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Molecularly rigid polymers with internal charges (positive charges induced by amine methylation) allow electroosmotic water flow to be tuned by adjusting the charge density (the degree of methylation). Here, a microporous polyamine (PIM-EA-TB) is methylated to give a molecularly rigid anion conductor. The electroosmotic drag coefficient (the number of water molecules transported per anion) is shown to increase with a lower degree of methylation. Net water transport (without charge flow) in a coupled anionic diode circuit is demonstrated based on combining low and high electroosmotic drag coefficient materials. The AC-electricity-driven net process offers water transport (or transport of other neutral species, e.g., drugs) with net zero ion transport and without driver electrode side reactions.

The enhancement of separation processes and electrochemical technologies such as water electrolysers1,2, fuel cells3,4, redox flow batteries5,6and ion-capture electrodialysis7depends on the development of low-resistance and high-selectivity ion-transport membranes. The transport of ions through these membranes depends on the overall energy barriers imposed by the collective interplay of pore architecture and pore–analyte interaction8,9. However, it remains challenging to design efficient, scaleable and low-cost selective ion-transport membranes that provide ion channels for low-energy-barrier transport. Here we pursue a strategy that allows the diffusion limit of ions in water to be approached for large-area, free-standing, synthetic membranes using covalently bonded polymer frameworks with rigidity-confined ion channels. The near-frictionless ion flow is synergistically fulfilled by robust micropore confinement and multi-interaction between ion and membrane, which afford, for instance, a Na+diffusion coefficient of 1.18 × 10−9m2s–1, close to the value in pure water at infinite dilution, and an area-specific membrane resistance as low as 0.17 Ω cm2. We demonstrate highly efficient membranes in rapidly charging aqueous organic redox flow batteries that deliver both high energy efficiency and high-capacity utilization at extremely high current densities (up to 500 mA cm–2), and also that avoid crossover-induced capacity decay. This membrane design concept may be broadly applicable to membranes for a wide range of electrochemical devices and for precise molecular separation.

Polymers of intrinsic microporosity (or PIMs) provide porous materials due to their highly contorted and rigid macromolecular structures, which prevent space-efficient packing. PIMs are readily dissolved in solvents and can be cast into robust microporous coatings and membranes. With a typical micropore size range of around 1 nm and a typical surface area of 700−1000 m2g−1, PIMs offer channels for ion/molecular transport and pores for gaseous species, solids, and liquids to coexist. Electrode surfaces are readily modified with coatings or composite films to provide interfaces for solid|solid|liquid or solid|liquid|liquid or solid|liquid|gas multiphase electrode processes.

A low cross-link density (LCD) network-PIM-1, which offers high compatibility with the polymer of intrinsic microporosity PIM-1, is synthesized by a modified PIM-1 polycondensation that combines both a tetrafluoro- and an octafluoro-monomer. To maximize the advantages of utilizing such cross-linked PIM-1 fillers in PIM-1-based mixed matrix membranes (MMMs), a grafting route is used to decorate the LCD-network-PIM-1 (dispersed phase) with PIM-1 chains, to further enhance compatibility with the PIM-1 matrix. Mixed-gas CO2/CH4(1:1, v/v) separation results over 160 days of membrane aging confirm the success of a relatively short (24 h) grafting reaction in improving the initial CO2separation performance, as well as hindering the aging of PIM-1/grafted-LCD-network-PIM-1 MMMs. For MMMs based on a 24 h grafting route, all the gas separation data surpass the 2008 Robeson upper bound by a significant margin, and the 160-day aged membranes show only 29% reduction from the initial CO2permeability, which is substantially less than the equivalent losses of nearly 70% and 48% for PIM-1 and traditionally fabricated MMMs counterparts, respectively. These results demonstrate the potential of network-PIM components for obtaining much more stable gas separation performance over extended periods of time.

The relationship, during physical aging, between the transport properties and Young’s modulus for films of polymers of intrinsic microporosity (PIM) was investigated using pure gas permeability and atomic force microscopy (AFM) in force spectroscopy mode. Excellent agreement of Young’s modulus measured for the archetypal PIM-1 with values obtained by other techniques in the literature, confirms the suitability of AFM force spectroscopy for the rapid and convenient assessment of mechanical properties. Results from different polymers including PIM-1 and five ultrapermeable benzotriptycene-based PIMs provide direct evidence that size selectivity is strongly correlated to Young’s modulus. In addition, film samples of one representative PIM (PIM-DTFM-BTrip) were subjected to both normal physical aging and to accelerated aging by thermal conditioning under vacuum for comparison. Accelerated aging resulted in a similar decrease in permeability and increase in Young’s modulus as normal aging, however, significant differences suggest that thermally induced accelerated aging occurs throughout the bulk of the polymer film whereas normal aging occurs predominantly at the surface of the film. For all PIMs, the increased in film rigidity upon aging led to an increase in gas size selectivity.

