use a complex, multistep procedure to synthesize a material that responds to a single analyte or narrow chemical class. In a few instances, very simple materials are quite selective for particular analytes examples include gold films to detect mercury (if sulfur compounds are not present to interfere) and palladium films for the detection of hydrogen (unsaturated hydrocarbons can interfere in this case). When such simple, obvious interfaces are unavailable or inadequate, scrutiny of the literature of interfacial chemistry, bulk-phase coordination chemistry, and catalysis (16) may point the way for the development of a tailored interface. But to utilize the one-analyte/one-(new)-film approach for general-purpose chemical detection systems, which could be called upon to recognize tens or hundreds of analytes in the presence of many interferants, is impractical, so alternatives must be examined. 

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