Multifunctional lanthanide MOFs with active sites as new platforms for smart sensing of methylmalonic acid and anti-counterfeiting applications

Insufficient intake of vitamin B-12 in humans can lead to the development of vitamin B-12 deficiency with involuntary movement disorders. In this work, a smartphone-enabled sensing platform was designed for early diagnosis of vitamin B-12 deficiency with involuntary movement disorders. Thus, a series of isostructural multifunctional lanthanide metal-organic frameworks (Ln-MOFs), {[Ln(L)(NMP)(H2O)(3)]center dot NMP center dot H2O}(n) (1-Ln, Ln = Eu, Tb, or EuxTb1-x and NMP = 1-methyl-2-pyrrolidinone), were synthesized via 5-(4-(tetrazol-5-yl)phenyl)isophthalic acid (H3L) and Ln(3+). 1-Ln exhibits a 4-linked two-dimensional (2D) structure with a parallel stacking and staggered arrangement between the layers, and a 3D supramolecular framework through hydrogen bonding. The fluorescence sensing studies demonstrate that 1-Eu exhibits high sensitivity and a low detection limit (1.07 x 10(-5) M) for methylmalonic acid, a potential marker of vitamin B-12 deficiency in urine. On the other hand, the prepared fluorescent ink displays color tunability and good stability, indicating that 1-Ln is a new potential anti-counterfeiting material.