Controlling the Uptake and Release of Semiochemicals in Channel-Type Metal-Organic Frameworks Through Pore Expansion.

Semiochemicals can be used to manipulate insect behaviour for sustainable pest management strategies, but their high volatility is a major issue for their practical implementation. Inclusion of these molecules within porous materials is a potential solution to this issue, as it can allow for a slower and more controlled release. In this work, we demonstrate that a series of Zr(IV) and Al(III) metal-organic frameworks (MOFs) with channel-type pores enable controlled release of three semiochemicals over 100 days by pore size design, with the uptake and rate of release highly dependent on the pore size.

Vanillin Cross-Linked Chitosan Film with Controlled Release of Green Tea Polyphenols for Active Food Packaging.

We report a novel cross-linked chitosan composite film containing vanillin, glycerol, and green tea extract. The effects of vanillin-mediated cross-linking and the incorporation of antimicrobial green tea polyphenols were investigated. The cross-linking effect, confirmed by Fourier transform infrared (FTIR) analysis, increased the tensile strength of the biopolymer film to 20.

Advances in two-dimensional materials for energy-efficient and molecular precise membranes for biohydrogen production.

Waste management has become an ever-increasing global issue due to population growth and rapid globalisation. For similar reasons, the greenhouse effect caused by fossil fuel combustion, is leading to chronic climate change issues. A novel approach, the waste-to-hydrogen process, is introduced to address the concern of waste generation and climate change with an additional merit of production of a renewable, higher energy density than fossil fuels and sustainable transportation fuel, hydrogen (H) gas.

Coupling Postsynthetic High-Temperature Oxidative Thermolysis and Thermal Rearrangements in Isoreticular Zinc MOFs.

Herein, we report coupling high temperature postsynthetic modifications (PSMs) in metal-organic frameworks (MOFs). Thermo-reactive propargyloxy-functionalized zinc IRMOFs (isoreticular metal-organic frameworks) prepared from 2-(prop-2-yn-1-yloxy)-[1,1'-biphenyl]-4,4'-dicarboxylic acid (HbpdcOCHCCH) were investigated for their high-temperature postsynthetic rearrangement (PSR) chemistry to heterocyclic chromenes and benzofurans and then coupled to solid-gas reactions with molecular oxygen. The selectivity for the initial molecular rearrangements was found to be inverted in the porous MOF environment compared to conventional melt reactions of the ester compound MebpdcOCHCCH and proceeded far more easily than the solid-state transformation from HbpdcOCHCCH, showing the potential of MOFs to give rise to different chemistry.

Solvent Sorption-Induced Actuation of Composites Based on a Polymer of Intrinsic Microporosity.

Materials that are capable of actuation in response to a variety of external stimuli are of significant interest for applications in sensors, soft robotics, and biomedical devices. Here, we present a class of actuators using composites based on a polymer of intrinsic microporosity (PIM). By adding an activated carbon (AX21) filler to a PIM, the composite exhibits repeatable actuation upon solvent evaporation and wetting and it is possible to achieve highly controlled three-dimensional actuation.

Inclusion of viologen cations leads to switchable metal-organic frameworks.

The reactions of Zn(NO)·6HO with the polycarboxylic acids 1,3-benzenedicarboxylic acid (Hmbdc), 1,4-benzenedicarboxylic acid (Hbdc), 1,3,5-benzenetricarboxylic acid (Hbtc) and 4,4'-biphenyldicarboxylic acid (Hbpdc) in the presence of methyl viologen iodide ([MV]I) in DMF gave anionic frameworks with methyl viologen species incorporated as counter-ions. When the reactions were carried out at 120 °C, the blue products [MV][Zn(mbdc)] (1-ht), [MV][HMV][NMeH][Zn(bdc)]·0.6DMF (2-ht), [MV][Zn(btc)]·DMF (4-ht) and [MV][Zn(bpdc)]·8DMF·10HO (5-ht) were formed, and these were shown to contain the radical cation [MV]˙.

Inclusion and release of ant alarm pheromones from metal-organic frameworks.

Zinc(ii) and zirconium(iv) metal-organic frameworks show uptake and slow release of the ant alarm pheromones 3-octanone and 4-methyl-3-heptanone. Inclusion of N-propyl groups on the MOFs allows for enhanced uptake and release over several months. In preliminary field trials, leaf cutting ants show normal behavioural responses to the released pheromones.

Post-synthetic modification of zirconium metal-organic frameworks by catalyst-free aza-Michael additions.

