Martin Johnston

Diatoms response to salinity changes: investigations using single pulse and cross polarisation magic angle spinning 29Si NMR spectra

Publisher: Royal Society of Chemistry (RSC)

Date: 2018

DOI: 10.1039/C8AN00948A

Abstract: Diatoms Thalassiosira pseudonana and Chaetoceros muelleri (Bacillariophyceae) were cultured at three different salinities and examined using 29 Si MAS-NMR spectroscopy.

Preparation, characterization and electrochemistry of carbon nanotubes directly attached to Si(100) surfaces

Publisher: IEEE

Date: 2006

DOI: 10.1109/ICONN.2006.340553

Effect of Modification Protocols on the Effectiveness of Gold Nanoparticles as Drug Delivery Vehicles for Killing of Breast Cancer Cells

Publisher: CSIRO Publishing

Date: 2016

DOI: 10.1071/CH16430

Abstract: The current study evaluated the potential of gold nanoparticles (AuNPs) for the delivery of Taxol to breast cancer cells (T47D) using an in vitro cell culture model. For this study, new loading approaches and novel chemical attachments were investigated. Five different gold nanoparticle-based complexes were used to determine their cytotoxicity towards T47D cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) viability assay. There was no significant decrease (P 0.05) in cell viability when T47D cells were treated with AuNPs that did not contain Taxol. However, cells were significantly killed by gold nanoparticles chemically conjugated to Taxol using three different approaches and one novel hybrid AuNP-Taxol nanoparticle, wherein no chemical bonds were involved. These Taxol-loaded AuNPs were more effective at inducing cell death in vitro than a solution of free Taxol used to treat cells. This result demonstrated that Taxol could be released from the particles in the cell culture media for subsequent therapeutic action. Additionally, the experiments proved that the Taxol-loaded AuNPs were more toxic in a dose dependent manner than Taxol as a formulation for the treatment of breast cancer cells. The results of this study suggest that gold nanoparticles have potential for the efficient delivery of Taxol to breast cancer cells. This could provide a future solution as an alternative application method to overcome adverse side effects resulting from current high-dose treatment regimes.

Polysulfides made from re-purposed waste are sustainable materials for removing iron from water

Publisher: Royal Society of Chemistry (RSC)

Date: 2018

DOI: 10.1039/C7RA11999B

Abstract: A polymer prepared by co-polymerisation of sulfur and canola oil removed Fe 3+ from water. Microwave irradiation was convenient in promoting the polymerisation.

Functionalised silica/epoxy nanocomposites with enhanced fracture toughness for large-scale applications

Publisher: SAGE Publications

Date: 11-05-2014

DOI: 10.1177/0021998314534867

Abstract: A small amount of commercial functional nanosilica was mechanically mixed with epoxy to enhance the composite fracture toughness. Nanosilicas with amino and epoxide functional groups show strong interfaces with epoxy, which suppress large aggregations and enhance resin-wettability, hence enhancing the fracture toughness of epoxy composites. Compared with other reports, less nanosilica content was needed to achieve the same fracture toughness values or similar enhancement ratio. Due to their commercial availability, the low-cost of the raw material and simple fabrication method, those nanocomposites have the potential for large-scale applications.

Insights into the complexation of N-Allyl-4-(4-(N-phenylureido)benzylamino)-1,8-naphthalimide with various anions

Publisher: Springer Science and Business Media LLC

Date: 31-05-2017

DOI: 10.1038/S41598-017-02470-0

Abstract: A new urea functionalised 4-amino-1,8-naphthalimide based fluorescent anion sensor was synthesised in 64% yield over three steps. Fluorescence and 1 H NMR titrations showed that the sensor complexes strongly with acetate and dihydrogen phosphate and to a lesser extent bromide. The corresponding binding stoichiometries were examined using 1 H NMR titrations. Results show that the sensor molecule initially forms 1:1 complexes through hydrogen bonding to the urea moiety, followed by secondary complexation to form higher order host:guest stoichiometries. Specifically, oxyanions complex to the sensor via hydrogen bonding through synergistic aryl C-H and N-H anion interactions in a 1:2 sensor:oxyanion arrangement. Furthermore, 2:1 sensor:oxyanion complexes are formed through an oxyanion linkage between two urea functionalities on different host molecules. This contrasts the majority of previous reports for similar hosts, which indicate 1:1 binding stoichiometry.

