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Harnessing Nanoscale Surface Interactions: Contemporary Synthesis, Applications and Theory provides coverage of contemporary theoretical and experimental approaches to understanding the interactions of molecules with nanomaterial surfaces and how to utilize these processes for improved synthesis and application of materials. The book reviews recently developed theoretical techniques to explore bonding interactions in nanoclusters and small molecules, along with modern molecular dynamics approaches for investigation adsorption of large molecules on nanomaterials. Novel experimental approaches are described that provide improved control of the synthesis of metal nanoparticles and measurement of their absorption properties. The potential for nanomaterials to address a range of environmental problems is also demonstrated by a selection of specific applications. Chapters discuss experimental synthesis approaches, experimental analysis and applications, and theoretical approaches for harnessing nanoscale surface interactions.

Phenothiazine based dyes are widely explored dyes for their antibacterial and photosensitising applications. Despite their amazing optical and photosensitising (theranostic) properties, their usage in nanomedicine is very low compared to other organic dyes. This is due to the lack of reactive functional groups for encapsulating them into metal oxide nanoparticles. This work describes the synthesis of three different phenothiazinium alkoxysilane derivatives by oxidative amination of 10H-phenothiazine using amino alkoxysilanes. The new derivatives were characterized using NMR, FT-IR, DSC/TGA, and mass spectral studies. Optical and photosensitising properties (absorption spectrum, photostability, and singlet oxygen quantum yield) of the silane derivatives were investigated using UV–Visible spectroscopy. These compounds are suitable for conjugation with silica in the sol-gel synthesis of silica nanoparticles and silica surface coaters, which will reduce dye leakage and improve the dye efficacy in the treatment of cancer and light activated antimicrobial surfaces.

Aims Organic carbon has been reported in deep regolithic profiles to depths of tens of metres, but the composition of the carbon compounds is unknown. Methods Residual carbon in the form of non-volatile low molecular weight compounds (LMWC) was characterised in three deep soil profiles to a depth of 19 m under farmland in south-western Australia following extraction with ethyl acetate and analysis by GC/MS. Pyrolysis and off-line thermochemolysis were used to characterise macromolecular organic carbon (MOC) to a depth of 29 m at a fourth site. Results Three compound classes occurred across the three different field locations: (1) terpenes, (2) fatty acids, amides and alcohols, and (3) plant steroids; indicating the influence of input of the past and present vegetation. Compounds related to fatty acids were the predominant residual carbon species in deep soils, and may be derived from plants and microorganisms. Biomarkers such as lignin, polysaccharides, proteins and terpenes at 0–0.1 m implied influences of vegetation, fire events and microorganisms. Pyrolysis found that polysaccharides were distributed mainly from 0 to 0.1 m, while aromatic compounds were consistently detected down to 29 m. Conclusions Carbon was stabilised in the form of aromatic compounds in deep soil, whereas other carbon sources such as cellulose, chitin, and N-containing compounds were confined to the surface soil. LMWC (Z)-docos-13-enamide and bis(6-methylheptyl) phthalate, were the main components throughout the soil profiles representing 53–81% of the LMWC, and were a greater proportion of the organic matter at depths of 18–19 m.

Aims This study identifies the contribution of leaf matter from individual plant species on water repellency with a focus on the composition of organic compounds and the role of heat in releasing these compounds to soil. Methods Leaf powder from four plant species (Banksia menziesii, Eucalyptus marginata, Allocasuarina fraseriana, Xanthorrhoea preissii) was mixed with acid-washed sand (AWS) under a range of temperatures and WR measured. Plant chemical composition was characterized by extraction of leaf powder and GC/MS analysis. Results Increasing concentrations of plant powder mixed with AWS increased WR for three species; whereas for X. preissii there was no WR at any concentration. Heating increased WR for all species over the range of 30 to 120 °C. B. menziesii had the greatest WR, which was associated with the largest diversity of fatty acids and n-alcohols and highest concentration of alkanes, whereas X. preissii with the smallest WR had only C16 alcohol and C16 fatty acids at relatively low concentration. Conclusions Physically mixing leaf powder with AWS allows the contribution of different plant species on WR to be directly examined. WR appears to be related to differences in the concentrations and diversity of n-alcohols, n-fatty acids, and high n-alkanes in the leaves. The observed temperature effects on WR provide insights into the kinetics of release and dispersal of organic compounds from interstitial material.

Electrolytic manganese dioxide (EMD) synthesized from different electrolytic baths with varying biopolymer additive concentrations has been investigated for application as an electrochemical supercapacitor. Alginic acid, also termed “alginate”, is a widely used biopolymer for various biological applications due to its physicochemical properties. Here, the EMD material synthesized with alginate crosslinking was introduced in the field of electrochemistry for supercapacitors. Different EMD and alginate composites were characterized to find the trade-off between the biopolymer content in the bath and the energy storage capability. Compared to the pristine EMD, the EMD composites at all of the alginate concentrations influenced both the physical and the electrochemical storage properties of the materials. The presence of alginate in the solution at higher concentrations altered the morphology from spindle-shaped to cactus-shaped with flutes. Rearranged morphology and enhanced particle size are attributed to the ability of the alginate to act as a template for binding the Mn2+ ions on the substrate in a relatively ordered and widely distributed manner. The EMD composite delivered 5 times higher capacitance (487 F g–1) than the pristine EMD at a current density of 1 mA cm–2 in a three-electrode system using a 2 M NaOH aqueous electrolyte. When the EMD composite was coupled with activated carbon, the asymmetric device exhibited 52 F g–1 capacitance at a current density of 2 mA cm–2 while giving excellent capacitance retention (94%) over 5000 cycles. The molecular dynamics simulation model supported the influence of alginate on ion–polymer interactions in the electrolytic bath. The simulations showed that the alginate provides a template for binding Mn2+ ions in a relatively ordered manner. It could assist the EMD/Alg composite growth in a more favorable condition for energy storage applications.

