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Based on almost 20 years of published research, the structure-property relationships of Polymers of Intrinsic Microporosity (PIMs) are considered. Following an analysis of the structure of the archetypal PIM-1 and how it contributes to its now well-understood properties, the key properties of solubility, thermal properties, gas adsorption and gas permeability are related to the structures of more recently prepared PIMs. In order to deliver their technological potential, it is recommended that further synthetic effort should focus both on broadening the structural diversity of PIMs and providing synthetically accessible variants. [ABSTRACT FROM AUTHOR]

Abstract: A series of novel 1,8-naphthalimide derivatives and dimers possessing reactive carboxylic acid, nitro, amine, or bromide functionality is prepared and their photophysical properties are studied. Those derivatives that contain amine substituents attached directly to the 1,8-naphthalimide unit display intense yellow-green fluorescence. [Copyright &y& Elsevier]

Based on cumulative research from the past two decades, this personal perspective defines the structurally unique features of Polymers of Intrinsic Microporosity (PIMs), which result in a distinct combination of properties, including solution-processability and microporosity, providing organic materials suitable for the fabrication of membranes that perform efficient molecular sieving. Image 1 • Personal reflection on the development of Polymers of Intrinsic Microporosity (PIMs). • Explanation of why PIMs form a distinct class of polymer and microporous material. • Re-definition of PIMs based on their method of synthesis, structure and properties. • Rigidity and sub-nanometre pore size combine to make PIM membranes selective. • Free volume is largely interconnected but only for the transport of small gases. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of novel monomers based upon the rigid 1,1′-spiro-bis(1,2,4,5-tetrahydro-6,7-dihydroxynaphthalene) framework is reported. These monomers can be used for the synthesis of polymers of intrinsic microporosity (PIMs) due to their reactive catechol units and nonlinear shape, which introduces the necessary sites of contortion into the resulting PIM. [Copyright &y& Elsevier]

The synthesis of the 1st, 2nd and 3rd generation phthalocyanine-centred and naphthalocyanine-centred poly(aryl ether) dendrimers possessing oligo(ethyleneoxy) surface groups is described. These materials are soluble in polar protic solvents. For both types of macrocycle, the tendency of the non-polar phthalocyanine core towards intermolecular cofacial aggregation is not reduced by peripheral dendritic substitution. However, the prohibition of cofacial aggregation can be achieved by placing the dendritic substituents at the axial sites of the silicon-containing macrocycle. A single crystal X-ray diffraction analysis of one of these compounds beautifully illustrates this concept. [Copyright &y& Elsevier]

Abstract An understanding of gas transport in polymers of intrinsic microporosity (PIMs) is limited by a lack of directly determined (experimental) sorption data and by quantitative inaccuracies in solubilities calculated indirectly from permeation time-lag analysis. To address this, we provide a detailed gas sorption analysis for seven different PIMs and assess the influence of the non-linear steady-state CO 2 concentration profiles on the apparent solubilities obtained from permeation experiments. Equilibrium sorption was analyzed with dual-mode sorption (DMS) and Guggenheim, Anderson and De Boer (GAB) models, which provided accurate descriptions of the data. The non-linear steady-state CO 2 concentration profiles were calculated using the thermodynamic Fick's law based on the DMS or GAB model coefficients. Once the thermodynamic term was incorporated into the model for permeation, better agreement between directly (gravimetric sorption) and indirectly (time-lag analysis) determined solubility was observed for most membranes. The monolayer capacities were found to be linearly dependent between the models and could be used for a qualitative comparison of the apparent surface area of PIM materials. Diffusivities determined from time-lag analysis were higher (e.g., PIM-Trip-TB, CO 2 , 111·10−8 m2 s−1) than those from sorption measurements (24·10−8 m2 s−1), probably due to substantially low mass uptake in Henry mode (11% of total sorption capacity). Thus, a careful gas sorption analysis in combination with time lag experiments provides a deeper insight into the transport behavior of gases in PIMs than when only time lag measurements are performed. Graphical abstract fx1 Highlights • Sorption of gases in seven polymers of intrinsic microporosity. • CO 2 solubility from time-lag analysis is overestimated in most of the PIMs. • Thermodynamic Fick's law allows for the correction of the solubility. • Apparent surface areas based on DMS, GAB and BET models are comparable and highly correlated. [ABSTRACT FROM AUTHOR]

