Materials and methods The melting points were determined by open capillary method and are uncorrected. The IR spectra (KBr disc) were recorded on a Nicolet-5700 FT-IR spectrophotometer. 1 H-NMR spectra were recorded on Bruker 300 MHz spectrometer using CDCl 3 and DMSO-d 6 as solvents and TMS as an internal standard (Figure S1). The chemical shifts are expressed in δ ppm. The mass spectra were recorded using Agilent- ...