Soil water repellency (SWR) is a widespread phenomenon that influences patterns of soil wetting, runoff, evapotranspiration and availability of water for plants. In natural ecosystems there is emerging evidence that some plants can take advantage of non-uniform wetting patterns, leading to the emergence of co-evolutionary behaviour. In this review, SWR is considered in terms of five spheres of influence. Given the presence of hydrophobic organic material in the biosphere, the strength, severity and persistence of SWR is influenced by properties at the surface of the lithosphere and prevailing conditions in the atmosphere and hydrosphere. These in turn, can be modified by activities in the anthroposphere. This review thus examines the strength, severity and persistence of non-wetting behaviour with reference to these five spheres of influence and also the interactions between the spheres. It is focused on (i) how SWR is characterised to provide insight into how different measurement techniques have specific operational ranges, (ii) how SWR has developed as an indirect consequence of evolution in natural ecosystems and (iii) how feedbacks across the different spheres have emerged. It demonstrates that management and restoration of natural ecosystems with water repellent soils is very different from management of productive crops in monocultural agricultural systems, controlled in the anthroposphere.

In this investigation, ITO-based bi-layer and tri-layer thin film coatings (~130 nm) were synthesized via a sol-gel spin-coating process and annealed at 500 °C. Thin layers of Au, Au-NPs, Ag-NPs and AgO were inserted underneath ITO films to form bi-layer thin film systems and/or encapsulated between two thin ITO layers to form tri-layer thin film systems. The effects of incorporating these layers with ITO thin films were investigated by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), UV–Vis spectroscopy, four-point probes and Hall effect. XRD results confirmed the presence of a body-centred cubic structure of indium oxide for all synthesized ITO-based coatings with an average grain size ~30 nm. FESEM images of all fabricated films revealed the formation of dense surfaces with grain-like morphologies confirming the formation of a polycrystalline structure of ITO. Optical studies on the Ag-NPs and Au-NPs colloidal solutions resulted in absorption peaks featured at wavelengths 405 and 531 nm, indicating the formation of 10–14 nm and 48 nm Ag and Au nanoparticles, respectively. The highest optical transparency and band gap energy were found to be ~91.5% and 3.75 eV for (AgO)I and (I(AgO)I) thin films, respectively. The lowest electrical resistivity of 1.2 × 10−4 Ω·cm, along with the highest carrier concentration of 11.4 × 1020 cm−3 and mobility 40 cm2/V.s were obtained from the IAuI thin film. An improvement in the power conversion efficiency (PCE) from 3.8 to 4.9% was achieved in an organic solar cell by replacing the conventional pure ITO electrode with the (I(AgO)I) electrode.

Amidines share the same N=C─N building framework with many essential biochemical substances. In this work, we present a comparative mechanistic study on the deamination reactions of 19 amidine and nucleobase derivatives by the use of density functional theory. All the computations are performed at the B3LYP/6‐31G(d,p) level in the gas phase and with the polarizable continuum model (PCM). Mechanisms of 2‐ and 3‐step pathways including six‐ or eight‐membered ring transition states were explored. Our results show that the overall activation energies for the deamination of amidine derivatives are close to those of nucleobase derivatives of the saturated C5─C6 bond, and lower than those of nucleobase derivatives of the unsaturated C5─C6 bond, while purine derivatives have the highest activation energies among all the derivatives studied. The 3‐step mechanism gives results that are more consistent with the available experimental data than the 2‐step mechanism. Based on the results of our current and previous work, we believe that the 3‐step mechanism is the most likely mechanism for the hydrolytic deamination reactions of amidine and nucleobase derivatives.

This work investigated the synthesis of carbohydrate functionalized methylene blue doped amine grafted mesoporous silica nanoparticles (MB AMSN) and their application in bioimaging. A single-pot synthesis methodology was developed via a modified co-condensation sol-gel technique for simultaneous incorporation of the dye molecule in the nanoparticles, with amine grafting for subsequent functionalization. The obtained nanoparticles (∼ 450 nm) are mesoporous and have a high surface area (538 m2/g), pore-volume (0.3 cm3/g), showed excellent UV-vis absorbance, and dye encapsulation efficiency (> 75 %). These fluorescent nanoparticles were further functionalized with carbohydrate molecules before application as contrast agents in bacterial cells. In the present study, gram-positive (E. coli) and gram-negative (B. subtilis) bacteria were used as model organisms. Confocal laser microscopy results showed that the nanoparticles are highly fluorescent, and SEM of glucose conjugated MB doped nanoparticles indicated close interaction with E. coli with no toxicity observed towards either bacterial cells. The results demonstrate that by suitable surface functionalization, the methylene blue doped silica nanoparticles can be used as bioimaging agents.

