
David C. ApperleyDurham University | DU · Department of Chemistry
David C. Apperley
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Publications (233)
The esterification of levulinic acid under acidic conditions to produce levulinate esters is of current significant interest due to the potential of these compounds as fuels and fuel additives. While a number of bespoke heterogeneous catalysts have been reported to be effective for this transformation, the use of widely available commercial catalys...
The photocatalytic and dielectric behaviors of Aurivillius oxyfluorides such as Bi2TiO4F2 depend sensitively on their crystal structure and symmetry but these are not fully understood. Our experimental work combined with symmetry analysis demonstrates the factors that influence anion order and how this might be tuned to break inversion symmetry. We...
Wide-dose-range 2D radiochromic films for radiotherapy, such as GAFchromic EBT, are based on the lithium salt of 10,12-pentacosadiynoic acid (Li-PCDA) as the photosensitive component. We show that there are two solid forms of Li-PCDA—a monohydrated form A and an anhydrous form B. The form used in commercial GAFchromic films is form A due to its sho...
Struvite-K (MgKPO4·6H2O) is a magnesium potassium phosphate mineral with naturally cementitious properties, which is finding increasing usage as an inorganic cement for niche applications including nuclear waste management and rapid road repair. Struvite-K is also of interest in sustainable phosphate recovery from wastewater and, as such, a detaile...
The influence of the intrapore cation on the fluorination of zeolite Y from dilute fluoride solutions has been studied, revealing fluoride reacts with the zeolite framework in the presence of a Brønsted acid to form [SiO3F] and [AlO3F] moieties. ²⁹Si{¹H} Cross-polarised MAS NMR indicates the reaction proceeds by the substitution of surface hydroxid...
To account for the charge transfer and covalent character in bonding between P and Bi centers, the electronic structures of [P(C6H4-o-CH2SCH3)3BiCl
n
](3-n)+ (n = 0-3) model species have been investigated computationally. On the basis of this survey a synthetic target compound with a dative P→Bi bond has been selected. Consecutively, the highly rea...
The hydroxy-pyrazole and 3-hydroxy-oxindole motifs have been utilised in several pharma and agrochemical leads but are distinctly underrepresented in the scientific literature due to the limited routes of preparation. We have developed a one-pot procedure for their synthesis starting from simple isatins. The method employs cheap and easy-to-handle...
In situ high-temperature powder X-ray diffraction experiments were undertaken for the coarse crystalline natural layered double hydroxides (LDHs) quintinite, hydrotalcite, stichtite, and iowaite in the temperature range 25-1000 • C, with thermal analyses of these minerals and their annealed forms carried out in parallel. In the temperature range fr...
The first selective oxidation of methane to methanol is reported herein for zinc‐exchanged MOR (Zn/MOR). Under identical conditions, Zn/FER and Zn/ZSM‐5 both form zinc formate and methanol. Selective methane activation to form [Zn‐CH3]⁺ species was confirmed by ¹³C MAS NMR spectroscopy for all three frameworks. The percentage of active zinc sites,...
In order to overcome the critical limitations of liquid electrolyte-based dye-sensitized solar cells, quasi-solid-state electrolytes have been explored as a means of addressing long-term device stability, albeit with comparatively low ionic conductivities and device performances. Although metal oxide additives have been shown to augment ionic condu...
We report the solid-state structural properties and phase transition behaviour of 1,4-dibromo-2,3,5,6-tetramethylbenzene, demonstrating that this material undergoes an order-disorder phase transition below ambient temperature (at ca. 156 K on cooling and ca. 159 K on heating). In both the high-temperature and low-temperature phases, the crystal str...
Pnictogen bond with bismuth: The flexibility of accordion‐like molecular skeletons paves the way for tunable pnictogen bonding between phosphorus and bismuth centres. The strength of this weak and mainly electrostatic interaction between the Bi and P centres strongly depends on the halogen substituent on bismuth. The first‐ever observation of a cou...
To study pnictogen bonding involving bismuth, flexible accordion‐like molecular complexes of the composition [P(C6H4‐o‐CH2SCH3)3BiX3], (X=Cl, Br, I) have been synthesised and characterised. The strength of the weak and mainly electrostatic interaction between the Bi and P centres strongly depends on the character of the halogen substituent on bismu...
Steroid molecules have a long history of incorporation into silicone elastomer materials for controlled release drug delivery applications. Previously, based on in vitro release testing and drug content analysis, we demonstrated indirectly that the contraceptive progestin levonorgestrel (LNG) chemically and irreversibly binds to addition cure silic...
