Search

The development of sensors for pH monitoring is of extreme importance in the monitoring of concrete and reinforced concrete structures. Imidazole derivatives are promising probes for pH sensing due to the amphoteric nature of their heterocyclic ring, which can be protonated/deprotonated upon pH changes. In this work, a triarylimidazole was synthesised and used as a dopant in an organic–inorganic hybrid (OIH) sol–gel matrix to obtain a pH-sensitive membrane for further application in optical fibre sensors (OFS). The triarylimidazole probe shows fluorimetric response in pH between 9 and 13, which is the desired range for monitoring carbonation of concrete. This degradation process lowers the highly alkaline pH of concrete (12.5–13) to values below 9, which creates favourable conditions for corrosion of concrete reinforcement. The OIH membranes used were based on Jeffamine THF170 and 3-glycidoxypropytrimethoxysilane precursors, which had already been shown to be suitable and resistant in contact with cement-based materials. The OIHs were doped with three different contents of the triarylimidazole and the structural, dielectric, thermal and optical properties of the pure and doped OIH materials were evaluated. The structural analysis showed that the presence of the triarylimidazole did not change the structural properties of the OIH material. Electrochemical impedance spectroscopy showed that in the doped samples the conductivity increased with the imidazole concentration. The er obtained for the doped samples ranged approximately from 11 to 19 and for the pure matrices was 8. Thermal analysis showed that these materials are stable up to 350 °C and that the presence of the probe did not change that feature. The optical properties showed that the prepared OIH materials have promising properties to be used as pH sensitive fluorimetric probes.

Carbonation and corrosion of reinforced concrete structures (RCS) are the two main phenomena that more often affect civil engineering structures. The main consequence of carbonation is the pH reduction of concrete to values between 9 and 6 which may compromise the RCS durability. Thus, the development of sensors that would predict concrete carbonation is of utmost importance. Fiber optic sensors (OFS) are commonly used for concrete applications due to their high sensitivity and resistance to external interference. This work reports the synthesis of organic-inorganic hybrid (OIH) materials for possible functionalization of OFS and application in concrete and RCS. As precursors, 3-glycidyloxypropyltrimethoxysilane (GPTMS) and Jeffamine® THF-170 were used. The OIH sol-gel materials were doped with phenolphthalein (phph) for pH sensing proposes and cetyl trimethyl ammonium bromide (CTAB) as surfactant. OIH with pH sensing ability properties were successfully obtained and the doping of the OIH matrix did not significantly changed the dielectric properties of the resultant material. Moreover, the results obtained in simulated concrete pore solutions, obtained for the OIH produced, showed to be promising for application in fresh concrete. The transmittance of the synthesized OIH materials decreased after the doping. The matrix shows intrinsic fluorescence and doping it only led to small deviations in the wavelength of the peak of maximum emission. No significative changes were obtained on the thermal profile of the OIHs. The pH variation was shown by the OIH material color change. Stability studies regarding the release of phph from the OIH matrix indicates that the proposed system reveals long-term stability., Thanks are due to Fundaçã para a Ciência e Tecnologia (FCT) and FEDER (European Fund for Regional Development)-COMPETE-QRENEU for financial support through the Chemistry Research Centre of the University of Minho (Ref. CQ/UM (UID/QUI/00686/2019 and UID/QUI/00686/2020)), project “SolSensors — Development of Advanced Fiber Optic Sensors for Monitoring the Durability of Concrete Struc tures”, reference POCI-01-0145-FEDER-031220, a PhD grant to R. P. C. L. Sousa (SFRH/BD/145639/2019), a BSc grant to B. Ferreira and a Scientific Initiation grant to S. Sousa under the SolSensors project POCI 01-0145-FEDER-031220 is also acknowledged. Artur J. M. Valen tethanks the Coimbra Chemistry Centre and FCT for financial support (UID/QUI/00686/2020, UID/QUI/00313/2020).