Soil water repellency (SWR) is an extensively occurring phenomenon on natural and agricultural soils with a severe impact on soil water relations and thus crop yields and ecosystem productivity. It is caused by long chain amphiphilic compounds that originate from plant cuticular waxes. However, the severity of SWR varies with soil physical properties and the concentration of the compounds closely associated with producing hydrophobic coatings on soil surfaces. The induction of SWR by hexadecane, isopropyl tetradecanoate, and palmitic acid (PA), as pure (individual) coatings and as coatings composed of binary mixtures, was investigated by applying a range of loadings on acid-washed sand (AWS) (300–500 μm diameter) and AWS with 5% kaolinite. Molarity of ethanol droplet (MED) tests were conducted to assess the severity of SWR. Palmitic acid was very effective at inducing SWR at loadings of >0.5 × 10–6 mol g–1. Hexadecane and isopropyl tetradecanoate had no effect on SWR when applied as single component coatings. However, when hexadecane was combined with palmitic acid, it enhanced the SWR effect of palmitic acid. In comparison, isopropyl tetradecanoate was found to partially mitigate the SWR caused by palmitic acid. The experimental measurements of SWR were complemented by fully atomistic molecular dynamics simulations that suggested variations of SWR could be explained through molecular level interactions, packing on different soil mineral surfaces and the surface characteristics of the mineral surfaces. In addition, H-donor interactions of PA were found to be instrumental in intermolecular and surface interactions. Furthermore, cohesion and packing of hydrocarbon chains were found to be important parameters favoring surface adhesion, which in turn led to the formation of hydrophobic molecular coatings. The finding that ester derivatives of long chain fatty acids do not induce water repellency suggests that the introduction of chemical or biological processes that pro

Soil water repellency affects vast regions of agricultural and native land across the globe. Sandy soils are most likely to develop non-wetting characteristics with susceptibility decreasing with clay content. This study uses molecular dynamics simulations combined with laboratory scale experiments to study the interactions and assembly of saturated C16 straight chain alcohol and carboxylic acid molecules on a range of soil surfaces. The development of severe water repellency on sand at low loading levels of palmitic acid (0.75 × 10−6 mol g−1) is explained in terms of favourable H-bonding with silica surfaces and the development of 2–3 layers of lateral aligned organic molecules on the mineral surface. The efficacy of kaolinite in lowering soil water repellency is attributed to the higher surface area of this mineral and favourable surface chemistry, which hinders formation of persistent organic multilayers.

In this work, indium tin oxide (ITO) and silver doped ITO thin films at different Ag concentrations (i.e. 2, 4, 6 and 10 atomic%) were fabricated via a sol-gel spin coating technique. The thin film coatings were post annealed at 500 °C. Structural, mechanical, surface morphology, electrical and optical characteristics of the ITO and Ag-doped ITO thin films were studied as a function of Ag concentrations. XRD results are consistent with the presence of body centered cubic structure of the indium oxide polycrystalline phase with a new peak for Ag at 2θ ≈ 38.2°, indicating that by introducing Ag atoms they do not remarkably change the structural characteristics of the ITO films. FESEM images display the formation of ITO and Ag-doped ITO nanoparticles and the average crystallite size increases after annealing treatment as well as the incorporation of Ag concentration. The mechanical properties of the thin films were characterised by nanoindentation technique, with significant improvement observed through a combination of Ag doping and annealing treatment, which helps enhancing the effectiveness of the grain boundary in obstructing the displacement movements. The observed improvement in E and H is 14% and 28% respectively, with the hardness and Young’s modulus finally reaching 6.7 GPa and 148 GPa, respectively. Loading carrying capability and wear resistance are also enhanced by doping and annealing treatment. After annealing at 500 °C, the thin film coatings with the electrical resistivity of 2.4 × 10−4 Ω cm, carrier concentration of 6.8 × 1020 cm−3 and carrier mobility of 37 cm2/V s were achieved when the Ag doping level was 4 at.%. On the other hand, the maximum optical transparency was found to be 92% for both ITO and 2% Ag-doped ITO thin films after being annealed at 500 °C. The variation of optical constants, such as absorption coefficient, refractive index and extinction coefficient with different Ag concentrations, were also studied.

Single-walled carbon nanotubes (SWCNTs) incorporated in indium tin oxide (ITO) were developed to fabricate transparent conductive thin films via a sol-gel spin coating technique. The fabricated thin films were annealed at 350 °C. The effects of incorporating SWCNTs and varying film thickness on crystal structure were systematically investigated by X-ray diffraction (XRD), Raman shift, surface elemental compositions, surface topography and roughness, optoelectronic characteristics, and mechanical properties. XRD results confirmed the body-centered cubic structure of indium oxide polycrystalline phase, indicating that the structural properties of the ITO films were not significantly altered by incorporating CNTs. The presence of CNTs in the ITO matrix was confirmed by analyses of Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray spectroscopy (EDX). FESEM images revealed the formation of SWCNTs/ITO nanoparticles, and the average crystallite size increased along with increasing film thickness. Electrical characteristics also improved as the film thickness increased. The lowest electrical resistivity (4.6 × 10-4 ω cm), as well as the highest carrier concentration (3.3 × 1020 cm-3) and carrier mobility (41 cm2/V s) were achieved from the 320 nm thick film. However, the optical transparency decreased from 91 to 87.5% as the film thickness increased from 150 to 320 nm. The hardness and Young's modulus of the prepared samples improved, with the increase of SWCNTs doping level, and achieved the maximum values of 28 and 306 GPa, respectively.