Electrochemical studies have been conducted at copper microelectrodes (125, 50, and 25 μm in diameter) immersed in aqueous 0.5 M NaCl. Cyclic and linear sweep voltammetry were used to explore the corrosion of copper in chloride media. Cyclic voltammetry revealed the reversible Cu(I)/Cu(0) potential at approximately −0.11 V vs. SCE associated with the formation of a dense CuCl blocking layer (confirmed by in situ Raman and fluorescence measurements). Although continuous dissolution of Cu(I) occurs, only an increase in the driving potential into the region of the Cu(II)/Cu(I) potential at approximately +0.14 V vs. SCE started more rapid and stochastic dissolution/corrosion processes. The corrosion process is demonstrated to be linked to two distinct mechanisms based on (A) slow molecular dissolution and (B) fast colloidal dissolution. A polymer of intrinsic microporosity (PIM-EA-TB) is employed to suppress colloidal processes to reveal the underlying molecular processes. [ABSTRACT FROM AUTHOR]

“Heterojunction” ionic diodes based on a Nafion cation conductor and a polymer of intrinsic microporosity (PIM) interfaced at a 6 μm thickness polyethylene-terephthalate (PET) film with 20 μm diameter microhole exhibit rectification effects in cation (K + ) flux. When combined with the precipitation reaction of potassium cations with perchlorate anions to give insoluble KClO 4 (solubility product ca. 1.05 × 10 −2 M 2 at 25 °C) at the PIM | Nafion interface, inversion of the rectification/diode effect occurs and the formerly “open” state changes into a “closed” state due to blocking of ion flow. The localised interfacial precipitation reaction is due to up to three orders of magnitude accumulation of K + at the PIM | Nafion interface and shown to be fast and reversible. The effects of K + /ClO 4 − concentration and of Na + interference are considered. The blocking process within the heterojunction ionic diode is suggested to be dynamic/fast and potentially useful as a diode sensor mechanism based on solubility product dependent precipitation. [ABSTRACT FROM AUTHOR]

Tröger's base (TB) is often used as a building block for the synthesis of Polymers of Intrinsic Microporosity (PIMs) due to its rigid bicyclic V-shaped structure. In this study the TB component in the structure of a PIM is replaced by 2,3:6,7-dibenzobicyclo[3.3.1]nonane, a purely carbocyclic analogue of TB. This modification results in only a slightly reduced amount of microporosity as determined using nitrogen adsorption. Further comparisons with previously reported PIMs indicate that this building unit (and therefore TB) is significantly less effective for the generation of intrinsic microporosity than spirobisindane, a commonly used structural unit for PIM synthesis. It appears that the V-shape of the 2,3:6,7-dibenzobicyclo[3.3.1]nonane and TB units allows closer contact between polymer chains thereby enhancing packing efficiency. [ABSTRACT FROM AUTHOR]

The enzymeless and operationally simple electrocatalytic oxidation of carbohydrates by “heterogenised” 4-benzoyloxy-TEMPO either (i) immobilised as microcrystals at a glassy carbon electrode surface or (ii) embedded into a polymer of intrinsic microporosity (PIM-EA-TB with 1027 m 2 g −1 BET surface area and highly rigid framework structure) has been studied in aqueous phosphate buffer of pH 12. It is shown that in contrast to microcrystal deposits, 4-benzolyoxy-TEMPO co-immobilised within PIM-EA-TB give stable catalytic responses for both, stationary and rotating disc electrode systems and for oxidation of glucose, sorbitol, and sucrose. The rigidity and intrinsic microporosity of PIM-EA-TB allow (slow) substrate and product diffusion, whilst maintaining 4-benzoyloxy-TEMPO immobilised in active molecular form. [ABSTRACT FROM AUTHOR]

A water-insoluble Polymer with Intrinsic Microporosity (or PIM, here for the particular case of the Tröger Base system PIM-EA-TB, BET area ca. 10 3 m 2 g - 1 ) is demonstrated to act as a rigid host environment for highly water-insoluble molecular catalysts, here tetraphenylporphyrinato-iron (FeTPP), surrounded by aqueous solution-filled micropores. A PIM-EA-TB film containing catalyst is deposited onto the electrode and immersed for voltammetry (i) with 4-(3-phenyl-propyl)-pyridine to give an organogel, or (ii) bare directly into aqueous solution. The porous host allows processes to be optimised as a function of solution phase, composition, and catalyst loading. Effective electron transfer as well as effective electrocatalysis is reported for aqueous oxygen and peroxide reduction. Given the use of completely water-insoluble catalyst systems, the methodology offers potential for application with a wide range of hitherto unexplored molecular electrocatalysts and catalyst combinations in aqueous media. [ABSTRACT FROM AUTHOR]