Membranes with fast and selective ion transport are widely used for water purification and devices for energy conversion and storage including fuel cells, redox flow batteries and electrochemical reactors. However, it remains challenging to design cost-effective, easily processed ion-conductive membranes with well-defined pore architectures. Here, we report a new approach to designing membranes with narrow molecular-sized channels and hydrophilic functionality that enable fast transport of salt ions and high size-exclusion selectivity towards small organic molecules. These membranes, based on polymers of intrinsic microporosity containing Tröger’s base or amidoxime groups, demonstrate that exquisite control over subnanometre pore structure, the introduction of hydrophilic functional groups and thickness control all play important roles in achieving fast ion transport combined with high molecular selectivity. These membranes enable aqueous organic flow batteries with high energy efficiency and high capacity retention, suggesting their utility for a variety of energy-related devices and water purification processes.

Nanohybrid materials based on nanoparticles of the intrinsically microporous polymer PIM-1 and graphene oxide (GO) are prepared from aqueous dispersions with a reprecipitation method, resulting in the surface of the GO sheets being decorated with nanoparticles of PIM-1. The significant blueshift in fluorescence signals for the GO/PIM-1 nanohybrids indicates modification of the optoelectronic properties of the PIM-1 in the presence of the GO due to their strong interactions. The stiffening in the Raman G peak of GO (by nearly 6 cm–1) further indicates p-doping of the GO in the presence of PIM. Kelvin probe force microscopy (KPFM) and electrochemical reduction measurements of the nanohybrids provide direct evidence for charge transfer between the PIM-1 nanoparticles and the GO nanosheets. These observations will be of importance for future applications of GO-PIM-1 nanohybrids as substrates and promoters in catalysis and sensing.

The synthesis of conventional porous crystals involves building a framework using reversible chemical bond formation, which can result in hydrolytic instability. In contrast, porous molecular crystals assemble using only weak intermolecular interactions, which generally do not provide the same environmental stability. Here, we report that the simple co-crystallization of a phthalocyanine derivative and a fullerene (C60or C70) forms porous molecular crystals with environmental stability towards high temperature and hot aqueous base or acid. Moreover, by using diamond anvil cells and synchrotron single-crystal measurements, stability towards extreme pressure (>4 GPa) is demonstrated, with the stabilizing fullerene held between two phthalocyanines and the hold tightening at high pressure. Access to open metal centres within the porous molecular co-crystal is demonstrated by in situ crystallographic analysis of the chemisorption of pyridine, oxygen and carbon monoxide. This suggests strategies for the formation of highly stable and potentially functional porous materials using only weak van der Waals intermolecular interactions. Porous molecular crystals are easy to fabricate but thought to have limited stability as they are bound by non-covalent interactions. Here, a porous crystal composed of C60and phthalocyanine is demonstrated with stability to heat, acid, base and high pressures.

The preparation of dense and asymmetric flat membranes from the blending of polybenzimidazole (PBI) and (1.5–20 wt %) of a polymer of intrinsic microporosity (PIM-EA(H2)-TB) is reported. Thermal characterization validated the blend by revealing a single glass transition temperature, which suggests the absence of polymer phase segregation. In addition, the decomposition activation energy and d-spacing of the blends follow trends that correlate with the amount of PIM component. The membranes have been tested for the separation of H2/CO2mixtures. The properties of the dense membranes, which also incorporate zeolitic imidazolate-8 (ZIF-8) nanoparticles, helped understanding of the behavior of the PIM/PBI blends by which phase inversion results in high separation performance asymmetric membranes. Asymmetric membranes show H2/CO2selectivities of 23.8 (10/90 wt % PIM/PBI) and 19.4 (20/80 wt % PIM/PBI) together with respective H2permeances of 57.9 and 83.5 GPU at 250 °C and 6 bar feed pressure. The gas separation performance of these asymmetric blends has been fitted to an empirical model, showing the influence of the amount of PIM and the feed pressure.

