Phosphates structure

Figure 10.1 Types of phosphate structures, (a) Where x = 12 to 14, the structure represents sodium polyphosphate, a phosphate typically used in HW heating and industrial steam boiler formulations. The structure is ill defined and described as glassy rather than crystalline. Where x = 2, it represents sodium tripolyphosphate, (b) This is the structure where effectively, x = 0, and represents trisodium phosphate (sodium orthophosphate), which is commonly supplied in either crystalline or anhydrous powder form and used as an alkalinity booster, boiler boil-out cleaner, and metal surfaces passivator.

Kumar, C.V. and Choudhari A. (2000) Proteins immobilized at the galleries of layered alpha-zirconium phosphate structure and activity studies. Journal of the American Chemical Society, 122, 830-837. 

Magnesium, Mg2+ 6, octahedral O-Carboxylate, phosphate Structure in hydrolases, isomerases, phosphate transfer, trigger reactions... 

Muscle glycogen phosphorylase is one of the most well studied enzymes and was also one of the first enzymes discovered to be controlled by reversible phosphorylation (by E.G. Krebs and E. Fischer in 1956). Phosphorylase is also controlled allosterically by ATP, AMP, glucose and glucose-6-phosphate. Structurally, muscle glycogen phosphorylase is similar to its hepatic isoenzyme counterpart composed of identical subunits each with a molecular mass of approximately 110 kDa. To achieve full activity, the enzyme requires the binding of one molecule of pyridoxal phosphate, the active form of vitamin B6, to each subunit. 

Several other iron phosphate structures have been described. The phase Li3Fe2(P04)3 has been stud-... 

A brief summary of their physical properties is provided in Table 14. Their effects on the flammability of the baseline electrolyte are also compared in Figure 75. Apparently, the combination of fluorina-tion with phosphate structure has brought the expected higher efficiency in suppressing burning. For example, with 20% TFP the electrolyte was rendered nonflammable. 

The fifth sapphyrin-phosphate structure to be solved is of the mixed chlo-ride/monobasic cyclic AMP salt of diprotonated sapphyrin 4 (Figure 9). While the general features of binding are similar to the other phosphate ester structures... 

Chemically, it is a challenge to design phosphate receptors. Also, it is of interest to see if the solid-state sapphyrin phosphate structures reflect events in solution. On the biological side, phosphate anions play critical roles in numerous metabolic and energy transduction processes.Also, phosphate entities are present in the active forms of many antiviral agents. ... 

The principles of the above reactions form the basis of a series of important metabolic interconversions involving the coenzyme pyridoxal phosphate (structure 2.41). This condenses with amino acids to form a Schiff base (structure 2.42). The pyridine ring in the Schiff base acts as an electron sink which very effectively stabilizes a negative charge. 

Some phosphate structures commonly used in water treatment are shown in Figure 5.1. 

The chemical shielding anisotropy (CSA) tensors for the simple phosphate structures listed in Table I, were calculated using ab initio methods. The isotropic tensor value (aiso), the three principal components (aa), the CSA anisotropy (Act) and asymmetry parameter (rj) were evaluated and are given in Table II. 

J.S. D Arrigo, Axonal surface charges evidence for phosphate structure, J. Membrane Biol. 22 (1975) 255-263. 

Molecular orbital calculations have also provided theoretical justification for these stereoelectronic effects in tetracovalent and pentacovalent phosphorus species (2-7). As has been shown in molecular orbital calculations on the X -P-X2 (X = 0,N) structural fragments, the X.-P bond is strengthened (as indicated by an increase in the Mulliken overlap population) while the P-X3 bond is weakened when the X atom lone pair is app to the P-X3 bond. Thus, in the g,t conformation of dimethyl phosphate (Structure ll the overlap population for the trans P-0 bond is. 017 electron lower than the overlap population for the gauche P-0 bond. As shown for g,t dimethyl phosphate one lone pair (shaded in 1) on the gauche bond oxygen is app to the trans bond, while no lone pairs on the trans bond oxygen are app to the gauche bond. Thus, the weakest X.-P bond has one app lone pair and no lone pairs on X. app to the P=X2 bond. 1... 

Chemical Name Morphinan, 3,17-dimethyl-, (9a,13a,14a)-, phosphate Common Name Dimemorfan phosphate Structural Formula ... 

Kalckar117118119 has shown that the enzymatic phosphorolysis of inosine (hypoxanthine 9-D-ribofuranoside) may give rise to the formation of a pentose phosphate, isolable as its barium salt. The phosphate was found to be non-reducing although easily hydrolyzed by either acid or alkali to equimolar quantities of phosphate and pentose. In view of these properties and the fact that it could be used for the enzymatic synthesis of purine ribosides, Kalckar has tentatively assigned to it the D-ribose 1-phosphate structure its ring structure and configuration at carbon 1 remain undetermined. 

Phosphorylation of the potassium salt of 2,2,6,6-tetramethylpiperi-3,4-dione (9) by chloro-phosphates (10) and (11) leads to the cyclic phosphate derivative (12) (Scheme 2) <85JOC209l>. This unusual product is formed due to intramolecular nitrogen participation and was characterized by 13C and 3IP NMR. There are no resonances in the 13C NMR spectra which would indicate the presence of an SPr group in the product and the 3IP NMR has a resonance at an unusual upfield shift indicating a cyclic phosphate. Structure (12) is consistent with these findings and with the extensive phosphorus-carbon and phosphorus-hydrogen coupling seen in its NMR spectra. 

In addition to the above one-dimensional structures, a strip-like cobalt phosphate structure has been isolated. The strip consists of two corner-shared chains fused together forming the architecture shown in Fig. 7.5a-c [18]. The one-dimensional linear chains are connected via a three-coordinated oxygen atom, giving rise to such an arrangement. This type of structure could be a key intermediate in the formation of framework solids from the basic one-dimensional chains. 

One can visualize the formation of the two-dimensional structures from the ladders. The ladders can undergo rotation, hydrolysis and condensation to form the layers, as shown schematically in Fig. 7.6. Such layered Zn and Co phosphate structures have been isolated and characterized [ 19-21 ]. 

We now examine a few select examples of three-dimensional metal phosphate structures. A novel iron phosphate, [(C4N3H16)(C4N3H15)] [Fe5F4(H2P04)(HP04)3(P04)3]H20, was prepared recently by employing hydro-thermal methods in the presence of diethylenetriamine (DETA) [29]. The three-dimensional structure can be considered as made from layers along... 

Figure 7.18. Various open-framework zinc phosphate structures formed from a single amine, TETA, by the variation of the synthetic conditions (Choudhury el al. [32]).

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