Rational Design and Functionalization of a Zinc Metal-Organic Framework for Highly Selective Detection of 2,4,6-Trinitrophenol.

To develop potential metal-organic frameworks (MOFs) for 2,4,6-trinitrophenol (TNP) detection, an amino-functionalized Zn-MOF, [NH2(CH3)2][Zn4O(bpt)2(bdc-NH2)0.5]·5DMF (where H3bpt = biphenyl-3,4',5-tricarboxylate, H2bdc-NH2 = 2-aminoterephthalic acid, and DMF = N,N-dimethylformamide), has been designed theoretically and synthesized experimentally. Its structure is composed of Zn4O(CO2)7 secondary building units linked by mixed ligands, exhibiting a three-dimensional framework. Fluorescence exploration revealed that the amino-functionalized Zn-MOF shows high selectivity and sensitivity for TNP, which agrees well with the predictions of theoretical simulations. This work provides a suitable means to develop new potential MOFs for TNP detection performance with a combination of experimental and theoretical perspectives.

The Uncommon Channel-Based Ln-MOFs for Highly Selective Fe3+ Detection and Superior Rhodamine†B Adsorption.

Two new isostructural 3D lanthanide-organic frameworks [H2 N(Me)2 ] [Ln3 (OH)(bpt)3 (H2 O)3 ] (DMF)2 ⋅(H2 O)4 (1-Ln; Ln=Sm and Eu) with a 1D channel (25 Å) have been successfully assembled from the rare trinuclear [Ln3 (OH)(COO)9 ] clusters and biphenyl-3,4',5-tricarboxylic acid (H3 bpt) and exhibit high stability towards water in the pH range 3-10. MOF 1-Eu is a promising luminescent probe for sensing Fe3+ in aqueous solution and is also selective towards rhodamine B (RhB) with a superior adsorption capacity of 735 mg g-1 , which is the highest among the reported Ln-MOFs for RhB removal so far. Periodic DFT calculations further confirmed the selective adsorption of rhodamine B over other dyes.

Accelerated crystallization of zeolites via hydroxyl free radicals.

In the hydrothermal crystallization of zeolites from basic media, hydroxide ions (OH(-)) catalyze the depolymerization of the aluminosilicate gel by breaking the Si,Al-O-Si,Al bonds and catalyze the polymerization of the aluminosilicate anions around the hydrated cation species by remaking the Si,Al-O-Si,Al bonds. We report that hydroxyl free radicals (•OH) are involved in the zeolite crystallization under hydrothermal conditions. The crystallization processes of zeolites-such as Na-A, Na-X, NaZ-21, and silicalite-1-can be accelerated with hydroxyl free radicals generated by ultraviolet irradiation or Fenton's reagent.

Temperature-dependence of the influence of the position-2-methyl group on the structure-directing effect of piperazine in the synthesis of open-framework aluminophosphates.

The temperature-dependence of the influence of the position-2-methyl group on the structure-directing effect of piperazine in the synthesis of open-framework aluminophosphates was investigated. By heating the initial mixture with the composition of Al2O3:1.5 P2O5:R:125 H2O at 160 °C, where R is the structure-directing agent of 2-methylpiperazine or piperazine, layered aluminophosphates APMeP150 (R = 2-methylpiperazine) and AP2pip (R = piperazine) were obtained. When the same initial reaction mixture was heated at 190 °C, layered aluminophosphates APMeP200 (R = 2-methylpiperazine) and AP2pip (R = piperazine) were crystallized. APMeP200 and AP2pip have the same inorganic sheet topology. We investigated the crystallization processes of the four open-framework aluminophosphates and found that increasing the heating temperature slowed the crystallization of the initial mixtures. The non-bonding interactions between the inorganic layers of the four open-framework aluminophosphates and the experimental or theoretically generated structure-directing agents were calculated. The possible starting points of the crystallization of the four open-framework aluminophosphates were analysed and compared. The temperature-dependence of the influence of the position-2-methyl group on the structure-directing effect of piperazine revealed that the structure-directing effect, the most important factor in the synthesis of zeolites and related open-framework materials, is determined by multiple factors. The structural parameters of the same compound can be affected by the synthesis conditions.

A bioscaffolding strategy for hierarchical zeolites with a nanotube-trimodal network.

