Control of peroxyoxalate chemiluminescence by nitrogen-containing ligand quenching: turning off and on by ligand–metal ion host–guest interactions
摘要:
The control of peroxyoxalate chemiluminescence (PO-CL) by the coordination of nitrogen-containing ligands and metal cations was investigated. Turning the CL off and on was done by PO-CL using 15-monoazacrown-5-tethered anthracene and alkali metal ions. CL quenching and regeneration was also observed in the separated molecular system of 15-monoazacrown-5 and the fluorophores. CL quenching by a number of ligands bearing dipicolylamino groups was evaluated by these PO-CL reactions and found to be closely related to their oxidation potentials, which is dependent on the Weller rate law for electron exchange and this provides strong support for the existence of the CIEEL PO-CL process. When Zn2+ or Cu2+ are added to the PO-CL system quenched by the ligand, N-[2-(2,2'-dipicolylamino)ethyl]aniline, CL was turned on because the electron donating ability of the ligands was modulated. This was controlled by the coordination of the studied metal ions and, therefore, this system results in CL because of host-guest interactions. (C) 2011 Elsevier Ltd. All rights reserved.
The control of peroxyoxalate chemiluminescence (PO-CL) by the coordination of nitrogen-containing ligands and metal cations was investigated. Turning the CL off and on was done by PO-CL using 15-monoazacrown-5-tethered anthracene and alkali metal ions. CL quenching and regeneration was also observed in the separated molecular system of 15-monoazacrown-5 and the fluorophores. CL quenching by a number of ligands bearing dipicolylamino groups was evaluated by these PO-CL reactions and found to be closely related to their oxidation potentials, which is dependent on the Weller rate law for electron exchange and this provides strong support for the existence of the CIEEL PO-CL process. When Zn2+ or Cu2+ are added to the PO-CL system quenched by the ligand, N-[2-(2,2'-dipicolylamino)ethyl]aniline, CL was turned on because the electron donating ability of the ligands was modulated. This was controlled by the coordination of the studied metal ions and, therefore, this system results in CL because of host-guest interactions. (C) 2011 Elsevier Ltd. All rights reserved.
Electrochemically active phenylenediamine probes for transition metal cation detection
A novel family of tetraalkyl-p-phenylenediamine (TAPD)-based ligands has been efficiently prepared by reductive amination of heterocyclic aldehydes. The redox properties of these electrochemical active ligands change dramatically upon complexation of the transition metal cations Zn2+, Ni2+ and Cd2+ leading to large oxidation potential shifts of up to 950 mV depending on the nature of the ligand. Complexes with a metal to ligand ratio of 1 ∶ 2 were formed and 113Cd NMR revealed an octahedral coordination sphere of the metal. All pyridyl derivatives show a distinct chemoselectivity (Zn2+ > Cd2+ > Ni2+). The thiophenyl containing derivatives display a particularly high selectivity for zinc cations (Zn2+ ≫ Ni2+, Cd2+).