Supplementary data to this article can be found online at https://doi.org/10.1016/j.dyepig.2022.111000, Stilbenes (diphenylethenes) are fully examined organic chromophores for very diverse applications. However, these molecules might show poor stability under irradiation because several simultaneous reactions (oxidative photocyclization and dimerization) can take place during the photochemical isomerization of their C=C bond. In this context, heteroarylethenes emerge as powerful counterparts thanks to their improved stability. In addition, the chosen heterocycles and their functionalization allows to fine tune and increase the speed at which the thermal back reaction occurs, broadening the scope of application of the resulting chromophores. Here we report on the thermal Z-to-E isomerization kinetics of a series of rationally designed heteroarylethenes and how the chemical architecture of the chromophore modulates the speed of the process. Specifically, the metastable Z isomers display relaxation times covering a wide time window, from a few hours to hundreds of microseconds. In fact, one of the studied dyes is the fastest heteroarylethene known to date. It should be also noticed that the described heteroarylethenes exhibit great photochemical stability, it being possible to switch them back and forth many times without degradation., This research was funded by the Ministerio de Ciencia, Innovacion y Universidades (Spain)/Agencia Estatal de Investigacion (Spain)/Fondo Europeo de Dearrollo Regional (FEDER, European Union), grant number PGC2018-095477-B-I00. Thanks are also due to Fundação para a Ciência e Tecnologia (FCT) and to FEDER-COMPETE for financial support through the research center CQUM (UID/QUI/0686/2016) and (UID/ QUI/0686/2020). The NMR spectrometers are part of the National NMR Network (PTNMR) and are partially supported by Infrastructure Project Nº 022161 (co-financed by FEDER through COMPETE 2020, POCI and PORL and FCT through PIDDAC). Authors also thank Prof. Santi Nonell for granting access to the nanosecond laser flash photolysis setup.

We propose a fiber-based environmental sensor that exploits the reflection phase shift tunability provided by the use of layered coatings composed of dielectric slabs spaced by conducting membranes. A transfer matrix study is done in a simplified theoretical model, for which an enhanced sensitivity of the reflection interference pattern to the output medium is demonstrated, in the typical refractive index range of liquid media. An experimental configuration using a cascaded Fabry-Perot microcavity coated by a graphene oxide/polyethylenimine (GO/PEI) multilayered structure is demonstrated. Its cost effective chemical production method makes graphene oxide-based hybrid coatings excellent candidates for future real-life sensing devices., 15 Pages + 12 Figures. Revised Version for Physical Review Applied

PhD fellowship (SFRH/BD/114674/2016) PTDC/FIS-NAN/0909/2014 Emerging organic contaminants (EOC) are synthetic or naturally occurring chemicals that have the potential to enter the environment and cause known or suspected adverse ecological and human health effects. Despite not being commonly monitored, EOC are often detected in effluents and water bodies because of their inefficient removal in conventional wastewater treatment plants. There is a growing concern about the presence and impact of EOC as well as the need for reliable and effective water monitoring using sensors capable of detecting the target molecules in complex media. Due to their specificities, such as fast response times, low cost, portability and user-friendly operation, electronic tongue (e-tongue) systems present some advantages over the traditional analytical techniques (e.g., chromatographic systems) used for environmental monitoring. We reviewed e-tongue sensors, focusing on their ability for real-time environmental monitoring. A bibliometric evaluation was carried out, along with a study of the status of the existing e-tongue systems, how they worked, and their applications in different fields. The potential of e-tongue sensors to detect organic contaminants in aqueous environmental matrices is discussed, with a particular focus on EOC. proof published

A new simple and easy-to-prepare imidazole-based probe 1 was synthesized and used to detect Cu(II) and biothiols (Cys, Hcy and GSH) in aqueous environments. Addition of increasing amounts of Cu(II) to water (pH 7.4)-acetonitrile 90:10 v/v solutions of probe 1 induced the apperance of a red-shifted absorption together with a marked colour change from colorless to deep blue. In addition, probe 1 was fluorescent and a marked emission quenching in the presence of Cu(II) was observed. The optical response is selective and other cations tested do not induce significant chromo-fluorogenic modulations. Limits of detection for Cu(II) of 0.7 and 3.2 μM using UV–visible and fluorescence data were determined. On the other hand, addition of Cys, Hcy and GSH to the deep-blue water (pH 7.4)-acetonitrile 90:10 v/v solutions of the 1-Cu(II) complex reulted in a marked bleaching together with the appearance of a highly emissive band centred at 475 nm. Other amino acids tested induced negligible response. The limits of detection for Cys, Hcy and GSH using 1-Cu(II) and emission data are 6.5, 5.0 and 10.2 μM, respectively. These optical changes were ascribed to a biothiol-induced demetallation process of the 1-Cu(II) complex that released the free probe. Besides, probe 1 is non-toxic and can be used for Cu(II) detection in HeLa cells., FCT - Generalitat Valenciana(PROMETEOII/2014/047); Spanish Government (projects MAT2015-64139-C4-1-R and AGL2015-70235-C2-2-R) and the Generalitat Valenciana (project PROMETEOII/2014/047). Thanks are also due to Fundação para a Ciência e a Tecnologia for financial support to the Portuguese NMR network (PTNMR, Bruker Avance III 400-Univ. Minho), FCT and FEDER (European Fund for Regional Development)-COMPETEQREN-EU for financial support to the research centre CQ/UM (Ref. UID/QUI/00686/2013 and UID/QUI/0686/2016), and a PhD grant to R. C. M. Ferreira (SFRH/BD/86408/2012), info:eu-repo/semantics/publishedVersion