Hierarchical zeolite monoliths with multimodal porosity are of paramount importance as they open up new horizons for advanced applications. So far, hierarchical zeolites based on nanotube scaffolds have never been reported. Inspired by the organization of biominerals, we have developed a novel precursor scaffolding-solid phase crystallization strategy for hierarchical zeolites with a unique nanotube scaffolding architecture and nanotube-trimodal network, where biomolecular self-assembly (BSA) provides a scaffolding blueprint. By vapor-treating Sil-1 seeded precursor scaffolds, zeolite MFI nanotube scaffolds are self-generated, during which evolution phenomena such as segmented voids and solid bridges are observed, in agreement with the Kirkendall effect in a solid-phase crystallization system. The nanotube walls are made of intergrown single crystals rendering good mechanical stability. The inner diameter of the nanotube is tunable between 30 and 90 nm by varying the thickness of the precursor layers. Macropores enclosed by cross-linked nanotubes can be modulated by the choice of BSA. Narrow mesopores are formed by intergrown nanocrystals. Hierarchical ZSM-5 monoliths with nanotube (90 nm), micropore (0.55 nm), mesopore (2 nm) and macropore (700 nm) exhibit superior catalytic performance in the methanol-to-hydrocarbon (MTH) conversion compared to conventional ZSM-5. BSA remains intact after crystallization, allowing a higher level of organization and functionalization of the zeolite nanotube scaffolds. The current work may afford a versatile strategy for hierarchical zeolite monoliths with nanotube scaffolding architectures and a nanotube-multimodal network leading to self-supporting and active zeolite catalysts, and for applications beyond.

Origin of the structure-directing effect resulting in identical topological open-framework materials.

In the synthesis of zeolites and related crystalline materials with open-frameworks, a single structure is obtained in the presence of many different templates, known as the "one-structure/multiple-templates" phenomenon. However, the reasons behind this phenomenon have yet to be elucidated. By analyzing the possible starting point of crystallization in several "one-structure/multiple-templates" systems and applying the molecular dynamics simulation to such systems, we found that the template-framework binding free energy level or charge transfer (exchange) degree was the key to the structure-directing effect of a template. This discovery explains why the structure-directing effect of a template can be affected by many variables, such as the nature of the source materials, molar composition of the initial reaction mixture (recipe), mineralizers, type of solvent, and heating temperature. In the synthesis of zeolites and related crystalline materials with open-frameworks, the template or organic additive played a topological structure-directing role instead of a structure-directing role.

Synthesis of chiral polymorph A-enriched zeolite Beta with an extremely concentrated fluoride route.

Chiral zeolitic materials with intrinsically chiral frameworks are highly desired because they can combine both shape selectivity and enantioselectivity. In the field of zeolite, the synthesis of chiral polymorph A of zeolite Beta or chiral polymorph A-enriched zeolite Beta is one of the biggest challenges. We demonstrate here a generalized extremely concentrated fluoride route for the synthesis of chiral polymorph A-enriched zeolite Beta in the presence of five achiral organic structure-directing agents. The polymorph A-enriched Ti-Beta shows a higher enantioselectivity for the asymmetric epoxidation of alkenes than the normal Ti-Beta.

A chiral open-framework fluoroaluminophosphate with enantiomeric excess in the bulk product.

A novel chiral open-framework fluoroaluminophosphate [C4N3H16][Al6P3O12F6(OH)6] was hydrothermally synthesized using diethylenetriamine as a structure-directing agent. The significant enantiomeric excess of the bulk product was confirmed by the solid state vibrational circular dichroism (VCD) spectrum.

AIE cation functionalized layered zirconium phosphate nanoplatelets: ion-exchange intercalation and cell imaging.

An aggregation-induced emission (AIE) probe, possessing a quaternary tetraphenylethene (TPEN) cation, was successfully intercalated into layered α-zirconium phosphate (α-ZrP) nanosheets by ion-exchange. The hybrid materials emit strong blue emissions in aqueous solution which can be used as an effective fluorescence label for HeLa cells.

Design and synthesis of two porous metal-organic frameworks with nbo and agw topologies showing high CO2 adsorption capacity.

Two novel porous copper-based metal-organic frameworks with nbo and agw topologies have been designed and synthesized using tetracarboxylate and tricarboxylate ligands, respectively. They possess large surface areas and high CO2 adsorption capacities (up to 170 cm(3)/g or 7.59 mmol/g at 0 °C under ambient pressure).

A 4 + 4 strategy for synthesis of zeolitic metal-organic frameworks: an indium-MOF with SOD topology as a light-harvesting antenna.

