Hg2+ detection by new anthracene pendant-arm derivatives of mixed N/S-, and N/S/O-donor macrocycles: Fluorescence, matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and DFT studies

The optical response of four new anthracenylmethyl pendant-arm derivatives (L1-L4) of the macrocyclic ligands [12]aneNS3, [12]aneNS2O, [15]aneNS2O2, and [12]aneN2SO toward the metal ions Zn(II, Cd(II),Pb(II), Cu(II),Hg(II), Ag(I),Fe(II),Co(II),Ni(II),Mn(II)Ca(II),Na(I),Mg(II) , and K(I) was investigated in 1:1 (v/v) MeCN/H2O solutions. A strong chelation enhancement of quenching effect was observed on the fluorescent emission intensity of L2 as a consequence of the host-guest interaction with Hg(II) and the formation of a 1:2 metal-to-ligand complex. Density functional theory calculations confirmed the formation of a sandwich-type complex between L2 and Hg(II) as a favorable process. A matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry study using the four ligands as active MALDI probes was also performed. L1-L4 have also been explored as fluorescence chemosensors in microsamples using NANODROP technology