Robust Mesoporous Functional Hydrogen-Bonded Organic Framework for Hypochlorite Detection.

Although tremendous progress has been achieved in the field of hydrogen-bonded organic frameworks (HOFs), the low stability, small/none pores, and difficult functionality severely obstruct their development. Herein, a novel robust mesoporous HOF (HOF-FAFU-1) decorated with a high density of free hydroxy moieties has been designed and readily synthesized in the de novo synthesis. In HOF-FAFU-1, the planar building blocks are connected to each other by typical intermolecular carboxylate dimers to form two-dimensional (2D) layers with sql topology, which are further connected to their adjacent layers by face-to-face π-π interactions to obtain a three-dimensional (3D) open mesoporous framework. Owing to the high density of intermolecular hydrogen bonding and strong π-π interactions, HOF-FAFU-1 is very stable, allowing it to retain its structure in aqueous solutions with a pH range of 1-9. Benefiting from the decorated hydroxy moieties, HOF-FAFU-1 was exploited as a fluorescent sensor for hypochlorite detection in water media by a turn-off mode, which cannot be realized by its nonhydroxy groups anchoring counterpart (HOF-TCBP). The proposed sensing system is highly efficient, validated by a very broad linear range (0-0.45 mM), fast response (15 s), and small limit of detection (LOD) (1.32 µM). The fluorescent quenching of HOF-FAFU-1 toward hypochlorite was also investigated, mainly being ascribed to the transformation of building blocks from the fluorescent reduced state to the nonfluorescent oxidative state. This work not only demonstrates that HOFs integrated with high stability and large pores as well as high density of functional groups can be simultaneously realized by judicious design of building blocks but also conceptually elucidates that such HOFs can effectively extend the application fields of HOFs.

Dual-emissive metal-organic framework: a novel turn-on and ratiometric fluorescent sensor for highly efficient and specific detection of hypochlorite.

Hypochlorite (ClO-) is widely used as a disinfectant, whose residue content in water should be strictly controlled due to the potential threat to human health in an inappropriate concentration. Herein, dual-emissive metal-organic frameworks with a UiO-66 prototype structure, PDA/Eu/PDA-UiO-66-NH2(x), were elegantly designed and prepared by a mixed ligand assembly and sequential post-synthesis strategy. Since blue emission is sensitive to ClO-, PDA/Eu/PDA-UiO-66-NH2(40) was selected as a model nanosensor for ratiometric and turn-on sensing of ClO- while red emission acts as a reference signal. Remarkably, PDA/Eu/PDA-UiO-66-NH2(40) shows high efficiency and specificity toward ClO- detection, as verified by a very short response time of 15 s, a wide linear range of 0.1-60 µM, a low detection limit of 0.10 µM, and excellent selectivity toward common competing ions. The recovery experiments show that the recoveries of spiking ClO- in tap water range from 96 to 103%. The rigidification of the coordinated H2N-BDC2- ligands should be responsible for the turn-on fluorescence of PDA/Eu/PDA-UiO-66-NH2(40). This work not only shows a highly efficient and specific fluorescent nanosensor for ClO- detection but also presents the first MOF-based fluorescent probe for turn-on and ratiometric sensing of ClO-.

Dual-Emissive Metal-Organic Framework as a Fluorescent "Switch" for Ratiometric Sensing of Hypochlorite and Ascorbic Acid.

The detection of hypochlorite (ClO-) content in tap water is extremely important because excess amounts of hypochlorite can convert into highly toxic species and inadequate amounts of hypochlorite cannot fully kill bacteria and viruses. Although several metal-organic frameworks (MOFs) have been successfully employed as fluorescent sensors for hypochlorite detection, all these sensors are based on single emission that responds to the dose of hypochlorite. Ratiometric sensors are highly desirable, which can improve the sensitivity, accuracy, and reliability via self-calibration. Herein, a nanoscale dual-emission multivariate 5-5-Eu/BPyDC@MOF-253-NH2 was synthesized by sequential mixed-ligand self-assembly and postsynthesis method. Among the two emission bands of 5-5-Eu/BPyDC@MOF-253-NH2, the strong blue emitting derived from ligands is sensitive to hypochlorite, while the red emitting derived from Eu(III) almost keeps invariable. Therefore, 5-5-Eu/BPyDC@MOF-253-NH2 was exploited as a fluorescent ratiometric nanosensor for "on-off" sensing of hypochlorite. Notably, the proposed sensing system showed an excellent performance including fast response (within 15 s), relative high specificity, wide linear range (0.1-30 µM), and low detection limit (0.094 µM). Besides, the suppressed blue emitting was recovered after the addition of ascorbic acid (AA) that consumes ClO- via the redox reaction. Therefore, 5-5-Eu/BPyDC@MOF-253-NH2 was further employed as a fluorescent ratiometric nanosensor for the "on-off-on" sensing of AA. This work represents the first MOF-based fluorescent "switch" for the ratiometric sensing of hypochlorite and the second for ratiometric sensing of AA.

