Chemistry Commons^™

Spontaneous Helix Formation In Non-Chiral Bent-Core Liquid Crystals With Fast Linear Electro-Optic Effect, Sithara P. Sreenilayam, Yuri Panarin, Jagdish K. Vij, Vitaly P. Panov, Anne Lehmann, Marco Poppe, Marko Prehm, Carsten Tschierske Carsten Tschierske

Articles

Liquid crystals (LCs) represent one of the foundations of modern communication and photonic technologies. Present display technologies are based mainly on nematic LCs, which suffer from limited response time for use in active colour sequential displays and limited image grey scale. Herein we report the first observation of a spontaneously formed helix in a polar tilted smectic LC phase (SmC phase) of achiral bent-core (BC) molecules with the axis of helix lying parallel to the layer normal and a pitch much shorter than the optical wavelength. This new phase shows fast (∼30 μs) grey-scale switching due to the deformation of …

Bis(Spirolactam) 1,3-Double-Armed Calix[4]Arene Compounds And Their Application As Extractants For The Determination Of Heavy Metal Ions, Fintan Kelleher, Mary Deasy, James Ward, Li Li, Fiona Regan

Articles

A number of double-armed calix[4]arene compounds, with proline-derived spirolactam ligating groups on the lower rim, have been synthesised and investigated as extractants of toxic heavy metal ions from aqueous solution. Pedersen’s extraction technique was employed to determine the capability of these new 1,3-distal derived calix[4]arene spiroalactams to extract selected heavy metal ions (e.g. Pb²⁺, Cd²⁺, Zn²⁺, Cu²⁺, Ni²⁺, Co²⁺) from an aqueous phase into an organic phase. The percentage extraction was calculated using UV-vis spectroscopy. All of the compounds synthesised demonstrated good selectivity for the heavy metals selected …

Determination Of The Polymerisation Rate Of A Low-Toxicity Diacetone Acrylamide-Based Holographic Photopolymer Using Raman Spectroscopy, Dervil Cody, Emilia Mihaylova, Luke O'Neill, Izabela Naydenova

Articles

The polymerisation rate of a low-toxicity Diacetone Acrylamide (DA)-based photopolymer has been measured for the first time using Raman spectroscopy. A value for the polymerisation rate of 0.020 s⁻¹ has been obtained for the DA photopolymer by modelling the polymerisation reaction dynamics as a stretched exponential or Kohlrausch decay function. This is significantly lower than the polymerisation rate of 0.100 s⁻¹ measured for the well known Acrylamide (AA)-based photopolymer composition. The effect of the additive glycerol on the polymerisation rate of the DA-based photopolymer has also been investigated. The inclusion of glycerol is observed to increase the rate …

Reference Material Development For Paralytic Shellfish Poisoning Toxins And Associated Analytical Applications, Stephen Burrell

Doctoral

Food poisoning incidences relating to marine biotoxins are a global phenomenon and have the potential to severely impact the aquaculture industry. As a result, and as a legislative requirement in the European Union (EU), many countries have implemented monitoring programmes for these compounds but their success relies on the availability of certain quality assurance tools, two of which are reference materials (RMs) and proficiency testing. The limited amounts of RMs, in particular matrix certified reference materials (CRMs) for paralytic shellfish poisoning (PSP) toxins has been a limiting factor in the implementation of alternatives to the mouse bioassay for routine monitoring …

Studies On The Synthesis Of Orthogonally Protected Azalanthionines, And Of Routes Towards B-Methyl Azalanthionines, By Ring-Opening Of N-Activated Aziridine-2-Crboxylates, Keith O'Brien, Keith Ó Proinsias, Fintan Kelleher

Articles

Orthogonally protected azalanthionines were successfully synthesised by the ring-opening of N-activated aziridine-2-carboxylates with protected diaminopropanoic acids (DAPs). The required DAPs were also prepared by ring-opening of N-activated aziridine-2-carboxylates with para-methoxybenzylamine, but it was found that the choice of aziridine protecting groups dictated both the success of the reaction as well as the regioselectivity of the isolated products. Attempts to extend the methodology to the preparation of the more sterically demanding b-methyl azalanthionines have, so far, been unsuccessful.