Pyrogenic carbon (PyC) is a polyaromatic residue of the incomplete combustion of biomass or fossil fuels. There is a growing recognition that PyC forms an important part of carbon budgets, due to production rates of 116–385 Tg C yr, and the size and ubiquity of PyC stocks in global carbon reservoirs. At least a proportion of PyC exists in a highly...
Sequential treatment of a previously-calcined solid oxide support (i.e. SiO2, γ-Al2O3, or mixed SiO2–Al2O3) with solutions of Cr{N(SiMe3)2}3 (0.71 wt% Cr) and a Lewis acidic alkyl aluminium-based co-catalyst (15 molar equivalents) affords initiator systems active for the oligomerisation and/or polymerisation of ethylene. The influence of the oxide...
Peatlands can accumulate organic matter into long-term carbon (C) storage within the soil profile. This study used solid state 13C nuclear magnetic resonance (13C-NMR) to investigate the transit of organic C through a peatland ecosystem to understand the molecular budget that accompanies the long term accumulation of C. Samples of biomass, litter,...
Adding fluoride into bioactive glasses leads to fluorapatite formation and a decrease in glass transition temperature. Recently, chloride has been introduced into glasses as an alternative to fluoride. The presence of the large chloride ion lowers glass crystallisation tendency and increases glass molar volume, which effectively facilitates glass d...
The reactivity of tin and lead phosphanido complexes with chalogens is reported. The addition of sulfur to [(BDI)MPCy2] (M = Sn, Pb; BDI = CH{(CH3)CN-2,6-iPr2C6H3}2) results in the formation of phosphinodithioates [(BDI)MSP(S)Cy2] regardless of the conditions; however, when selenium is added to [(BDI)MPCy2], a selenium insertion product, phosphinos...
Anion-exchange membranes (AEM) containing saturated-heterocyclic benzyl-quaternary ammonium (QA) groups synthesised by radiation-grafting onto poly(ethylene-co-tetrafluoroethylene) (ETFE) films are reported. The relative properties of these AEMs are compared with the benchmark radiation-grafted ETFE-g-poly(vinylbenzyltrimethylammonium) AEM. Two AEM...
The technique of stray field diffusion NMR is adapted to study the diffusion properties of water in monodisperse wet foams. We show for the first time, that the technique is capable of observing q-space diffusion diffraction peaks in monodisperse aqueous foams with initial bubble sizes in the range of 50-85μm. The position of the peak maximum can b...
A combination of solid-state NMR techniques, including 13C/1H correlation, 2H magic-angle spinning NMR and first principles calculation are employed to characterise the role of water in different hydration states of sildenafil citrate. The 13C spectrum is fully assigned for the first time and direct correlations made with respect to the crystal str...
Valsartan (VAL) is an antihypertensive drug marketed in an amorphous form. Amorphous materials can have different physicochemical properties depending on preparation method, thermal history etc., but the nature of such materials is difficult to study by diffraction techniques. This study characterizes two different amorphous forms of valsartan (AR...
Catalytic strategies for the efficient transformation of abundant sustainable bioderived molecules, such as glycerol, into higher value more useful products is an important research goal. In this study, we demonstrate that atom efficient dehydrative etherification reactions of glycerol with activated alcohols are effectively catalyzed by nanoporous...
We present the first direct evidence of Na-ion mobility in sodium strontium silicate fast ion conductors, based on variable temperature (23)Na solid state NMR spectroscopy and spin-lattice relaxation measurements.
Cu2+ cations complexed by linear polyamines have been studied as structure-directing agents (SDAs) for the direct synthesis of copper-containing microporous silicoaluminophosphate (SAPO) materials. The complexing ligands diethylenetriamine (DETA), N-(2-hydroxyethyl)ethylenediamine (HEEDA), triethylenetetramine (TETA), N,N′-bis(2-aminoethyl)-1,3-pro...
Lewis base adducts of tetra-alkoxy diboron compounds, in particular bis(pinacolato)diboron (B2 pin2 ), have been proposed as the active source of nucleophilic boryl species in metal-free borylation reactions. We report the isolation and detailed structural characterization (by solid-state and solution NMR spectroscopy and X-ray crystallography) of...
We report the solvent-mediated supramolecular assembly of pillar[5]quinone (P[5]Q), a symmetric cyclamer containing five benzoquinone moieties bridged by five alternating methylene units. The supramolecular assembly of P[5]Q is shown to be facilitated by 1,1,2,2-tetrachloroethane (TCE) as solvent, producing a microcrystalline solvate material P[5]Q...
