Thermodynamic study on six tricyclic nitrogen heterocyclic compounds by thermal analysis and effusion techniques

The molar sublimation and vaporization enthalpies of acridine, phenanthridine, 1,7-phenanthroline,1,10-phenanthroline, 4,7-phenanthroline and phenazine were determined at the averages of theirrespective experimental temperature ranges (crgH0m(<T>) and lgH0m(<T>), respectively) from thetemperature dependencies of vapor pressure determined using Knudsen Effusion Mass Loss (KEML),Torsion Effusion (TE) and Isothermal Thermogravimetry (ITG) above their solid and liquid phases. Thefusion characteristics (melting temperatures and the molar standard enthalpies of fusion at their meltingtemperatures) measured by Differential Scanning Calorimetry (DSC) were compared with the availableliterature values. Solid and liquid vapor pressure data determined by KEML, TE and ITG techniques aswell as crgH0m(<T>) and lgH0m(<T>) values, adjusted at 298.15 K by using the values of Cp(cr) andCp(l) calculated by a well-known group additivity method, were found to be fairly correlated and are con-sistent with the available literature data. Final crgH0m(298.15 K) values were also provided as weightedaverages of all the available data.