Metal-Organic Frameworks Based On Pyridyl-Tetrazole Ligands Containing Ester Or Carboxylate Pendant Arms, Ursula Sheridan, John Gallagher, Morten Bjerrum, Adrienne Fleming, Fintan Kelleher, John Mcginley

Articles

The coordination of pyridyl-tetrazole derivatives containing ester substituents, at either the N-1 or N-2 position of the tetrazole ring, with copper(II) chloride results in the formation of either 1:1 or 1:2 copper to ligand complexes, depending on the ligand. However, when the ester functionality is changed to a carboxylate group, the resulting complexation reactions yield metal-organic frameworks. The resulting structures vary dramatically in pore size, depending on both reaction solvents and position of carboxylate group on the tetrazole ring. Despite the presence of sodium cations in the reaction mixtures, no sodium incorporation was ever observed in any of the complexes. …

Selection Of The Process Parameters For The Mass Plating Of Discrete Electronic Components, Ann Hopper

Articles

The miniaturisation of electronic components coupled with requirements for high temperature lead free soldering has forced the improvement of the termination finish of surface mount components to meet the critical demands of the electronic industry. In the present work the processing parameters necessary to plate miniature multilayer varistors (MLV’s) have been explored. The tooling selected was a “Rotary flow-thru’ plater” which achieved high volume plating with

Electrodeposition And Characterisation Of Copolymers Based On Pyrrole And 3,4-Ethylenedioxythiophene In Bmim Bf4 Using A Microcell Configuration, Lavinia Astratine, Edmond Magner, John Cassidy, Tony Betts

Articles

Electrochemical copolymerization of pyrrole (Py) and 3,4-ethylenedioxythiophene (EDOT) was performed in an ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, (BMIM BF4) employing a ‘micro-cell’ in order to use the materials efficiently. Characterization of the copolymers formed on an ITO substrate was performed for different Py: EDOT ratios (1:2, 1:1, 2:1) in both aqueous and ionic liquid electrolytes. Electrochemical and spectroelectrochemical analysis revealed that the properties of the copolymer depend upon the Py/EDOT monomer ratio used. The copolymer PPy-co-PEDOT (2:1) displayed good stability, a switching time of 20 s and a colouration efficiency of 101.3 C-1cm2. The presence of Py in the copolymer stabilised …

Using Structure-Based Organic Chemistry Online Tutorials With 2 Automated Correction For Student Practice And Review, Timothy O'Sullivan, Gráinne Hargaden

Articles

This article describes the development and implementation of an open-access organic chemistry question bank for online tutorials and assessments at University College Cork and Technological University Dublin. SOCOT (structure-based organic chemistry online tutorials) may be used to supplement traditional small-group tutorials, thereby allowing students to develop essential problem-solving skills in organic chemistry. This online approach may be used for both formative and summative assessment. Students complete one problem set weekly or fortnightly, which consists of a number of questions of varying difficulty. A wide range of question types is possible; for example, prediction of reaction products, identification of reaction intermediates …

In Vitro Oxygen Availability Modulates The Effect Of Artesunate On Hela Cells, James Murray, Sandra Gannan, Sarah Rawe, James Murphy

Articles

Background/Aim: Hypoxia can affect chemo - therapeutic drug efficacy in cancer patients, yet related in vitro assays in oxygen-rich environment remain the norm. Such levels are well beyond normoxic/hypoxic levels typically experienced by normal tissues/tumor masses. The present study evaluated how artesunate anti-tumor efficacy is modulated by oxygen availability in HeLa cells and its implications for future in vitro analyses. Materials and Methods: Real-time cell analysis was employed to evaluate HeLa cell toxicity to artesunate at 21%, 4% or 1% oxygen. Cell count analysis was performed to validate real-time data. Results: An increase in artesunate efficacy was observed when oxygen …