Biogenic volatile organic compounds (BVOCs) are continually emitted from plants and are also a component of smoke during vegetation fire. Although vegetation fire events have been shown to have implications for the dynamics of soil water repellency (SWR) and there have been anecdotal reports that forest smoke can induce water repellency, the role of BVOCs in this process has not been explored. Accordingly, we investigated a selection of major BVOCs (cis-3-hexen-1-ol; levoglucosenone; 2-methyl-3-buten-2-ol; cineole; α-phellandrene; α-terpinene) that are emitted from the dominant native vegetation of Australia during fire. The potential of each compound to induce SWR was investigated by applying different loadings on acid washed sand (AWS) (300–350 µm diameter) and then assessing water repellency with the molarity of ethanol drop test. A long-chain amphiphilic molecule (palmitic acid) was also applied to AWS for comparison. Although palmitic acid was effective at inducing water repellency, the BVOCs were not, even at high loadings (5 × 10−4 mol g−1). Fully atomistic molecular dynamics simulations complemented the experimental measurements. These studies suggested that poor expression of water repellency by the BVOCs could be explained by their tendency to exhibit weak interactions towards the quartz surface but strong molecule–molecule attractions. In comparison, the long-chain amphiphilic molecules exhibited a balance between molecule–molecule and molecule–surface interactions that favored surface adhesion, which in turn led to the formation of a hydrophobic layer.

The tris-glycinatochromium(III) complex ([Cr(gly)3]) has been proposed as a nutritional supplement and treatment for Type 2 diabetes. The exact mode of action of this and other Cr(III) supplements is not known but may involve redox reactions with biomolecules. In this study fac-[Cr(gly)3] was synthesized and the electrochemical properties investigated by cyclic voltammetry. The complex undergoes a reversible one electron reduction with E1/2=−0.66 to −0.69 V that is essentially independent of scan rate. Thermal decomposition was explored by differential scanning calorimetry under nonisothermal conditions from 30−1000 °C. Structural parameters obtained from DFT calculations are in good agreement with crystallographic data. The reduced form of the complex has a high-spin quintet electronic configuration due to the small crystal field splitting from the weak π-donor ligands. Both the theoretical calculations and the electrochemical measurements demonstrate that the complex is stable in the anionic form. These results indicate that [Cr(gly)3] can undergo reversible electron transfer, which may play a role in it's biological activity.

The focus of this study is on a sol–gel method combined with spin-coating to prepare high-quality transparent conducting oxide (TCO) films. The structural, morphological, optical and electrical properties of sol–gel-derived pure and Ti-doped indium tin oxide (ITO) thin films were studied as a function of the concentration of the Ti (i.e. 0 at%, 2 at% and 4 at%) and annealing temperatures (150 °C–600 °C). FESEM measurements indicate that all the films are ~350 nm thick. XRD analysis confirmed the cubic bixbyite structure of the polycrystalline indium oxide phase for all of the thin films. Increasing the Ti ratio, as well as the annealing temperature, improved the crystallinity of the films. Highly crystalline structures were obtained at 500 °C, with average grain sizes of about 50, 65 and 80 nm for Ti doping of 0 at%, 2 at% and 4 at%, respectively. The electrical and optical properties improved as the annealing temperature increased, with an enlarged electronic energy band gap and an optical absorption edge below 280 nm. In particular, the optical transmittance and electrical resistivity of the samples with a 4 at% Ti content improved from 87% and 7.10 × 10−4 Ω.cm to 92% and 1.6 × 10−4 Ω.cm, respectively. The conductivity, especially for the annealing temperature at 150 °C, is acceptable for many applications such as flexible electronics. These results demonstrate that unlike the more expensive and complex vacuum sputtering process, high-quality Ti-doped ITO films can be achieved by fast processing, simple wet-chemistry, and easy doping level control with the possibility of producing films with high scalability.

Mechanisms for the deamination of ammeline (AMN), guanine (Gua), and their analogues with nH2O (n = 1–3) have been investigated using B3LYP and G3MP2B3. The deamination reactions of AMN and Gua with 3H2O/OH−, and protonated AMN and Gua with 3H2O, were investigated using DFT. The rationale behind this work was to compare the deamination reactions of AMN and Gua analogues. Optimized geometries of the reactants, transition states, intermediates, and products were determined at B3LYP/6-31G(d,p) level of theory, and solvent calculations were performed using the solvation model on density (SMD). Thermodynamic properties (ΔH, and ΔG), proton affinities (PAs), gas-phase basicities (GBs), deprotonation enthalpies (ΔacidH), and gas-phase acidities (ΔacidG) were also calculated. For the SN2 mechanism, deamination can proceed via two possible pathways involving either two- or three-stepwise mechanisms producing a tetrahedral intermediate via four-, six-, or eight-membered transition states. The lowest overall activation energies of 128 (131) and 131 (133) kJ mol−1 at B3LYP/6-31G(d,p) in the gas phase (SMD) were obtained for the deamination of AMN and Gua with 3H2O, whereas the values of 140 (115) and 139 (117) kJ mol−1 were obtained for AMN and Gua with 3H2O/OH−, respectively. For protonated AMN and Gua with 3H2O in the gas phase (SMD), the overall activation energies are 233 (155) and 240 (162) kJ mol−1, respectively.

Stabilisation and modulation of nanocluster reactivity are key elements for the development of these materials as versatile and selective catalysts. This study presents a preliminary investigation of the interaction of ligands with a gallium nanocluster (Ga13). The amphoteric nature of Ga13 means that both a Lewis base (NH3) and a Lewis acid (BH3) strongly adsorb to the surface of the cluster. More importantly, ligand coordination modifies the electronic structure of the cluster, leading to an enhancement of reactivity. In particular, NH3 coordination was found to lower the energy barrier for H2 chemisorption by 10% and BH3 coordination led to reduction of the barrier by 20%. These results demonstrate the potential for ligand coordination as a means of accelerating reactions on cluster surfaces.

