Highly selective and sensitive detection of toxic metals by fluorescent Bicyclic Calix[4]arene-based sensors

Este trabalho foi financiado pelo Concurso Anual para Projetos de Investigação, Desenvolvimento, Inovação e Criação Artística (IDI&CA) 2016 do Instituto Politécnico de Lisboa. Código de Referência IPL/2016/NoSeMeTox_ISELDevelopment 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.info:eu-repo/semantics/publishedVersio

9-Borafluoren-9-yl and diphenylboron tetracoordinate complexes of 8-quinolinolato ligands with heavy-atoms substituents: synthesis, fluorescence and application in OLED devices

This work describes the synthesis and characterisation of new tetrahedral boron complexes, incorporating bromine- or iodine-substituted 8-quinolinolato chelate chromophores connected to 9-borafluoren-9-yl or diphenylboron orthogonal fragments. The molecular features and photophysical properties of these complexes are analysed in both solution and solid state. Steady-state photophysical studies reveal photoluminescence quantum yields (Φf) ranging from 0.02 to 0.15 and prompt fluorescence (PF) lifetimes (τf) between 2 and 16 ns. Time-resolved photophysical experiments show the presence of delayed fluorescence (DF) and phosphorescence at both 77 K and room temperature. The DF intensity increases with a rise in temperature. This variation is ascribed to an enhancement in the intersystem crossing (ISC) process promoted by the bromine or iodine heavy-atom effect. Investigations into the dependence of DF intensity relative to the excitation dose indicate emissions stemming either from Triplet-Triplet Annihilation (TTA), Thermally Activated Delayed Fluorescence (TADF), or a combination of these competing mechanisms. The effect is related to the size and number of heavy-atom substituents in each boron complex. A study of the DF emission intensity as a function of the excitation dose reveals that diiodo-substituted 8-quinolinolato boron complexes, whether rigid or flexible, display TADF emission. Rigid 5,7-dibromo- and 5-chloro-7-iodo-substituted 8-quinolinolato complexes exhibit a combined TADF-TTA mechanism, whereas the other complexes predominantly demonstrate pure TTA emission. DFT and TDDFT calculations showed that the ground state structures reproduced the experimental geometries and only small increases in bond lengths were observed in the excited state geometries. The low energy absorption bands displayed mainly intra-ligand π→π* (8-quinolinato) character. The fluorescence emission energies were well reproduced, while the singlet-triplet energy gaps were relatively high. Ultimately, organic light-emitting diodes (OLEDs) are fabricated using the most luminescent boron complexes. The best OLED is obtained when using complex 3a, which displays green electroluminescence (EL) (λEL = 502 nm) with maximum external quantum efficiency (EQEmax) of 2.5% and maximum luminance (Lmax) of 2200 cd m-2

9-Borafluoren-9-yl and diphenylboron tetracoordinate complexes of F- and Cl-substituted 8-quinolinolato ligands: synthesis, molecular and electronic structures, fluorescence and application in OLED devices

Six new four-coordinate tetrahedral boron complexes, containing 9-borafluoren-9-yl and diphenylboron cores attached to orthogonal fluorine- and chlorine-substituted 8-quinolinolato ligand chromophores, have been synthesised, characterised, and applied as emitters in organic light-emitting diodes (OLEDs). An extensive steady-state and time-resolved photophysical study, in solution and in the solid state, resulted in the first-time report of delayed fluorescence (DF) in solid films of 8-quinolinolato boron complexes. The DF intensity dependence on excitation dose suggests that this emission originates from triplet–triplet annihilation (TTA). Density functional theory (DFT) and time-dependent density functional theory (TDDFT) studies give insight into the ground and excited state geometries, electronic structures, absorption energies, and singlet–triplet gaps in these new organoboron luminophores. Finally, given their highly luminescent behaviour, organic light-emitting diode (OLED) devices were produced using the synthesised organoboron compounds as emissive fluorescent dopants. The best OLED displays green-blue (λmaxEL = 489 nm) electroluminescence with an external quantum efficiency (EQE) of 3.3% and a maximum luminance of 6300 cd m−2