A detailed analysis of the basic transport parameters of two triptycene-based polymers of intrinsic microporosity (PIMs), the ultrapermeable PIM-TMN-Trip and the more selective PIM-BTrip, as a function of temperature from 25 to 55 °C, is reported. For both PIMs, high permeability is based on very high diffusion and solubility coefficients. The contribution of these two factors on the overall permeability is affected by the temperature and depends on the penetrant dimensions. Energetic parameters of permeability, diffusivity, and solubility are calculated using Arrhenius–van’t Hoff equations and compared with those of the archetypal PIM-1 and the ultrapermeable, but poorly selective poly(trimethylsilylpropyne). This considers, for the first time, the role of entropic and energetic selectivities in the diffusion process through highly rigid PIMs. This analysis demonstrates that how energetic selectivity dominates the gas-transport properties of the highly rigid triptycene PIMs and enhances the strong size-sieving character of these ultrapermeable polymers.

The promise of ultrapermeable polymers, such as poly(trimethylsilylpropyne) (PTMSP), for reducing the size and increasing the efficiency of membranes for gas separations remains unfulfilled due to their poor selectivity. We report an ultrapermeable polymer of intrinsic microporosity (PIM-TMN-Trip) that is substantially more selective than PTMSP. From molecular simulations and experimental measurement we find that the inefficient packing of the two-dimensional (2D) chains of PIM-TMN-Trip generates a high concentration of both small (<0.7 nm) and large (0.7–1.0 nm) micropores, the former enhancing selectivity and the latter permeability. Gas permeability data for PIM-TMN-Trip surpass the 2008 Robeson upper bounds for O2/N2, H2/N2, CO2/N2, H2/CH4and CO2/CH4, with the potential for biogas purification and carbon capture demonstrated for relevant gas mixtures. Comparisons between PIM-TMN-Trip and structurally similar polymers with three-dimensional (3D) contorted chains confirm that its additional intrinsic microporosity is generated from the awkward packing of its 2D polymer chains in a 3D amorphous solid. This strategy of shape-directed packing of chains of microporous polymers may be applied to other rigid polymers for gas separations.

Polymers of intrinsic microporosity (PIMs) are a class of porous organic polymer (POP) that form microporous solids due to the inefficient packing of their rigid and contorted macromolecular chains. In contrast to other types of POP, PIMs are not comprised of a network of cross-linked covalent bonds so that they can be dissolved in organic solvents and processed into robust films, coatings or fibres. Here, over twelve years’ accumulated research on the synthesis of PIMs is reviewed. To date, three types of polymerisation reaction have been used successfully to prepare PIMs of sufficient molecular mass to form robust self-standing films. These involve the formation of dibenzodioxin, Tröger’s base and imide linkages between monomeric units. This rapid development of synthetic methods for preparing PIMs has been driven by their rich potential for numerous diverse applications and this synergistic relationship between synthesis and functionality is set to continue.

A thin film of Nafion, of approximately 5 μm thickness, asymmetrically deposited onto a 6 μm thick film of poly(ethylene terephthalate) (PET) fabricated with a 5, 10, 20, or 40 μm microhole, is shown to exhibit prominent ionic diode behavior involving cation charge carrier (“cationic diode”). The phenomenon is characterized via voltammetric, chronoamperometric, and impedance methods. Phenomenologically, current rectification effects are comparable to those observed in nanocone devices where space-charge layer effects dominate. However, for microhole diodes a resistive, a limiting, and an overlimiting potential domain can be identified and concentration polarization in solution is shown to dominate in the closed state.

A study integrating advanced experimental and modeling tools was undertaken to characterize the microstructural and interfacial properties of mixed matrix membranes (MMMs) composed of the zeolitic imidazolate framework ZIF-8 nanoparticles (NPs) and two polymers of intrinsic microporosity (PIM-1 and PIM-EA-TB). Analysis probed both the initial ZIF-8/PIM-1 colloidal suspensions and the final hybrid membranes. By combination of dynamic light scattering (DLS) and transmission electron microscopy (TEM) analytical and imaging techniques with small-angle X-ray scattering (SAXS), the colloidal suspensions were shown to consist mainly of two distinct kinds of particles, namely, polymer aggregates of about 200 nm in diameter and densely packed ZIF-8-NP aggregates of a few 100 nm in diameter with a 3 nm thick polymer top-layer. Such aggregates are likely to impart the granular texture of ZIF-8/PIMs MMMs as shown by SEM-XEDS analysis. At the molecular scale, modeling studies showed that the surface coverage of ZIF-8 NPs by both polymers appears not to be optimal with the presence of microvoids at the interfaces that indicates only a moderate compatibility between the polymer and ZIF-8. This study shows that the microstructure of MMMs results from a complex interplay between the ZIF-8/PIM compatibility, solvent, surface chemistry of the ZIF-8 NPs, and the physicochemical properties of the polymers such as molecular structure and rigidity.

