Wood Cellulose Nanofibers Grafted with Poly(ε-caprolactone) Catalyzed by ZnEu-MOF for Functionalization and Surface Modification of PCL Films.

Renewable cellulose nanofiber (CNF)-reinforced biodegradable polymers (such as polycaprolactone (PCL)) are used in agriculture, food packaging, and sustained drug release. However, the interfacial incompatibility between hydrophilic CNFs and hydrophobic PCL has limited further application as high-performance biomaterials. In this work, using a novel ZnEu-MOF as the catalyst, graft copolymers (GCL) with CNFs were grafted with poly(ε-caprolactone) (ε-CL) via homogeneous ring-opening polymerization (ROP), and used as strengthening/toughening nanofillers for PCL to fabricate light composite films (LCFs). The results showed that the ZnEu-MOF ([ZnEu(L)2(HL)(H2O)0.39(CH3OH)0.61]·H2O, H2L is 5-(1H-imidazol-1-yl)-1,3-benzenedicarboxylic acids) was an efficient catalyst, with low toxicity, good stability, and fluorescence emissions, and the GCL could efficiently promote the dispersion of CNFs and improve the compatibility of the CNFs and PCL. Due to the synergistic effect of the ZnEu-MOF and CNFs, considerable improvements in the mechanical properties and high-intensity fluorescence were obtained in the LCFs. The 4 wt% GCL provided the LCF with the highest strength and elastic modulus, which increased by 247.75% and 109.94% compared to CNF/PCL, respectively, showing the best elongation at break of 917%, which was 33-fold higher than CNF/PCL. Therefore, the ZnEu-MOF represented a novel bifunctional material for ROP reactions and offered a promising modification strategy for preparing high-performance polymer composites for agriculture and biomedical applications.

Defective Metal-Organic Frameworks with Tunable Porosity and Metal Active Sites for Significantly Improved Performance in Styrene Oxidation.

Metal active sites and sufficient porosity in metal-organic frameworks (MOFs) are crucial parameters determining the performances of catalysis, guest molecule adsorption, etc. Herein, through in situ introduction of Ru sites with different levels to Cu-BTC structure together with post-synthetic activation at 180 °C, a series of hierarchically porous CuRu-BTC (HP-CuRu-BTC) MOFs were obtained. Besides, selective thermal decomposition (STD) treatment was carried out at 240 °C to further tune the hierarchical pores and metal sites, yielding rare case of metal nanoparticles (NPs)@HP-CuRu-BTC composites. After full characterization by XRD, N2 physisorption, SEM, ICP and XPS, these HP-CuRu-BTC and NPs@HP-CuRu-BTC samples possess high surface area (682-1199 m2 g-1 ), hierarchical pores and highly distributed metal sites with reduced oxidation states (Cu+ and Ru2+ ), indicating regulation of both metal sites and hierarchical pores. The HP-CuRu-BTC and NPs@HP-CuRu-BTC were further employed as catalysts for the heterogeneous styrene oxidation reaction under mild condition. Compared to microporous Cu-BTC with unary metal component, HP-CuRu-BTC-3 and NPs@HP-CuRu-BTC-3 exhibited more than 2 times higher styrene conversion after 7 hours reaction under same condition.

Directing group strategies in rhodium-catalyzed C-H amination.

Construction of a carbon-nitrogen bond is one of the most prevalent operations in nature and organic synthesis. The resulting amino compounds are privileged structural fragments in natural products, pharmaceutical drugs, and functional materials. With the rapid advancement of C-H bond activation, directing-group strategies in C-H amination catalyzed by rhodium have emerged. This reaction approach considerably enhances the step economy and atom economy of the reaction, and it complies with green chemistry and atom economy. The reactivity and selectivity of chelation-assisted rhodium-catalyzed C-H amination are discussed in relation to the types of aminating reagent, as well as the challenges and future development prospects in this field.

Copper mixed-triazolate frameworks featuring the thiophene-containing ligand towards enhanced photodegradation of organic contaminants in water.