Nanoporous alumino- and borosilicate materials, produced using an evaporation-induced self-assembly approach (EISA), efficiently catalyse the Meinwald rearrangement of epoxides in dimethyl carbonate (DMC) to produce the corresponding carbonyl compounds in high yield and excellent selectivity.
Detonation-prepared nanocrystalline diamond powders usually contain hydrogen. Herein, the synthesis of practically hydrogen-free nanodiamond particles by detonation of benzotrifuroxan (BTF) and their comprehensive characterization by elemental analysis, X-ray diffraction, electron microscopy, DSC/TGA, and BTE specific-surface determination is descr...
Soluble sulfate ions in nuclear waste can have detrimental effects on cementitious wasteforms and disposal facilities based on Portland cement. As an alternative, Ba(OH)2–Na2SO4–blast furnace slag composites are studied for immobilisation of sulfate-bearing nuclear wastes. Calcium aluminosilicate hydrate (C–A–S–H) with some barium substitution is t...
[FeL3][BF4]2·xH2O (L = 3-(pyrazinyl)-1H-pyrazole) shows negative thermal expansion between 150-240 K but positive thermal expansion at 240-300 K, linked to rearrangement of anions and water molecules within pores in the lattice.
In this work we report the applicability of ZrO2/ZnO anchored onto a variety of MgO:SiO2 materials as heterogeneous catalysts for the conversion of ethanol to 1,3-butadiene
The solvent formation of phenobarbital, an important drug compound with an unusually complex polymorphic behavior, was studied in detail. Monosolvates with acetonitrile, nitromethane, dichloromethane and 1,4-dioxane were produced and characterized by single crystal and powder X-ray diffraction, thermoanalytical methods, FT-IR, Raman and solid-state...
Although the use of ball milling to induce reactions between solids (mechanochemical synthesis) can provide lower-waste routes to chemical products by avoiding solvent during the reaction, there are further potential advantages in using one-pot multistep syntheses to avoid the use of bulk solvents for the purification of intermediates. We report he...
High aluminum containing nanoporous aluminosilicate materials, produced by an evaporation-induced self-assembly process, efficiently catalyze the formation of unsymmetrical ethers by a dehydrative etherification reaction in high isolated yields. By carrying out the reaction under dilute conditions, the quantities of reagents can be reduced to near...
Although the use of ball milling to induce reactions between solids (mechanochemical synthesis) can provide lower-waste routes to chemical products by avoiding solvent during the reaction, there are further potential advantages in using one-pot multistep syntheses to avoid the use of bulk solvents for the purification of intermediates. We report he...
Barbital is a hypnotic agent that has been intensely studied for many decades. The aim of this work was to establish a clear and comprehensible picture of its polymorphic system. Four of the six known solid forms of barbital (denoted I°, III, IV, V) were characterized by various analytical techniques and the thermodynamic relationships between the...
The effect of uranium on glass structure is of interest in the context both of geological and nuclear waste glasses. In this study, solid state Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR) spectroscopy was used to establish the effect of UO3 on the bulk structure of mixed alkali borosilicate glass. The effects of increasing UO3 content...
Solid-state NMR is used to characterise dynamics in the ethanol solvate of the pharmaceutical material formoterol fumarate and its associated desolvate. Jump rates and activation barriers for dynamic processes such as phenyl ring rotation and methyl group rotational diffusion are derived from 1D-EXSY and (13)C spin-lattice relaxation times respecti...
Radiation-grafted anion-exchange membranes (AEM) containing pendent benzyltrimethylammonium, 1-benzyl-3-methylimidazolium and 1-benzyl-2,3-dimethylimidazolium functional head-groups were synthesised with ion-exchange capacities in the range 1.7-1.9 meq g-1. The ionic conductivities of the AEMs were also comparable (24.5 +/- 1.8 mS cm-1 at 50 [degre...
In the primary walls of growing plant cells, the glucose polymer cellulose is assembled into long microfibrils a few nanometers in diameter. The rigidity and orientation of these microfibrils control cell expansion, and cellulose synthesis is therefore a key factor in the growth and morphogenesis of plants. Celery collenchyma is a useful model syst...
The aluminum complex Alq3 (q = 8-hydroxyquinolinate), which has important applications in organic light-emitting diode materials, is shown to be readily synthesized as a pure phase under solvent-free mechanochemical conditions from Al(OAc)2OH and 8-hydroxyquinoline by ball milling. The initial product of the mechanochemical synthesis is a novel ace...
