Abstract:

Two hydrazone componds(E)-N'-(2,4-dihydroxybenzylidene)-pyrrole-2-carbohydrazide C₁₂H₁₁N₃O₃(Ⅰ) and (E)-N'-(2-hydroxy-3-methoxybenzylidene)-pyrrole-2-carbohydrazide C₁₃H₁₄N₃O₄(Ⅱ) have been synthesized from 2,4-dihydroxybenzaldehyde and 2-hydroxy-3-methoxybenzaldehyde with pyrrole-2-carbohydrazide, respectively. The compounds have been characterized by IR spectroscopy, elemental analysis, ¹H NMR spectroscopy, single-crystal X-ray diffraction and thermogravimetric analysis. The crystal of compound Ⅰ belonged to monoclinic crystal lattice, space group P2₁/c, Z=4, with unit cell parameters a=1.2586(4) nm, b=0.8050(3) nm, c=1.1914(4) nm, and compound Ⅱ crystallized in the orthorhombic system, space group P2₁2₁2₁, Z=4, with unit cell parameters a=0.4756(2) nm, b=1.2491(6) nm, c=2.2145(11) nm. The TG-DTG result shows that the compounds Ⅰ and Ⅱ display good thermal stability, the maximum decomposition peaks are at the temperature of 267.59 ℃ and 284.79 ℃, and their apparent activation energy values are 176.6 kJ/mol and 122.9 kJ/mol, respectively. The thermogenic curves of the compounds Ⅰ and Ⅱ reacting with calf thymus DNA(CT-DNA) measured by viscosity and microcalorimetry, indicate that the interactions of compounds Ⅰ and Ⅱ with CT-DNA belong to the intercalation mode, and the interacting processes are all endothermic, their enthalpies are ΔH(Ⅰ)=4.67 kJ/mol and ΔH(Ⅱ)=4.40 kJ/mol, respectively.

Key words: hydrazone, crystal structures, thermal stability, calf thymus DNA