Functionalised electrospun membranes (TETA-PVC) for the removal of lead(ii) from water.

Driven by the need for delivering sustainable water purification solutions for the removal of heavy metals from water, electrospun PVC membranes were functionalised with triethylenetetramine (TETA) and were used to remove lead(ii) ions selectively from water. The membranes were characterised and their adsorption behavior towards the removal of lead from water was investigated. The incorporation of TETA on the membrane's surface significantly improved the removal efficiency of lead(ii) up to 99.

Thiosemicarbazone modified zeolitic imidazolate framework (TSC-ZIF) for mercury(ii) removal from water.

Zeolitic imidazolate frameworks (ZIF-8), and their derivatives, have been drawing increasing attention due to their thermal and chemical stability. The remarkable stability of ZIF-8 in aqueous and high pH environments renders it an ideal candidate for the removal of heavy metals from wastewater. In this study, we present the preparation of novel aldehyde-based zeolitic imidazolate frameworks (Ald-ZIF) through the integration of mixed-linkers: 2-methylimidazole (MIM) and imidazole-4-carbaldehyde (AldIM).

Guest Binding Drives Host Redistribution in Libraries of Co L Cages.

Two Co L tetrahedral cages prepared from similar building blocks showed contrasting host-guest properties. One cage did not bind guests, whereas the second encapsulated a series of anions, due to electronic and geometric effects. When the building blocks of both cages were present during self-assembly, a library of five Co L L cages was formed in a statistical ratio in the absence of guests.

Topological transformation of a trefoil knot into a [2]catenane.

Topological transformation of a zinc-templated trefoil knot, Zn-TK, into a zinc-templated [2]catenane, Zn-[2]C, was studied. The net reaction 2 Zn-TK→3 Zn-[2]C was accomplished in 89% yield by heating a solution of Zn-TK in DO. Kinetic investigation by H NMR spectroscopy and high resolution mass spectrometry revealed that the mechanism is complex, involving a large pool of intermediates that form after imine bond cleavage.

Post-synthetic modifications of cadmium-based knots and links.

Three topologically non-trivial cadmium(ii)-based complexes-Cd-[2]C, Cd-TK and Cd-SL-were simultaneously self-assembled in a dynamic library, individually isolated and fully characterized using solid-state, gas-phase and solution-phase techniques. Post-synthetic modifications, including reduction and transmetalation, were subsequently achieved. Imine bond reduction followed by demetallation led to the isolation of the corresponding organic molecules [2]C, TK and SL.

[C-H···anion] interactions mediate the templation and anion binding properties of topologically non-trivial metal-organic structures in aqueous solutions.

Two synthetic approaches-temperature variation and anion templation-allowed for the selective formation of a [2]catenane ( ) or a trefoil knot ( ), or for the enhanced formation of a Solomon link ( ), all from a simple set of starting materials (Zn(ii) acetate, diformylpyridine (DFP) and a diamino-2,2'-bipyridine (DAB)) in mixed aqueous solutions. The catenane formed exclusively at 90 °C in a 1 : 1 mixed solvent of DO and MeOD. In the presence of bromide ion as template, formed exclusively at 50 °C in the same solvent.

Cation- and anion-exchanges induce multiple distinct rearrangements within metallosupramolecular architectures.

Different anionic templates act to give rise to four distinct Cd(II)-based architectures: a Cd2L3 helicate, a Cd8L12 distorted cuboid, a Cd10L15 pentagonal prism, and a Cd12L18 hexagonal prism, which respond to both anionic and cationic components. Interconversions between architectures are driven by the addition of anions that bind more strongly within a given product framework. The addition of Fe(II) prompted metal exchange and transformation to a Fe4L6 tetrahedron or a Fe10L15 pentagonal prism, depending on the anionic templates present.

Predicting paramagnetic 1H NMR chemical shifts and state-energy separations in spin-crossover host-guest systems.

The behaviour of metal-organic cages upon guest encapsulation can be difficult to elucidate in solution. Paramagnetic metal centres introduce additional dispersion of signals that is useful for characterisation of host-guest complexes in solution using nuclear magnetic resonance (NMR). However, paramagnetic centres also complicate spectral assignment due to line broadening, signal integration error, and large changes in chemical shifts, which can be difficult to assign even for known compounds.

Selective encapsulation and sequential release of guests within a self-sorting mixture of three tetrahedral cages.

A mixture of two triamines, one diamine, 2-formylpyridine and a Zn(II) salt was found to self-sort, cleanly producing a mixture of three different tetrahedral cages. Each cage bound one of three guests selectively. These guests could be released in a specific sequence following the addition of 4-methoxyaniline, which reacted with the cages, opening each in turn and releasing its guest.

High-fidelity stereochemical memory in a Fe(II)4L4 tetrahedral capsule.

A new class of Fe(II)4L4 capsules, based upon a tritopic trialdehyde subcomponent, is reported. One such capsule was prepared diastereoselectively through the incorporation of a chiral amine residue. This amine was displaced by an achiral one, while maintaining the stereochemistry of the cage framework (99% ee); this cage retained its stereochemistry even after 4 days at 90 °C.

Guest binding subtly influences spin crossover in an FeII₄L₄ capsule.

How much should we switch? Two FeII₄L₄ tetrahedral capsules were shown to undergo thermally induced spin crossover (SCO). Guest binding to one of these capsules was observed to affect the thermodynamics of its SCO in solution, leading to different spin transition temperatures between the empty host (blue) and the host-guest complex (red). HS: high spin; LS: low spin.

Subcomponent self-assembly and guest-binding properties of face-capped Fe4L4(8+) capsules.

A general method for preparing Fe(4)L(4) face-capped tetrahedral cages through subcomponent self-assembly was developed and has been demonstrated using four different C(3)-symmetric triamines, 2-formylpyridine, and iron(II). Three of the triamines were shown also to form Fe(2)L(3) helicates when the appropriate stoichiometry of subcomponents was used. Two of the cages were observed to have nearly identical Fe-Fe distances in the solid state, which enabled their ligands to be coincorporated into a collection of mixed cages.