A spatially orthogonal hierarchically porous acid–base catalyst for cascade and antagonistic reactions

Abstract

Materials characterisationNitrogen porosimetry was undertaken on a Quantachrome Autosorb IQTPX porosimeter with analysis using ASiQwin v3.01 software. Samples were degassed at 150ºC for 12 h before recording N2 adsorption/desorption isotherms. BET surface areas were calculated over the relative pressure range 0.02-0.2. Mesopore properties were calculated applying the BJH (Barrett-Joyner-Halenda) method to the desorption isotherm for relative pressures >0.35, and fitting of isotherms to the relevant DFT (density functional theory) kernel within the software package. Powder X-ray diffraction patterns were recorded using a Bruker D8 diffractometer employing a Cu K (1.54 Å) source fitted with a Lynx eye high-speed strip detector. Low-angle patterns were recorded for 2θ = 0.3-8º with a step size of 0.01º. Wide-angle patterns were recorded for 2θ = 10-80º with a step size of 0.02º. XPS spectra were recorded using a Kratos Axis HSi spectrometer fitted with an Al kα (1486.6 eV) monochromated source and a charge neutraliser. High resolution spectra were run with a pass energy of 40. All spectra were calibrated to adventitious carbon (284.8 eV). Peak fitting was performed using CASAv2.3.18PR1.0. All peaks were fit with a Shirley background and a GL(30) lineshape. Thermogravimetric analysis was conducted using a Mettler-Toledo TGA/DSC 2 STAR* system at 10 ºC min -1 under flowing N2/O2 (80:20 v/v 20 cm 3 min -1 ) fitted with a Pfeiffer ThermoStar mass spectrometer. CO2 titrations were performed using a Quantachrome ChemBET 3000. Samples were outgassed at 400 ºC under flowing helium (20 cm 3 min -1 ) for 1 hour prior to analysis. Transmission electron microscopy (TEM) imaging was performed using a JEOL 2100F FEG TEM with a Schottky field-emission source, equipped with an Oxford INCAx-sight Si(Li) detector for energy-dispersive spectroscopy (EDX). High-resolution (scanning) transmission electron microscopy (S)TEM images were recorded on either a FEI Tecnai F20 FEG TEM operating at 200 kV equipped with an

Hard x-ray photoelectron spectroscopy: a snapshot of the state-of-the-art in 2020

“…The Ag Lα has found successful application in a number of areas. [116][117][118][119] 2.2.5. Custom systems A number of custom built systems are also in operation often combining X-ray sources and analysers from different suppliers.…”

Compartmentalization and Photoregulating Pathways for Incompatible Tandem Catalysis

“…Scientists have developed multicompartmental catalytic systems based on various strategies including the use of sol–gels, Pickering emulsion droplets, supramolecular metal complex architectures, , and polymers. , Catalytic frameworks fabricated from these materials have realized compartmentalization for multiple active catalytic sites, as epitomized by the cell, and enabled multistep nonorthogonal transformations. − ,− Incorporating responsive elements into the support structures has rendered them “smart”, i.e., allowing for reversible alterations of the physical and chemical properties in response to external stimuli such as temperature, , pH, light, , or enzymes. , The properties of the resulting smart materials impart an additional bioinspired control over single-step catalytic transformations. ,− Manipulation of multicatalytic tandem sequences, however, remains challenging and restricted to the regulation of reactivities via temperature actuation. , This limitation significantly affects the choice of catalysts and limits the feasibility of performing one-pot tandem catalysis at arbitrary temperature ranges. To date, no “smart” catalytic system can use or control different switchable states to tune and activate a desired synthetic pathway among many possible ones during a multistep synthesis.…”

Low‐Field NMR Relaxation Analysis of High‐Pressure Ethane Adsorption in Mesoporous Silicas

“…These time constants exhibit well‐defined relationships with molecular rotational and translational dynamics within the unrestricted bulk liquid phase [18] . For fluids confined to porous solids, however, the correspondence between time constants and molecular dynamics is perturbed by the attendant pore structure, [19,20] facilitating characterisation of a range of material and interfacial properties including pore sizes [21,22] and connectivity, [23–25] surface areas, [26,27] confinement effects [28–30] and adsorption interactions [31–37] . Papaioannou et al [38] .…”