A molecularly rigid polyamine based on a polymer of intrinsic microporosity (PIM-EA-TB) is shown to capture and stabilize platinum nanoparticles during colloid synthesis in the rigid framework. Stabilization here refers to avoiding aggregation without loss of surface reactivity. In the resulting rigid framework with embedded platinum nanoparticles, the volume ratio of platinum to PIM-EA-TB in starting materials is varied systematically from approximately 1.0 to 0.1 with the resulting platinum nanoparticle diameter varying from approximately 4.2 to 3.1 nm, respectively. Elemental analysis suggests that only a fraction of the polymer is “captured” to give nanocomposites rich in platinum. A transition occurs from electrically conducting and electrochemically active (with shorter average interparticle distance) to nonconducting and only partially electrochemically active (with longer average interparticle distance) polymer–platinum composites. The conducting nanoparticle network in the porous rigid macromolecular framework could be beneficial in electrocatalysis and in sensing applications.

Redox-active organic materials have emerged as promising alternatives to conventional inorganic electrode materials in electrochemical devices for energy storage. However, the deployment of redox-active organic materials in practical lithium-ion battery devices is hindered by their undesired solubility in electrolyte solvents, sluggish charge transfer and mass transport, as well as processing complexity. Here, we report a new molecular engineering approach to prepare redox-active polymers of intrinsic microporosity (PIMs) that possess an open network of subnanometer pores and abundant accessible carbonyl-based redox sites for fast lithium-ion transport and storage. Redox-active PIMs can be solution-processed into thin films and polymer–carbon composites with a homogeneously dispersed microstructure while remaining insoluble in electrolyte solvents. Solution-processed redox-active PIM electrodes demonstrate improved cycling performance in lithium-ion batteries with no apparent capacity decay. Redox-active PIMs with combined properties of intrinsic microporosity, reversible redox activity, and solution processability may have broad utility in a variety of electrochemical devices for energy storage, sensors, and electronic applications.

Graphitic carbon nitride (g-C3N4) is known to photogenerate hydrogen peroxide in the presence of hole quenchers in aqueous environments. Here, the g-C3N4photocatalyst is embedded into a host polymer of intrinsic microporosity (PIM-1) to provide recoverable heterogenized photocatalysts without loss of activity. Different types of g-C3N4(including Pt@g-C3N4, Pd@g-C3N4, and Au@g-C3N4) and different quenchers are investigated. Exploratory experiments yield data that suggest binding of the quencher either (i) directly by adsorption onto the g-C3N4(as shown for α-glucose) or (ii) indirectly by absorption into the microporous polymer host environment (as shown for Triton X-100) enhances the overall photochemical H2O2production process. The amphiphilic molecule Triton X-100 is shown to interact only weakly with g-C3N4but strongly with PIM-1, resulting in accumulation and enhanced H2O2production due to the microporous polymer host.

Polymers of intrinsic microporosity (PIMs) possess molecular structures composed of fused rings with linear units linked together by a site of contortion so that the macromolecular structure is both rigid and highly non‐linear. For PIM‐1, which has previously demonstrated encouraging gas permeability data, the site of contortion is provided by the monomer 5,5′,6,6′‐tetrahydroxy‐3,3,3′,3′‐tetramethyl‐1,1′‐spirobisindane. Here we describe the synthesis and properties of a PIM derived from the structurally related 6,6′,7,7′‐tetrahydroxy‐4,4,4′,4′‐tetramethyl‐2,2′‐spirobischromane and copolymers prepared from combination of this monomer with other PIM‐forming biscatechol monomers, including the highly rigid monomer 9,10‐dimethyl‐9,10‐ethano‐9,10‐dihydro‐2,3,6,7‐tetrahydroxyanthracene. Generally, the polymers display good solubility in organic solvents and have high average molecular masses ($\overline {M} _{{\rm w}} $) in the range 80 000–200 000 g · mol−1and, therefore, are able to form robust, solvent‐cast films. Gas permeability and selectivity for He, H2, N2, O2, CO2, and CH4were measured for the polymers and compared to the values previously obtained for PIM‐1. The spirobischromane‐based polymers demonstrate enhanced selectivity for a number of gas pairs but with significantly lower values for permeability. The solubility coefficient for CO2of two of the copolymers exceed even that of PIM‐1, which previously demonstrated the highest value for a membrane‐forming polymer. Therefore, these polymers might be useful for gas or vapor separations relying on solubility selectivity.

