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 and density functional theory studies

The optical response of four new anthracenylmethyl pendant-arm derivatives (L1-L4) of the macrocyclic ligands [12]aneNS(3), [12]aneNS(2)O, [15]aneNS(2)O(2), and [12]aneN(2)SO toward the metal ions Zn(2+), Cd(2+), Pb(2+), Cu(2+), Hg(2+), Ag(+), Fe(2+), Co(2+), Ni(2+), Mn(2+), Ca(2+), Na(+), Mg(2+), and K(+) was investigated in 1:1 (v/v) MeCN/H(2)O 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(2+) 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(2+) 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.