By using a thiophene-containing triazole ligand -3,5-di(thiophen-2-yl)-1H-1,2,4-triazole (3,5-Th2-tzH) and 3,5-diphenyl-1H-1,2,4-triazole (3,5-Ph2-tzH) in different molar ratio in the reactant, copper(I) mixed-triazolate frameworks CuMtz-1 {[Cu8(3,5-Ph2-tz)6-x(3,5-Th2-tz)x](BF4)2(CH3OH)3} (x = 0.5 for CuMtz-1a and 1.1 for CuMtz-1b) were firstly synthesized and characterized by PXRD, IR, 1H NMR, SEM, TG and UV-vis DRS. They have been evaluated as photocatalysts for the degradation of organic pollutants in water. It was found that the rate constants towards the degradation of both traditional and emerging organic contaminants over CuMtz-1b were significantly improved, i.e. by 160% for methyl orange, 210% for rhodamine B, 80% for methyl blue and 180% for sulfasalazine in comparison with that catalyzed over the parent MOF CuTz-1 {[Cu8(3,5-Ph2-tz)6](BF4)2(CH3OH)3} under Xe lamp irradiation in the absence of H2O2. More importantly, the degradation efficiency of methyl orange and sulfasalazine by CuMtz-1b without the addition of H2O2 was quite comparable with that by CuTz-1 with the addition of H2O2 under both Xe lamp irradiation and natural sunlight. The enhancement on the degradation efficiency can be attributed to the increased light absorption ability and the change of the band structure caused by the incorporation of thiophene-containing triazole ligand.

Ultrahigh luminescence quantum yield lanthanide coordination polymer as a multifunctional sensor.

The investigation and development of advanced multifunctional and sensitive sensors with high luminescent quantum yield and the capability of detecting different analytes, such as metal ions, is imperative. Due to its inherent properties the lanthanide coordination complex is one candidate for sensing applications, particularly for multifunctional sensors. Herein, we present two series of alkali ion decorated lanthanide coordination polymers (Ln-CPs), which show ultrahigh luminescence quantum yields (QYs) of 77% (1a) and 92% (2a). To the best of our knowledge, 1a represents the first trifunctional lanthanide complex sensor that can simultaneous detect and discriminate three different analytes, namely H+/Cd2+/Cr3+ through a multimode optical response. Furthermore, the limit of detection (LOD) for Cr3+ is an ultralow value of 2.0 × 10-9 M with a sensing time of 2 h, which is comparable to the most sensitive Cr3+ chemosensor. More interestingly, 92% (2a) is an unprecedented luminescence QY among the reported lanthanide coordination complexes.

Highly Efficient Photocatalytic Degradation of Dyes by a Copper-Triazolate Metal-Organic Framework.

A copper(I) 3,5-diphenyltriazolate metal-organic framework (CuTz-1) was synthesized and extensively characterized by using a multi-technique approach. The combined results provided solid evidence that CuTz-1 features an unprecedented Cu5 tz6 cluster as the secondary building unit (SBU) with channels approximately 8.3 Šin diameter. This metal-organic framework (MOF) material, which is both thermally and chemically (basic and acidic) stable, exhibited semiconductivity and high photocatalytic activity towards the degradation of dyes in the presence of H2 O2 . Its catalytic performance was superior to that of reported MOFs and comparable to some composites, which has been attributed to its high efficiency in generating . OH, the most active species for the degradation of dyes. It is suggested that the photogenerated holes are trapped by CuI , which yields CuII , the latter of which behaves as a catalyst for a Fenton-like reaction to produce an excess amount of . OH in addition to that formed through the scavenging of photogenerated electrons by H2 O2 . Furthermore, it was shown that a dye mixture (methyl orange, methyl blue, methylene blue, and rhodamine B) could be totally decolorized by using CuTz-1 as a photocatalyst in the presence of H2 O2 under the irradiation of a Xe lamp or natural sunlight.

Encapsulation of Bimetallic Metal Nanoparticles into Robust Zirconium-Based Metal-Organic Frameworks: Evaluation of the Catalytic Potential for Size-Selective Hydrogenation.

The realization of metal nanoparticles (NPs) with bimetallic character and distinct composition for specific catalytic applications is an intensively studied field. Due to the synergy between metals, most bimetallic particles exhibit unique properties that are hardly provided by the individual monometallic counterparts. However, as small-sized NPs possess high surface energy, agglomeration during catalytic reactions is favored. Sufficient stabilization can be achieved by confinement of NPs in porous support materials. In this sense, metal-organic frameworks (MOFs) in particular have gained a lot of attention during the last years; however, encapsulation of bimetallic species remains challenging. Herein, the exclusive embedding of preformed core-shell PdPt and RuPt NPs into chemically robust Zr-based MOFs is presented. Microstructural characterization manifests partial retention of the core-shell systems after successful encapsulation without harming the crystallinity of the microporous support. The resulting chemically robust NP@UiO-66 materials exhibit enhanced catalytic activity towards the liquid-phase hydrogenation of nitrobenzene, competitive with commercially used Pt on activated carbon, but with superior size-selectivity for sterically varied substrates.

