Rapid naked-eye luminescence detection of carbonate ion through acetonitrile hydrolysis induced europium complexes

Abstract

The in situ hydrolysis of acetontrile to acetate was utilized to construct crystal structures of lanthanide complexes for two analogous ligands, including dimeric [Ln₂(Hhpip)₂(OAc)₆] (Ln = Eu, Tb, Dy; Hhpip = 2-(2-hydroxyphenyl)imidazo[4,5-f][1,10]phenanthroline) and two-dimensional polymeric [Tb(hnpip)(OAc)₂]_n, where hnpip⁻ is the hydroxyl-deprotonated form of 2-(2-hydroxy-5-nitrophenyl)imidazo[4,5-f][1,10]phenanthroline acting as a tridentate bridging ligand. The former had a [Ln₂(μ-η¹:η²-OAc)₂(μ-η¹:η¹-OAc)₂(η²-OAc)₂] subunit, whereas in the latter, [Tb₂(μ-η¹:η²-OAc)₂] and [Tb₂(μ-η¹:η¹-OAc)₂] subunits are alternately aligned. The DMSO solution of [Eu₂(Hhpip)₂(OAc)₆] and [Eu₂(pip)₂(OAc)₆] (pip is 2-phenylimidazo[4,5-f][1,10]phenanthroline) were found to have a specific and prompt photoluminescence response to CO₃²⁻ with significant emission colour change. The limit of detection was about 10 μM, depending on the complex and wavelength monitored.