Enhancement of Propadiene/Propylene Separation Performance of Metal–Organic Frameworks by an Amine-Functionalized Strategy

Here, a hexanuclear Co6(μ3-OH)6 cluster-based metal–organic framework (MOF), [Co6(μ3-OH)6(BTB)2(bpy)3]n (JXNU-15) (bpy = 4,4′-bipyridine), with the 1,3,5-tri(4-carboxyphenyl)benzene (BTB3–) ligand was synthesized for the challenging propadiene/propylene separation. The combination of a large pore volume and a suitable pore environment boosts the significantly high propadiene (C3H4) uptake (311 cm3 g–1 at 298 K and 100 kPa) for JXNU-15. An amine-functionalized MOF of JXNU-15(NH2) was further obtained with the 1,3,5-tri(4-carboxyphenyl)benzene analogue of 3,3″-diamino-5′-(3-amino-4-carboxyphenyl)-[1,1′:3′,1″-terphenyl]-4,4″-dicarboxylic ligand. The comparative studies of propadiene/propylene(C3H4/C3H6) separation performance between isostructural JXNU-15 and JXNU-15(NH2) are provided. JXNU-15(NH2) exhibits an impressive C3H4 capacity at low pressures with 69.1 cm3 g–1 at 10 kPa, which is twice that of JXNU-15 under the same conditions. Moreover, the separation selectivity of JXNU-15(NH2) is 1.3-fold higher as compared to JXNU-15. JXNU-15(NH2) with enhanced C3H4/C3H6 separation performance was elegantly illustrated by gas separation experiments and theoretical simulations. This work presents an amine-functionalized strategy for the enhancement of the C3H4/C3H6 separation performance of MOF

Incorporation of Computed Tomography and Magnetic Resonance Imaging Function into NaYF₄:Yb/Tm Upconversion Nanoparticles for in Vivo Trimodal Bioimaging

Rational design and fabrication of multimodal imaging nanoprobes are of great significance for in vivo imaging. Here we report the fabrication of a multishell structured NaYF₄:Yb/Tm@NaLuF₄@NaYF₄@NaGdF₄ nanoprobe via a seed-mediated epitaxial growth strategy for upconversion luminescence (UCL), X-ray computed tomography (CT), and magnetic resonance (MR) trimodal imaging. Hexagonal phase NaYF₄:Yb/Tm is used as the core to provide UCL, while the shell of NaLuF₄ is epitaxially grown on the core not only to provide an optically inert layer for enhancing the UCL but also to serve as a contrast agent for CT. The outermost NaGdF₄ shell is fabricated as a thin layer to give the high longitudinal relaxivity (<i>r</i>₁) desired for MR imaging. The transition shell layer of NaYF₄ not only provides an interface to facilitate the formation of NaGdF₄ shell but also inhibits the energy transfer from inner upconversion activator to surface paramagnetic Gd³⁺ ions. The fabricated multishell structured nanoprobe shows intense near-infrared UCL, high <i>r</i>₁ value of 3.76 mM^–1 s^–1, and in vitro CT contrast effect. The multishell structured nanoprobe offers great potential for in vivo UCL/CT/MR trimodal imaging. Further covalent bonding of folic acid makes the multishell structured nanoprobe promising for in vivo targeted UCL imaging of tumor-bearing mice