Synthesis, characterization and structural analysis of bis-schiff bases using 3,3'-methylendianiline and salicylaldehyde derivatives

Seven N,N'-bis(salicylidene)diamines of common formula (2-OH-(5X)C6H3C=N)(2)-Z [Z = CH2(m-C6H4), X = H (1a), X = CH3 (lb), X = CI (lc), X = Br (1d), X = NO2 (le), X = OH (1f) and (2-OH-(3OH) C6H3C= N)(2)-Z [Z = CH2(m-C6H4) (1g)] have been synthesized and characterized by IR, NMR and mass spectroscopy. Molecular structures of la-ld and lg were elucidated by X-ray diffraction, the structures are stabilized by two intramolecular O-H center dot center dot center dot N hydrogen bonds. Furthermore, intermolecular bonds as O-H center dot center dot center dot O, C-H center dot center dot center dot O, C-H center dot center dot center dot N and C-H center dot center dot center dot Hal stabilize the structures at supramolecular level. Compound lg showed in one side and intramolecular O-H center dot center dot center dot N hydrogen bond and, at the other side and N-H center dot center dot center dot O hydrogen bond, showing the presence of enol and keto tautomers at the same molecule, which could be attractive to use in sensors and no -lineal optics. Besides, compounds la-ld showed weak intermolecular 7-interactions. (C) 2019 Elsevier B.V. All rights reserved.