Dipeptide biomaterials are strong piezoelectric materials that can convert applied mechanical forces into electricity. We have developed large-scale hybrid electrospun arrays containing N-tert-butoxycarbonyl (Boc) diphenylalanine in the form of nanotubes embedded in biocompatible polymers. These nanofibers exhibit strong piezoelectric properties when a periodic mechanical force is applied. The nanostructured hybrid materials were produced by the electrospinning technique. Optical absorption measurements show four bands in the spectral region 240-280 nm indicating quantum confinement due to nanotube formation of Boc-diphenylalanine in dichloromethane solutions. A strong blue photoluminescence emission was observed from nanotubes crystallized inside the fiber arrays during the electrospinning process. These two dimensional hybrid biomaterial structures are able to generate voltage, current and density power of up to 30 V, 300 nA and 2.3 mu W cm(-2), respectively, when a periodical force of 1.5 N is applied. The dipeptide-polymer electrospun arrays can power several liquid-crystal display panels and may be used for biomedical applications and as bio-energy sources., We are grateful to the FUNDACAO PARA A CIENCIA E TECNOLOGIA (FCT) for a post-doctoral grant to R.M.F. Batista (SFRH/BPD/79333/2011), and FEDER (European Fund for Regional Development)-COMPETE-QREN-EU for financial support through the Physics Centers of the Universities of Minho and Porto (Ref. UID/FIS/04650/2013) and the Chemistry Research Centre of the University of Minho (Ref. UID/QUI/00686/2013 and UID/QUI/0686/2016). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased within the framework of the National Program for Scientific Re-equipment, contract REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT.

A Fabry–Pérot acoustic sensor based on a graphene oxide membrane was developed with the aim to achieve a faster and simpler fabrication procedure when compared to similar graphene-based acoustic sensors. In addition, the proposed sensor was fabricated using methods that reduce chemical hazards and environmental impacts. The developed sensor, with an optical cavity of around 246 µm, showed a constant reflected signal amplitude of 6.8 ± 0.1 dB for 100 nm wavelength range. The sensor attained a wideband operation range between 20 and 100 kHz, with a maximum signal-to-noise ratio (SNR) of 32.7 dB at 25 kHz. The stability and sensitivity to temperatures up to 90◦C was also studied. Moreover, the proposed sensor offers the possibility to be applied as a wideband microphone or to be applied in more complex systems for structural analysis or imaging. publishersversion published

It is currently of huge importance to find alternatives to fossil fuels to produce clean energy and to ensure the energy demands of modern society. In the present work, two types of hybrid solar cell devices were developed and characterized. The photoactive layers of the hybrid heterojunctions comprise poly (allylamine chloride) (PAH) and graphene oxide (GO) and TiO2 or ZnO films, which were deposited using the layer-by-layer technique and DC-reactive magnetron sputtering, respectively, onto fluorine-doped tin oxide (FTO)-coated glass substrates. Scanning electron microscopy evidenced a homogeneous inorganic layer, the surface morphology of which was dependent on the number of organic bilayers. The electrical characterization pointed out that FTO/(PAH/GO)50/TiO2/Al, FTO/(PAH/GO)30/ZnO/Al, and FTO/(PAH/GO)50/ZnO/Al architectures were the only ones to exhibit a diode behavior, and the last one experienced a decrease in current in a low-humidity environment. The (PAH/GO)20 impedance spectroscopy study further revealed the typical impedance of a parallel RC circuit for a dry environment, whereas in a humid environment, it approached the impedance of a series of three parallel RC circuits, indicating that water and oxygen contribute to other conduction processes. Finally, the achieved devices should be encapsulated to work successfully as solar cells.

