Accelerating the Phosphatase-like Activity of Uio-66-NH₂ by Catalytically Inactive Metal Ions and Its Application for Improved Fluorescence Detection of Cardiac Troponin I

Compared with natural enzymes, nanozymes usually exhibit much lower catalytic activities, which limit the sensitivities of nanozyme-based immunoassays. Herein, several metal ions without enzyme-like activities were engineered onto Uio-66-NH2 nanozyme through postsynthetic modification. The obtained Mn+@Uio-66-NH2 (Mn+ = Zn2+, Cd2+, Co2+, Ca2+and Ni2+) exhibited improved phosphatase-like catalytic activities. In particular, a 12-fold increase in the catalytic efficiency (kcat/Km) of Uio-66-NH2 was observed after the modification with Zn2+. Mechanism investigations indicate that both the amino groups and oxygen-containing functional groups in Uio-66-NH2 are the binding sites of Zn2+, and the modified Zn2+ ions on Uio-66-NH2 serve as the additional catalytic sites for improving the catalytic performance. Furthermore, the highly active Zn2+@Uio-66-NH2 was used as a nanozyme label to develop a fluorescence immunoassay method for the detection of cardiac troponin I (cTnI). Compared with pristine Uio-66-NH2, Zn2+@Uio-66-NH2 can widen the linear range by 1 order of magnitude (from 10 pg/mL–1 μg/mL to 1 pg/mL–1 μg/mL) and also lower the detection limit by 5 times (from 4.7 pg/mL to 0.9 pg/mL)

Copper-Catalyzed Enantioselective Intramolecular Aryl C–N Coupling: Synthesis of Enantioenriched 2‑Oxo-1,2,3,4-tetra­hydro­quinoline-3-carbox­amides via an Asymmetric Desymmetrization Strategy

The differentiation of two nucleophilic amide groups in malonamides through a copper-catalyzed enantioselective intramolecular aryl C–N coupling reaction is demonstrated based on an asymmetric desymmetrization strategy. Such a method afforded enantioenriched 2-oxo-1,2,3,4-tetra­hydro­quinoline-3-carboxamides in high yields and moderate to good enantioselectivity

Pd-Catalyzed Asymmetric Intramolecular Aryl C–O Bond Formation with SDP(O) Ligand: Enantioselective Synthesis of (2,3-Dihydrobenzo[<i>b</i>][1,4]dioxin-2-yl)methanols

Employing a chiral spirodiphosphine monoxide ligand with 1,1′-spirobiindane backbone (SDP­(O)), a desymmetrization strategy of Pd-catalyzed intramolecular asymmetric aryl C–O coupling of 2-(2-halophenoxy)­propane-1,3-diols, was developed. The SDP­(O) ligand shows much better results than its SDP counterpart. The protocol provides an efficient and highly enantioselective method for the synthesis of 2-hydroxymethyl-1,4-benzodioxanes. Density functional theory studies provide a model that accounts for the origin of the enantioselectivity