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- Polímeros fluorescentes para a detecção de metais tóxicosPublication . Fialho, Carina B.; Barata, Patrícia; Prata, José V.; Costa, Alexandra I.As reconhecidas capacidades dos calixarenos como receptores moleculares sintéticos, capazes de interagir e formar, selectivamente, complexos com espécies moleculares e iónicas, suscitaram o nosso interesse na sua incorporação em sistemas poliméricos conjugados, perspectivando a ocorrência da amplificação do sinal de transdução em processos de detecção de explosivos [1] e biomoléculas [2]. Na presente comunicação será apresentada a síntese, caracterização e aplicação sensorial a metais tóxicos de polímeros baseados em unidades de calix[4]arenos ditópicos e dietinil-9-propil-9H-carbazoles (CALIX-OCF-PPE-2,7-CBZeCALIX-OCF-PPE-3,6-CBZ).
- Metal ion recognition induced by calix[4]arene carbazole containing polymersPublication . D. Barata, Patrícia; Costa, Alexandra; Fialho, Carina B.; Prata, José VirgílioSensing and recognition of ions and neutral molecules via synthetic receptors are of current interest in supramolecular chemistry because of their significant importance in several areas, such as chemistry, biology and environment. Compared with small molecules, polymers-based sensors displayed several importante advantages like signal amplification. In this way, the incorporation of molecular receptors such as calixarenes with conjugated polymer backbones is expected to enhance the signaling events related to a host–guest interaction. The preorganized binding sites, easy derivatization and flexible three-dimensional steric structures make calixarenes ideal construction platforms for molecular design to generate fluorescente receptors. The use of calixarenes as supramolecular scaffolds for this type of architectures has been explored and the sensing abilities of resultant polymers toward metal and molecular ions established. Based on the high sensitivity shown by the non-polymeric analogue CALIX-OCP-CBZ (notshown), to toxic metal cations, we decide two extend the sensing study to polymer materials. Herein, we report the preliminar results of the chemosensing ability of a new bicyclic calix[4]arene-carbazole-polymer (CALIX-OCP-PPE-CBZ) towards the detection of toxic metals in fluid phase.
- Highly selective and sensitive detection of toxic metals by fluorescent Bicyclic Calix[4]arene-based sensorsPublication . D. Barata, Patrícia; Fialho, Carina B.; Prata, José Virgílio; Costa, Alexandra I.Development of fast and portable chemosensors for trace detection of toxic metals, in particular those which are mostly present in the environment due to natural phenomenon and human activities (e.g. cadmium, mercury and lead), is a challenging area of current research.1 Calixarenes are one of the most widespread scaffolds in host-guest chemistry because of their rigid structures, which make them perfect candidates for complexation studies with ions and neutral molecules. Metal ions commonly bind at the lower rim of the calixarene moiety. Host-guest interaction can be enhanced by proper choice of additional binding sites containing nitrogen, oxygen, sulfur or a combination of them, and specifically designed calixarene architectures. Exploring the inherent capabilities of certain fluorescent calixarene-based compounds for establishing strong host:guest interactions, several sensing materials have been developed and tested by us towards the detection of neutral molecular species.2. We report in this communication the chemosensing ability of CALIX-OCP-CBZ and CALIX-OCP (Scheme 1) towards the detection of toxic metals, either by using the sensing element in fluid phase or solid state.
- Novel bicyclic fluorescent calix[4]arene-based sensors for toxic metalsPublication . Costa, Alexandra; Fialho, Carina B.; Barata, Patrícia; Prata, José VirgílioCalix[4]arene has been widely exploited as the basic molecular framework for many fluorescent chemosensors in the construction of selective binding sites given its structural rigidity (particularly important when the recognition and reporting events are to be undertaken in fluid phase), various conformations, and facile introduction of fluorophores. Exploring the inherent capabilities of certain fluorescent calixarene scaffolds for establishing strong host:guest interactions, several sensing materials have been recently developed by us [1]. In the same line of research new bicyclic calix[4]arene-based fluorescent chemosensors containing amides as coordination sites (ionophore) and carbazole segments as fluorescent signaling moieties (CALIX-AMD-CBZ) are being developed and that are expected to have high ability toward the detection of metallic cations in solution. However its complex synthesis and characterization has led to the use of a similar compound based on narrow rim 1,3-oxacyclophane tethered calix[4]arene derivatives integrating the same fluorescent segments (CALIX-OCP-2-CBZ) [2] as fluorophore in the present communication. Herein we report the most significant photophysical properties and sensory capabilities of CALIX-OCP-2-CBZ towards divalent ions (Cd2+, Cu2+, Hg2+, Pb2+) by fluorescence spectroscopy in fluid phase.
- Evaluation of the molecular architecture of fluorescence calix[4]arene-based sensors in detection of toxic metalsPublication . Costa, Alexandra; Barata, Patrícia; Fialho, Carina B.; Prata, José VirgílioChemical sensors have been playing a crucial role in analytical chemistry, bio-medicinal science and environmental chemistry. Chemosensors offer na accurate and low-cost finding of anions, cations, enzymes and toxic metal ions with high selectivity and sensitivity. In this regard, many organic compounds have been synthesized and are being used as successful chemosensors, however calixarenes offer distinct advantage in term of selectivity and the easy incorporation of a fluorophore into the structure. Cation complexing ligands containing calix[4]arene have been used to obtain more selective metal ions receptors. Herein, we report fluorescente calix[4]arene-based sensors with diferente molecular architecture [3] and their potentialities to address the detection of toxic metals. Using fluorescence as the signal transduction technique, experiments have shown that CALIX-OCP-2-CBZs are the most sensitiveto Cu.
- New bicyclic fluorescent calix[4]arene-polymers for molecular sensing in fluid phasePublication . Barata, Patrícia; Costa, Alexandra; Fialho, Carina B.; Prata, José VirgílioOver the last two decades, investigations in the field of conjugated polymers (CPs) have attracted significant attention due to their unique optical and electrochemical properties, in particular, their application in sensing devices. Sensory signal amplification (compared to small-molecules), versatile structures that can be easily adapted to adjust solubility, are some of the features that have made CPs fluorescence sensory platform of choice in the recente years. The incorporation of calixarenes, a class of synthetic molecular receptors possessing intramolecular cavities capable of selectively interact and establish specific host-guest complexes with neutral and ionic molecular guests in solution and solid-state, in CPs allows the construction of systems with enhance sensitive and selective capabilities towards explosives, contaminants, and biological materials. In this communication we report the results of the chemosensing ability of newly designed bicyclic calix[4]arene-carbazole-polymers (Calix-OCP-PPE-CBZs) with distinguished carbazole linkages in the polymer main chain, towards the detection of explosives (nitroaromatic compounds (NACs) and nitroaliphatic compounds) and nitroanilines (Nas) in liquide phase.
- Calix[4]arene-carbazole-containing polymers synthesis, properties and thin films as molecular sensorsPublication . Costa, Alexandra; Barata, Patrícia; Fialho, Carina B.; Prata, José VirgílioCalix[4]arenes, an interesting bow-shaped macrocyles, have been explored due to their valuable properties, e.g. molecular recognition, proving outstanding complexability towards neutral and ionic guests of several origins. In this communication we report the synthesis and the chemosensing ability on the solid state of a new bicyclic calix[4]arene-based polymers integrating phenylene-ethynylene-carbazole units as fluorescente segments (Calix-OCP-PPE-CBZs), in the detection of several nitroanilines (NAs) in vapor phase.