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14N NMR Spectroscopy for detection of binding interaction between sodium azide and hydrated Fullerene by titration method
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1  University of Santiago de Compostela


The presence of human pharmaceutical compounds in surface waters is an emerging issue in environmental science. Low levels of many active pharmaceutical ingredients are detected in the aquatic environment as a result of pharmaco-chemical industrial waste spill-offs in draining water.   In the manufacturing of pharmaceutical drug substances azides are used as reagents or when they are generated somehow in the synthesis, it may be necessary to demonstrate that these impurities are sufficiently removed to levels below an appropriate safety threshold.  Sodium azide is an example of an azide for which the environmental exposure limits have been reasonably well characterized. The treatment of waste and industrial water can be conducted by removing dissolved materials and ions in water using membrane separation technology with ultra- and nanofiltration (NF) and reverse osmosis (RO) membranes. To achieve better effluent water quality, tertiary treatment with activated carbon adsorption is used.  To analyze the risk of pharmaceuticals in the environment, a proposed validated methodology by NMR spectroscopy will support the evaluation of the eco-toxicological hazards during the early development process of pharmaceuticals.

Keywords: sodium azide; fullerene; 14N NMR spectroscopy; nanofiltration
Comments on this paper
Humbert G. Díaz
Are there studies of the effect of fullerene funcionalization?
Dear authors,

One question. It is known that fullerenes can be functionalized by chemical synthesis attaching different substituents (-COOR, OR, etc.) to the the fullerene. Do you know previous studies on the effect of fullerene functionalization over nanofiltration and over this method in particular?

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Tamar Chachibaia
Thank you for your question.

Many studies considering the removal of toxic anions from natural waters and purified wastewaters by means of RO and NF have been performed and in significant part of them promising results were obtained (Velizarov et al, 2004).

Surface modification of NF membranes is well reviewed and documented by Liu et al 2011.

By Chae et al. (2009) was developed method of dip coating with Fullerenes of NF membranes.

Besides coating of NF by Fullerenes in water treatment are used carbon filters containing Fullerenes.

Our study is the first attempt to study interaction between NaN3 and Fullerenes by means of non-chemical reaction based approach.

14N NMR spectroscopy we considered as one of the most suitable methods for the characterization of azides to show resonance signals corresponding to the three non-equivalent nitrogen atoms.
Azides are dipoles and have ambiphilic nature, which means that they can react with electrophiles and nucleophiles at the same time

Molecules of Fullerenes contain 30 double bonds of 6- and 5- member cycles. Carbon-carbon bond distances are frequently used to describe and predict the regioselectivity of reaction on a fullerene compound. [6,6] bonds present the shortest bond distances as a result of the higher electronic density, on the other hand, [5,6] bonds are usually larger. Shorter C-C bond distances are in principle associated with enhanced reactivity, as they exhibit more double bond character that facilitates the interaction with dipoles. Reactions of [6,6] bonds of Fullerene are nucleophilic in nature, the property, which allowed non-chemical interaction between C60 and NaN3.