The reactions of the zirconium MOF [Zr6O4(OH)4(bdc-NH2)6] (UiO-66-NH2, bdc-NH2 = 2-amino-1,4-benzenedicarboxylate) with the Michael acceptors acrylonitrile (CH2[double bond, length as m-dash]CHCN), acrylic acid (CH2[double bond, length as m-dash]CHCO2H), methyl acrylate (CH2[double bond, length as m-dash]CHCO2Me) and methyl vinyl ketone (CH2[double bond, length as m-dash]CHC(O)Me) led to post-synthetic modification of the MOF through C-N bond formation without loss of crystallinity. The reactions with acrylonitrile and acrylic acid go to completion, yielding [Zr6O4(OH)4(bdc-NHCH2CH2CN)6] (UiO-66-AN, 1) and [Zr6O4(OH)4(bdc-NHCH2CH2CO2H)6] (UiO-66-AA, 2) respectively, whereas those with methyl acrylate and methyl vinyl ketone are incomplete, yielding [Zr6O4(OH)4(bdc-NH2)0.66(bdc-NHCH2CH2CO2Me)5.

Post-Synthetic Mannich Chemistry on Metal-Organic Frameworks: System-Specific Reactivity and Functionality-Triggered Dissolution.

The Mannich reaction of the zirconium MOF [Zr O (OH) (bdc-NH ) ] (UiO-66-NH , bdc-NH =2-amino-1,4-benzenedicarboxylate) with paraformaldehyde and pyrazole, imidazole or 2-mercaptoimidazole led to post-synthetic modification (PSM) through C-N bond formation. The reaction with imidazole (Him) goes to completion whereas those with pyrazole (Hpyz) and 2-mercaptoimidazole (HimSH) give up to 41 and 36 % conversion, respectively. The BET surface areas for the Mannich products are reduced from that of UiO-66-NH , but the compounds show enhanced selectivity for adsorption of CO over N at 273 K.

Evaluating Iodine Uptake in a Crystalline Sponge Using Dynamic X-ray Crystallography.

The uptake of gaseous iodine into the crystalline sponge material [(ZnI)(tpt)]·0.7triphenylene·0.3PhNO·0.

The effect of metal distribution on the luminescence properties of mixed-lanthanide metal-organic frameworks.

A series of lanthanide metal-organic frameworks (MOFs) of the general formula [Ln(Hodip)(HO)]·nHO (Sm, 1; Eu, 2; Gd, 3; Tb, 4; Dy, 5; Er, 6; Hodip = 5,5'-oxydiisophthalic acid) have been prepared and shown crystallographically to have isostructural three-dimensional frameworks. The fluorescence emission spectra of the europium compound 2, which is red, and the terbium compound 4, which is green, show characteristic peaks for transitions involving the metal centres, whereas that for the gadolinium compound 3 is dominated by transitions involving Hodip. Using a 1 : 1 : 1 mixture of europium, gadolinium and terbium nitrates in the synthesis resulted in the mixed-metal MOF [GdTbEu(Hodip)(HO)]·nHO 7, for which the ratio of the metal ions was determined using EDX spectroscopy.

Mechanical characterisation of polymer of intrinsic microporosity PIM-1 for hydrogen storage applications.

Polymers of intrinsic microporosity (PIMs) are currently attracting interest due to their unusual combination of high surface areas and capability to be processed into free-standing films. However, there has been little published work with regards to their physical and mechanical properties. In this paper, detailed characterisation of PIM-1 was performed by considering its chemical, gas adsorption and mechanical properties.

Furnishing Amine-Functionalized Metal-Organic Frameworks with the β-Amidoketone Group by Postsynthetic Modification.

Postsynthetic modification (PSM) of amino-functionalized metal-organic frameworks (MOFs) to those bearing pendant β-amidoketone arms using diketene is herein reported. Three unique MOF families demonstrate the scope of this transformation, which both is atom-economical and yields high conversions. In each case, the crystallinity was retained, and instances of exceptional solid-state ordering were observed in the PSM products, which has allowed detailed crystallographic characterization in multiple instances.

An Iodine-Vapor-Induced Cyclization in a Crystalline Molecular Flask.

A vapor-induced cyclization has been observed in the host environment of a crystalline molecular flask (CMF), within which 1,8-bis(2-phenylethynyl)naphthalene (bpen), a diarenynyl system primed for cyclization, was exposed to iodine vapor to yield the corresponding indeno[2,1-α]phenalene species. The cyclization process, unique in its vapor-induced, solvent-free nature, was followed spectroscopically, and found to occur concurrently with the displacement of lattice solvent for molecular iodine in CMF⋅0.75 bpen⋅2.

Ion flow in a zeolitic imidazolate framework results in ionic diode phenomena.

Ionic transport (for applications in nanofluidics or membranes) and "ionic diode" phenomena in a zeolitic imidazolate framework (ZIF-8) are investigated by directly growing the framework from aqueous Zn(2+) and 2-methylimidazole as an "asymmetric plug" into a 20 μm diameter pore in a ca. 6 μm thin poly-ethylene-terephthalate (PET) film.

