Synthesis, turn-on fluorescence signals towards Zn2+ and Hg2+ and monoamine oxidase A inhibitory activity using a molecular docking approach of morpholine analogue Schiff base linked organosilanes

A new set of morpholine analogue Schiff base linked organosilanes (5a-5c) was prepared. The prepared compounds were characterized using (H-1 and C-13) NMR and mass spectrometry. The sensing ability of receptor 5a was demonstrated towards different metal ions such as Ag+, Ba2+, Ca2+, Cd2+, Na+, Cs+, K+, Pb2+, Rb+, Ni2+, Zn2+, Hg2+ and Co2+ using UV-visible and Fluorescence analyses, showing good selectivity and sensitivity towards Zn2+ and Hg2+ in a MeOH-H2O (9 : 1 v/v) solvent system. A turn-on fluorescence response towards both Zn2+ and Hg2+ was observed based on the collective effect of C = N isomerization, intramolecular charge transfer (ICT) and chelation induced enhanced fluorescence (CHEF). Benesi-Hildebrand (B-H) plots and calibration curves were employed to measure the association constants and limits of detection, respectively. The binding mechanisms of compound 5a with Zn2+ and Hg2+ were confirmed using H-1 NMR and theoretically by DFT calculations. Further, molecular docking analysis was carried out against monoamine oxidase A (PDB ID-2BXS) to determine the probable binding sites, giving a binding energy of -9.5 kcal mol(-1).

Automated summary

A new set of morpholine analogue Schiff base linked organosilanes (5a-5c) were synthesized and characterized. The sensing ability of 5a towards different metal ions was demonstrated, showing good selectivity and sensitivity towards Zn2+ and Hg2+. The binding mechanisms between compound 5a and Zn2+, Hg2+ were confirmed experimentally and theoretically.