The synthesis and characterization of mono-, bis- and tris-glycinatochromium(III) complexes by elemental analysis, UV–Vis, electron paramagnetic resonance (EPR), ATR-FTIR and Raman spectroscopy has been performed in this work. IR stretching bands obtained from DFT calculations of the mono-, bis- and tris-glycinatochromium(III) complexes are in good agreement with experimental data. Different mechanistic pathways were explored for the water exchange reactions of [Cr(+NH3CH2COO−)(H2O)5]3+ and its conjugate base species including, associative interchange (Ia), and dissociative (D) mechanisms. The lowest activation enthalpies for the mono- and bis-complexes are obtained for the Ia pathways with explicit outer sphere solvation (88 and 76 kJ mol−1), which are in good agreement with the experimental values (87 and 75 kJ mol−1). In comparison, tris-glycinatochromium(III) undergoes aquation via the dissociative (D) mechanism. Investigation of these systems in the pH range ∼3.0 to ∼8.5 by UV–Vis monitoring, helps identify the speciation of these complexes in physiological environments.

Titanium-doped indium tin oxide thin films were synthesized via a sol-gel spin coating process. Surface chemical bonding states and mechanical properties have been investigated as a function of titanium content (2 and 4 at%) and annealing temperature ranging from 400 to 600 °C with increments of 100 °C. Raman analysis was performed to study the phonon vibrations for the prepared samples and the results revealed the existence of ITO vibrational modes. The elemental compositions, bonding states and binding energies of the film materials were investigated using X-ray photoelectron spectroscopy (XPS) technique. The XPS results indicated that the ratio of the metallic elements (In, Sn, Ti) to the oxygen on the surface of the thin film coatings decreased due to the increase of the oxide layer on the surface of the thin films. Also, by increasing the annealing temperature up to 600 °C, the Ti 2p and Cl 2p signals were no longer detected for both 2 and 4 at% Ti contents, respectively, due to the thicker surface oxidation layer. Mechanical properties of the synthesized films were also evaluated using a nanoindentation process. Variations in the hardness (H) and the elastic modulus (E) were observed with different Ti at% and annealing temperatures. The hardness is within the range of 6.3–6.6 GPa and 6.7–6.8 GPa for 2 and 4 at% Ti content samples, respectively, while the elastic modulus is within the ranges of 137–143 and 139–143 GPa for 2 at% and 4 at% Ti contents samples, respectively. A combination of the highest H and E were achieved in the sample of 4% Ti content annealed at 600 °C. Furthermore, the H/E ratio ranges from 4.5 × 10−2 to 5.0 × 10−2 which reflects a reasonable level of wear resistance.

Two wet digestion methods were evaluated using pure kaolinite as background for quantifying small concentrations of carbon (<0.05% total organic carbon (TOC)) in deep kaolinitic regolith in south-Western Australia. The limit of detection and limit of quantification of the Walkley-Black method (0.015 and 0.050% TOC respectively) were approximately five times lower than those of the Heanes method (0.085 and 0.281% TOC respectively). Both methods showed excellent linearity (R2>0.99) using prepared standards (lignin, humic acid, cellulose and chitin mixed with kaolinite and their combinations), in the concentration range 0.008-1.000% TOC. However, the percentage carbon recovery values were underestimated for chitin. The Walkley-Black method (TOCWB, %) was evaluated with 94 calibration and 27 validation deep soil samples (1-35m soil depth) and compared with a dry combustion (Elementar) technique (TOCactual, %). The predictive equation (TOCactual≤1.66TOCWB+0.018) (R2≤0.91) obtained from the calibration set agreed well with the benchmark dry combustion values (root mean square error≤0.017) and is recommended for quantification of deep soil carbon in other kaolinitic regoliths.

We have explored speciation of halochromium(III) complexes under physiological conditions involving both conjugate-base formation and halide-water exchange using DFT. Conjugate base formation is spontaneous under neutral and alkaline conditions. Several different pathways were explored for the water exchange reaction of cis- or trans-Cr(III) complexes in the series trans-[Cr(H2O)3(OH)X2]0 (X=Cl− or Br−) and cis- or trans-[Cr(H2O)4(OH)X]+, (X= F−, Cl−, Br−, or I−) including, associative interchange (Ia), dissociative interchange (Id) and dissociative (D) mechanisms. We have also investigated nucelophilic attack by OH− on [Cr(H2O)5X]+ species, (X=Cl− or Br−). The lowest overall activation enthalpies (ΔH≠) obtained for the F and Cl systems of [Cr(H2O)4(OH)X]+, are from the Ia pathway, whereas for the Br and I systems the Id pathway was found, consistent with experiment. The importance of outer sphere solvation was investigated with the addition of up to five explicit water molecules in the second coordination sphere. The ΔH≠ values for the aquation of cis-[Cr(H2O)4(OH)X]+…3H2O, are lower than the corresponding values for [Cr(H2O)5X]2+. This indicates that there will be greater speciation of chromium(III) halides under physiological conditions. These values also imply that chromium(III) derivatives that may be active in the treatment of physiological disorders such as Type(II) diabetes will be formed at different rates depending on the identity of the starting halide.

Bond dissociation energies (BDEs), radical stabilization energies (RSEs) and the enthalpies of formation (Δf H°(AA∙)) for the Cα-centered radical of 20 common α-amino acids were calculated at the G3MP2 level of theory. In addition, BDEs and Δf H°(AA∙) for the Cα-centered radicals were calculated via atomization, homolytic, isogyric and isodesmic reactions using 31 reference compounds. RSEs for the α-amino acid radicals reveal a strong captodative effect due to the resonance stabilization. Intramolecular H-bonding and steric repulsion between the side chains and –NH2 and ‒COOH also have an effect on the stability of α-carbon-centered radicals. For the key small reference compounds investigated, the BDEs (Δf H°(AA∙)) computed with isodesmic reactions were found to be quite consistent with each other in terms of mean absolute deviations (MADs) and root-mean-square deviations between 2.0 (2.6) and 3.2 (4.4) kJ mol−1 from experimental data.