Intrinsic catalytic activity of rhodium nanoparticles with respect to reactive oxygen species scavenging: implication for diminishing cytotoxicity.

Noble metal nanoparticles (NPs) and their hybrids have demonstrated a strong potential to mimic the catalytic activity of natural enzymes and diminish oxidative stress. There is a large space to explore the intrinsic catalytic activity of Rh NPs with respect to reactive oxygen species (ROS) scavenging. We found that Rh NPs can quench H2O2, •OH, O2•-, 1O2 and inhibit lipid peroxidation under physiological conditions. In vitro cell experiments proved that Rh NPs have great biocompatibility and protect cells from oxidative damage caused by H2O2. This study can provide important insights that could inform future biological applications.

Platinum nanoparticles: an avenue for enhancing the release of nitric oxide from S-nitroso-N-acetylpenicillamine and S-nitrosoglutathione.

Nitric oxide (NO) is an endogenous bioregulator with established roles in diverse fields. The difficulty in the modulation of NO release is still a significant obstacle to achieving successful clinical applications. We report herein our initial work using electron spin resonance (ESR) spectroscopy to detect NO generated from S-nitroso-N-acetylpenicillamine (SNAP) and S-nitrosoglutathione (GSNO) donors catalyzed by platinum nanoparticles (Pt NPs, 3 nm) under physiological conditions. With ESR spectroscopy coupled with spin trapping and spin labeling techniques, we identified that Pt NPs can significantly promote the generation of NO from SNAP and GSNO under physiological conditions. A classic NO colorimetric detection kit was also employed to verify that Pt NPs truly triggered the release of NO from its donors. Pt NPs can act as promising delivery vehicles for on-demand NO delivery based on time and dosage. These results, along with the detection of the resulting disulfide product, were confirmed with mass spectrometry. In addition, cellular experiments provided a convincing demonstration that the triggered release of NO from its donors by Pt NPs is efficient in killing human cancer cells in vitro. The catalytic mechanism was elucidated by X-ray photo-electron spectroscopy (XPS) and ultra-high performance liquid chromatography/high-resolution mass spectrometry (UHPLC-HRMS), which suggested that Pt-S bond formation occurs in the solution of Pt NPs and NO donors. Identification of Pt NPs capable of generating NO from S-nitrosothiols (RSNOs) is an important step in harnessing NO for investigations into its clinical applications and therapies.

Exploring the activities of ruthenium nanomaterials as reactive oxygen species scavengers.

Research on noble metal nanoparticles (NPs) able to scavenge reactive oxygen species (ROS) has undergone a tremendous growth recently. However, the interactions between ruthenium nanoparticles (Ru NPs) and ROS have never been systematically explored thus far. This research focused on the decomposition of hydrogen peroxide (H2O2), scavenging of hydroxyl radicals (•OH), superoxide radical (O2•-), singlet oxygen (1O2), 2,2'-azino-bis(3-ethylbenzenothiazoline- 6-sulfonic acid ion (ABTS•+), and 1,1-diphenyl-2-picrylhydrazyl radical (•DPPH) in the presence of commercial Ru NPs using the electron spin resonance technique. In vitro cell studies demonstrated that Ru NPs have excellent biocompatibility and exert a cytoprotective effect against oxidative stress. These findings may spark fresh enthusiasm for the applications of Ru NPs under relevant physiologically conditions.

Lanthanide Germanate Cluster Organic Frameworks Based on {Ln8Ge12} Clusters: From One-Dimensional Chains to Two-Dimensional Layers and Three-Dimensional Frameworks.

