Self assembled pseudo double helix architecture and anion sensing behavior of a coumarin based ICT probe

The X-ray diffraction (XRD) studies of a coumarin based hydrazone (receptor 1) have revealed self assembled pseudo double helix architecture involving closed shell O---O interactions besides other supramolecular interactions. The receptor (1) an intramolecular charge transfer (ICT) probe detected acetate, benzoate and dihydrogenphosphate through naked-eye in DMSO. The 1:1 stoichiometry was confirmed for all the anions. The 1H NMR studies indicated classical and non-classical hydrogen bonding through –NH and Ar–H protons of the receptor, respectively, during recognition process of the acetate through receptor (1). The theoretical studies through density functional theory (DFT) using B3LYP exchange functional with the basis set 6-311G∗∗ supported the UV–vis and 1H NMR studies. The time dependent density functional theory (TDDFT) computations of UV–vis excitations for the receptor (1) and receptor–acetate complex agreed well with our experimental findings. The cyclic voltammetric studies also supported formation of receptor–acetate complex.