Nanoporous silicate materials, produced using an evaporation-induced self-assembly (EISA) approach, are highly effective catalysts for transacetalization reactions. Both acyclic acetals and ketals undergo rapid exchange in the presence of low loadings of nanoporous aluminosilicate materials and diols and triols to generate the corresponding cyclic...
The solid-state structures of two polymorphs and two alcoholates (ethanol and isopropanol) of formoterol fumarate have been investigated by a combination of NMR techniques. First-principles shielding computations are combined with NMR data to successfully relate peaks to their crystallographic positions for the solvates, including atoms that are in...
Solid View of a Sigma Complex
For decades, it has been clear from kinetic studies that saturated hydrocarbons can also act as weak ligands, often just prior to bond cleavage reactions. These short-lived intermediates—termed “σ complexes” because the donated electrons reside in single (sigma symmetry) C-H bonds—have been glimpsed spectroscopically b...
In this paper we examine the effect of Ga doping on the structure and conductivity of the high Li ion content garnet-related system, La(3)Zr(2)Li(7)O(12). Without Ga doping, La(3)Zr(2)Li(7)O(12) is tetragonal and has low Li ion conductivity. The introduction of Ga leads to a change to a cubic unit cell, and a large enhancement in the conductivity....
A series of heavier group 14 element, terminal phosphide complexes, M(BDI)(PR(2)) (M = Ge, Sn, Pb; BDI = CH{(CH(3))CN-2,6-iPr(2)C(6)H(3)}(2); R = Ph, Cy, SiMe(3)) have been synthesized. Two different conformations (endo and exo) are observed in the solid-state; the complexes with an endo conformation have a planar coordination geometry at phosphoru...
The validity of the structure of diterbutaline sulphate diacetic acid solvate in the Cambridge Crystallographic Database (code ZIYXAG) was checked using 13C solid-state NMR together with shielding computations and was found to be in error as far as the geometry of one acetic acid molecule is concerned. A new X-ray diffraction study confirmed the ex...
In this paper we report the successful synthesis of the cubic oxyanion containing perovskites, Ba(2)Sc(2-x)P(x)O(5+x) (x = 0.4, 0.5), with the samples analysed through a combination of X-ray diffraction, NMR, TGA, Raman spectroscopy and conductivity measurements. Conductivity measurements indicate a p-type contribution to the conductivity in oxidiz...
A simple aqueous-processable alkaline ionomer (amenable to scale-up) has been developed for enhancing electrode/electrolyte interfaces in clean energy devices (e.g. alkaline polymer electrolyte membranefuelcells). The water uptake of the alkaline ionomer is tuneable allowing its use as a tool for fundamental studies into these interfaces.
The Lewis base adduct of B(2)pin(2) and the NHC (1,3-bis(cyclohexyl)imidazol-2-ylidene), which was proposed to act as a source of nucleophilic boryl groups in the β-borylation of α,β-unsaturated ketones, has been isolated, and its solid state structure and solution behavior was studied. In solution, the binding is weak, and NMR spectroscopy reveals...
The structure of cellulose microfibrils in wood is not known in detail, despite the abundance of cellulose in woody biomass and its importance for biology, energy, and engineering. The structure of the microfibrils of spruce wood cellulose was investigated using a range of spectroscopic methods coupled to small-angle neutron and wide-angle X-ray sc...
The structural properties of a new polymorph of a material distributed commercially as “hexaketocyclohexane octahydrate” have been determined directly from powder X-ray diffraction data, employing the direct-space genetic algorithm technique for structure solution followed by Rietveld refinement. It is shown that the molecule actually present in th...
An investigation of the nature of the carbonaceous species deposited upon mordenite by reaction with methanol has been undertaken. The nature of the species has been shown to be a strong function of both temperature and time on stream. Upon reaction at 300 °C a range of alkyl and aromatic species, consistent with the development of an active hydroc...
High resolution 29Si, 27Al, 15N and 17O MAS NMR spectra have been collected for a series of yttrium oxynitride glasses with varying nitrogen contents. The results show that as the proportion of nitrogen in the glass increases, the proportion of [SiON3], [SiO2N2] and [SiO3N] coordinations systematically increase at the expense of [SiO4]. The 27Al NM...
The NMR spectra of polymorphs I, II, and III of the pharmaceutical drug compound phenobarbital are discussed in relation to the crystal structures. Whilst some features can be explained by inspection of the structures, others require more detailed work. In this paper, shielding computations for the ¹³C, ¹⁵N, and ¹H nuclei using crystallographic rep...
