The synthesis and sensing capabilities of new amide, urea and nitrile calix4arenes

The synthesis and host-guest chemistry of new structures based on neutral calix[4]arene supramolecular platforms is investigated. Hosts are substituted to varying degrees with functionalised appendages to form cavities for selectively complexing guests. Functional groups include ureas, amides and nitriles, targeting cations and anions as guest species. The main methods used for transducing complexation events are potentiometry and fluorescence. The various hosts and guests investigated attempt to reflect the versatility and ongoing evolution of state-of- the-art calixarene chemistry within the field of supramolecular chemistry. Throughout the thesis there is particular emphasis on relating host structural changes to changing analytical signal upon complexation with a particular guest. This is the link between the sensing signal and chemistry at a molecular level, the heart of every chemical sensor. The main achievements of this work are a) the development of a urea based chloride selective host with ratiometric fluorescence transduction using pyrenes, b) nitrile based mercury(I1) and silver(1) selective hosts using potentiometric transduction, c) the investigation of an amide-calix[4]arene bromide selective host based on potentiometric transduction, d) the developmet of urea-calix[4]arene ionophores showing potential for improved electrochemical aqueous nitrate sensing and e) a contribution to supramolecular synthesis techniques is made by way of a new semi-preparative liquid chromatographic method for the efficient isolation of pure target compounds

A wearable electrochemical sensor for the real-time measurement of sweat sodium concentration

We report a new method for the real-time quantitative analysis of sodium in human sweat, consolidating sweat collection and analysis in a single, integrated, wearable platform. This temporal data opens up new possibilities in the study of human physiology, broadly applicable from assessing high performance athletes to monitoring Cystic Fibrosis (CF) sufferers. Our compact Sodium Sensor Belt (SSB) consists of a sodium selective Ion Selective Electrode (ISE) integrated into a platform that can be interfaced with the human body during exercise. No skin cleaning regime or sweat storage technology is required as the sweat is continually wicked from the skin to a sensing surface and from there to a storage area via a fabric pump. Our results suggest that after an initial equilibration period, a steady-state sodium plateau concentration was reached. Atomic Absorption Spectroscopy (AAS) was used as a reference method, and this has confirmed the accuracy of the new continuous monitoring approach. The steady-state concentrations observed were found to fall within ranges previously found in the literature, which further validates the approach. Daily calibration repeatability (n 1⁄4 4) was +/- 3.0% RSD and over a three month period reproducibility was +/- 12.1% RSD (n 1⁄4 56). As a further application, we attempted to monitor the sweat of Cystic Fibrosis (CF) sufferers using the same device. We observed high sodium concentrations symptomatic of CF ($60 mM Na+) for two CF patients, with no conclusive results for the remaining patients due to their limited exercising capability, and high viscosity/low volume of sweat produced

An Ionic Liquid Based Sensor for Diclofenac Determination in Water

This paper details a miniaturised, solid state ion-selective electrode selective for diclofenac. The sensor comprises a novel ionic liquid electroactive material – an imidazolium–diclofenac ion associate. The ion associate is present in a plasticised poly(vinyl chloride) (PVC) membrane on planar carbon electrodes, with an intermediate poly(3,4-ethylenedioxythiophene) layer. The sensitivity and selectivity of the sensor were determined using chronopotentiometric methods. In response to diclofenac, a slope of −53.3 ± 3.6 mV/dec was observed. A limit of detection of 2.90 × 10−3 g L−1 is reported, with a linear range of 3.18 × 10−3 g L−1 to 3.18 g L−1. The sensors show good selectivity towards diclofenac against pertinent interferent molecules, with a response time of \u3c15 \u3es

Robust, Bridge-less Ion-selective Electrodes with Significantly Reduced Need for Pre- and Post-application Handling

We are demonstrating robust, single-layer ion-selective electrode (ISE) utilizing simple Ag/AgCl electrode as solid support without the need for intermediate polymer layer. We have created and chemically linked a family of imidazolium ionic liquids (ILs) with poly (vinyl chloride) (PVC) using click chemistry, resulting in hybrid materials with tunable characteristics. The resultant material inherently contains chloride ion thus offering the ability to stabilize interfacial potential. This allowed us to construct very simple, single-layer membranes with significantly reduced need for conditioning as an added bonus compared to traditional sensors. Chemical immobilization of ISE membrane components also led to extended lifetime as the potential for material loss is reduced and detection limits are lowered. In our characterization we focused on perchlorate as a model ion. It\u27s levels of around 10−7 M could be repeatedly quantified over a 100 day period despite constant exposure of ISEs to aqueous solution over this time. Most importantly, the electrodes exhibited stable and reproducible signal with significantly simplified pre- and post-operation handling protocols. This offers potential for in situ applications as well as to advanced fabrication techniques and miniaturization. Simplicity of construction and operation, and low cost of the solid substrate allows for disposable ISE formats

Novel integrated paired emitter-detector diode (PEDD) as a miniaturized photometric detector in HPLC