Under hydrothermal conditions, six series of novel lanthanide (Ln) organogermanates (LnGs) [Ln8Ge12(µ3-O)24E12(H2O)16]·14H2O (Ln(3+) = Pr(3+), 1; Nd(3+), 2; Sm(3+), 3; Eu(3+), 4; Gd(3+), 5; one-dimensional (1-D) LnG cluster organic chain (LnGCOC)), {[Nd8Ge12(µ3-O)24E12(H2O)10](µ2-H2O)2[Nd8Ge12(µ3-O)24E12(H2O)16]}·18H2O (6, two-dimensional (2-D) planar LnG cluster organic layer (LnGCOL)), {[Ln2GeE(HO)2O(H2O)(CH3COO)2(CO3)]2[Ln8Ge12E12(µ3-O)24(H2O)10]}·6H2O (Ln(3+) = Pr(3+), 7; Nd(3+), 8; 2-D wave-shaped LnGCOL), [TbGeE(HO)2O(H2O)(pca)]2[Tb8Ge12E12(µ3-O)24(H2O)8]·10H2O (9, three-dimensional (3-D) LnG cluster organic framework (LnGCOF)), {([Nd(pza)2(H2O)2]2[Nd8Ge12E12(µ3-O)24(H2O)12])([Nd(pza)2]2[Nd8Ge12E12(Hpza)2(µ3-O)24(H2O)10])}·4OH·14H2O (10, 3-D LnGCOF), {[Nd8Ge12E12(µ3-O)24(H2O)10][Nd(pca)(pda)(H2O)]2}·12H2O (11, 3-D LnGCOF) and {[Nd8Ge12E12(µ3-O)24(H2O)10][Nd(pza)(pda)(H2O)]2}·12H2O (12, 3-D LnGCOF) (Hpca = 2-picolinic acid, H2pda = 2,6-pyridinedicarboxylic acid, Hpza = 2-pyrazinecarboxylic acid) were prepared by introducing the second auxiliary ligands into the organogermanate-lanthanide-oxide reaction system. The obtainment of these LnGs realized the utilization of the second auxiliary ligands inducing the assembly from 1-D LnGCOCs to 2-D LnGCOLs and 3-D LnGCOFs based on LnG cluster (LnGC) {Ln8Ge12E12(µ3-O)24(H2O)16}({Ln8Ge12}) units and Ln-organic complexes or organic ligand connectors. It should be noted that the well-organized structural constructions of 1-12 can be visualized as the gradual replacement of active water sites located at equatorial and polar positions on the hypothetical [Ln8Ge12(µ3-O)24E12(H2O)18] LnGC core with oxygen or nitrogen atoms from organic ligands. The solid-state luminescent properties of 2, 3, 4, 6, and 8-12 have been investigated at room temperature.

A zeolite CAN-type aluminoborate with gigantic 24-ring channels.

A cancrinite type aluminoborate with gigantic 24-ring channels has been made under solvothermal conditions using Al(i-PrO)3 as the Al source and amines as the structure directing agents. Its framework is alternately constructed from B5O10 clusters and AlO4 units, no Al-O-Al linkages exist in the structure. Notably, the wall of the 24-ring channels has odd 11-ring windows, resulting in an unprecedented 3D intersecting channel system.

A polyoxometalate-organic supramolecular nanotube with high chemical stability and proton-conducting properties.

The use of 1H-1,2,4-triazole-3-thiol (H2trzS) has led to a rare inorganic-organic hybrid supramolecular nanotube built from novel Ni5-substituted polyoxotungstates, which presents interesting structural characteristics, high chemical stability, and proton-conducting properties.

The coordination polymer poly[[aqua(µ-oxalato)[1H-1,2,4-triazole-5(4H)-thione]cadmium(II)] monohydrate].

The title complex, {[Cd(C2O4)(C2H3N3S)(H2O)]·H2O}n, has a two-dimensional metal-organic framework, with the Cd(II) cation coordinated by three oxalate ligands, a 1H-1,2,4-triazole-5(4H)-thione (H2trzS) ligand and a water molecule. The CdO6S and oxalate units form an extended two-dimensional layered structure, with the terminal H2trzS ligands bonded to the Cd(II) sites through the thione S atoms. Hydrogen-bond interactions exist between adjacent layers.

A tubular one-dimensional polymer constructed from alternating clusters of europium(III)-water and copper(I) chloride bridged by 4-(pyridin-4-yl)benzoate.

A new 3d-4f heterometallic polymer, poly[[aqua-µ3-chlorido-[µ3-4-(pyridin-4-yl)benzoato]tris[µ2-4-(pyridin-4-yl)benzoato]dicopper(I)erbium(III)] dihydrate], {[Cu2Er(C12H8NO2)4Cl(H2O)]·2H2O}n, was synthesized by the hydrothermal reaction of Er2O3, CuCl2·2H2O and 4-(pyridin-4-yl)benzoic acid in the presence of HClO4. The asymmetric unit contains one Er(3+) cation, two Cu(+) cations, one Cl(-) anion, four deprotonated 4-(pyridin-4-yl)benzoate ligands, one coordinated aqua ligand and two solvent water molecules. This tubular one-dimensional polymer is constructed from alternating clusters of europium(III)-water and copper(I) chloride bridged by 4-(pyridin-4-yl)benzoate ligands. Extensive hydrogen-bonding interactions involving both the coordinated and the solvent water molecules provide further stabilization to the structure.

Poly[[tetra-aqua-di-µ(4)-oxalato-µ(2)-oxalato-dineo-dymium(III)] dihydrate].