Compositional control of pore geometry in multivariate metal-organic frameworks: an experimental and computational study.

A new approach is reported for tailoring the pore geometry in five series of multivariate metal–organic frameworks (MOFs) based on the structure [Zn2(bdc)2(dabco)] (bdc = 1,4-benzenedicarboxylate, dabco = 1,8-diazabicyclooctane), DMOF-1. A doping procedure has been adopted to form series of MOFs containing varying linker ratios. The series under investigation are [Zn2(bdc)(2-x)(bdc-Br)x(dabco)]·nDMF 1 (bdc-Br = 2-bromo-1,4-benzenedicarboxylate), [Zn2(bdc)(2-x)(bdc-I)x(dabco)]·nDMF 2 (bdc-I = 2-iodo-1,4-benzenedicarboxylate), [Zn2(bdc)(2-x)(bdc-NO2)x(dabco)]·nDMF 3 (bdc-NO2 = 2-nitro-1,4-benzenedicarboxylate), [Zn2(bdc)(2-x)(bdc-NH2)x(dabco)]·nDMF 4 (bdc-NH2 = 2-amino-1,4-benzenedicarboxylate) and [Zn2(bdc-Br)(2-x)(bdc-I)x(dabco)]·nDMF 5.

Bismuth coordination networks containing deferiprone: synthesis, characterisation, stability and antibacterial activity.

A series of bismuth-dicarboxylate-deferiprone coordination networks have been prepared and structurally characterised. The new compounds have been demonstrated to release the iron overload drug deferiprone on treatment with PBS and have also been shown to have antibacterial activity against H. pylori.

Gas sensing using porous materials for automotive applications.

Improvements in the efficiency of combustion within a vehicle can lead to reductions in the emission of harmful pollutants and increased fuel efficiency. Gas sensors have a role to play in this process, since they can provide real time feedback to vehicular fuel and emissions management systems as well as reducing the discrepancy between emissions observed in factory tests and 'real world' scenarios. In this review we survey the current state-of-the-art in using porous materials for sensing the gases relevant to automotive emissions.

The synthesis and characterisation of coordination and hydrogen-bonded networks based on 4-(3,5-dimethyl-1H-pyrazol-4-yl)benzoic acid.

The synthesis, structural and thermal characterisation of a number of coordination complexes featuring the N,O-heteroditopic ligand 4-(3,5-dimethyl-1H-pyrazol-4-yl)benzoate, HL are reported. The reaction of H2L with cobalt(II) and nickel(II) nitrates at room temperature in basic DMF/H2O solution gave discrete mononuclear coordination complexes with the general formula {[M(HL)2(H2O)4]·2DMF} (M = Co (1), Ni (2)), whereas the reaction with zinc(II) nitrate gave [Zn(HL)2]∞, 3, a coordination polymer with distorted diamondoid topology and fourfold interpenetration. Coordination about the tetrahedral Zn(II) nodes in 3 are furnished by two pyrazolyl nitrogen atoms and two carboxylate oxygen atoms to give a mixed N2O2 donor set.

A facile single crystal to single crystal transition with significant structural contraction on desolvation.

5-Ethynyl-1,3-benzenedicarboxylic acid (H2ebdc) reacted with lead(II) acetate trihydrate yields a 1D ladder network, [Pb(ebdc)(MeOH)]2·H2O (1). Removing crystals of 1 from the mother liquor results in a facile single crystal to single crystal transition, yielding 2D [Pb(ebdc)] net (2) with a change in space group from I2/a to P1̄.

Incorporation by coordination and release of the iron chelator drug deferiprone from zinc-based metal-organic frameworks.

A series of new zinc-based metal-organic framework materials has been prepared in which deferiprone is incorporated as a chelating ligand on infinite or tri-zinc secondary building units following deprotonation. Deferiprone is immediately released from the MOFs on treatments with 1 N hydrochloric acid or buffer, but slow release is observed in ethanoic acid.

Formation of low density hydrous iron oxide via conformal transformation of MIL-53(Fe).

Hydrous iron oxide materials with a predefined shape, photo-electrochemical activity, low density (estimated to be 0.32 g cm(-3)), and high fractal porosity (BET ca. 117 m(2) g(-1)) are formed via internal hydrolytic transformation of the crystalline metal-organic framework MIL-53(Fe) in dilute aqueous hydroxide.

A reagentless thermal post-synthetic rearrangement of an allyloxy-tagged metal-organic framework.

Direct heating of a metal-organic framework provides a simple, controllable way of effecting a covalent post-synthetic modification. Herein we report that an allyloxy-tagged zinc metal-organic framework undergoes a thermally-promoted aromatic Claisen rearrangement through which the framework connectivity and porosity are maintained.