Passive Sampling For Quality Monitoring Of Irish Marine Waters, Philip White

Doctoral

This study details the steps involved in fabrication, deployment and retrieval of mainly polydimethyl siloxane (PDMS) passive sampling devices deployed in a number of locations in and around Ireland in an attempt to derive dissolved water concentrations of contaminants in-situ. PDMS samplers were initially deployed in the Burrishoole catchment, Co. Mayo in conjunction with the collection of biological tissues and sediment to investigate the source of elevated dioxins in the catchment. Passive samplers were used to generate dissolved water concentrations of persistent organic pollutants (POPs) and also to successfully screen for the presence of dioxins in the water column. The …

Progress In Zeolite Synthesis Promotes Advanced Applications, Moussa Zaarour, Biao Dong, Izabela Naydenova, Richard Retoux, Svetlana Mintova

Articles

This article outlines the importance of zeolite synthesis and their unique physicochemical characteristics promoting advanced applications. The main strategies for preparation of zeolites including organic-template assisted, organic-template free and alternative procedures are considered for synthesis of crystallites offering control and fine-tuning of their properties. Besides, rational design of zeolites with pre-determined structure, porosity, size, morphology, and composition are more viable by studying carefully the chemical and physical parameters controlling the zeolite synthesis and understanding the crystallization mechanism. Finally, a particular attention to the preparation of zeolites with nanosized dimensions and their utilization in innovative applications including photovoltaic, medicine and holographic …

Concern-Driven Integrated Toxicity Testing Strategies For Nanomaterials - Report Of The Nanosafety Cluster Working Group 10, Hugh Byrne, Agnes G. Oomen, Peter M.J. Bos, Teresa F. Fernandes, Kerstin Hund-Rinke, Diana Boraschi, Karin Aschberger, Stefania Gottardo, Frank Von Der Kammer, Dana Kühnel, Danail Hristozov, Antonio Marcomini, Lucia Migliore

Articles

Bringing together topic-related European Union-(EU)-funded projects, the so-called “NanoSafety Cluster” aims at identifying key areas for further research on risk assessment procedures for nanomaterials (NM). The outcome of NanoSafety Cluster Working Group 10, this commentary presents a vision for concern-driven integrated approaches for the (eco-)toxicological testing and assessment (IATA) of NM. Such approaches should start out by determining concerns, i.e. specific information needs for a given NM based on realistic exposure scenarios. Recognized concerns can be addressed in a set of tiers using standardized protocols for NM preparation and testing. Tier 1 includes determining physico-chemical properties, non-testing (e.g. structure …

A Simple Inexpensive Method For The Rapid Testing Of The Photocatalytic Activity Of Self Cleaning Surfaces, Andrew Mills, James Hepburn, David Hazafy, Christopher O'Rourke, Josef Krysa, Michal Baudys, Martin Zlamal, Hana Bartkova, Claire Hill, Kim Winn, Morten Simonsen, Erik Sogaard, Suresh Pillai, Nigel Leyland, Rachel Fagan, Frank Neumann, Christina Lampe, Tobias Graumann

Articles

A rapid semi-quantitative, inexpensive method,using a simple digital scanner and an indicator ink, suitable for use in the laboratory, or in the field, for assessing the photocatalytic activity of commerical photocatalytic self-cleaning materials such as glass, is described. The repeatability of the current method is found to be hight and better than many of the previously reported ISO photocatalyst tests.

