The synthesis, spectroscopic and electrochemical characterisation of Ruthenium (II) polypyridyl complexes containing a catechol moiety

The synthesis, spectroscopic and electrochemical characterisation of ruthenium (II) polypyridyl mononuclear and dinuclear complexes o f a 5-(2-pyridyl)-l,2,4-triazole ligand containing a catechol moiety are described. Chapter one is an introduction relevant to the work described in the thesis. The methods of characterisation, which are described in chapter two, include High Performance Liquid Chromatography, 'H-NMR, UV/Visible spectroscopy, fluorimetry, electrochemistry, spectroelectrochemistry, in ass spectrometry, X-Ray crystallography and lifetime emission measurements. Chapter three, describes the synthesis o f the mononuclear ruthenium (II) complexes of the protected catechol ligand 3-(r,2'-dim ethoxyphenyl)-5-(pyridin-2-yl)-l,2,4-triazole. The protected catechol moiety results in coordination of the Ru(Lx)2 (where Lx is bpy, dgbpy, phen, d8-phen or dcbpy) via N1 of the triazole and N1 of the pyridyl ring, which is confirmed by X-Ray crystallography. The synthesis of deuteriated complexes, is of significant benefit for the purposes of structural elucidation. Examination of the acidbase chemistry of the complexes by UV/Visible spectroscopy reveals information about the location of the excited state. The excited state of all the complexes is located on Lx. Electrochemical studies show a reversible metal centred Run/Rum couple. Evidence of irreversible oxidation of the dimethoxy moieties is observed at more anodic potentials. Chapter four describes the deprotection of the Ru(Lx)2 complexes o f 3 -(l',2 '- dimethoxyphenyl)-5-(pyridin-2-yl)-l,2,4-triazole forming complexes with a peripheral catechol binding site. These catechol complexes are precursors for the synthesis of dinuclear ruthenium complexes bound through the catechol binding site, the subject of chapter five, and for complexation of various other transition metals such as Fe(II), Fe(III) and Cu(II), the subject of chapter six. The electrochemical studies of the complexes in chapter four are complicated in comparison to their protected analogues. The oxidation of the catechol ligand precedes that of the metal centre and is quasireversible. Pretreatment of the glassy carbon electrode was necessary to resolve the processes due to adsorption of oxidised species onto the surface of the electrode. Attachment of the catechol complexes to nanocrystalline T i0 2 films indicates incident photon-to-current efficiency (IPCE) of greater than 30%. Chapter five describes the synthesis o f the dinuclear complexes o f 3 -(l',2 '- dihydroxyphenyl)-5-(pyridin-2-yl)-l,2,4-triazole from the mononuclear complexes discussed in chapter four. Semipreparative HPLC was required for purification and the dinuclear complexes were isolated in the semiquinone form. The complexes were characterised by mass spectrometry, HPLC and elemental analysis. Electrochemical analysis shows a reversible one-electron process for the hq/sq process and quasi reversible one electron processes for the sq/q and for the metal centre bound via the triazole. The second metal centre is not accessible with the conditions used. The complexes exhibit weak emission at neutral conditions. Finally chapter six explores the complexation of the mononuclear catechol complexes with various transition metals by titration of the catechol complexes with known molar equilavents of the metal. The stability constants and stoichiometry were estimated by attention to changes in the UV/VIS and emission spectra. The most interesting results were achieved with Fe(II), Fe(III) and Cu(II)

Rhodium-catalysed arylative cyclisations of malonate esters by 1,4-rhodium migration

Rhodium-catalysed intramolecular arylative cyclisations of malonate esters, generating highly functionalised bicycles has been described. The key step is a known alkenyl-to-aryl 1,4-rhodium migration. The reaction is considered to proceed through regioselective carbometallation of the tethered alkyne, followed by alkenyl-to-aryl 1,4-migration and subsequence intramolecular 1,2-addition to the ester moiety. Discovery and preliminary results were conducted by Dr. S. Karad. Through the use of a bisphosphine base ligand, good levels of enantiocontrol were achieved

Rhodium-catalyzed arylative cyclization of alkynyl malonates by 1,4-rhodium(I) migration

The synthesis of functionalized 1-tetralones by the rhodium(I)-catalyzed reaction of alkynyl malonates with arylboronic acids is described. These arylative cyclizations proceed via an alkenyl-to-aryl 1,4-Rh(I) migration as a key step. Preliminary results of an enantioselective variant of these reactions are also presented

Rhodium-catalyzed arylative cyclization of alkynyl malonates by 1,4-rhodium(I) migration

The synthesis of functionalized 1-tetralones by the rhodium(I)-catalyzed reaction of alkynyl malonates with arylboronic acids is described. These arylative cyclizations proceed via an alkenyl-to-aryl 1,4-Rh(I) migration as a key step. Preliminary results of an enantioselective variant of these reactions are also presented

