A bifunctional 2,2':6',2 double prime -terpyridine-based ligand for ratiometric Cu(II) sensing

• Published in: Journal of coordination chemistry 2017-04, Vol.70 (7), p.1123-1136
• Main Authors: Abdalrahman, MA, Abebe, F, Briggs, J, Kassel, W S, Burdette, S C, Seitz, W R, Planalp, R P
• Format: Article
• Language: English
• Subjects: Binding; Copolymerization; Crosslinking; Ligands; Mathematical models; Receptors; Sensors; Speciation
• ISSN: 0095-8972; 1029-0389
• DOI: 10.1080/00958972.2017.1300660

Synthesis and characterization of the bifunctional sensor receptor ligand N-([2,2':6',2 double prime -terpyridine]-4'-yl)methy l)-N-propylacrylamide (1) and the model ligand N-([2,2':6',2 double prime -terpyridine]-4'-yl)methy l)-N-propylisobutyramide (2) are described. Ligand 1 is a receptor for Cu(II) that is copolymerizable with N-isopropylacrylamide giving a ratiometric sensor of weakly bound Cu(II) in environmental waters. Ligand 2 is a model for copolymerized 1 whereby the reactive acrylamide group is replaced by isobutyramide. Solution speciation of complexes of Cu(II) and Zn(II) with 2 were investigated spectroscopically and their solid-state structures were studied through single-crystal X-ray diffraction. Solution UV-vis and fluorescence studies show a preference of 2 toward Cu(II) over Na(I), Zn(II), Cu(II), Co(II), Mn(II), Ni(II), Cd(II), and Pb(II) in accord with the Irving-Williams series and other coordination principles. Solution speciation determined in a weakly coordinating aqueous-organic (60 : 40 DMF/H sub(2)O) medium indicates 1 : 1 Cu(II):2 binding as desired in that formation of [Cu(2) sub(2)] super(2+) would crosslink the polymer sensor. The crystal structures of [Cu(2)(NO sub(3)) sub(2)] and [Zn(2)(NO sub(3)) sub(2)].MeOH.1/2Et sub(2)O display distorted octahedral geometries where 2 coordinates meridionally and two nitrate groups occupy the remaining sites around the metal center.