Simultaneous introduction of various palladium active sites into MOF via one-pot synthesis: Pd@[Cu3-xPdx(BTC)2]n.

Simultaneous incorporation of palladium within Pd-Pd and/or Pd-Cu paddlewheels as framework-nodes and Pd nanoparticle (NP) dispersion into MOF have been achieved for the first time via one-pot synthesis. In particular, the framework substitution of Cu(2+) by Pd(2+) as well as the pore loading with PdNPs have been confirmed and characterized by XPS. The obtained solids featuring such multiple Pd-sites show enhanced catalytic activity in the aqueous-phase hydrogenation of p-nitrophenol (PNP) with NaBH4 to p-aminophenol (PAP).

Ruthenium Metal-Organic Frameworks with Different Defect Types: Influence on Porosity, Sorption, and Catalytic Properties.

By employing the mixed-component, solid-solution approach, various functionalized ditopic isophthalate (ip) defect-generating linkers denoted 5-X-ipH2 , where X=OH (1), H (2), NH2 (3), Br (4), were introduced into the mixed-valent ruthenium analogue of [Cu3 (btc)2 ]n (HKUST-1, btc=benzene-1,3,5-tricarboxylate) to yield Ru-DEMOFs (defect-engineered metal-organic frameworks) of the general empirical formula [Ru3 (btc)2-x (5-X-ip)x Yy ]n . Framework incorporation of 5-X-ip was confirmed by powder XRD, FTIR spectroscopy, ultrahigh-vacuum IR spectroscopy, thermogravimetric analysis, (1) H NMR spectroscopy, N2 sorption, and X-ray absorption near edge structure. Interestingly, Ru-DEMOF 1 c with 32 % framework incorporation of 5-OH-ip shows the highest BET surface area (≈1300 m(2) g(-1) , N2 adsorption, 77 K) among all materials (including the parent framework [Ru3 (btc)2 Yy ]n ). The characterization data are consistent with two kinds of structural defects induced by framework incorporation of 5-X-ip: modified paddlewheel nodes featuring reduced ruthenium sites (Ru(δ+) , 0<δ<2, type A) and missing nodes leading to enhanced porosity (type B). Their relative abundances depend on the choice of the functional group X in the defect linkers. Defects A and B also appeared to play a key role in sorption of small molecules (i.e., CO2 , CO, H2 ) and the catalytic properties of the materials (i.e., ethylene dimerization and the Paal-Knorr reaction).

Single-Molecule-Magnet Behavior in a [2 × 2] Grid Dy(III)4 Cluster and a Dysprosium-Doped Y(III)4 Cluster.

Thanks to the MeCN hydrolysis in situ reaction, a [2 × 2] square grid Dy(III)4 cluster based on a polypyridyl triazolate ligand, [Dy4(OH)2(bpt)4(NO3)4(OAc)2] (1), was separated successfully and characterized through single-crystal X-ray diffraction and SQUID magnetometry. The frequency-dependent signals in the out-of-phase component of the susceptibility associated with slow relaxation of the magnetization confirmed that complex 1 displays single-molecule magnet (SMM) behavior. Two distinct slow magnetic relaxation processes, with effective energy barriers Ueff1 = 93 cm(-1) for fast relaxation and Ueff2 = 143 cm(-1) for slow relaxation observed under a zero direct-current field, are mainly attributed to the origin of single-ion behavior, which can be further acknowledged by the magnetic investigation of a dysprosium-doped yttrium cluster. Besides, it should be noted that complex 1 represents so far the highest energy barrier among the pure Dy(III)4 SMMs.

The first {Dy4} single-molecule magnet with a toroidal magnetic moment in the ground state.

A toroidal magnetic moment in the absence of a conventional total magnetic moment was first observed in a novel tetranuclear dysprosium cluster with nonmagnetic ground state. The toroidal state is quite robust with respect to variations of the exchange parameters.