Thin graphene oxide (GO) film layers are being widely used as sensing layers in different types of electrical and optical sensor devices. GO layers are particularly popular because of their tuned interface reflectivity. The stability of GO layers is fundamental for sensor device reliability, particularly in complex aqueous environments such as wastewater. In this work, the stability of GO layers in layer-by-layer (LbL) films of polyethyleneimine (PEI) and GO was investigated. The results led to the following conclusions: PEI/GO films grow linearly with the number of bilayers as long as the adsorption time is kept constant, the adsorption kinetics of a GO layer follow the behavior of the adsorption of polyelectrolytes, and the interaction associated with the growth of these films is of the ionic type since the desorption activation energy has a value of 119 ± 17 kJ/mol. Therefore, it is possible to conclude that PEI/GO films are suitable for application in optical fiber sensor devices, most importantly, an optical fiber-based interrogation setup can easily be adapted to investigate in situ desorption via a thermally stimulated process. In addition, it is possible to draw inferences about film stability in solution in a fast, reliable way when compared with the traditional ones.

Triclosan (TCS) is being detected in breast milk and in infants of puerperal women. The harmful effects caused by this compound on living beings are now critical and thus it is pivotal find new tools to TCS monitoring. In the present study, an electronic tongue (e-tongue) device comprising an array of sputtered thin films based on Multi-Walled Carbon Nanotubes and titanium dioxide was developed to identify TCS concentrations, from 10−15 to 10−5 M, in both water and milk-based solutions. Impedance spectroscopy was used for device signal transducing and data was analyzed by principal component analysis (PCA). The e-tongue revealed to be able to distinguish water from milk-based matrices through the two Principal Components (PC1 and PC2), which represented 67.3% of the total variance. The PC1 values of infant formula milk powder prepared with tap water (MT) or mineral water (MMW) follows a similar exponential decay curve when plotted with the logarithm of concentration. Therefore, considering the TCS concentration range between 1015 and 10−9 M, the PC1 values are fitted by a straight line and values of −1.9 ± 0.2 and of 7.6 × 10−16 M were calculated for the sensor sensitivity and sensor resolution, respectively. Additionally, a strong correlation (R = 0.96) between MT and MMW PC1 data was found. These results have shown that the proposed device corresponds to a promisor method for the detection of TCS in milk-based solutions.

A series of novel substituted-azo dyes 8-(aryldiazenyl)quinolin-5-ol (5a-i) were synthesized by the coupling reaction of 5-hydroxyquinoline with diazotized aniline derivatives in the presence of NaNO2 in HCl/H2O mixture. The study of the spectroscopic and solvatochromic properties were performed by FT-IR, 1H and 13C-NMR and UV-Visible spectroscopies. The tautomerism of these dyes was studied using the deuteration technique and solvatochromic measurements. Photochromic properties of these 5-hydroxyquinoline azo dyes were also examined via E/Z and Z/E photochemical isomerization reactions and compared with the existing 8-hydroxyquinoline analogous. The novel substituted-azo dyes exhibited higher Z/E thermal isomerization rates and have larger absorbance wavelength range than their 8-hydroxyquinoline analogous, making them potential molecular switches., FCT - Swinburne University of Technology(UID/QUI/00686/2020)

Layer-by-layer films of poly (allylamine hydrochloride) (PAH) and graphene oxide (GO) were characterized, looking at growth with the number of bilayers, morphology, and electrical properties. The PAH/GO films revealed a linear increase in absorbance with the increase in the number of deposited bilayers, allowing the determination that 10.7 ± 0.1 mg m−2 of GO is adsorbed per unit of area of each bilayer. GO absorption bands at 146, 210, 247 and 299 nm, assigned to π-π* and n-π* transitions in the aromatic ring (phenol) and of the carboxylic group, respectively, were characterized by vacuum ultraviolet spectroscopy. The morphological characterization of these films demonstrated that they are not completely uniform, with a bilayer thickness of 10.5 ± 0.7 nm. This study also revealed that the films are composed of GO and/or PAH/GO fibers and that GO is completely adsorbed on top of PAH. The electrical properties of the films reveal that PAH/GO films present a semiconductor behavior. In addition, a slight decrease in conduction was observed when films were prepared in the presence of visible light, likely due to the presence of oxygen and moisture that contributes to the damage of GO molecules. publishersversion published