First-principle calculations based on density functional theory have been used to investigate the stability and electronic structures of double-walled (n1, n1)-(n2, n2) (4 ≤ n1 ≤ 8, n1 + 3 ≤ n2 ≤ n1 + 6) germanium carbide nanotubes (GeCNTs). For any given (n1, n1) inner tube, the corresponding (n1, n1)-(n1 + 5, n1 + 5) GeCNT has the highest formation energy and binding energy per atom, which indicate that the (n1, n1)-(n1 + 5, n1 + 5) nanotube is stable. The (5, 5)-(10, 10) GeCNT has been found to be a particularly stable geometry. The interlayer interaction between the two layers of the double-walled GeCNT leads to an obvious coupling, which results in a narrowing of the band gap.

The electronic structures of triple-, quadruple- and quintuple-walled armchair silicon carbide nanotubes (SiCNTs) are investigated using first-principle calculations based on dispersion-corrected density functional theory. Band shifts narrow the band gaps of multi-walled SiCNTs and form significant coupling in different layers of the nanotubes, which originate from the differences in the work functions and band gaps of the individual layers. With the increase of the layer number of the multi-walled SiCNT, the similarity in the electronic structures of the two outer layers is increased and the influence of the band shifts is weakened. Therefore, the electronic properties of SiCNTs formed with more than three layers are largely independent of their layer number.

The mechanism for aquation of dihalotetraaquachromium(III) complexes (trans-[Cr(H2O)4TX]+, where X or T = Cl, Br, or I), including a common component of many nutritional supplements (X, T = Cl) has been investigated using density functional theory. A number of mechanistic pathways were explored including associative interchange (Ia), and dissociative (D) mechanisms. The overall activation enthalpy for the D pathway of the dichloro (trans-[Cr (H2O)4Cl2]) system calculated at the PBE0/cc-pVDZ level, with inclusion of an explicit outer sphere water molecule and in aqueous solution (PCM), is in excellent agreement with the experimental result. The results provide a detailed understanding of the mechanism for the hydrolysis of trans-Cr(III) complexes, which could be useful in understanding the speciation of Cr(III) complexes in physiological environments.

The molecular nature (Ga2)n of gallium makes this an interesting metal to investigate for the development of novel nano-materials. However, establishment of a targeted approach to manipulating the properties of gallium clusters requires a detailed understanding of how doping affects the bonding in these species. In this study, the bonding of gallium nanoclusters has been investigated using electron deformation densities and Regional Density Functional Theory (RDFT). Bonding throughout Ga12X clusters is generally intermediate between covalent and metallic. However, the presence of Ga2 subunits is clearly identified in clusters with endohedral dopants (Ga12X, X = Al, Si, P, Ga, Ge, As). Although there is evidence of Ga2 subunits in exohedral doped clusters, localised bonding to the dopant generally leads to significant disruption to the cluster framework. Maps of electronic chemical potential provide understanding for the observed differences in regioselectivity for hydrogen adsorption.

The mechanism for the substitution reactions of halopentaaquachromium(III) complexes in the series, [CrX(H2O)5]2+, where X = F−, Cl−, Br−, or I− have been investigated using density functional theory. Several different mechanistic pathways were explored including associative interchange (Ia), dissociative (D) and the associatively activated dissociation mechanisms (Da). The lowest overall activation enthalpy (ΔH‡) obtained for the fluoride system is for the Ia pathway, with immediate proton abstraction leading to the formation of HF and the conjugate base. For the chloride, bromide and iodide systems the Da pathway has the lowest ΔH‡ values. Activation enthalpies determined at the PBE0/cc-pVDZ level, in aqueous solution (PCM), are in excellent agreement with the experimental results (MAD is 1.0 kJ mol−1). Reaction profiles were analyzed in terms of activation volumes to explain the observed trends.

Details are provided of a simple, quick, and safe laboratory exercise to analyze the tin content of a bronze sample. The experiment is set in the context of analyzing filings from a bronze artefact (“cannon”) of unknown origin. Students work in teams to complete separate parts of the experiment and to produce replicate sets of results. The procedure is designed in such a way as to demonstrate the basic principles of oxidation and reduction, spectroscopy and analytical chemistry at a level suitable for upper secondary school students. It also provides an opportunity to introduce students to advanced analytical instrumentation that is not generally available in secondary schools. The experiment was developed to be completed in a single 50 minute session and has been successfully conducted with over 200 middle- to upper-level secondary school students.

Near-infrared (NIR) reflecting pigments offer the potential to incorporate thermal insulating qualities into paint coatings. Experimental reflectance measurements are presented of a series of perylene based pigments, revealing significant variations in the NIR region as a function of derivatisation and substitution. Theoretical methods are applied to account for the observed trends. Derivatisation of perylene leads to an extension of the π-aromatic system, resulting in a bathochromic shift of UV/Vis absorption maxima towards the NIR region. However, this is insufficient to account for the observed variations in NIR reflectance. In comparison, overtones and combination modes of fundamental IR vibrations appear to be more important in explaining the observed variations in NIR reflectance/absorbance. Aromatic groups lead to a small number of intense NIR bands, while alkyl groups generally lead to a greater number of less intense NIR bands. However, neighbouring group effects and/or a molecular dipole moment can substantially alter the intensity of these bands.

