Thermal characterization of some guanylhydrazones by thermal and nonthermal techniques

Abstract

2-[(3,5-di-tert-butyl-4-hydroxyphenyl)methylene]-hydrazinecarboximidamide (WE010), 2-([1,1 0 -biphenyl]-4-ylmethylene)-hydrazinecarboximidamide (WE014), and 2-[(3,4-dichlorophenyl)methylene]-hydrazinecarboximidamide (WE017) are guanylhydrazone derivatives widely studied biologically and chemically; however, there are no studies regarding their thermal behaviors. The present study aims to apply the thermal analyses: differential scanning calorimetry (DSC), differential scanning calorimetry coupled to the photovisual system (DSC-photovisual), and thermogravimetry (TG), to characterize the guanylhydrazones, as well as HPLC and FTIR. The DSC curve of WE010 shows a melting process with T onset at 190°C and peak at 193.5°C (DH 41.0 J g -1 ). Due to the symmetry of the melting peaks obtained by DSC, it is possible to calculate the purity of the sample (98.87 %). The DSC curve of WE014 shows the melting process in the range of 208-213°C, with a melting peak at 211°C (DH 61 J g -1 ).The DSC curve of WE017 showed T onset at 215°C and peak temperature of 219°C (DH 55 J g -1 ). The TG curve of WE010, WE014, and WE017 presents initial decomposition temperatures of 186.95, 197.31, and 195.44°C, respectively. The DSC-photovisual confirmed the results of DSC and TG. The HPLC determined the purities of the samples and confirmed the results of DSC. The FTIR confirmed the thermal data. Thus, the use of thermal analysis is an important tool for the characterization of molecules with therapeutic potential contributing to the characterization and evaluation of their stability as well as nonthermal technique with complementary tool.

Development and Validation of HPLC-DAD and UHPLC-DAD Methods for the Simultaneous Determination of Guanylhydrazone Derivatives Employing a Factorial Design

“…Galvão et al evaluated some guanylhydrazones employing thermal analysis and observed that some guanylhydrazones other than the main product were present in very small quantities. These data were confirmed by HPLC analysis [ 13 ].…”