Heterocyclic aldehydes show a variety of optical properties and the versatility of their reactivity allows them to yield a wide range of more complex compounds, with application in areas such as medicinal, materials and supramolecular chemistry. The biological and environmental relevance of certain molecules and ions turns them into targets for the design of molecular recognition systems. Recently, heterocyclic aldehydes have been reported in the literature as ion chemosensors. Following the group’s work on optical chemosensors, for the detection and quanti-fication of ions and molecules with environmental and medicinal relevance, this work reports the synthesis and characterization of two heterocyclic aldehydes based on the thieno[3,2-b]thiophene core, by Suzuki coupling, as well as the synthesis of the corresponding precursors. Preliminary chemosensory studies for the synthesized heterocyclic aldehydes in the presence of selected cati-ons were also performed, in solution, in order to determine their potential application as optical chemosensors., This research was funded by Fundação para a Ciência e Tecnologia (FCT) and FEDER (European Fund for Regional Development)-COMPETE-QRENEU for financial support through the Chemistry Research Centre of the University of Minho (Ref. CQ/UM (UID/QUI/00686/2019 and UID/QUI/00686/2020), project “SolSensors—Development of Advanced Fiber Optic Sensors for Monitoring the Durability of Concrete Structures”, reference POCI-01-0145-FEDER-031220, and a PhD grant to R.P.C.L.S. (SFRH/BD/145639/2019). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network (PTNMR) and are partially supported by Infrastructure Project No 022161 (co-financed by FEDER through COMPETE 2020, POCI and PORL and FCT through PIDDAC).

The synthesis and characterization of a new fluorogenic substrate for granzyme B (GzmB) is reported. The substrate design was based on the fluorescence resonance energy transfer (FRET) principle using 5-(2′-aminoethyl)aminonaphthalene sulfonic acid (Edans) and 4-[[4′-(N,N-dimethylamino)phenyl]diazenyl]benzoic acid (Dabcyl) as a donor–acceptor pair, linked to a specific sequence for GzmB (AAD), with an additional amino acid as the anchoring point (K). The tetrapeptide was synthesized by microwave-assisted solid-phase peptide synthesis (MW-SPPS) and coupled to Dabcyl and Edans at its N- and C-termini, respectively. The obtained probe was purified by semi-preparative HPLC and characterized by NMR, UV/Vis absorption and fluorescence spectroscopy and mass spectrometry., The authors acknowledge Fundação para a Ciência e Tecnologia—FCT (Portugal), for funding through CQUM (UIDB/00686/2020) and project PTDC/QUI-COL/28052/2017. The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased within the framework of the National Program for Scientific Re-equipment, contract REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT.

The design and synthesis of organic molecules for recognition of biologically/environmentally important metal ions has emerged as a highly regarded research field. The BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) core is a versatile signaling molecule that can be fine-tuned with functional groups to create selective binding sites to improve its optical proper-ties. As an extension of the work developed in our research group, we report the synthesis and characterization of a BODIPY functionalized with triphenylamino and a formyl group at the meso and 2-position, respectively, for the highly selective detection of Cu2+ and Fe3+. The preliminary study of the BODIPY derivative as optical chemosensor was carried out in acetonitrile solution in the presence of different cations, and interactions with Cu2+ and Fe3+ induced a perceptible color change. UV-visible titrations showed changes in the absorption spectra upon the addition of three equivalents of each cation, with the appearance of a new absorption band at 693 nm., This research was funded by Foundation for Science and Technology (FCT) for financial support to CQ/UM (UID/QUI/00686/2020) and project PTDC/QUI-COL/28052/2017. Thanks are also due to Fundação para a Ciência e Tecnologia (Portugal) for financial support to the Portuguese NMR network (PTNMR, Bruker Avance III 400-Univ. Minho).

Ions exist widely in biological and environmental media, and the scarcity or excess of these species can have adverse consequences. BODIPY dyes appear as heterocyclic organic compounds capable of recognizing metal ions in solution and in cells, through optical signals (colorimetric and/or fluorimetric), and their photophysical properties can be adjusted through the func-tionalization of the BODIPY core. In continuation of the work developed recently, our research group reports the synthesis of a meso-anthracene-BODIPY derivative and the respective charac-terization by 1H and 13C nuclear magnetic resonance (NMR) and UV-Vis absorption spectrosco-pies. The preliminary study of the chemosensory capacity of the BODIPY derivative was also car-ried out in the presence of several cations in acetonitrile solution, which shows a selective colori-metric response for Cu2+ and Fe3+., This research was funded by the Foundation for Science and Technology (FCT) for financial support to CQ/UM (UIDB/QUI/00686/2020) and project PTDC/QUI-COL/28052/2017. Thanks are also due to Fundação para a Ciencia e Tecnologia (Portugal) for financial support to the Portuguese NMR Network (PTNMR, Bruker Avance III 400-Univ. Minho).

