Phosphonic acid-functionalized

A series of 1-aminoalkanediphosphonic acids has been reported by the treatment of the N-phenylthiourea derivatives of a>-diethoxyphos-phinoylaldehydes with triphenyl phosphite.343 This constitutes an approach toward the analogues of aspartic and glutamic acid in which both carboxylate sites have been replaced by phosphonic acid functions. A similar approach has also been reported to be of use for the preparation of (diphenyl ester) phosphonate analogues of ornithine, lysine, and homolysine.344345... 

For the synthesis of peptides, the phosphonic moiety in most cases should be masked as a diester. Diesters of 1-aminoalkylphosphonic acids can be synthesized directly or by esterification of 1-aminoalkylphosphonic acids. If peptides with the free phosphonic moiety are the desired products, then methods are available for the selective removal of both ester groups. Peptides with a free C-terminal phosphonic acid functionality can be synthesized directly from the free 1-aminoalkylphosphonic acids. In addition, methods for synthesis of the peptides with C-terminal phosphonates directly from the peptides are also available. In general, most methods for the synthesis of peptide bonds work well for the synthesis of peptides with C-terminal phosphonates if diesters of 1-aminoalkylphosphonic acids are used. Bulky diaryl esters give yields similar to the diethyl esters. Therefore, the most challenging step in the synthesis of peptide phosphonates is the synthesis of 1-aminoalkylphosphonic acids and/or their esters. It is not possible in this section to review all of the literature data and only examples of several general methods are included. This will still provide a variety of methods for the efficient synthesis 1-aminoalkylphosphonic acids, their esters, and related peptide derivatives. 

K. H. Nam and L. L. Tavlarides, Synthesis of a high-density phosphonic acid functional mesoporous adsorbent, application to Chromium(III) removal, Chem. Mater. 17, 1597-1604 (2005). 

Not many publications report performance data with BAM s membranes. The only publication we are aware of is by Stone et al., which also discusses the possibility of introducing a phosphonic acid functionality [98]. Figure 27.55 shows the performance data from this source. 

C. Stone, T.S. Daynard, L.Q. Hu, C. Mah, and A.E. Steck. Phosphonic acid functionalized proton exchange membranes for PEM fuel cells. Journal of New Materials for Electrochemical Systems 3, 43-50 2000. 

These compounds were synthesized because it was noticed that several competitive inhibitors of the NMDA receptor had alpha-amino carboxylic acid and phosphonic acid functionalities separated by 3-5 carbons. All of the inhibitors shown in Fig. 11.11 have K- values for inhibition of the NMDA receptor of 10 juM or less. In general, nitrogen substituents larger than those shown decrease receptor affinity. In addition, substitution on the second nitrogen decreases affinity. 

This is directly evidenced by the echo attenuation of the proton resonance in PFG-NMR experiments of phosphonic acid functionalized oligomer [104], Only the echo of the phosphonic protons is attenuated ivhile the echo of the oligomer protons is only slightly affected by the magnetic field gradient (Fig. 23.9). The reader may recall that complexation of phosphoric acid and a basic polymer does not show any sign of this effect (see Fig. 23.7), which opens the way to the development of true single ion conductors. 

Stokes, K.K., Henze, K., and McCullough, R.D., New phosphonic acid functionalized, regioregular polythiophenes. Macromolecules 36, 7114—7118, 2003. lovu, M.C. et al., Regioregular poly(3-alkylthiophene) conducting block copolymers, Polymer 46, 8582-8586, 2005. 

Binsu VV, Nagarale RK, Shahi VK (2005) Phosphonic acid functionalized aminopropyl triethoxysilane-PVA composite material organic-inorganic hybrid proton-exchange membranes in aqueous media. J Mater (Them 15 4823 831... 

David et al have tested these new diblock copolymers as additives for adhesion/anticorrosive properties of metals. In order to protect against corrosion, a coating system was prepared consisting of a blend of poly(VDF) (inhibiting water penetration) with poly(MMA)-Z)-poly(monophosphonic acrylate) diblock copolymer with 10 wt% [compared to poly(VDF)]. This diblock copolymer was obtained by atom transfer radical polymerization using post-functionalization and hydrolysis to introduce the phosphonic acid function onto the polymeric backbone. The anticorrosive properties of virgin poly(VDF) were also determined without any additive to be compared... 

Similar to phosphoric acid, phosphonic acids are intrinsically proton conductive. However, phosphonic acids can he covalently attached to polymers in order to prevent leaching. Comparative studies of sulfonic acid, imidazole, and phosphonic acid functionalized model eompounds have indicated that phosphonie acids possess attractive features for applications in high-temperature PEMFCs. This has spawned extensive research in recent years to prepare and study phosphonated polymers as proton conductors under low humidity eonditions. ... 

In addition to the effect of the PEI moiety, we have also compared the effect of two chemical modification methods (A-methylene phosphonation and quatemization) on the transfectability of the CP copolymer. A-methylene phosphonation is a chemical approach to increase the water solubility of chitosan via the introduction of the phosphonic acid function (Heras et al. 2001) whereas quatemization is an old process that comprises methyl iodide-mediated N, N, A-trimethylation for the fabrication of chitosan soluble in water at the physiological pH (Thanou et al. 2002). In weighing... 

K. K. Stokes, K. Heuze and R. D. McCullough. New phosphonic acid functionalized, regioregular polythiophenes. 

Y. Zhang, B. Yue, S. Han, L. Yan, Synergetic proton conducting effect in acid-base composite of phosphonic acid functionalized polystyrene and triazolyl functionalized polystyrene, RSC Adv. 4 (2014) 33702-33712. 

Such thin-film assembly is not limited to silica surfaces it has been extended to other surfaces, such as gold and germanium (231). Film construction is initiated by first depositing a bifunctional thiol on gold or amino silane on germanium surfaces such that a spacer consisting of phosphonic acid function is... 

Steininger H, Schuster M, Kreuer KD, Maier J (2006) Intermediate temperature proton conductors based on phosphonic acid functionalized oligosiloxanes. Solid State Ionics 177 2457-2462... 

H. R. Allcock, M. A. Hofmann, C. M. Ambler, S. N. Lvov, X. Y. Zhou, E. Chalkova, J. Weston, Phenyl phosphonic acid functionalized poly[aryloxyphosphazenes] as proton-conducting membranes for direct methanol fuel cells, J. Membr. Sci. 201, 47-54 (2002)... 

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