SERS and NMR Studies of Typical Aggregation-Induced Emission Molecules

Publisher: American Chemical Society (ACS)

Date: 02-07-2015

DOI: 10.1021/ACS.JPCA.5B05478

Abstract: Over recent decades, aggregation-induced emission (AIE) molecules have attracted increasing attention. Restriction of intramolecular rotation (RIR) has been widely accepted as the cause of the emission when AIE molecules aggregate into clusters. The intramolecular rotation of AIE molecules can be monitored by molecular vibration spectra such as nuclear magnetic resonance (NMR), infrared, and Raman, especially surface-enhanced Raman scattering (SERS) which has high sensitivity down to a single molecule. We employed SERS and NMR to study the AIE emission mechanism and compared experimental results with simulation data to monitor the RIR. Interestingly, we found that intramolecular rotation was also restricted for in idual AIE molecules loaded onto SERS substrate surfaces due to the laid-down configuration.

Scanning tunneling microscopy investigation of nonanuclear [3 × 3] Mn^IIsupramolecular grids

Publisher: IOP Publishing

Date: 13-12-2005

DOI: 10.1088/0964-1726/15/1/028

Optical properties of covalently anchored single-walled carbon nanotube arrays on silicon (100) surfaces

Publisher: SPIE

Date: 27-12-2006

DOI: 10.1117/12.695611

A Tetra‐Porphyrin Host Exhibiting Interannular Cooperativity

Publisher: Wiley

Date: 10-09-2019

DOI: 10.1002/CHEM.201903636

Abstract: Recently identified as another form of cooperativity, interannular cooperativity is rarely observed in supramolecular chemistry. A tetra‐porphyrin molecular tweezer with two bis‐porphyrin binding sites is reported that exhibits archetypal interannular cooperativity when complexing 1,4‐diazabicyclo[2.2.2]octane (DABCO). The UV/Vis titration data best supported a 1:2 plus 2:2 plus 1:4 complexation model (host:guest), giving K 12 =6.32×10 13 m −2 , K 22 =3.04×10 20 m −3 , and K 14 =1.92×10 16 m −4 in CHCl 3 . The NMR titration data supported the formation of two sandwich species, including tetra‐porphyrin⋅(DABCO) 2 as the major species, although there are speciation differences between UV/Vis and NMR concentrations. Using statistical analysis, interannular cooperativity (γ) for tetra‐porphyrin⋅(DABCO) 2 was determined to be negative ( γ =2.41×10 −3 ), which may be explained by DABCO being too small to be optimally bound simultaneously at both bis‐porphyrin binding sites.

Enantioselective Synthesis of α-Fluoro-β ³ -amino Esters: Synthesis of Enantiopure, Orthogonally Protected α-Fluoro-β ³ -lysine

Publisher: American Chemical Society (ACS)

Date: 08-10-2010

DOI: 10.1021/JO101600C

Abstract: The scope of a tandem conjugate addition-fluorination sequence performed on α,β-unsaturated esters using the enantiopure lithium amide derived from (S)-N-benzyl-N-(α-methylbenzyl)amine, and the electrophilic fluorinating agent N-fluorobenzenesulfonimide has been investigated. Using this method, α-fluoro-β(3)-amino esters can be obtained in up to quantitative yield and 80:20 to >99:1 dr. This simple methodology does not rely on the use of α-amino acids from the chiral pool and thus provides the potential for the preparation of enantiopure α-fluoro-β(3)-amino acids with a wide variety of side chains. Its utility was demonstrated through the synthesis of orthogonally protected (2S,3S)-α-fluoro-β(3)-lysine.

Characterization of a Porphyrin-Containing Dye-Sensitized Solar Cell

Publisher: American Chemical Society (ACS)

Date: 22-07-2004

DOI: 10.1021/JP048073I

Mass spectrometry imaging reveals new biological roles for choline esters and Tyrian purple precursors in muricid molluscs

Publisher: Springer Science and Business Media LLC

Date: 09-2015

DOI: 10.1038/SREP13408

Abstract: Despite significant advances in chemical ecology, the biodistribution, temporal changes and ecological function of most marine secondary metabolites remain unknown. One such ex le is the association between choline esters and Tyrian purple precursors in muricid molluscs. Mass spectrometry imaging (MSI) on nano-structured surfaces has emerged as a sophisticated platform for spatial analysis of low molecular mass metabolites in heterogeneous tissues, ideal for low abundant secondary metabolites. Here we applied desorption-ionisation on porous silicon (DIOS) to examine in situ changes in biodistribution over the reproductive cycle. DIOS-MSI showed muscle-relaxing choline ester murexine to co-localise with tyrindoxyl sulfate in the biosynthetic hypobranchial glands. But during egg-laying, murexine was transferred to the capsule gland and then to the egg capsules, where chemical ripening resulted in Tyrian purple formation. Murexine was found to tranquilise the larvae and may relax the reproductive tract. This study shows that DIOS-MSI is a powerful tool that can provide new insights into marine chemo-ecology.

