Impact of N-substituents on crystal packing of N-alkyl-N′-tosylpiperazines and development of new polymorph of tosylbis(2-(tosyloxy)ethyl)amine: Synthesis, DFT, photophysical, cytotoxic property

Abstract

Diethanol amine (DEA) was selected as a lead compound to prepare N-tosyldiethanol amine 1, N-tosylbis(2-(tosyloxy)ethyl)amine 2 and disubstituted piperazines ca N-alkyl-N′-tosylpiperazines 3–5 in high yield. The new compounds were characterized by using relevant techniques viz. MS, IR, 1H, 13C, DEPT 135 NMR, UV–vis. absorption and fluorescence spectral studies. Single crystal X-ray diffraction technique was used to detect a new polymorphic form of 2 and to measure the influence of various N-substituents on the association of molecules of 3–5 in the solid state. Evidently, the introduction of N-cyclohexyl substituent in 3 successfully switches off all the synthons ca CH…O and CH…N seen in compound 4 and 5. Compounds 4 and 5 holding N-furfuryl and N-benzyl substituents, respectively, adopt other packing strategies based on CH…O, CH…N (4) and CH…O (5) interactions. The antitumor activity of 1–5 was evaluated in vitro against Hep 3B and IMR 32 by the MTT assay and the results were compared with cisplatin. Remarkably, some compounds were found extremely active against both the cell lines and proved to be more potent as cytotoxic agents than cisplatin. Density functional theory and molecular docking studies have been performed to rationalize the experimental results.