“…These peak assignments are consistent with previously published 31 P NMR data. Magic angle spinning 31 P NMR studies of Zr(O 3 PCH 2 COOH) 2 in which all phosphonate groups are bound to zirconium metal revealed a 31 P isotropic chemical shift near 0 ppm, and solution-phase chemical shifts of phosphonic acids generally fall in the range of −16 to −37 ppm. , 2 Solid state MAS 31 P NMR spectra (a−d) of samples A−D.…”
Section: Resultsmentioning
confidence: 99%
“…Additionally, a number of solid state NMR studies have been undertaken to investigate immobilized transition metal catalysts on solid supports − and surface modification of chromatographic substrates. − Solid state NMR studies of metal−phosphonate systems have been reported by two other groups. Studies by Thompson and co-workers have focused on elucidating structural features using chemical shift anisotropic powder patterns − and on studying the intragallery reaction chemistry of layered zirconium bis(phosphonoacetic acid). , Gao and Reven have recently reported the use of 13 C and 31 P solid state NMR to study conformation of carbon chains and extent of metal−phosphonate cross-linking in partial monolayers of octadecylphosphonic acid on zirconated fumed silica …”
Solid state static and magic angle spinning (MAS) 31 P NMR have been used to assess the efficiency of hydrolysis of surface-bound phosphonate ester moieties using variations of two hydrolysis reactions. Inefficient phosphonate ester hydrolysis has limited the quality of polar hafnium R,ω-bis(phosphonate) multilayer films with nonlinear optical properties prepared in our laboratory. To incorporate second-order nonlinear optical (NLO) activity into self-assembled films, oriented monolayers are prepared using NLO chromophores with a phosphonic acid moiety on one end of the molecule and a phosphonate ester group on the other. After the phosphonic acid end is bound to a surface metal layer, the terminal ester must be converted to a phosphonic acid group via hydrolysis in order to bind additional metal and bis(phosphonate) layers. Such hydrolysis reactions are well-known in solution but are not necessarily efficient when one of the reactants is confined to a surface. To determine the best method of hydrolysis for surface-bound phosphonate esters, 10-(diethylphosphonate)decylphosphonic acid was self-assembled onto Hf-functionalized Cab-O-Sil to give a high-surface-area silica with surface phosphonate ester groups. Samples were hydrolyzed via two different chemical methods under varying conditions. Phosphonic acid and phosphonate ester surface groups have distinct signatures in their solid state static and MAS 31 P NMR spectra, and the latter technique provides an unambiguous assessment of the efficiency of different hydrolysis procedures. This type of study is of general utility for evaluating a wide variety of surface reactions.
“…These peak assignments are consistent with previously published 31 P NMR data. Magic angle spinning 31 P NMR studies of Zr(O 3 PCH 2 COOH) 2 in which all phosphonate groups are bound to zirconium metal revealed a 31 P isotropic chemical shift near 0 ppm, and solution-phase chemical shifts of phosphonic acids generally fall in the range of −16 to −37 ppm. , 2 Solid state MAS 31 P NMR spectra (a−d) of samples A−D.…”
Section: Resultsmentioning
confidence: 99%
“…Additionally, a number of solid state NMR studies have been undertaken to investigate immobilized transition metal catalysts on solid supports − and surface modification of chromatographic substrates. − Solid state NMR studies of metal−phosphonate systems have been reported by two other groups. Studies by Thompson and co-workers have focused on elucidating structural features using chemical shift anisotropic powder patterns − and on studying the intragallery reaction chemistry of layered zirconium bis(phosphonoacetic acid). , Gao and Reven have recently reported the use of 13 C and 31 P solid state NMR to study conformation of carbon chains and extent of metal−phosphonate cross-linking in partial monolayers of octadecylphosphonic acid on zirconated fumed silica …”
Solid state static and magic angle spinning (MAS) 31 P NMR have been used to assess the efficiency of hydrolysis of surface-bound phosphonate ester moieties using variations of two hydrolysis reactions. Inefficient phosphonate ester hydrolysis has limited the quality of polar hafnium R,ω-bis(phosphonate) multilayer films with nonlinear optical properties prepared in our laboratory. To incorporate second-order nonlinear optical (NLO) activity into self-assembled films, oriented monolayers are prepared using NLO chromophores with a phosphonic acid moiety on one end of the molecule and a phosphonate ester group on the other. After the phosphonic acid end is bound to a surface metal layer, the terminal ester must be converted to a phosphonic acid group via hydrolysis in order to bind additional metal and bis(phosphonate) layers. Such hydrolysis reactions are well-known in solution but are not necessarily efficient when one of the reactants is confined to a surface. To determine the best method of hydrolysis for surface-bound phosphonate esters, 10-(diethylphosphonate)decylphosphonic acid was self-assembled onto Hf-functionalized Cab-O-Sil to give a high-surface-area silica with surface phosphonate ester groups. Samples were hydrolyzed via two different chemical methods under varying conditions. Phosphonic acid and phosphonate ester surface groups have distinct signatures in their solid state static and MAS 31 P NMR spectra, and the latter technique provides an unambiguous assessment of the efficiency of different hydrolysis procedures. This type of study is of general utility for evaluating a wide variety of surface reactions.
“…An almost constant shift of ∼7 ppm between these peaks was observed, and following this chemical shift trend, the remaining resonance at −6.2 ppm was assigned to H 3 PO 4 units. 31 P CP-MAS spectra recorded at low spinning frequency also indicated a weak chemical shift anisotropy (<20 ppm) ruling out the presence of a phosphonate environment . It should be noted that, in addition to these main lines, a peak of very weak intensity (<0.5%) at a chemical shift (−33.6 ppm) characteristic of pyrophosphate units was also observed.…”
Different routes for preparing zirconium phosphonate-modified surfaces for immobilizing biomolecular probes are compared. Two chemical-modification approaches were explored to form self-assembled monolayers on commercially available primary amine-functionalized slides, and the resulting surfaces were compared to well-characterized zirconium phosphonate monolayer-modified supports prepared using Langmuir-Blodgett methods. When using POCl3 as the amine phosphorylating agent followed by treatment with zirconyl chloride, the result was not a zirconium-phosphonate monolayer, as commonly assumed in the literature, but rather the process gives adsorbed zirconium oxide/hydroxide species and to a lower extent adsorbed zirconium phosphate and/or phosphonate. Reactions giving rise to these products were modeled in homogeneous-phase studies. Nevertheless, each of the three modified surfaces effectively immobilized phosphopeptides and phosphopeptide tags fused to an affinity protein. Unexpectedly, the zirconium oxide/hydroxide modified surface, formed by treating the amine-coated slides with POCl3/Zr(4+), afforded better immobilization of the peptides and proteins and efficient capture of their targets.
“…We expect that DMPA will form a strong complex with Zr 4+ based on a wealth of literature covering the formation of Zrphosphates and phosphonates [3,[12][13][14][15][16][17][18][19][20][21][22][23][25][26][27][28][29]31,[34][35][36][37][38]. For the other phospholipid head groups, intuition suggests that steric considerations would preclude the efficient formation of a ZP complex with a phospholipid.…”
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