The title compound, {[Nd(2)(C(2)O(4))(3)(H(2)O)(4)]·2H(2)O}(n), was synthesized hydro-thermally in the presence of bis-(carb-oxy-ethyl-germanium) sesquioxide. It is isostructural with the corresponding Pr compound [Yang et al. (2009). Acta Cryst. E65, m1152-m1153]. The Nd(3+) cation is nine-coordinated and its coordination polyhedron can be described as a distorted tricapped trigonal prism. Two Nd(3+) ions are connected by two O atoms from two oxalate ions to give a dinuclear Nd(2) unit. The unit is further linked to four others via four oxalate ions yielding a layerparallel to (0-11). The linkages between the layers by neighbouring oxalate anions lead to a three-dimensional framework with channels along the c axis. The coordinating and free water mol-ecules are located in the channels and make contact with each other and the host framework by weak O-H⋯O hydrogen bonds.

Open-framework aluminoborates co-templated by two types of primary amines.

A series of open-framework aluminoborates (ABOs), [CH(3)NH(3)][(CH(3)CH(2))(2)NH(2)][Al(B(5)O(10))] (1), [CH(3)CH(2)NH(3)][(CH(3)CH(2))(2)NH(2)][Al(B(5)O(10))] (2), [CH(3)CH(2)NH(3)][(CH(3))(2)NH(2)](H(2)O)(0.5)[Al(B(5)O(10))] (3) and [CH(3)NH(3)][CH(3)CH(2)NH(3)](H(2)O)(2)[Al(B(5)O(10))] (4) have been made co-templated by two types of primary amines under solvothermal conditions and characterized by elemental analysis, IR, TGA, UV-Vis, powder XRD, single crystal XRD and NLO determination, respectively. These four ABOs display two structural types: 1, 2 and 3 are isostructural and exhibit CrB(4) topology, showing three different layers along three different directions; while 4 contains 8-, 14-ring layers, which are packed along the [001] direction to form a noncentrosymmetric 3D framework with 8-, 14-ring channels, showing second harmonic generation (SHG) response that is about 0.5 times that of KDP (KH(2)PO(4)). The electronic structure calculations for 1 and 4 also have been performed.

Metal-organogermanate frameworks built by two kinds of infinite Ge-O chains with high thermostability and luminescent properties.

A bifunctional metalloligand with metal-C (Ge-C) bonds, bis(carboxyethylgermanium) sesquioxide (H(2)E(2)Ge(2)O(3), where E = -CH(2)CH(2)COO(-)), has been used to make metal-organometallic frameworks (MOMFs) Cd(1.5)(E(3)Ge(3)O(5)) (1) and Pb(E(2)Ge(2)O(3)) (2). In the structures, the inorganic Ge(2)O(3) cores of the metalloligands polymerize to form two kinds of infinite Ge-O chains, and the organic carboxyls induce the Cd and Pb ions to produce Cd-O and Pb-O chains. Further, the Ge-O chains link the Cd-O/Pb-O chains via -CH(2)CH(2)- groups to result in two novel MOMFs, showing high thermostability and blue-violet emission.

Two additive-induced isomeric aluminoborates templated by methylamine.

Two additive-induced isomeric aluminoborates, (CH(3)NH(3))(2)(H(2)O)(2)[Al(B(5)O(10))] (1) and (CH(3)NH(3))(H(2)O)[Al(B(5)O(10))] (2), have been obtained by using small methylamine molecules as structure directing agents (SDA) under solvothermal conditions and characterized by elemental analysis, IR, TGA, powder X-ray diffraction, single-crystal X-ray diffraction, NLO determination, UV-vis spectral investigation, electronic structure calculation and ion exchange. Different arrangements of B(5)O(10) units and AlO(4) tetrahedra results in two different structures with two pairs of helical channels along [100] and [010] directions, respectively. Interestingly, the two frameworks with noncentrosymmetric and chiral space groups separately exhibit the same diamond topologies and display good second harmonic generation efficiencies of about 2.0 times the value of KDP.

Lanthanide germanate cluster organic frameworks constructed from {Ln(8)Ge(12)} or {Ln(11)Ge(12)} cage cluster building blocks.

Through the use of bis(carboxyethylgermanium) sesquioxide as the germanium source, lanthanide has been successfully introduced into germanate systems under hydrothermal conditions, resulting in a novel lanthanide germanate cluster organic framework with twofold-interpenetrating nets built from Nd(8)Ge(12) cluster units. To avoid the interpenetration, a second ligand, 2-picolinic acid, was introduced into the above system, resulting in the formation of a series of noninterpenetrating networks constructed from Ln(11)Ge(12) cluster units, as expected.