Spectroscopy, Crystal and Molecular Structures of New 4-Acylpyrazolone Dinitrophenylhydrazones

Still looking at the development of new materials with unique properties and taking advantage of the nucleophilic properties of amines to form stable azomethines, dinitrophenylhydrazine was reacted with 4-ethyl-5-methyl-2-phenyl-pyrazol-3-one and then with 4-propyl-5-methyl-2-phenyl-pyrazol-3-one to get 4-ethyl-5-methyl-2-phenyl-pyrazol-3-one dinitrophenylhydrazone (Empp-Dh) and 4-propyl-5-methyl-2-phenyl-pyrazol-3-one dinitrophenylhydrazone (Pmpp-Dh), respectively, via a simple condensation reaction in a one-pot synthesis system. Careful interpretations of results from elemental analysis, mass and NMR spectroscopy were in agreement with single-crystal X-ray diffraction data. Reported Schiff bases in their single-crystal solid state exist in imine keto tautomer form, each crystallizing in a monoclinic crystal system, with a space group of C2/c (No. 15) in Empp-Dh and P21/c (No. 14) in Pmpp-Dh. They have extensive intra- and inter-molecular hydrogen as well as C–H···π-ring interactions