Novel Grafting onto Silica via Aldehyde Functionality

Publisher: Springer Science and Business Media LLC

Date: 2009

DOI: 10.1007/S12633-009-9008-0

Ruthenium Porphyrin Functionalized Single-Walled Carbon Nanotube Arrays—A Step Toward Light Harvesting Antenna and Multibit Information Storage

Publisher: American Chemical Society (ACS)

Date: 14-06-2008

DOI: 10.1021/JA801142K

Mixed assembly of ferrocene/porphyrin onto carbon nanotube arrays towards multibit information storage

Publisher: IEEE

Date: 02-2008

DOI: 10.1109/ICONN.2008.4639275

The synthesis of enantiopure α-fluoro and α-,α--difluoro-β3-arginine derivatives

Publisher: CSIRO Publishing

Date: 2014

DOI: 10.1071/CH13590

Abstract: The synthesis of a set of monofluorinated, difluorinated, and non-fluorinated N-acetylated-β3-arginine esters, potential inhibitors of trypsin-like proteases, is described. Elaboration to the target compounds from previously reported enantiopure precursors derived from 3-hydroxypropanal involved 6–7 steps and was achieved in 48–65 % overall yield. The α,α-difluoro-β3-arginine derivative was found to be particularly prone to hydrolysis. Three β3-arginine derivatives were tested for their ability to inhibit trypsin, the α,α-difluoro compound being assayed in the form of a carboxylate zwitterion.

Molecular Tweezers with Freely Rotating Linker and Porphyrin Moieties

Publisher: Wiley

Date: 05-04-2013

DOI: 10.1002/EJOC.201300207

Direct attachment of well-aligned single-walled carbon nanotube architectures to silicon (100) surfaces: a simple approach for device assembly

Publisher: Royal Society of Chemistry (RSC)

Date: 2007

DOI: 10.1039/B615096A

Abstract: A new approach for the attachment of vertically-aligned shortened carbon nanotube architectures to a silicon (100) substrate by chemical anchoring directly to the surface has been demonstrated for the first time. The ordered assembly of single-walled carbon nanotubes (SWCNTs) was accomplished by hydroxylating the silicon surface followed by a condensation reaction with carboxylic acid functionalised SWCNTs. This new nanostructure has been characterised by X-ray photoelectron, Raman and Fourier transform infrared (FTIR) spectroscopy as well as scanning electron and atomic force microscopy. The assembly behaviour of SWCNTs onto the silicon surface shows a fast initial step producing isolated functionalised carbon nanotubes or nanotube bundles anchored to the silicon surface followed by a slower step where the adsorbed nanotubes grow into larger aggregates via van der Waals interactions between adsorbed and solvated nanotubes. The electrochemical and optical properties of the SWCNTs directly attached to silicon have also been investigated. These new nanostructures are excellent electrochemical electrodes. They also fluoresce in the wavelength range 650-800 nm. The successful attachment of the SWCNTs directly to silicon provides a simple, new avenue for fabrication and development of silicon-based nanoelectronic, nano-optoelectronic and sensing devices. Compared to existing techniques, this new approach has several advantages including low operating temperature, low cost and the possibility of further modification.

Purified Brominated Indole Derivatives from Dicathais orbita Induce Apoptosis and Cell Cycle Arrest in Colorectal Cancer Cell Lines

Publisher: MDPI AG

Date: 11-10-2013

DOI: 10.3390/MD11103802

Diastereoselective synthesis of aliphatic alpha,alpha-difluoro-beta3-amino esters via a sonocatalyzed Reformatsky reaction

Publisher: American Chemical Society (ACS)

Date: 28-11-2012

DOI: 10.1021/OL202969W

Abstract: (R)-2-Phenylglycine ethyl ester was found to be a cheap and effective auxiliary for the preparation of aliphatic α,α-difluoro-β(3)-amino esters via a Reformatsky reaction performed under sonication conditions. The products were obtained in good to high yield and ≥96:4 dr, thus providing a new stereoselective route to this under-represented class of compounds. A facile one-pot removal of the phenylglycine moiety and concomitant Boc protection subsequently afforded the corresponding Boc-protected β(3)-amino esters in excellent yield.