The synthesis of octaazaphthalocyanine (AzaPc) derivatives, with bulky phenoxyl substituents placed at eight peripheral positions and containing either H+, Ni2+or Zn2+ions in their central cavity, is described. The required precursors, derivatives of pyrazine‐2,3‐dicarbonitrile, were prepared using a nucleophilic aromatic substitution reaction between 2,6‐diisopropylphenol or 2,6‐diphenylphenol and 5,6‐dichloropyrazine‐2,3‐dicarbonitrile. Analysis of the resulting AzaPcs by UV/Visible and 1H NMR spectroscopy confirms that steric isolation of the AzaPc cores was enforced both in solution and in the solid state. X‐ray diffraction studies of single crystals of the AzaPcs reveal that solvent inclusion takes place in each case. Of particular significance is the finding that the zinc derivative of 2,3,9,10,16,17,23,24‐octa‐(2,6‐diisopropylphenoxy)octaazaphthalocyanine provides nanoporous cubic crystals, containing massive (8 nm3) solvent‐filled voids, similar to those of the analogous phthalocyanine derivative. Exchange of the included solvent within the voids can be readily achieved by using a number of alternative solvents including water. Based on the observed loading of included water, the internal volume of this nanoporous cubic crystal appears to be more hydrophilic than its phthalocyanine counterpart.

Microporous organic polymers offer the possibility of storing hydrogen safely at low temperatures and moderate pressures via physisorption. A range of polymers of intrinsic microporosity (PIMs) have been studied. The best PIM to date is based on a triptycene monomer and takes up 2.7% H2by mass at 10 bar/77 K. Hypercrosslinked polymers (HCPs) also show promising performance, particularly at pressures >10 bar. The form of the H2isotherm is influenced by the micropore distribution, a higher concentration of ultramicropores (pore size <0.7 nm), as found in PIMs, being associated with enhanced low pressure adsorption. The performance of polymers relative to other microporous materials (carbons and metal‐organic frameworks) is compared and promising methods to enhance the hydrogen uptake of microporous polymers are suggested.

Two novel homologous series of phthalocyanines were prepared from 2,2‐dialkylindane and 2,2‐dialkyl‐1,3‐benzodioxole precursors. It was anticipated that attaching alkyl chains to five‐membered rings, fused to the peripheral sites of the phthalocyanine ring, would result in the adoption of an out‐of‐plane configuration and thereby discourage cofacial aggregation, to provide an analogy with picket‐fence porphyrins. This strategy proved partially successful. Some members of the series of phthalocyanines derived from 2,2‐dialkyl‐1,3‐benzodioxoles, in which the alkyl chains are linked to the phthalocyanine via a cyclic ketal, form spin‐coated thin films in which the phthalocyanine cores are perfectly isolated. This behaviour is associated with the formation of a disordered crystal that appears as a mesophase in the thermal profile of these materials. However, the phthalocyanines derived from 2,2‐dialkylindanes display a columnar mesophase over a wide temperature range, with some liquid crystalline derivatives at ambient temperature. A single‐crystal X‐ray diffraction structure of the octahexyl derivative of this series shows how the columnar assembly accommodates the out‐of‐plane alkyl chains by tilting the macrocyclic plane of the phthalocyanine components with respect to the axis of the column. This study helps to emphasise the importance of both the steric and electronic effects of substituents on the packing behaviour of phthalocyanines in the condensed phase, and especially the role of electron‐donating oxygen atoms directly attached to the ring.

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This tutorial reviewdescribes recent research directed towards the synthesis of polymer-based organic microporous materials termed Polymers of Intrinsic Microporosity (PIMs). PIMs can be prepared either as insoluble networks or soluble polymers with both types giving solids that exhibit analogous behaviour to that of conventional microporous materials such as activated carbons. Soluble PIMs may be processed into thin films for use as highly selective gas separation membranes. Preliminary results also demonstrate the potential of PIMs for heterogeneous catalysis and hydrogen storage.

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Novel types of microporous material are required for chemoselective adsorptions, separations and heterogeneous catalysis. This concept article describes recent research directed towards the synthesis of polymeric materials that possess microporosity that is intrinsic to their molecular structures. These polymers (PIMs) can exhibit analogous behaviour to that of conventional microporous materials, but, in addition, may be processed into convenient forms for use as membranes. The excellent performance of these membranes for gas separation and pervaporation illustrates the unique character of PIMs and suggests immediate technological applications.