Highlights: [•] Intrinsically microporous polymers are introduced as electrode modifier. [•] Binding of indigo carmine and PdCl4 − are demonstrated. [•] Formation of Pd metal and catalysis are demonstrated. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we describe the synthesis and physical characterisation of polymers derived from hydroxyl containing bowl-shaped “centrotriindane” and propellane-type “triptindane” monomers using the dibenzodioxin-forming polymerisation reaction with 2,3,5,6-tetrafluoroterephthalonitrile. Evaluation of the microporosity of the resulting polymers via nitrogen adsorption measurements revealed apparent Brunauer-Emmett-Teller (BET) surface areas in the range of 555–1039 m2 g−1 which can be related to the distinct shape of the monomeric units. An evaluation of the shape of the monomers, using X-ray crystallography, helps to explain the degree of microporosity of the polymers from which they are made. [Copyright &y& Elsevier]

Abstract: New water soluble and fluorescent PAMAM-based dendritic molecules based on the naphthalimide derivative 7H-benz[de]benzimidazo[2,1-a]isoquinoline-7-one as the fluorescent unit, have been prepared and their photophysical properties studied in aqueous solution over a wide pH range. The dendrons are all strongly fluorescent through an intramolecular charge transfer (ICT) excited state, but this can be modulated by photoinduced electron transfer (PeT) processes, which increases with higher PAMAM dendron generation. [Copyright &y& Elsevier]

Abstract: Sorbent hollow fibres, generally prepared by fully encapsulating an adsorbent within a polymer binder such as polyethersulfone (PES), provide a low pressure drop alternative to conventional packed beds. These fibres have a high external surface area to volume ratio, enabling smaller bed sizes, and a highly porous structure resulting in low mass transfer resistance while maximising sorption efficiency. However, adsorbent hollow fibres prepared with PES suffer from loss of some adsorption capacity due to the polymer binder. This paper describes a novel formulation of composite hollow fibres containing activated carbon and PIM-1, a polymer of intrinsic microporosity, as an active binder designed to enhance the total adsorption capacity. Octane has been selected as a model hydrocarbon, and nitrogen and octane isotherms are reported for both PES and PIM-1 based hollow fibres, each containing the same activated carbon. Theoretical BET surface areas were calculated for each type of fibre based on a weighted average of the surface areas of its individual components (i.e. polymer and carbon). The measured surface area of the PIM-1 fibres was remarkably consistent with the theoretical value, while the measured surface area and octane uptake for PES fibres were ∼10% lower than the theoretical values, indicating some blockage of the adsorbent by the polymer matrix. PIM-1 adsorbent fibres were found to fully utilise the capacity of the supported carbon, as well as providing additional sites for adsorption on the polymer, resulting in a maximum octane uptake of 50%w/w – approximately twice that of the PES-based fibres. [Copyright &y& Elsevier]

Abstract: Octaazaphthalocyanines with eight phenoxy groups in the peripheral sites are prepared for the first time using the simple synthetic procedure of heating their pyrazine-2,3-dicarbonitrile precursor in quinoline. This process avoids transetherification, which has hindered previous attempts at preparing metal-free octaazaphthalocyanines. Metal-containing derivatives were also prepared by adding the appropriate metal salt to the reaction mixture. Bulky iso-propyl or phenyl groups at the 2,6-positions of the phenoxy substituents prevent self-association of the octaazaphthalocyanine cores even in the solid state. [Copyright &y& Elsevier]

A novel unsymmetrically substituted phthalocyanine, which contains an extended planar core and a pair of adjacent peripheral hydroxyl groups is synthesised and used to prepare planar phthalocyanine oligomers. These materials act as macrodiscotic liquid crystals giving a columnar mesophase, which is stable over a large temperature range. [Copyright &y& Elsevier]

Microporous materials are solids that contain interconnected pores of molecular dimensions (i.e. <2 nm). Such materials possess large surface areas, typically 300-1500 m2 g−1, and are of great technological importance for adsorption and heterogeneous catalysis. There are two main classes of microporous materials widely used in industry: crystalline zeolites (aluminosilicates) and activated carbons. In the past decade, there has been an intense effort to optimize the porosity of these materials for various applications. However, it is recognized that the design of entirely new microporous materials would open up exciting opportunities for fundamental research and industrial applications. [Copyright &y& Elsevier]