Figure 2.
The stability assessments of 2 and 2-TFA. (A) A clear solution of 2 in d-chloroform was subjected to a purity assessment by 1H NMR spectroscopy at various storage times (fresh prepared (≤1 h); 1 day; 4 days). (B) The HPLC purity of fresh prepared 2-TFA was 95.74%. The fresh prepared 2-TFA in a solid state was stored at room temperature for another 6 days and then dissolved in water for HPLC analysis. The HPLC purity was decided as 95.55%. The fresh prepared 2-TFA was dissolved in DMSO and the resulting solution was stored at room temperature for another 6 days. HPLC purity of 2-TFA in the DMSO solution was 94.66%.