The detection of pollutant traces in the public water supply and aquifers is essential for the safety of the population. In this article, we demonstrate that a simple electrochemical procedure in acidic solution can be employed for enhancing the sensitivity of flexible screen-printed carbon electrodes (SPEs) to detect bisphenol-A (BPA), hydroquinone, and catechol, simultaneously. The SPEs were pretreated electrochemically in a H2SO4 solution, which did not affect their morphology, yielding high current signals with well separated oxidation peaks. The sensitivity values were 0.28, 0.230, and 0.056 &micro, A L &micro, mol&minus, 1 with detection limits of 0.12, 0.82, and 0.95 &micro, mol L&minus, 1 for hydroquinone, catechol, and BPA, respectively. The sensors were reproducible and selective for detecting BPA in plastic cups, and with adequate specificity not to be affected by interferents from water samples. The simple, inexpensive, and flexible SPE may thus be used to detect emerging pollutants and monitor the water quality.

The imidazole ring is a planar heterocycle whose derivatives are applied in several scientific areas, such as medicinal, materials and supramolecular chemistry. The presence of the imidazole ring in these structures is the key to the development of new drugs, since it is ubiquitous in naturally occurring biological structures. Therefore, over the past few decades, several imidazole derivatives have been synthesized and occupy a unique position in the field of medicinal chemistry due to their diverse biological activities. In order to continue the work developed by the research group, we report the synthesis of 2,4,5-tri(hetero)arylimidazole derivatives and their characterization by 1H and 13C nuclear magnetic resonance (NMR) and UV-Vis absorption spectroscopies. As a complement to the characterization of the synthesized 2,4,5-tri(hetero)arylimidazole derivatives, a screening for antibacterial activity showed the inhibition of Staphylococcus aureus proliferation, suggesting antibacterial activity. Therefore, these new compounds have the potential for the development of new drugs.

Palladium has wide application in different contexts and, as a consequence, high levels of palladium in the environment have been reported, representing a risk to human health. Considering the interest to develop more selective and sensitive chemosensors for this analyte, two novel benzoxazolyl-alanine derivatives bearing a crown ether moiety were studied as potential fluorimetric chemosensors for palladium detection. Preliminary chemosensory studies for these unnatural amino acids in the presence of selected metal cations were performed in acetonitrile solution and in aqueous mixtures of sodium dodecyl sulfate (SDS, 20 mM, pH 7.5) solution with acetonitrile, 90:10 v/v. In acetonitrile solution, these probes had a fluorescence response for different cations but, most importantly, in SDS aqueous solution both compounds displayed a selective fluorescence response in the presence of palladium.

PD/00193/2012 UIDB/04378/2020 UIDB/00068/2020 SFRH/BD/106032/2015 Abstract: Halogenated uracil derivatives are of great interest in modern cancer therapy, either as chemotherapeutics or radiosensitisers depending on their halogen atom. This work applies UV-Vis spectroscopy to study the radiation damage of uracil, 5-bromouracil and 5-fluorouracil dissolved in water in the presence of gold nanoparticles upon irradiation with an Nd:YAG ns-pulsed laser operating at 532 nm at different fluences. Gold nanoparticles absorb light efficiently by their surface plasmon resonance and can significantly damage DNA in their vicinity by an increase of temperature and the generation of reactive secondary species, notably radical fragments and low energy electrons. A recent study using the same experimental approach characterized the efficient laser-induced decomposition of the pyrimidine ring structure of 5-bromouracil mediated by the surface plasmon resonance of gold nanoparticles. The present results show that the presence of irradiated gold nanoparticles decomposes the ring structure of uracil and its halogenated derivatives with similar efficiency. In addition to the fragmentation of the pyrimidine ring, for 5-bromouracil the cleavage of the carbon-halogen bond could be observed, whereas for 5-fluorouracil this reaction channel was inhibited. Locally-released halogen atoms can react with molecular groups within DNA, hence this result indicates a specific mechanism by which doping with 5-bromouracil can enhance DNA damage in the proximity of laser irradiated gold nanoparticles. Graphical abstract: [Figure not available: see fulltext.]. publishersversion published