A novel low power, low cost, highly sensitive, miniaturized light emitting diode (LED) based flow detector has been used as optical detector for the detection of sample components in high performance liquid chromatography (HPLC). This colorimetric detector employs two LEDs, one operating in normal mode as a light source and the other is reverse biased to work as a light detector. Instead of measuring the photocurrent directly, a simple timer circuit is used to measure the time taken for the photocurrent generated by the emitter LED (λmax 500 nm) to discharge the detector LED (λmax 621 nm) from 5 V (logic 1) to 1.7 V (logic 0) to give digital output directly without using an A/D converter. Employing a post-column reagent method, a Nucleosil 100-7 (functionalised with iminodiacetic acid (IDA) groups) column was used to separate a mixture of transition metal complexes, manganese (II) and cobalt (II) in PAR. All optical measurements were taken by using both the in built HPLC variable wavelength detector and the proposed paired-emitter-detector-diode (PEDD) optical detector configured in-line for data comparison. The concentration range investigated using the PEDD was found to give a linear response to the Mn (II) and Co (II) PAR complexes. The effects of flow rate and emitter LED light source intensity were investigated. Under optimised conditions the PEDD detector offered a linear range of 0.9-100 µM and LOD of 0.09 µM for Mn-PAR complex. A linear range of 0.2-100 µM and LOD of 0.09 µM for Co-PAR complex was achieved

Simple, Robust, and Plasticizer-Free Iodide-Selective Sensor Based on Copolymerized Triazole-Based Ionic Liquid

Novel solid-contact iodide-selective electrodes based on covalently attached 1,2,3 triazole ionic liquid (IL) were prepared and investigated in this study. Triazole-based IL moieties were synthesized using click chemistry and were further copolymerized with lauryl methacrylate via a simple one-step free radical polymerization to produce a "self-plasticized" copolymer. The mechanical properties of the copolymer are suitable for the fabrication of plasticizer-free ion-selective membrane electrodes. We demonstrate that covalently attached IL moieties provide adequate functionality to the ion-selective membrane, thus achieving a very simple, one-component sensing membrane. We also demonstrate that the presence of iodide as the counterion in the triazole moiety has direct influence on the membrane's functionality. Potentiometric experiments revealed that each electrode displays high selectivity toward iodide anions over a number of inorganic anions. Moreover, the inherent presence of the iodide in the membrane reduces the need for conditioning. The nonconditioned electrodes show strikingly similar response characteristics compared to the conditioned ones. The electrodes exhibited a near Nernstian behavior with a slope of -56.1 mV per decade across a large concentration range with lower detection limits found at approximately 6.3 × 10(-8) M or 8 ppb. These all-solid-state sensors were utilized for the selective potentiometric determination of iodide ions in artificial urine samples in the nanomolar concentration range

EMBALANDO O PASSADO: O design aplicado na música

Edições especiais com capas e encartes de CDs diferenciados tem sido a grande cartada das gravadoras na busca de aumentar as vendas. Dessa forma, foi criado um layout para embalagem (capa) de CD, juntamente com o encarte, promovendo uma coletânea da banda de rock Scorpions, focada nos anos 1960/1970. Para a confecção desse material, buscou-se, com a ajuda dos elementos do design gráfico, proporcionar um layout agradável, visando a escolha do melhor material para esse projeto, visto que foi estudado e abordado desde a criação do design, sintetizando o surgimento das primeiras capas de vinil e até mesmo conhecendo melhor a banda que será retratada; dessa forma, consolidando bases sólidas para o resultado final, mostrando qual o melhor material para a confecção desse produto, visando não degradar o meio ambiente. A metodologia é algo muito pessoal para o designer, visto que, por vezes, na execução de um projeto, usa-se uma metodologia própria. Nesse caso, foi usada a metodologia aprendida durante o curso, ensinada por Alexandre Schermach, que possibilita o designer a ter mais liberdade. Essa metodologia usada é baseada no Design Thinking e de Bonsiepe. Cada lâmina do encarte representa uma fase da banda, mostrando curiosidades e remetendo o fã musical à sua história, passando a ideia de ser um material guardado por anos por eles. Aos fãs da música, a relação foto/texto faz com que o material tenha maior interação com eles. Após a criação do layout, houve uma dedicação em relação ao material usado. O miolo foi feito em papel fotográfico fosco, pois por meio das pesquisas, notou-se uma qualidade superior de impressão, apresentando boa resistência e superfície, fazendo com que o consumidor tenha um apreço maior, aumentando a vida útil, e não gerará mais lixo, diferentemente do papel reciclado, que não apresenta uma impressão perfeita, amarela com o tempo e gasta mais recursos para sua produção. A capa é baseada nas primeiras embalagens de discos, sendo usadas sobras de cadernos capa dura. As edições especiais são uma alternativa para as gravadoras na busca de aumentar vendas, dessa forma, é necessário ter um material atraente. Quando se compra alguma edição especial, busca-se guardar o registro, para que possa ser repassado de geração para geração, mantendo-se intacto, rico em detalhes e resistência mesmo com o passar dos anos, evitando o seu descarte no lixo, prolongando sua vida útil, diferentemente do papel reciclado.Palavras-chave: Design gráfico. Encarte. Papel reciclado. Vinil

5′,6-Dichloro-1′,3′,3′-trimethyl­spiro­[2H-1-benzopyran-2,2′-indoline]

In the crystal structure of the title compound, C19H17Cl2NO, the indoline and benzopyran ring systems are approximately perpendicular to each other. The indoline ring is in an envelope conformation with the spiro C atom as the flap. The N atom of the indoline ring forms a pyramidal environment, the sum of the angles at this atom being 352.46°