New bicyclic fluorescent calix[4]arene-polymers for molecular sensing in fluid phase

Este trabalho foi financiado pelo Concurso Anual para Projetos de Investigação, Desenvolvimento, Inovação e Criação Artística (IDI&CA) 2016 do Instituto Politécnico de Lisboa. Código de referência IPL/2016/NoSeMeTox_ISELOver 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.info:eu-repo/semantics/publishedVersio

Evaluation of the molecular architecture of fluorescence calix[4]arene-based sensors in detection of toxic metals

Este trabalho foi financiado pelo Concurso Anual para Projetos de Investigação, Desenvolvimento, Inovação e Criação Artística (IDI&CA) 2016 do Instituto Politécnico de Lisboa. Código de referência IPL/2016/NoSeMeTox_ISELChemical 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.info:eu-repo/semantics/publishedVersio

Novel bicyclic fluorescent calix[4]arene-based sensors for toxic metals

Este trabalho foi financiado pelo Concurso Anual para Projetos de Investigação, Desenvolvimento, Inovação e Criação Artística (IDI&CA) 2016 do Instituto Politécnico de Lisboa. Código de referência IPL/2016/NoSeMeTox_ISELCalix[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.info:eu-repo/semantics/publishedVersio

Calix[4]arene-carbazole-containing polymers synthesis, properties and thin films as molecular sensors

Este trabalho foi financiado pelo Concurso Anual para Projetos de Investigação, Desenvolvimento, Inovação e Criação Artística (IDI&CA) 2016 do Instituto Politécnico de Lisboa. Código de referência IPL/2016/NoSeMeTox_ISELCalix[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.info:eu-repo/semantics/publishedVersio

Polímeros fluorescentes para a detecção de metais tóxicos

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).info:eu-repo/semantics/publishedVersio

Metal ion recognition induced by calix[4]arene carbazole containing polymers

Este trabalho foi financiado pelo Concurso Anual para Projetos de Investigação, Desenvolvimento, Inovação e Criação Artística (IDI&CA) 2016 do Instituto Politécnico de Lisboa. Código de referência IPL/2016/NoSeMeTox_ISELSensing 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.info:eu-repo/semantics/publishedVersio

Nosocomial acute gastroenteritis outbreak caused by an equine-like G3P[8] DS-1-like rotavirus and GII.4 Sydney[P16] norovirus at a pediatric hospital in Rio de Janeiro, Brazil, 2019

Worldwide, rotavirus (RVA) and norovirus are considered major etiological agents of acute gastroenteritis (AGE) in pediatric population admitted to hospitals. This study describes the investigation of nosocomial infections caused by emergent RVA and norovirus strains reported at a pediatric hospital in southern Brazil in May 2019. This outbreak affected 30 people among children and adults. Nine stool samples (eight children and one nurse) were obtained and analyzed by RT-qPCR to detect and quantify RVA and norovirus. Positive samples were genotyped by sequencing and subjected to phylogenetic analysis. We detected RVA in 44.4% (4/9) and norovirus in 55.5% (5/9) at high viral loads, ranging from 3.5 × 107 to 6.1 × 107 and 3.2 × 102 to 3.2 × 109 genome copies/g of stool, respectively. Co-infections were not observed. RVA VP4 and VP7 gene sequencing in combination with polyacrylamide gel electrophoresis identified the circulation of equine-like G3P[8] DS-1-like, and the partial sequencing of the other nine genes revealed that strains possessed I2-R2-C2-M2-A2-N1-T2-E2-H2 genotype background. The emergent recombinant norovirus variant, GII.4 Sydney[P16], was identified by ORF1-2 sequencing. Active surveillance and effective prevention measures should be constantly reinforced to avoid the spread of nosocomial viral infections into hospitals, which could severely affect pediatric patients admitted with underlying health conditions