New porphyrin-imidazole derivatives were synthesised by Radziszewski reaction between 2-formyl-5,10,15,20-tetraphenylporphyrin 1 and several (hetem)aromatic 1,2-diones, which after cationization afforded promising monocationic photosensitizers 3a-d. Singlet oxygen studies have demonstrated that all the cationic porphyrin-imidazole conjugates 3a-d were capable to produce cytotoxic species. These photosensitizers were able to photoinactivate Eschericha coli and their inactivation profile was improved in the presence of KI., The authors are grateful to University of Aveiro and FCT/MCT for the financial support for QOPNA research Unit (FCT UID/QUI/00062/2019), the LAQV-REQUIMTE (UIDB/50006/2020), CESAM (UID/AMB/50017/2019) and CQUM (QUI/UI0686/2018) through national founds and, where applicable, co-financed by the FEDER, within the PT2020 Partnership Agreement, and to the Portuguese NMR Network. The research contract of N.M.M. Moura (REF.-048-88-ARH/2018) is funded by national funds (OE), through FCT - Fundacao para a Ciencia e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19.

Triclosan (TCS) is a bacteriostatic used in household items that promotes antimicrobial resistance and endocrine disruption effects both to humans and biota, raising health concerns. In this sense, new devices for its continuous monitoring in complex matrices are needed. In this work, sensors, based on polyelectrolyte layer-by-layer (LbL) films prepared onto gold interdigitated electrodes (IDE), were studied. An electronic tongue array, composed of (polyethyleneimine (PEI)/polysodium 4-styrenesulfonate (PSS))5 and (poly(allylamine hydrochloride/graphene oxide)5 LbL films together with gold IDE without coating were used to detect TCS concentrations (10&minus, 15&ndash, 10&minus, 5 M). Electrical impedance spectroscopy was used as means of transduction and the obtained data was analyzed by principal component analysis (PCA). The electronic tongue was tested in deionized water, mineral water and wastewater matrices showing its ability to (1) distinguish between TCS doped and non-doped solutions and (2) sort out the TCS range of concentrations. Regarding film stability, strong polyelectrolytes, as (PEI/PSS)n, presented more firmness and no significant desorption when immersed in wastewater. Finally, the PCA data of gold IDE and (PEI/PSS)5 sensors, for the mineral water and wastewater matrices, respectively, showed the ability to distinguish both matrices. A sensitivity value of 0.19 &plusmn, 0.02 per decade to TCS concentration and a resolution of 0.13 pM were found through the PCA second principal component.

SFRH/BD/135820/2018 UID/EEA/50014/2019 UID/FIS/00068/2019 M-ERA-NET2/0002/2016 The use of graphene oxide-based coatings on optical fibers are investigated, aiming to tune the reflectivity of optical fiber surfaces for use in precision sensing devices. Graphene oxide (GO) layers are successfully deposited onto optical fiber ends, either in cleaved or hollow microspheres, by mounting combined bilayers of polyethylenimine (PEI) and GO layers using the Layer-by-Layer (LbL) technique. The reflectivity of optical fibers coated with graphene oxide layers is investigated for the telecom region allowing to both monitor layer growth kinetics and cavity characterization. Tunable reflective surfaces are successfully attained in both cleaved optical fibers and hollow microsphere fiber-based sensors by simply coating them with PEI/GO layers through the LbL film technique. publishersversion published

Antifouling biocides are toxic to the marine environment impacting negatively on the aquatic ecosystems. These biocides, namely, tributyltin (TBT) and Cu(I) compounds, are used to avoid biofouling; however, their toxicity turns TBT and Cu(I) monitoring an important health issue. Current monitoring methods are expensive and time-consuming. This review provides an overview of the actual state of the art of antifouling paints' biocides, including their impact and toxicity, as well as the reported methods for TBT and Cu(I) detection over the past decade. The principles of optical fiber sensors (OFS) applications, with focus on environmental applications, and the use of organic chemosensors in this type of sensors are debated. The multiplexing ability of OFS and their application on aquatic environments are also discussed., The authors would like to gratefully acknowledge the financial. support from Foundation for Science and Technology, I.P (FCT) for the PhD grant SFRH/BD/145639/2019, to the project “SolSensors — Development of Advanced Fiber Optic Sensors for Monitoring the Durability of Concrete Structures”, reference POCI-01- 0145-FEDER-031220 supported by the Program Budget COMPETE — Operational Program Competitiveness and Internationalization — COMPETE 2020 and the Lisbon. Regional Operational Program in its FEDER component and by the budget of FCT and the support of Centro de Química, CQUM, financed by FCT under the project UID/QUI/00686/2020. The authors would like to gratefully acknowledge and recognize the efforts of the two anonymous reviewers for critically reading and providing useful suggestions that were very helpful in improving the manu script readability.