The reactivity of metal nanoclusters can vary significantly as a function of the valence electronic configuration of the cluster. Hydrogen adsorption provides a simple probe to investigate variations in reactivity of nanoclusters and identify factors that contribute to regioselectivity of interactions. In this study density functional theory is used to investigate the structures, stabilities, and electronic properties of doped gallium nanocluster hydrides, Ga12XH (X = B, C, Al, Si, P, Ga, Ge, and As). Hydrogen adsorption is found to be energetically favorable, but there is significant isomerization with respect to adsorption site. Consequently, adsorption energies vary not only with valence electronic configuration, but also with adsorption site. This regioselectivity of hydrogen adsorption is analyzed in terms of cluster bonding and frontier orbital interactions.

A simple, quick, and safe laboratory exercise is detailed that provides a link between chemistry, extractive metallurgy, and hydrometallurgy. Students are provided with a scenario in which they need to "research" a procedure to selectively recover nickel from simple "ore liquors". In this context, the experiment focuses on the selective precipitation of metal ions from solution using simple chelating agents. Students work in teams to complete separate parts of the experiment, testing a possible procedure for an industry client. The teams then come together as a group to interpret and discuss the results before deciding what to report to the client. The experiment was developed to be completed in a single 40 min session and has been successfully conducted with over 200 middle- to upper-level high school students.

We have applied a theoretical modelling approach to aid in the rational design of contamination resistant coatings. Using in silico nano-indentation we have characterised the adhesion between a contaminant particle and engineered polymer surfaces that include functionalised-surface-crosslinked and functionalised non-surface-crosslinked polyesters. The roughness, density and morphology of the surfaces were dynamically monitored as the coatings responded to the approaching particle. Our results suggest that surface crosslinking provides a stable platform for incorporation of functional groups that would otherwise migrate into the bulk substrate upon aging. However surface crosslinking with rigid cyclic curing agents renders the coatings far too stiff, which can result in slip whereby surface crosslinkers shift to the side of the incoming contaminant particle, leading to both the exposure of the flexible substrate and the envelopment of the contaminant. This type of deformation negates steric repulsions of the functional groups, crucial for preventing undesirable adhesion. In contrast, functionalisation combined with flexible acyclic surface crosslinks results in superior contamination resistance.

Responsive surfaces show potential for many applications; however, the molecular mechanisms of their responsive behavior are often dependent on the nature and properties of the substrate and this dependence is not fully understood. We present a molecular dynamics study on the mechanical response of poly(ethylene glycol) (PEG) grafted on substrates of varying flexibility in "dry" conditions. Our in silico surface loading tests show that when PEG is grafted onto a hard substrate (silica), there is a significant reduction in adhesion to a solid surface, owing to augmented steric repulsions at the interface. However, when the same chains are tethered onto a soft substrate (polyester), interfacial adhesion is strengthened. We find that the deformable substrate allows significant rearrangement of the subsurface and grafted segments during loading. Asperities along the rough soft surface also provide free volume for the tethered chains to occupy, enabling them to carpet the surface and increasing the density at the interface. Our results explain the molecular basis of the mechanical response of PEG when grafted onto hard and soft substrates and provide a rationale for surface protection using PEG.

The stability and reactivity of metal nanoclusters are critically dependent on the valence electronic configuration of the cluster. Many "magic" electronic configurations are inaccessible for pure trivalent metal clusters: However, doping is one method by which the electronic configuration and properties of a cluster can be significantly modified or even tailored. Density functional theory is used in this study to investigate the structures, stabilities and electronic properties of doped gallium nanoclusters, Ga12X (X = B, C, N, Al, Si, P, Ga, Ge, and As). In all cases doping of the cluster leads to increased stability relative to Ga-13. Stabilization is largely due to electronic contributions, although for many of the clusters the dopant also induces a small increase in the stability of the Ga-12 framework Generally, the endohedrally doped isomers are either lower in energy or close in energy to the isomers with the dopant at the surface of the cluster. Endohedral Ga12C is the most stable cluster and exhibits the most jellium-like orbital structure. Trends in vertical ionization potentials and electron affinities can be explained in terms of the interactions in frontier orbitals and generally adhere to the predictions of the jellium model.

We have used density functional theory to investigate how Al13 cluster dimers can be formed with or without a bridging hydrogen. We have identified several stable dimers in which 0, 1, or 2 hydrogen atoms link two bare clusters together. Each of these structures can adsorb further H atoms in atop sites on the surface of the dimer. Additional dimers were identified with 3 and 4 H atoms linking the clusters but these are only stable in the multihydrogenated form. Reaction profiles for the formation of these dimers from a range of cluster and H atom combinations indicate that the dimer structures are energetically favored over the isolated clusters. This observation may have significant implications for the design of cluster-assembled materials.

