Optical recognition of Y(III) using a naphthalene based tetra-imine derivative andamide-imine based iron complex

A naphthalene based tetra-imine derivative (DNB), prepared by condensation of 2-(amino methyl)-aniline with 2-hydroxy naphthaldehyde and 2, 6-(diformyl)-p-cresol in a sequential manner can detect Y(III) via sky blue emission (λ_em = 478 nm, λ_ex = 400 nm)in aqueous DMSO media. On the other hand, a Fe(II) complex (MTASFe), derived from an amide-imine conjugate also recognizes Y(III) through blue emission (λ_em = 454 nm, λ_ex = 300 nm) in the same media. For the first case, the sensing is attributed to the chelation of Y(III) by DNB leading to inhibition of excited state intra-molecular proton transfer (ESIPT) whereas the displacement of Fe(II) by Y(III) from MTASFe is responsible for fluorescence enhancement in later case. The limit of detection of DNB and MTASFe for Y(III) are 17.56 nM and 68.33 nM respectively. Silica immobilized DNB is capable of solid-phase extractive recovery of Y(III). DNB impregnated paper strip is suitable for optical detection of Y(III).