The synthesis and properties of two non-planar and highly rigid pentamers containing four phthalocyanine units linked, viaa spirocyclic fused ring system, to a central phthalocyanine or porphyrin core is described. It is shown that the rigidity of these novel oligomers, together with the large number of structural isomers of irregular shape induced by the presence of the four spiro-centres, inhibits efficient packing of the macrocycles in the solid state. Therefore, the UV–visible absorption spectrum of spin-coated films of these materials is almost identical to that obtained from the non-aggregated oligomers in dilute solution. Nitrogen adsorption measurements indicate a high surface area for one of the pentamers, which is consistent with some degree of microporosity.

The concept of free volume is useful for explaining aspects of the chain mobility and permeability of polymers, even though its precise definition is subject to debate. Polymers that trap a large amount of interconnected free volume in the glassy state behave in many respects like microporous materials and potentially find application in membrane separations and heterogeneous catalysis. The development is outlined of a new type of polymer, for which the molecular structure contains sites of contortion e.g.spiro-centres within a rigid backbone e.g.ladder polymer. These polymers of intrinsic microporosity PIMs include both insoluble network polymers and soluble non-network polymers that may be processed into membranes or other useful forms. Experimental methods are discussed for elucidating the free volume or micropore distribution, and the behaviour of PIMs is compared with that of the ultrapermeable polymer poly1-trimethylsilyl-1-propyne.

Purpose.To evaluate the cytotoxicity, permeation, and transport mechanisms of PAMAM dendrimers and surface-modified cationic PAMAM dendrimers using monolayers of the human colon adenocarcinoma cell line, Caco-2. Methods.Cytotoxicity was determined using the MTT assay. The effect of dendrimers on monolayer integrity was determined from measurements of transepithelial electrical resistance (TEER) and [14C]mannitol apparent permeability coefficient (Papp). The Pappof dendrimers through monolayers was measured in both the apical (A)-to-basolateral (B) and B→A directions at 4°C and 37°C and also in the presence and absence of ethylenediamine tetraacetic acid (EDTA) and colchicine. Results.The cytotoxicity and permeation of dendrimers increased with both concentration and generation. The cytotoxicity of cationic dendrimers (G2, G3, G4) was greater than that of anionic dendrimers (G2.5, G3.5) but was reduced by conjugation with lauroyl chloride; the least cytotoxic conjugates were those with six attached lauroyl chains. At 37°C the Pappof cationic dendrimers was higher than that of anionic dendrimers and, in general, increased with the number of attached lipid chains. Cationic dendrimers decreased TEER and significantly increased the Pappof mannitol. Modified dendrimers also reduced TEER and caused a more marked increase in the Pappof mannitol. The Pappvalues of dendrimers and modified dendrimers were higher in the presence of EDTA, lower in the presence of colchicine, and lower at 4°C than at 37°C. Conclusions.The properties of dendrimers may be significantly modified by surface engineering. Conjugation of cationic PAMAM dendrimers with lauroyl chloride decreased their cytotoxicity and increased their permeation through Caco-2 cell monolayers. Both PAMAM dendrimers and lauroyl-PAMAM dendrimer conjugates can cross epithelial monolayers by paracellular and transcellular pathways.

The synthesis and properties of a nanoporous network polymer incorporating 5,6,11,12,17,18-hexaazatrinapthylene Hatn as the rigid functional unit is described. This material is readily prepared from the efficient dibenzodioxane forming reaction between 2,3,8,9,14,15-hexachloro-5,6,11,12,17,18-hexaazatrinaphthylene and 5,5′,6,6′-tetrahydroxy-3,3,3′,3′-tetramethyl-1,1′-spirobisindane and exhibits a high BET surface area 775 m2g−1 similar to that obtained from related nanoporous networks based on phthalocyanine and porphyrin macrocycles. The ability of the Hatn unit to bind to metal ions was shown by the sequential binding of three palladiumii dichloride moieties to a soluble model Hatn compound using a 1H NMR titration experiment. When exposed to an excess of palladiumii dichloride in chloroform solution, the Hatn nanoporous network is shown to adsorb 3.9 mmol g−1of the metal complex. The resulting material retains porosity BET surface area 347 m2g−1 and should be useful as a heterogeneous catalyst. The Hatn network polymer is also shown to be effective for the adsorption of phenol from aqueous solution with a maximum adsorption of 5 mmol g−1, which is a significant improvement over the performance of activated carbon reported in similar studies.

