Chelation of and ThIV by N,N′-bis(pyridoxylideneiminato)R (R = n-propyl, diethylamine), new dianionic Schiff bases derived from vitamin B6: Synthesis and structural features of [Th(pyr2pen)2] (pen = 1,3-propylendiamine), [UO2(pyr2pen)(CH3OH)] and [UO2(pyr2dien)] · 2H2O (dien = diethylenetriamine). Searching further modelings for heavy metals damage inhibition in living beings