ABSTRACT
Herein, an unprecedented cadmium-based metal-organic framework (JNU-106) fabricated by utilizing pyrazole-functionalized tetraphenylethylene ligands (Py-TPE) and rod-shaped secondary building units is reported, possessing a new (3,3,3,6,6,8)-connected topological network. Thanks to the ingeniously designed intramolecular charge transfer behavior, which originates from the congruent coplanarity between Py and TPE, JNU-106 exhibits intense green luminescence with a quantum yield increased by 1.5 times. The phenomenon of remarkable fluorescence quenching of JNU-106 reveals that it possesses extremely high anti-interference performance, superior sensitivity, and dedicated selectivity toward tetracycline antibiotics (TCAs) in aqueous solutions, which are comparable to those of the state-of-the-art porous sensing compounds. Taking the theoretical calculations and experimental results into account, the luminescence quenching is mainly attributed to the internal filtration effect and the static quenching effect. Considering the portable and rapid performance of JNU-106-based testing strips for sensing TCAs, the fabricated JNU-106 provides an alternative for ecological monitoring and environmental governance.
ABSTRACT
A direct and facile access to enantioenriched pyroglutamate derivatives bearing a unique quaternary stereogenic center has been developed via Cu(I)/BINAP-catalyzed tandem Michael addition-elimination of α-substituted aldimino esters with Morita-Baylis-Hillman (MBH) carbonates followed by a deprotection/lactamization protocol, which performs well over a broad scope of substrates and provides biologically active pyroglutamate derivatives in good yields and excellent enantioselectivities.