A zeolitic metal-organic framework with a SOD topology, (Et2NH2)[In(BCBAIP)]·4DEF·4EtOH (H4BCBAIP: 5-(bis(4-carboxybenzyl)amino)isophthalic acid) (1), has been constructed by a 4 + 4 synthetic strategy from tetrahedral organic building units and In(3+) ions. Compound 1 could adsorb organic dyes and be used as a light-harvesting antenna.

AIE luminogen bridged hollow hydroxyapatite nanocapsules for drug delivery.

A new type of organophosphonic acid, (4,4'-(1,2-diphenylethene-1,2-diyl)bis(4,1-phenylene))bis(methylene)diphosphonic acid (PATPE), based on tetraphenylethene has been prepared, and its ester derivative exhibits the characteristic property of aggregation-induced emission (AIE) in DMSO-H2O solution. The PATPE is then fabricated into hydroxyapatite by a one-pot condensation process to form hollow mesoporous nanocapsules of ellipsoidal morphology. The AIE luminogen-bridged hollow hydroxyapatite nanocapsules emit strong blue light under UV irradiation, which is further used for drug delivery using ibuprofen (IBU) as a model drug. The fluorescence intensity of the materials varies greatly with the loading and release of IBU, suggesting that the drug release process may be tracked in terms of the change of luminescence intensity. The biocompatibility of AIE luminogen functionalized material is also evaluated on HUH7 human hepatoma cells using the MTT assay. The low cytotoxicity of the materials reveals that the as-prepared multifunctional hydroxyapatite will be a new candidate for simultaneous drug delivery and cell imaging in potential bioapplications.

A novel (3,3,6)-connected luminescent metal-organic framework for sensing of nitroaromatic explosives.

A novel metal-organic framework [Cd3(CPEIP)2(DMF)3]·solvent (1) based on a neutral non-oxo triangular [Cd3(COO)6] secondary building unit (SBU), was synthesized under solvothermal conditions by using a rigid unsymmetrical tricarboxylate ligand 5-((4-carboxyphenyl)ethynyl)isophthalic acid (H3CPEIP). Single-crystal X-ray diffraction analysis reveals that compound 1 crystallizes in the monoclinic space group C2/c. The crystal structure exhibits a rare (3,3,6)-connected three-dimensional (3-D) framework with vertex symbol of (4(2).6)(4(3))(4(5).6(4).8(6)). The incorporation of CPEIP(3+) into 1 gives rise to high luminescence in solid state. The emission of micrometer-sized compound 1 (1') dispersed in ethanol could be quenched efficiently by picric acid (PA), indicating that this compound could be utilized as a chemosensor for detection of aromatic explosives.

Structures and properties of lanthanide metal-organic frameworks based on a 1,2,3-triazole-containing tetracarboxylate ligand.

A family of 3D lanthanide metal-organic frameworks, [La(HTADIP)(H(2)O)(4)]·xH(2)O (2 < x < 2.5) (1), [Eu(HTADIP)(H(2)O)(4)]·H(2)O (2), [Tb(HTADIP)(H(2)O)(3)]·2H(2)O (3), and [Er(HTADIP)(H(2)O)(3)]·2H(2)O (4) (H(4)TADIP = 5,5'-(1H-1,2,3-triazole-1,4-diyl)diisophthalic acid), have been hydrothermally synthesized and characterized. The unsymmetrical 1,2,3-triazole-containing tetracarboxylate ligand was synthesized through the copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction of diethyl-5-azidoisophthalate (M1) and diethyl-5-ethynylisophthalate (M2). Single-crystal X-ray diffraction analyses for 1-4 reveal that they are isostructural. These compounds crystallize in the monoclinic P2(1)/c space group with the rutile topology. The luminescent properties of compounds 2 and 3 were investigated and characteristic Eu(III) and Tb(III) emissions are observed. Compound 3 exhibits selective luminescent sensing behavior for Cu(2+) ions in aqueous solution. The magnetic properties of compounds 3 and 4 were studied.

Distribution of trivalent metal cations in alumino-/gallogermanate zeolites with JST topology.