Synthesis Of Orthogonally Protected 1,2-Diaminopropanoic Acids By Ring-Opening Of 3-Unsubstituted N-Activated Aziridine 2-Carboxylates With Para-Methoxybenzylamine: A Study Of The Regioselectivity Of The Reaction, Fintan Kelleher, Keith O'Brien

Articles

Orthogonally protected 1,2-diaminopropanoic acids (DAPs) have been synthesised in good yields by the ring-opening of 3-unsubstituted N-activated aziridine 2-carboxylates with para-methoxybenzylamine. The choice of both the N-activating group and ester alkyl group had a significant influence on the ratio of attack at the a or b positions of the aziridine. However, the regiochemical outcome is not predictable.

Overview Of The Recent Fda Process Validation Guidance For Medicinal Product Development And Manufacture, Nuala Calnan (Editor)

Conference Papers

This conference paper presents an overview of the recently published FDA Process Validation Guideline for the development and manufacture of medicinal drug products. It discusses the impacts of conducting life cycle based validation activities and highlights the future challenges in meeting the ongoing 'Continued Process Validation' (CPV) expectations of the regulator. It also presents the latest information on the EU draft Process Validation Guidance - due for publication in late 2013 / 2014.

Utilising Caging Techniques To Investigate Metal Assimilation In Nucella Lapillus, Mytilus Edulis And Crassostrea Gigas At Three Irish Coastal Locations, Michelle Giltrap, Ailbhe Macken, Maria Davoren, Evin Mcgovern, Barry Foley, Martin Larsen, Jonathan White, Brendan Mchugh

Articles

Pollution by metals has been of increasing concern for a number of decades but at present, the mechanism of metal accumulation in sentinel species is not fully understood and further studies are required for environmental risk assessment of metals in aquatic environments. The use of caging techniques has proven to be useful for assessment of water quality in coastal and estuarine environments. This study investigates the application of caging techniques for monitoring uptake of 20 elements in three marine species namely Nucella lapillus, Mytilus edulis and Crassostrea gigas. Stable isotopes were used to determine predatory effects and also used for …

Uv And Visible Light Activated Tio2 Photocatalysis Of 6-Hydroxymethyluracil, A Model Compound For The Potent Cyanotoxin Cylindrospermopsin, Cen Zhao, Miquel Pelaez, Dionysios Dionysiou, Suresh Pillai, John Byrne, Kevin O'Shea

Articles

TiO₂ photocatalyses of 6-hydroxymethyl uracil (6-HOMU) a model compound for the potent cyanotoxin, cylindrospermopsin (CYN), were carried out employing visible and UV irradiation using different non-metal doped TiO₂ materials, nitrogen and fluorine-TiO₂ (NF-TiO₂), phosphorus and fluorine-TiO₂ (PF-TiO₂) and sulfur-TiO₂ (S-TiO₂). The model compound was readily degraded under UV TiO₂ photocatalysis with pseudo-first-order rate constants (k) of 2.1, 1.0, and 0.44 h⁻¹ for NF-TiO₂, PF-TiO₂ and S-TiO₂, respectively. Under visible light activated (VLA), NF-TiO₂ was the most active photocatalyst, PF-TiO …

Synthesis Of Orthogonally Protected Azalanthionines (Lanazanines) By Sequential Ring-Opening Of N-Substituted Aziridine 2-Carboxylates, Keith O'Brien, Keith Ó Proinsias, Fintan Kelleher

Articles

Orthogonally protected azalanthionines (lanazanines, 4-azadiaminopimelic acids or b-aminoalaninoalanines) have been synthesised in good yields by the ring-opening of N-protected aziridine 2-carboxylates with suitably protected diaminopropanoic acids (DAPs). The required DAPs were also synthesised by ring-opening of N-protected aziridine 2-carboxylates with para-methoxybenzylamine.