Surface mounted porphyrin-nanotube arrays: Towards energy-harvesting surfaces

Publisher: IEEE

Date: 02-2008

DOI: 10.1109/ICONN.2008.4639283

Procyanidin oligomers. A new method for 4→8 interflavan bond formation using C8-boronic acids and iterative oligomer synthesis through a boron-protection strategy

Publisher: Elsevier BV

Date: 2012

DOI: 10.1016/J.TET.2011.10.039

Synthesis, Structure, and Biological Applications of α -Fluorinated β -Amino Acids and Derivatives

Publisher: Wiley

Date: 11-2012

DOI: 10.1002/CBDV.201200307

Abstract: This review gives a broad overview of the state of play with respect to the synthesis, conformational properties, and biological activity of α-fluorinated β-amino acids and derivatives. General methods are described for the preparation of monosubstituted α-fluoro-β-amino acids (Scheme 1). Nucleophilic methods for the introduction of fluorine predominantly involve the reaction of DAST with alcohols derived from α-amino acids, whereas electrophilic sources of fluorine such as NFSI have been used in conjunction with Arndt-Eistert homologation, conjugate addition or organocatalyzed Mannich reactions. α,α-Difluoro-β-amino acids have also been prepared using DAST however, this area of synthesis is largely dominated by the use of difluorinated Reformatsky reagents to introduce the difluoro ester functionality (Scheme 9). α-Fluoro-β-amino acids and derivatives analyzed by X-ray crystal and NMR solution techniques are found to adopt preferred conformations which are thought to result from stereoelectronic effects associated with F located close to amines, amides, and esters (Figs. 2-6). α-Fluoro amide and β-fluoro ethylamide/amine effects can influence the secondary structure of α-fluoro-β-amino acid-containing derivatives including peptides and peptidomimetics (Figs. 7-9). α-Fluoro-β-amino acids are also components of a erse range of bioactive anticancer (e.g., 5-fluorouracil), antifungal, and antiinsomnia agents as well as protease inhibitors where such fluorinated analogs have shown increased potency and spectrum of activity.

Molecular tweezers with a rotationally restricted linker and freely rotating porphyrin moieties

Publisher: Royal Society of Chemistry (RSC)

Date: 2018

DOI: 10.1039/C8OB00944A

Abstract: The different host–guest behaviour of non-interconvertible bis-porphyrin tweezer isomers was examined, contributing to ongoing discussions regarding rigidity/flexibility and preorganisation in synthetic receptors.

The Synthesis and Characterisation of a Free-Base Porphyrin-Perylene Dyad that Exhibits Electronic Coupling in Both the Ground and Excited States

Publisher: Wiley

Date: 18-12-2009

DOI: 10.1002/CHEM.200801779

Electron-transfer characteristics of ferrocene attached to single-walled carbon nanotubes (SWCNT) arrays directly anchored to silicon(100)

Publisher: Elsevier BV

Date: 06-2007

DOI: 10.1016/J.ELECTACTA.2007.03.071

Observation of the keto tautomer of d-fructose in D2O using 1H NMR spectroscopy

Publisher: Elsevier BV

Date: 2012

DOI: 10.1016/J.CARRES.2011.11.003

29Si{1H} CP-MAS NMR comparison and ATR-FTIR spectroscopic analysis of the diatoms Chaetoceros muelleri and Thalassiosira pseudonana grown at different salinities

Publisher: Springer Science and Business Media LLC

Date: 31-01-2013

DOI: 10.1007/S00216-013-6746-Z

Abstract: Diatoms are key indicators of marine environmental health. To further understand how diatoms respond to varying degrees of salinity, either due to climate change or brine waste discharge into marine environments, two different diatom species were studied. Thalassiosira pseudonana and Chaetoceros muelleri were cultured at three different salinities namely, 26 practical salinity units (PSU or parts per thousand), 36 PSU (standard salinity for culturing of seawater species) and 46 PSU. Changes in silica and organic content within the cultured diatoms were analysed using solid-state (29)Si{(1)H} cross-polarization-magic angle spinning (CP-MAS) nuclear magnetic resonance (NMR) and attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopies coupled with analysis of variance. (29)Si CP-MAS NMR showed that qualitatively the Q4:Q3 area ratios of C. muelleri, grown away from standard salinities, increased in response to the formation of more condensed (2 ≡SiOH → ≡Si-O-Si≡ + H2O) and/or an increase in closely associated organic matter to the Q4 component of the diatoms. This was not observed for T. pseudonana. However, both species showed the appearance of a new peak centered at 1575-1580 cm(-1) in the ATR-FTIR spectra, designated as the C═N band of nitrogenous purine-type compounds. Further, the C. muelleri species was shown to produce more extracellular polymeric substances at non-standard salinities. On this basis, results suggest that there is a strong relationship between diatom composition and salinity and that C. muelleri is more sensitive to its environment than T. pseudonana.