A series of zeolitic alumino- and gallogermanate compounds, |M(II)(en)(3)|[M(III)(2)Ge(4)O(12)] (M(II) = Ni, Co, Zn; M(III) = Al, Ga; en = ethylenediamine), has been synthesized using in situ formed [M(II)(en)(3)](2+) cations as the structure-directing agents. These zeolitic compounds exhibit the same JST framework topology which is built exclusively of 3-rings. Their structures were determined by single-crystal X-ray diffraction. The frameworks of these compounds are constructed from M(III)- and Ge-centred tetrahedra. According to inductively coupled plasma (ICP) analyses, the ratios of M(III)/Ge are 1/2 in all these compounds. The resulting negative charges in these frameworks are compensated by extra-framework [M(II)(en)(3)](2+) cations. Single crystal structural analyses show that there are two crystallographically distinct atom sites for M(3+). According to the ICP results and the unique structural feature of JST, the most reasonable distribution of M(3+) cations in these structures was deduced.

A novel decanuclear Co(II) cluster with adamantane-like metallic skeleton supported by 8-hydroxyquinoline and in situ formed CO3(2-) anions.

A novel decanuclear Co(II) cluster, [Co(10)(Q)(12)(µ(6)-CO(3))(4)]·2.5DMF (1) (Q = 8-hydroxyquinoline), has been synthesized under solvothermal conditions and characterized by powder XRD, TGA and IR spectroscopy. Single-crystal X-ray diffraction analysis shows that 1 represents a new type of decanuclear cobalt cluster with an approximate supertruncated tetrahedral shape coordinated with coexisted Q ligands and in situ formed µ(6)-bridging CO(3)(2-) anions. Meanwhile, 1 is the largest aggregate in metal-Q coordination chemistry. Another distinguishing feature of 1 is the adamantane-like metallic skeleton with point symbol {6(3)}(2){6}(3), which is observed in the polynuclear metal complexes for the first time. Furthermore, it is considered that the in situ formed CO(3)(2-) anions have a crucial effect on the formation of the resultant unexpected polynuclear structures. The magnetic studies show that antiferromagnetic (AF) interactions exist within 1.

LEV-zeotype magnesium aluminophosphates with variable Mg/Al ratios.

By using two different organic amines, n-methylpiperidine and 1,2-diaminocyclohexane (DACH), as the structure-directing agents (SDAs), two magnesium aluminophosphate molecular sieves |(C(6)H(14)N)(2)|[Mg(2)Al(7)(PO(4))(9)] and |(C(6)H(14)N(2))(1.4)(H(2)O)(2)H(2)|[Mg(2)Al(5)(PO(4))(7)], denoted as MgAPO-CJ67(a) and MgAPO-CJ67(b), have been synthesized under hydrothermal conditions. They are the first example of Mg incorporated aluminophosphates with the LEV-zeotype structure. The magnesium and aluminum atoms co-occupy the same crystallographic positions in the frameworks of MgAPO-CJ67(a) and MgAPO-CJ67(b), but with different Mg/Al ratios of 1 : 3.5 and 1 : 2.5, respectively. MgAPO-CJ67(a) exhibits higher thermal stability upon calcination than MgAPO-CJ67(b), and its framework keeps intact after the removal of occluded organic SDAs. The N(2) adsorption on the calcined MgAPO-CJ67(a) sample gives the BET surface area of 386 m(2) g(-1). NH(3)-temperature programmed desorption (NH(3)-TPD) analysis shows that MgAPO-CJ67(a) has a medium acidity.

K3[Tb(x)Eu(1-x)Ge3O8(OH)2] (x = 1, 0.88, 0.67, 0): 2D-layered lanthanide germanates with tunable photoluminescent properties.

A family of novel 2D-layered lanthanide germanates K(3)[Tb(x)Eu(1-x)Ge(3)O(8)(OH)(2)] (x = 1, 0.88, 0.67, 0; denoted as TbGeO-JU-87, Tb(0.88)Eu(0.12)GeO-JU-87, Tb(0.67)Eu(0.33)GeO-JU-87, and EuGeO-JU-87) were synthesized under mild hydrothermal conditions in a concentrated gel system. They are isostructural, as confirmed by the powder X-ray diffraction analysis. The single-crystal X-ray diffraction analysis of EuGeO-JU-87 reveals that it is a 2D-layered [EuGe(3)O(8)(OH)(2)](n)(3n-) anionic framework, which is built up from GeO(4)H/GeO(4) tetrahedra and EuO(6) octahedra by sharing vertex O atoms. Charge neutrality is achieved by K(+) ions located in the free void space. Interestingly, photoluminescence studies show that Tb(0.88)Eu(0.12)GeO-JU-87 and Tb(0.67)Eu(0.33)GeO-JU-87 exhibit a high Tb(3+)-to-Eu(3+) energy-transfer efficiency and the Tb(x)Eu(1-x)GeO-JU-87 system displays tunable photoluminescent properties.