Experimental Demonstration of a Mode Shape-Based Scour-Monitoring Method for Multispan Bridges with Shallow Foundations

A vibration-based scour monitoring approach applicable to bridges with multiple simply supported spans on shallow foundations is experimentally investigated in this paper. A monitoring strategy based on the relative changes in pier mode shape amplitudes due to scour is postulated. The first global mode shape of a bridge structure with multiple spans is extracted from acceleration measurements using an output-only approach, Frequency Domain Decomposition (FDD). The relative changes of the pier mode shape amplitudes under scour are then tracked. Here, each pier mode shape value is compared with the mean values of the remaining piers in a process that creates a Mean-Normalised Mode Shape (MNMS). The approach is demonstrated on a scaled model of a bridge with four spans, supported on sprung foundations, where scour is simulated by the replacement of springs with springs of lower stiffness corresponding to a reduction in foundation stiffness. It is shown that at a given ‘scoured’ pier, significant increases in the MNMS value occur, suggesting that the location of the scour can be identified. The magnitude of the MNMS at a given pier also increases with an increase in stiffness loss due to scour. In practice, the approach would work best by carrying out a visual inspection of the bridge to establish the initial health condition at the time of sensor installation. After this initial process, the bridge can be monitored remotely for scour on an ongoing basis

Exploring Mars at the nanoscale: applications of transmission electron microscopy and atom probe tomography in planetary exploration

The upcoming Mars Sample Return (MSR) mission aims to deliver small quantities of Martian rocks to the Earth. Investigating these precious samples requires the development and application of techniques that can extract the greatest amount of high quality data from the minimum sample volume, thereby maximising science return from MSR. Atom probe tomography (APT) and transmission electron microscopy (TEM) are two complementary techniques that can obtain nanoscale structural, geochemical and, in the case of atom probe, isotopic information from small sample volumes. Here we describe how both techniques operate, as well as review recent developments in sample preparation protocols. We also outline how APT has been successfully applied to extraterrestrial materials in the recent past. Finally, we describe how we have studied Martian meteorites using TEM and APT in close coordination in order to characterise the products of water/rock interactions in t h e cru st of Ma r s – a k ey sc ie n ce goal of MSR. Our results provide new insights into the Martian hydrosphere and the mechanisms of anhydrous-hydrous mineral replacement. In light of the unique results provided by these tools, APT and TEM should form a crucial part at the culmination of a correlative analytical pipeline for MSR mission materials

Interventions to prevent obesity in school-aged children 6-18 years: An update of a Cochrane systematic review and meta-analysis including studies from 2015–2021

Background Childhood obesity remains a global public health priority due to the enormous burden it generates. Recent surveillance data suggests there has been a sharp increase in the prevalence of childhood obesity during the COVID-19 pandemic. The Cochrane review of childhood obesity prevention interventions (0–18 years) updated to 2015 is the most rigorous and comprehensive review of randomised controlled trials (RCTs) on this topic. A burgeoning number of high quality studies have been published since that are yet to be synthesised. Methods An update of the Cochrane systematic review was conducted to include RCT studies in school-aged children (6-18 years) published to 30 June 2021 that assessed effectiveness on child weight (PROSPERO registration: CRD42020218928). Available cost-effectiveness and adverse effect data were extracted. Intervention effects on body mass index (BMI) were synthesised in random effects meta-analyses by setting (school, after-school program, community, home), and meta-regression examined the association of study characteristics with intervention effect. Findings Meta-analysis of 140 of 195 included studies (183,063 participants) found a very small positive effect on body mass index for school-based studies (SMD –0·03, 95%CI –0·06,–0·01; trials = 93; participants = 131,443; moderate certainty evidence) but not after-school programs, community or home-based studies. Subgroup analysis by age (6–12 years; 13–18 years) found no differential effects in any setting. Meta-regression found no associations between study characteristics (including setting, income level) and intervention effect. Ten of 53 studies assessing adverse effects reported presence of an adverse event. Insufficient data was available to draw conclusions on cost-effectiveness. Interpretation This updated synthesis of obesity prevention interventions for children aged 6–18 years, found a small beneficial impact on child BMI for school-based obesity prevention interventions. A more comprehensive assessment of interventions is required to identify mechanisms of effective interventions to inform future obesity prevention public health policy, which may be particularly salient in for COVID-19 recovery planning. Funding This research was funded by the National Health and Medical Research Council (NHMRC), Australia (Application No APP1153479)

Gold(I)-Catalyzed Nucleophilic Allylation of Azinium Ions with Allylboronates

Gold(I)-catalyzed nucleophilic allylations of pyridinium and quinolinium ions with allylboronates are reported. Transmetalation of the allylboronate with gold produces nucleophilic allylgold(I) species that add to the 4-position of the azinium ion with complete regioselectivity to give functionalized 1,4-dihydropyridines and 1,4-dihydroquinolines. Density functional theory (DFT) calculations provided mechanistic insight