Several members of a novel series of styrene-containing liquid crystal monomers, based on the cyanobiphenyl mesogenic group, possess thermally stable nematic phases. These materials display a large odd–even effect, relating to the length of the flexible spacer between the styrene and cyanobiphenyl units, which is very similar to previously described liquid crystal ‘dimers’ composed of two cyanobiphenyl units. It is shown that styrene (i.e. 4-vinylphenoxy) is an excellent terminal group for cyanobiphenyl mesogens as compared to a number of other phenyloxy groups. In addition, a compatible bifunctional mesogenic crosslinker is described. Photopolymerisation of an aligned film of a low-melting eutectic mixture derived from these compounds is achieved using cationic initiation in aerobic conditions.

Macrodiscotic materials are liquid crystalline systems composed of an extended planar structure. It is anticipated that the self-ordering of such materials will result in interesting mechanical and electronic properties. Two synthetic strategies for the realisation of macrodiscotic materials are reviewed: firstly, the preparation of molecules which possess a single extended discotic core and secondly, the assembly of rigid, planar macromolecules composed of a random array of fused discotic units. Oxanthrene-based phthalonitrile precursors, prepared by high yielding reactions between catechols and 4,5-dichlorophthalonitrile, are used to explore both strategies for the synthesis of macrodiscotic materials that incorporate phthalocyanine (Pc) as the discotic unit.

The synthesis, structural characterisation and properties of a number of phthalocyanine‐containing dendrimers are described. Peripheral substitution of phthalocyanine (Pc) with four poly(aryl ether) dendritic wedges (1st, 2nd or 3rd generation) produces materials whose properties are dominated both by the columnar self‐association of the Pc core and by the glass‐forming character of the dendritic substituents. Asymmetric Pcs containing a single poly(aryl ether) dendron display a columnar mesophase, the structure of which can be frozen into an anisotropic glass at room temperature. Placing the dendritic wedges at the axial sites of silicon phthalocyanine prohibits self‐association and gives materials from which can be fabricated robust, isotropic solid solutions of Pc with high glass transition temperatures. A single crystal X‐ray diffraction analysis of one of these compounds illustrates the ability of the axial dendrons to prevent cofacial aggregation in the solid state.

The synthesis of a novel side-chain liquid crystalline polymer in which cholesterol mesogenic units are linked to a styrene backbone by a tris(ethyleneoxy) spacer is described. This amphiphilic polymer displays an unusual discontinuity in its monolayer behaviour at the air–water interface. This behaviour appears to be associated with the attainment of a closely-packed arrangement of the cholesterol units at higher values of surface pressure. Glancing angle X-ray diffraction shows that a well-ordered Y-type film is obtained if deposition is performed at a surface pressure above that of the apparent rearrangement.

The optical and electronic properties of the phthalocyanine (Pc) macrocycle make it suitable for a wide range of applications. The enormous diversity of Pc-containing polymers, developed over thirty years of research, offers the prospect of readily processed materials in which covalent linkages can be used to control the ordering and arrangement of the Pc units. This article reviews both the synthesis and study of Pc-containing polymers. The types of polymer are classified by the way in which the macrocycle is incorporated within the macromolecular structure as either network, main-chain or side-chain polymers. In addition, recent work on the incorporation of the Pc macrocycle as polymer end-groups or as the core unit in a number of dendrimers is also described.

Phthalocyanine (Pc) derivatives in which substituents hold the Pc units in isolation from one another in the solid state are potentially useful materials. Three synthetic approaches to achieve this goal are described: the construction of a dendrimer about a Pc core; the incorporation of alkyl side chains which are forced to lie out of the plane of the macrocycle; and the synthesis of sterically crowded hexadeca-substituted derivatives. The effectiveness of each of these strategies is readily measured by comparing the visible absorption spectrum of a spin-coated film with that obtained from the non-aggregated Pc in dilute solution. These studies show that the size of the substituents is of secondary importance for their efficiency in inducing Pc isolation. Of more importance is the substituents' adopted position relative to the Pc ring. Copyright © 2000 John Wiley & Sons, Ltd.

Phthalocyanine (Pc) derivatives in which substituents hold the Pc units in isolation from one another in the solid state are potentially useful materials. Three synthetic approaches to achieve this goal are described: the construction of a dendrimer about a Pc core; the incorporation of alkyl side chains which are forced to lie out of the plane of the macrocycle; and the synthesis of sterically crowded hexadeca-substituted derivatives. The effectiveness of each of these strategies is readily measured by comparing the visible absorption spectrum of a spin-coated film with that obtained from the non-aggregated Pc in dilute solution. These studies show that the size of the substituents is of secondary importance for their efficiency in inducing Pc isolation. Of more importance is the substituents' adopted position relative to the Pc ring.

