The use of natural and unnatural amino acids has many biomedical applications, including methods of pharmaceutical development and delivery, tissue engineering and mutangenesis. However, there is a challenge the efficiency of synthetic methods. One synthetic method relies on metal complexation of a glycine Schiff’s base to protect the amino and carboxyl groups of the glycine. While there have been several modifications of the ligand system employed by this method, recent alterations have included the incorporation of various electron withdrawing groups. These alterations are hypothesized to increase the acidity of the C-H bond on the α-carbon of the glycine, thus allowing for milder conditions thus increasing the generality and efficiency of the method. In our previous work, we have have determined the pKa’s of the α-carbon of a series of glycine metal complexes through UV-Vis spectrophotometric methods of analysis in non-aqueous solvent conditions. While UV-Vis analysis was a method that could be used to monitor changes in equilibrium in our system, we recognized that there may be examples where a chromophore may not be present in the sample and other methods would be needed for analysis. We have worked on developing a method of analysis using 1H-NMR to monitor the changes in equilibrium and as a means for determination of the pKa of the complex. Challenges in the method development process and current results will be discussed in this poster.

Method development and validation of pKa determination of glycine-metal complexes by 1H-NMR

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