Cyclophosphazene difference

Proton-decoupled P-NMR spectra can also be used for structural elucidation of mixed substituent containing cyclophosphazenes. Different types of three-spin systems such as AB2, AX2, ABC, ABX or AMX can be observed. Similarly, the P H -NMR spectra of cyclotetraphosphazenes can be diagnostic of the structure of the compound. Usually a combination of proton and phosphorus NMR can be quite useful in arriving at the structure of the cyclophosphazene compounds. 

To evaluate the influence of structural parameters governed by the cyclophosphazene core concerning the valency and the spatial orientation of epitopes, as well as the nature of linkers directly related to the ligation technique used for the mannoside incorporation, the authors performed preliminary kinetic turbidimetric assays with Con A. Insoluble cross-linked complexes formed rapidly for all compounds, without marked difference for the hexavalent analogues. On the other hand, the incorporation of additional mannosyl units led merely to statistical binding-affinity enhancements, notably for the less-dense decamer 194, which presents favorable extended intersugar distances. 

Cyclophosphazene compounds were dissolved just before use in 10 nM NaClO and added to DNA. The final DNA concentration was O.lOmgml" and the reactions were run at room temperature in the dark for several days (2-5 days, depending on the compound). The different cyclophosphazene-DNA complexes corresponded to values of rj (number of cyclophosphazene molecules introduced per nucleotide) varying from 0 to 100 depending on the solubility of the drugs. 

The association constants to a site (K) and the ratio (r) of bound EtdBr per nucleic acid phosphate were determined for the different cyclophosphazene-DNA complexes using Scatchard s method The number Of binding sites per base (n) for the non-complexed DNA has been found equal to 0.20 and the value of K to 1.2 X 10 M, in agreement with previously reported data and... 

A set of cyclophosphazene-DNA matrices was investigated in order to obtain more information about the possible structural modifications of DNA due to the different possible modes of binding of the drugs and to thus gain insight into the origin of their antitumor properties. 

Metal complexes of cyclophosphazenes have aroused considerable interest from both structural and biomedical points of viewO). The coordination of cyclophosphazenes to metal ions occurs in different ways ... 

As a result of the extensive compilation of basicity data for cyclo-triphosphazenes, it has been possible to evaluate substituent constants for different groups (2 78-180). These constants, can be used to calculate the pKa value of a cyclophosphazene derivative containing one or more substituents (179, 180). Hence, a comparison of calculated and observed pKa values can often provide information for the complete characterization of a derivative (180). Basicity data for cyclotetrapho-sphazenes and higher homologs are limited (175, 321), and substituent constants have not been evaluated. 

P NMR study of the chiral configuration of the unsymmetrical substituted cyclophosphazenes (146) and (147), prepared from (136) via (144) and (145), has shown these compounds to be diastereoisomeric each consisting of two different racemic mixtures. The spermine-bridged cyclophosphazenes (148) appear to exist in meso and racemic forms, which for the gfem-diphenyl derivative were separated by column chromatography and investigated by NMR spectroscopy and X-ray structure determinations. ... 

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