Structure regulation for ultra-high luminescence quantum yield lanthanide complex and simultaneous detection of cancer marker and ferrous ion

The exploitation of a highly selective and sensitive probe to detect both cancer marker and metal ion is of great importance. In this work, the “one stone two bird” agent of 1,10-phenanthroline (phen) is designed to disrupt the polymeric lanthanide MOFs (LnMOFs, [Ln(CHO₂)₃]_n, Ln = Tb, 1a; Eu, 1b, CHO₂ = formic acid) {[Ln(CHO₂)₄·(C₂H₈N)]_n, Ln = Y, 2a; Gd, 2b; Dy, 2c, C₂H₈N = dimethylamine}) into a soluble mononuclear species [Ln(phen)₂(NO₃)₃, Ln = Tb, 3a; Eu, 3b] as well as to provide an antenna for efficient photons absorption, resulting in an ultra-high luminescence quantum yield (QY, 90%) europium complex. The luminescence QY is among the highest record of monomeric (zero-dimensional) lanthanide complexes. Furthermore, mononuclear Tb³⁺ complex (3a) functions as a multiplex sensor towards both Fe²⁺ and cancer marker of 5-hydroxyindole-3-acetic acid (5-HIAA). Importantly, the limit of detection (LOD) for sensing 5-HIAA is an ultra-sensitive value of 1 × 10⁻⁸ mol/L, which is even lower than that necessary for the early diagnosis of carcinoid tumors. More interestingly, sensing results in simulated urine reveals that 3a has potential application for early diagnosis in the clinic.