Uniform thin films are needed for the exploration and exploitation of the fascinating optical and electronic properties of the phthalocyanine (Pc) macrocycle. Spin-coating has been demonstrated to be a simple, fast and reproducible method of fabricating uniform films. However, solubility in a volatile organic solvent is a prerequisite for this technique and previous studies have shown that groups placed on the Pc macrocycle can have a profound effect on the nanoscale structure of the resulting film. In this paper we attempt to establish some fundamental structure–property relationships which determine the molecular packing within such films. Previous studies are reviewed and the film forming properties of a number of Pc derivatives are examined. In particular, the formation of films in which the Pc cores are isolated from each other by the use of novel, sterically crowded hexadeca-substituted Pcs is examined.

The synthesis and liquid crystalline properties of unsymmetrically substituted Pcs which contain both alkyl and hydroxy terminated tetra(ethyleneoxy) side-chains are described. Despite poor Langmuir-Blodgett film forming properties, the amphiphilic Pcs are of interest as they display a variety of columnar mesophases and the ability to form self-ordered lamellar films by simple solvent casting. Lamellar order can be obtained in spin-coated films of these derivatives by annealment at a temperature at which the Pc is liquid crystalline. These self-ordering spin-coated films are an alternative to the laborious Langmuir-Blodgett technique for the fabrication of highly ordered and uniform films of functional molecular materials.

A nucleophilic aromatic substitution reactionbetween a sterically hindered phenol and 4‐nitrophthalonitrile, 3‐nitrophthalonitrile or 6‐fluoro‐2,3‐napthalonitrile has been used to prepare precursors for the synthesis of a number of phthalocyanines, such as 1, and naphthalocyanines bearing bulky substituents.

Alternating Langmuir–Blodgett (LB) multilayers have been prepared from a non-polymeric hemicyanine and a poly(4-vinylpyridine) 66% quaternised with docosyl bromide, and from a non-polymeric azobenzene and the same pyridinium polymer. With both types of multilayer the intensity of the SHG signal increased as the square of the number of layers up to a thickness ofca. 60 bilayers. The slopes of the plots correspond to second order susceptibilities of 17.5 and 9 pm V–1 respectively. Although these properties and the stabilities of the films over time compare favourably with many other LB films described in the literature, these films prepared from ‘active’ non-polymeric amphiphiles and a ssive’ polymeric amphiphile are not as satisfactory as the closely related all-polymeric films described previously.

A number of novel amphiphilic phthalocyanines (Pcs) have been prepared containing long alkyl (-C16H33) and oligo(ethyleneoxy) chains (-O(C2H4O)3CH3) in the peripheral positions. All the Pcs prepared showed liquid crystalline behaviour, with most compounds giving two mesophases. Optical microscopy suggests that the lower temperature mesophase (M1) is a discotic rectangular mesophase, and that the higher temperature mesophase (M2) is a discotic hexagonal phase.

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We are developing new types of polymer – termed polymers of intrinsic microporosity (PIMs) – which in the solid state behave like molecular sieves. As pervaporation membranes, they show selectivity for organics over water. As gas separation membranes, they exhibit a remarkable combination of high permeability and good selectivity for gas pairs such as O2/N2.

A novel triptycene-based polymer of intrinsic microporosity Trip-PIM displays enhanced surface area 1065 m2g−1 and reversibly adsorbs 1.65 hydrogen by mass at 1 bar77 K and 2.71 at 10 bar77 K.

A metal–organic framework with tailored porosity provides a mixed matrix membrane with excellent performance for natural gas purification and butane isomer separation.

The synthesis of a novel phthalocyanine mesogen, containing four flexible side chains terminated with a bulky trityl moiety, is described. This compound forms a well defined anisotropic glass, indefinitely stable at room temperature, in which the hexagonal ordered structure of its columnar mesophase is preserved. Such a glassy state should be useful for anisotropic conductivity studies.

Nichtstreuende Gläser, die bezüglich Kristallisation unbegrenzt stabil sind, lassen sich aus den Titelverbindungen herstellen. In diesen festen Lösungen verhindern die dendritischen Substituenten wirksam stärkere Wechselwirkungen zwischen den Phthalocyanin-Einheiten (siehe rechts).

Nonscattering glasses that are indefinitely stable with respect to crystallization can be prepared from the title compounds. In these solid solutions, the dendritic substituents effectively suppress interactions between the phthalocyanine units (see the structure depicted on the right).