Charcoal is a key component of the Black Carbon (BC) continuum, where BC is characterized as a recalcitrant, fire-derived, polyaromatic material. Charcoal is an important source of palaeoenvironmental data, and of great interest as a potential carbon sink, due to its high apparent environmental stability. However, at least some forms of charcoal ar...
In this paper we report the utility of a variety of silica impregnated bi- and trimetallic catalysts for the conversion of ethanol into 1,3-butadiene. The highest selectivity observed was 67%. The catalysts have been characterised via29Si solid-state NMR spectroscopy, TEM, XPS, pXRD and nitrogen adsorption studies. Different silica materials have b...
A screening of crystallization conditions for the diastereomeric salts formed by L/D-malic acid and a common resolving agent, L-Ephedrine, in water is reported. So far, 7 different forms of salts with 1:1 and 2:1 stoichiometries were successfully crystallized, including one previously reported 1:1 LL salt. All new salts were characterized by differ...
In this paper we report the successful incorporation of phosphate and sulfategroups into the ionic conductor, Ba2In2O5, with the samples analysed through a combination of X-ray diffraction, NMR, TGA, Raman spectroscopy and conductivity measurements. The results show that such oxyanion incorporation leads to a conversion from an ordered brownmilleri...
Six of the more easily accessible forms of phenobarbital (Pbtl-I, II, III, IV, V, VI) were characterized by a variety of analytical methods (thermal analysis, solution calorimetry, X-ray diffraction methods, infrared, Raman and solid-state NMR spectroscopy), in order to get a clear picture of this complex polymorphic system and to eliminate severe...
Powder X-ray diffraction (XRD) has been exploited to establish the structural properties of a porous interpenetrated mixed-ligand metal-organic framework material prepared by solid-state grinding, recognizing that product phases from mechanochemical synthesis are typically microcrystalline powders. The importance of subjecting the powder XRD data t...
In the solid oxide fuel cell (SOFC) field, the presence of silicon impurities is commonly considered to be detrimental to the performance due to segregation as silica at the grain boundaries. In this paper we demonstrate, however, that silicon doping into Ba2In2O5 leads to a significant enhancement in the oxide ion conductivity. The results indicat...
A range of chloroindate(iii) ionic liquid systems was prepared by mixing of 1-alkyl-3-methylimidazolium chloride with indium(iii) chloride in various ratios, expressed as the mol fraction of indium(iii) chloride, chi(InCl(3)). For chi(InCl(3))</= 0.50, the products were liquids, whereas for chi(InCl(3)) > 0.50, the products were biphasic (suspensio...
In this Communication, we report the unprecedented solid-state structures for a series of zinc(II) silsesquioxane complexes. Initial catalytic data for the ring-opening polymerization of rac-lactide are also presented together with analogous heterogeneous species.
Ist er es oder ist er es nicht? Die Reaktion von [PdMe2(tmeda)] mit Pyridyl-N-di(tert-butyl)phosphanylimin liefert spontan einen ungewöhnlichen zweikernigen Palladium(I)-Komplex mit diradikalischem Liganden, der sich in Reaktionen mit neutralen Liganden und Chlorbenzol wie eine „maskierte“ Form von Pd0 verhält.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
The ability of nanoporous aluminosilicate materials, synthesized using an evaporation-induced self-assembly (EISA) approach, to function as catalysts for the formation of β-amino alcohols from aromatic amines and epoxides was assessed. Materials containing high aluminium loadings displayed catalytic activity, giving the desired β-amino alcohols in...
Charcoal is the result of natural and anthropogenic burning events, when biomass is exposed to elevated temperatures under conditions of restricted oxygen. This process produces a range of materials, collectively
known as pyrogenic carbon, the most inert fraction of which is known as Black Carbon (BC). BC degrades extremely slowly, and is resistant...
This study investigates the potential of low-temperature oxygen plasma ashing as a technique for decontaminating charcoal and wood samples prior to radiocarbon dating. Plasma ashing is demonstrated to be rapid, controllable and surface-specific, and clear differences are identified in the rate of ashing in different organic materials. However, the...
Molecular modeling has been used to assist in the design of a new structure directing agent (SDA) for the synthesis of the AlPO 4 form of STA-2, bis-diazabicyclooctane-butane (BDAB). This is incorporated as a divalent cation within the large cages of STA-2, as determined via a combination of solid-state 13 C and 15 N MAS NMR, supported by 14 N and...