A Highly Efficient Tio2-Xcx Nano-Heterojunction Photocatalyst For Visible-Light Induced Antibacterial Applications, Vinodkumar Etacheri, Michael Seery, Stephen Hinder, Georg Michlits, Suresh Pillai

Articles

Visible-light-induced antibacterial activity of carbon-doped anatase-brookite titania nano-heterojunction photocatalysts are reported for the first time. These heterostructures were prepared using a novel low temperature (100 °C) non-hydrothermal low power microwave (300 W) assisted method. Formation of interband C 2p states was found to be responsible for the band gap narrowing of the carbon doped heterojunctions. The most active photocatalyst obtained after 60 minutes of microwave irradiation exhibits a 2-fold higher visible-light induced photocatalytic activity in contrast to the standard commercial photocatalyst Evonik-Degussa P-25. Staphylococcus aureus inactivation rate constant for carbon-doped nano-heterojunctions and the standard photocatalyst was 0.0023 and -0.0081 min …

The Bench Synthesis Of Silver Nanostructures Of Variable Size And An Introductory Analysis Of Their Optical Properties, Aoife Power, Tony Betts, John Cassidy

Articles

A laboratory practical was designed for use by both undergraduate and second level students to demonstrate the synthesis and characterisation of tuneable silver colloids. It clearly illustrates the novel optical properties of silver nanoparticles compared to the bulk metal. The synthesis is both rapid and repeatable, and can be conducted on the laboratory bench at room temperature.

Synthesis And Modification Of Octafluoro[2.2]Paracyclophane (Parylene Af4), Craig Hicks, Brendan Duffy, Gráinne Hargaden

Articles

Parylenes are a class of organic compounds which have gained significant attention due to their application as coatings in areas such as medical devices and electronics. This review highlights the development of synthetic pathways to Octafluoro[2.2]Paracyclophane, commonly referred to as parylene AF4. Methods which have been used to functionalise AF4 are also presented.

Sol-Gel Characteristics For Corrosion Resistance Of Anodised Aluminium, Michael Whelan, John Cassidy, Brendan Duffy

Articles

Conventional anodising electrolytes based on sulphuric acid, oxalic acid and phosphoric acid have been used to form nanoporous layers on AA3003-H14 and sealed with silane based sol-gel sealers. It is shown that the sol-gel chemistries have varying levels of pore penetration depending on the synthesis conditions. The extent of sol-gel penetration and pore sealing is analysed by electron microscopy and energy dispersive x-ray spectroscopy. To describe the sealing phenomena observed a sol-gel penetration and sealing rating has been proposed to explain the interactions of the sol-gels with the pores of the anodised layers. The corrosion resistance of the sol-gel sealed …

Novel Microwave Assisted Synthesis Of Zns Nanomaterials, Suresh Pillai, Michael Seery, Damian Synnott, John Colreavy, Stephen Hinder

Articles

A novel ambient pressure microwave-assisted technique is developed in which silver and indium modified ZnS is synthesised. The as prepared ZnS is characterised by X-ray diffraction, UV-Vis spectroscopy, X-ray photoelectron spectroscopy and luminescence spectroscopy. This procedure produced crystalline materials with particle sizes below 10 nm. The synthesis technique leads to defects in the crystal which induce mid energy levels in the band gap and lead to indoor light photocatalytic activity. Increasing the amount of silver causes a phase transition from cubic blende to hexagonal phase ZnS. In a comparative study, when the ZnS cubic blende is heated in a conventional …

Unlocking The Knowledge: The Key To Delivering The Compliance And Business Benefits Outlined In Ich Q10 For Medicinal Product Manufacture, Nuala Calnan (Editor)

Conference Papers

This paper presents the challenges of delivering a holistic approach to the Pharmaceutical Quality System (Q10) expectations for medicinal product manufacture. It reviews the key findings from the recent ‘Operational Excellence in the Pharmaceutical Industry’ St. Gallen Uni. benchmarking report and explores the theme of 'Knowledge as the Key'. It explores how can we utilise familiar OPEX, Lean/ Six Sigma tools to capture this knowledge and deliver the expectations and opportunities for ICH Q10 and discusses this researchers study in the area of knowledge management and operational excellence.
It also includes a review of both the Regulatory Drivers and recent …