The bond dissociation energies (BDEs) and radical stabilization energies (RSEs) which result from 166 reactions that lead to carbon-centered radicals of the type center dot CH2X, center dot CHXY and center dot CXYZ, where X, Y and Z are any of the fourteen substituents H, F, Cl, NH2, OH, SH, CH=CH2, C equivalent to CH, BH2, CHO, COOH, CN, CH3, and CF3, were calculated using spin-restricted and -unrestricted variants of the double-hybrid B2-PLYP method with the 6-311+G(3df, 2p) basis set. The interactions of substituents X, Y, and Z in both the radicals (center dot CXYZ) and in the precursor closed-shell molecules (CHXYZ), as well as the extent of additivity of such interactions, were investigated by calculating radical interaction energies (RIEs), molecule interaction energies (MIEs), and deviations from additivity of RSEs (DARSEs) for a set of 152 reactions that lead to di-(center dot CHXY) and tri-(center dot CXYZ) substituted carbon-centered radicals. The pairwise quantities describing the effects of pairs of substituents in trisubstituted systems, namely pairwise MIEs (PMIEs), pairwise RIEs (PRIEs) and deviations from pairwise additivity of RSEs (DPARSEs), were also calculated for the set of 61 reactions that lead to trisubstituted radicals (center dot CXYZ). Both ROB2-PLYP and UB2-PLYP were found to perform quite well in predicting the quantities related to the stabilities of carbon-centered radicals when compared with available experimental data and with the results obtained from the high-level composite method G3X(MP2)-RAD. Particular selections of substituents or combinations of substituents from the current test set were found to lead to specially stable radicals, increasing the RSEs to a maximum of +68.2 kJ mol(-1) for monosubstituted radicals center dot CH2X (X = CH=CH2), +131.7 kJ mol(-1) for disubstituted radicals center dot CHXY (X = NH2, Y = CHO), and +177.1 kJ mol(-1) for trisubstituted radicals center dot CXYZ (X = NH2, Y = Z = CHO).

Molecular monolayers reduce the amount of water lost to evaporation due to their ability to form closely packed films at the air-water interface. However, they are susceptible to loss from the water surface and poor performance on exposure to wind. This study combines experimental and theoretical techniques to investigate the properties of a small molecule monolayer mixed with comb polymers. The study reveals that at high concentrations of polymer the monolayer exhibits increased mechanical stability which improves the resistance to disruption by wind. Inclusion of hydrophilic functional groups along the backbone of the polymer leads to further improvements in wind stability. However, the improved wind stability observed in the composites comes at the expense of poorer water evaporation resistance.

The leaf of the lotus plant provides an elegant example of how a natural surface can remain clean even in the dirtiest of environments. The leaf’s fine-scale surface structure combined with its hydrophobic chemistry ensures that water droplets bead off its surface, carrying away contaminant particles [1]. An alternative dirt-shedding surface, also found in nature, is based on hydrophilic surface chemistry. Water droplets that come into contact with hydrophilic surfaces spread, forming a thin film of water and lifting contaminant from the surface. There is significant motivation to pursue both of these types of behaviour for artificial systems because of the wide range of possible applications ranging from self-cleaning paints to dirt-resistant clothing. However, for some applications, pertinent to the system in question, the synthesis of a self-cleaning surface is indeed a difficult task to achieve, and one needs to first elucidate the precise properties required to generate a certain level of resistance to the adhering contaminant. Atomistic simulations provide a useful tool to gain such insight and add value to surfaces where stay-clean properties are highly desirable. Here, using force-field-based molecular mechanics and dynamics, we explore the properties of polymer surfaces in order to develop design aspects for self-cleaning industrial paint-coatings. A polyester surface model is constructed, on the basis of a realistic cured paint coating [2] while various carbon models are selected [3–6], to emulate commonly encountered atmospheric dirt particulates [7–10]. The purpose of this work is to gain a fundamental understanding of the nature of interactions between contaminant and polymer coating in various environments, including aqueous conditions [11], and explore nanoscale modifications of the coating that help reduce the strength of the adhering contaminant. The modifications are based on hydrophobic or alternatively hydrophilic surface treatments. Here we demo

This study compares the performance of the all-atom molecular dynamics force fields OPLS-AA and COMPASS, and the united-atom GROMOS96 ff53a6 force field, for organic monolayers at aqueous interfaces, as a function of surface density, temperature, and system size. Where possible, comparison with experimental data was undertaken and used to scrutinize the performance of each force field. We find close agreement between the all-atom force fields (OPLS and COMPASS) and experiment for the description of organic monolayers on water. However, the united-atom force field 53a6 tends to exhibit poorer agreement than the all-atom force fields

The structure and bonding in charged and doped aluminum clusters have been investigated using Regional Density Functional Theory (RDFT). The RDFT method provides a measure of the electronic stress tensor from which it is possible to determine bond indices and electronic chemical potential. We find that the distribution of bond indices on the surface of Al12X clusters provides not only an understanding of the internal bonding and stability but also some insight into the regioselectivity observed in reactions of the clusters.

This study examines intermolecular interactions of a monolayer of octadecanol (CH3(CH2)17OH) on water as a function of surface density and temperature, using classical molecular dynamics simulations. We observe increased interaction between the alkyl chains (van der Waals) and hydroxyl groups (H-bonding) with increased surface density, which leads to increased order and packing within the monolayer. We also identified clear trends in the intermolecular interactions, ordering and packing of the monolayer molecules as a function of temperature. The observed trends can be closely related to features of the current empirical theories of evaporation resistance.

We present a simulation methodology to chemically cross-link the surface of fully atomistic models of polymers. We simulated nanoindentation of the cross-linked model surfaces whereby nanoparticles (fullerene in this case) are used to probe different regions of the polymer surface enabling us to characterize the surface hardness of the polymer film and calculate the work of adhesion between polymer and nanoparticle. The cross-linked polyester surfaces are constructed using hexamethylene and isophorone di-isocyanate cross-linkers. Our results indicate that, despite surface cross-linking with hexamethylene di-isocyanate molecules, the polymer top surface still maintains significant softness. The hexamethylene cross-links that protrude from the surface are deformable, resulting in a strong adhesion between the surface and carbon particle. In contrast, isophorone surface crosslinking results in significantly weaker adhesion with carbon, due to the less deformable rigid structure formed at the top layer. In this case, while rigidity is imparted to the polymer top surface, the flexibility of the core region of the polymer is maintained.