Chemical analysis of four capsules containing the controlled substance analogues 4-methylmethcathinone, 2-fluoromethamphetamine, α-phthalimidopropiophenone and N-ethylcathinone

Publisher: Elsevier BV

Date: 04-2010

DOI: 10.1016/J.FORSCIINT.2009.12.048

Abstract: In August 2007, four capsules containing white powders, said to have originated from an Israel-based Internet company "Neorganics", were anonymously delivered to the Royal Adelaide Hospital, South Australia. The capsules were analysed and the active components were identified including 4-methylmethcathinone, 2-fluorometh hetamine, alpha-phthalimidopropiophenone and N-ethylcathinone, all of which were unlisted within South Australian controlled substance regulations. We examined the relevant scientific literature surrounding these chemicals and present both GCMS and NMR data for 4-methylmethcathinone and alpha-phthalimidopropiophenone, which have previously received little attention. We also present the vapour- and condensed-phase infrared spectra (IR) of 4-methylmethcathinone as these have also not been reported in the literature previously. We discuss the issues surrounding whether these chemicals can be classified as controlled substance analogues and the likely impact this could have on prosecutions of in iduals distributing these products.

29Si Solid-State NMR Analysis of Opal-AG, Opal-AN and Opal-CT: Single Pulse Spectroscopy and Spin-Lattice T1 Relaxometry

Publisher: MDPI AG

Date: 04-03-2022

DOI: 10.3390/MIN12030323

Abstract: Single pulse, solid-state 29Si nuclear magnetic resonance (NMR) spectroscopy offers an additional method of characterisation of opal-A and opal-CT through spin-lattice (T1) relaxometry. Opal T1 relaxation is characterised by stretched exponential (Weibull) function represented by scale (speed of relaxation) and shape (form of the curve) parameters. Relaxation is at least an order of magnitude faster than for silica glass and quartz, with Q3 (silanol) usually faster than Q4 (fully substituted silicates). 95% relaxation (Q4) is achieved for some Australian seam opals after 50 s though other s les of opal-AG may take 4000 s, while some figures for opal-AN are over 10,000 s. Enhancement is probably mostly due to the presence of water/silanol though the presence of paramagnetic metal ions and molecular motion may also contribute. Shape factors for opal-AG (0.5) and opal-AN (0.7) are significantly different, consistent with varying water and silanol environments, possibly reflecting differences in formation conditions. Opal-CT s les show a trend of shape factors from 0.45 to 0.75 correlated to relaxation rate. Peak position, scale and shape parameter, and Q3 to Q4 ratios offer further differentiating feature to separate opal-AG and opal-AN from other forms of opaline silica. T1 relaxation measurement may have a role for provenance verification. In addition, definitively determined Q3/Q4 ratios are in the range 0.1 to 0.4 for opal-AG but considerably lower for opal-AN and opal-CT.

Tetra-porphyrin molecular tweezers: two binding sites linked via a polycyclic scaffold and rotating phenyl diimide core

Publisher: Royal Society of Chemistry (RSC)

Date: 2016

DOI: 10.1039/C6OB01588C

Abstract: Tetra-porphyrin molecular tweezers linked by rigid polycyclic arms, capable of interannular cooperativity, are synthesised using imide–boronic acid coupling.

Analysis of the hydrolysis of inulin using real time 1H NMR spectroscopy

Publisher: Elsevier BV

Date: 05-2012

DOI: 10.1016/J.CARRES.2012.03.001

Reaction of Sulfur and Sustainable Algae Oil for Polymer Synthesis and Enrichment of Saturated Triglycerides

Publisher: American Chemical Society (ACS)

Date: 05-07-2022

DOI: 10.1021/ACSSUSCHEMENG.1C08139

Discovery Projects - Grant ID: DP0211286

Start Date: 04-2002

End Date: 06-2005

Amount: $280,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP100200624

Start Date: 11-2011

End Date: 12-2013

Amount: $430,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0557818

Start Date: 02-2005

End Date: 12-2009

Amount: $210,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0777033

Start Date: 04-2008

End Date: 03-2011

Amount: $350,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0668489

Start Date: 2006

End Date: 12-2007

Amount: $800,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE210100163

Start Date: 2021

End Date: 05-2023

Amount: $860,365.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE130100168

Start Date: 2013

End Date: 12-2014

Amount: $1,235,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE0989336

Start Date: 08-2009

End Date: 12-2010

Amount: $560,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE210100139

Start Date: 2021

End Date: 07-2023

Amount: $1,240,000.00

Funder: Australian Research Council