Nitrogen And Copper Doped Solar Light Active Tio2 Photocatalysts For Water Decontamination, Mike Fisher, Donal Keane, Pilar Fernandez-Ibanez, John Colreavy, Stephen Hinder, Kevin Mcguigan, Suresh Pillai

Articles

A novel class of photocatalytic coating capable of degrading bacterial and chemical contaminants in the presence of visible sunlight wavelengths was produced by depositing a stable photocatalytic TiO

2 film on the internal lumen of glass bottles via a sol–gel method. This coating was prepared in either undoped form or doped with nitrogen and/or copper to produce visible light-active TiO2 films which were annealed at 600 ◦C and were characterized by Raman and X-ray photoelectron spectroscopy. The presence of doped and undoped TiO2 films was found to accelerate the degradation of methylene blue in the presence of natural sunlight, while …

The Influence Of Auxiliary Ligands On The Photophysical Characteristics Of A Series Of Ruthenium (Ii) Polypyridyl Complexes, Luke O'Neill, Laura Perdisatt, Christine O'Connor

Articles

A series of ruthenium polypyridyl complexes were studied using UV/Vis absorption and luminescence spectroscopy as well as luminescence lifetime determination by time correlated single photon counting (TCSPC). The complexes were characterised with regard to the variation in the electronic band-gap as a result of the sequential variation of the auxiliary ligand 2,2’-bipyridine (bpy), 1,10-phenanthroline (phen) and 2,2’-biquinoline (biq) ligands while the main ligand remained constant for three different main ligand types. Luminescence yields were calculated and correlated with structural and electronic variation. It was found that both the absorption and emission characteristics could be tailored through the systematic variation of …

A Review On The Visible Light Active Titanium Dioxide Photocatalysts For Environmental Applications, Miguel Pelaez, Nicholas Nolan, Suresh Pillai, Michael Seery, Polycarpos Falaras, Athanassios G. Kontos, Patrick S.M. Dunlop, Jeremy W.J. Hamiltone, J. Anthony Byrne, Kevin O’Shea, Mohammad H. Entezari, Dionysios D. Dionysiou

Articles

Development of visible light active (VLA) titania photocatalysts

Fujishima and Honda (1972) demonstrated the potential of titanium dioxide (TiO 2) semiconductor mate-rials to split water into hydrogen and oxygen in a photo-electrochemical cell. Their work triggered the development of semiconductor photocatalysis for a wide range of environmental and energy applica-tions. One of the most significant scientific and commercial advances to date has been the development of visible light active (VLA) TiO2 photocatalytic materials. In this review, a background on TiO2 struc-ture, properties and electronic properties in photocatalysis is presented. The development of different strategies to modify TiO2 for the utilization …

An Analysis Of Drug Dissolution In Vivo, David Mcdonnell

Doctoral

The testing of drug dissolution rates from solid dosage forms is a very important area of research within the pharmaceutical industry. The ability to produce drugs with a given dissolution rate will lead to improved performance in the treatment of patients and will be of economic benefit to the pharmaceutical industry. However, dissolution testing in laboratories, aimed at reflecting in-vivo conditions, can be both time consuming and costly. Currently, most simulations of drug dissolution take place in standardized USP (United States Pharmaceutical) apparatuses. A number of these apparatuses exist, and it is the aim of this thesis to analyse drug …

Stiefel And Grassmann Manifolds In Quantum Chemistry, Eduardo Chiumiento, Michael Melgaard

Articles

We establish geometric properties of Stiefel and Grassmann manifolds which arise in relation to Slatertype variational spaces in many-particle Hartree-Fock theory and beyond. In particular, we prove thatthey are analytic homogeneous spaces and submanifolds of the space of bounded operators on the single-particle Hilbert space. As a by-product we obtain that they are complete Finsler manifolds. These geometric properties underpin state-of-the-art results on existence of solutions to Hartree-Fock type equations.