19 research outputs found
Heterogeneous organocatalysts composed of microporous polymer networks assembled by Tröger's base formation
Reagentless Electrochemiluminescence from a Nanoparticulate Polymer of Intrinsic Microporosity (PIM-1) Immobilized onto Tin-Doped Indium Oxide
In contrast to most common electrochemiluminescence (ECL) techniques that require either an additional reagent or continuous pulsing between oxidative and reductive potentials, here a fluorescent polymer of intrinsic microporosity (PIM-1) is shown to exhibit intrinsic ECL without the need for a co-reactant at positive applied potentials and as a function of pH. PIM-1 is known to possess high microporosity (based on its rigid and contorted molecular structure) and excellent fluorescence properties. By depositing a nanoparticulate form of the PIM-1 material onto tin-doped indium oxide, we achieve a hierarchically porous deposit with good sustained ECL activity in aqueous media. The mechanism for this reagentless ECL is suggested to be linked to reactive oxygen species produced at positive potentials and discussed in terms of potential analytical applications.EPSRC [EP/K004956/1, EP/K008102/2]SCI(E)[email protected]
Laser Chemosensor with Rapid Responsivity and Inherent Memory Based on a Polymer of Intrinsic Microporosity
This work explores the use of a polymer of intrinsic microporosity (PIM-1) as the active layer within a laser sensor to detect nitroaromatic-based explosive vapors. We show successful detection of dinitrobenzene (DNB) by monitoring the real-time photoluminescence. We also show that PIM-1 has an inherent memory, so that it accumulates the analyte during exposure. In addition, the optical gain and refractive index of the polymer were studied by amplified spontaneous emission and variable-angle ellipsometry, respectively. A second-order distributed feedback PIM-1 laser sensor was fabricated and found to show an increase in laser threshold of 2.5 times and a reduction of the laser slope efficiency by 4.4 times after a 5-min exposure to the DNB vapor. For pumping at 2 times threshold, the lasing action was stopped within 30 s indicating that PIM-1 has a very fast responsivity and as such has a potential sensing ability for ultra-low-concentration explosives
Toward an Understanding of the Microstructure and Interfacial Properties of PIMs/ZIF-8 Mixed Matrix Membranes
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
Triptycene-based organic molecules of intrinsic microporosity
Four Organic Molecules of Intrinsic Microporosity (OMIMs) were prepared by fusing triptycene-based components to a biphenyl core. Due to their rigid molecular structures that cannot pack space efficiently, these OMIMs form amorphous materials with significant microporosity as demonstrated by apparent BET surface areas in the range of 515–702 m2 g–1. Bulky cyclic 1′,2′,3′,4′-tetrahydro-1′,1′,4′,4′-tetramethylbenzo units placed on the triptycene termini are especially efficient at enhancing microporosity
CCDC 756767: Experimental Crystal Structure Determination
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures
Polymers of intrinsic microporosity (PIMs): Robust, solution-processable, organic nanoporous materials
Gas separation membranes from polymers of intrinsic microporosity
When polymeric membranes are employed to remove selectively one component from a gaseous mixture, there is generally a trade-off between selectivity and permeability. Data are presented for two polymers of intrinsic microporosity, PIM-1 and PIM-7, which show a significant advance across the previous upper bound of performance for commercially important gas pairs, including O2/N2 and CO2/CH4. The exceptional properties of PIMs arise from their rigid but contorted molecular structures, which frustrate packing and so create free volume, coupled with chemical functionality giving strong intermolecular interactions