UID/AMB/04085/2019. UID/FIS/00068/2019. PTDC/FIS-NAN/0909/2014. SFRH/BD/114674/2016. Triclosan, which is a bacteriostatic used in household items, has raised health concerns, because it might lead to antimicrobial resistance and endocrine disorders in organisms. The detection, identification, and monitoring of triclosan and its by-products (methyl triclosan, 2,4-Dichlorophenol and 2,4,6-Trichlorophenol) are a growing need in order to update current water treatments and enable the continuous supervision of the contamination plume. This work presents a customized electronic tongue prototype coupled to an electrochemical flow reactor, which aims to access the monitoring of triclosan and its derivative by-products in a real secondary effluent. An electronic tongue device, based on impedance measurements and polyethylenimine/poly(sodium 4-styrenesulfonate) layer-by-layer and TiO2, ZnO and TiO2/ZnO sputtering thin films, was developed and tested to track analyte degradation and allow for analyte detection and semiquantification. A degradation pathway trend was observable by means of principal component analysis, being the sample separation, according to sampling time, explained by 77% the total variance in the first two components. A semi-quantitative electronic tongue was attained for triclosan and methyl-triclosan. For 2,4-Dichlorophenol and 2,4,6-Trichlorophenol, the best results were achieved with only a single sensor. Finally, working as multi-analyte quantification devices, the electronic tongues could provide information regarding the degradation kinetic and concentrations ranges in a dynamic removal treatment. publishersversion published

Push–pull terpyridine derivatives were synthesized and characterized in order to study the variations produced in their optical and electronic properties by linking different (hetero)aromatic electron donor moieties at position 4 of the electron deficient terpyridine moiety. The final donor-acceptor systems were synthesized in fair to good yields by Kröhnke condensation of the precursor aldehydes, with 2-acetylpyridine. Hyper-Rayleigh scattering in dioxane solutions using a fundamental wavelength of 1064 nm was employed to evaluate their second-order nonlinear optical properties. Terpyridine derivative functionalized with the 9-ethyl-9H-carbazolyl group exhibited the largest first hyperpolarizability (beta = 610 × 10-30 esu, using the T convention) thus indicating its potential application as a second harmonic generation (SHG) chromophore. Terpyridine derivatives were also used as ligands for the synthesis of novel [RuII(tpy)(NCS)3]– complexes, prepared in good yields by a two-step procedure involving the preparation of [RuIII(tpy)(Cl3] as precursors. RutheniumII complexes display a broad absorption in the visible range, accounting for their very dark color. Their redox behaviour is mainly characterized by the RuII-RuIII oxidation and by the ligand-centred reduction, whose potentials can be finely tuned by the electronic properties of the aromatic substituents on the terpyridine ligand. Hyper-Rayleigh scattering in methanol solutions using a fundamental wavelength of 1064 nm was also employed to evaluate their second-order nonlinear optical properties., Thanks are due to Fundação para a Ciência e a Tecnologia and FEDERCOMPETE for financial support through Centro de Química (UID/QUI/ 00686/2013 and UID/QUI/0686/2016), and a PhD grant to S. S. M. Fernandes (SFRH/BD/87786/2012). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased with funds from FCT and FEDER. The pulsed laser system was acquired within the framework of the grant (PTDC/CTM/105597/2008) from the Portuguese Foundation for Science and Technology (FCT) with funding from FEDER-COMPETE., info:eu-repo/semantics/publishedVersion

Unnatural alanine derivatives bearing a benzoxazole at the side chain, acting simultaneously as the coordinating and reporting unit, via fluorescence changes, were synthesised with a furan ring at position 2, substituted with different (hetero)aryl substituents, in order to tune the photophysical and chemosensory properties of the resulting compounds. The amino acid derivatives were prepared in protected form at their N- and C-termini, with tert-butoxycarbonyl urethane and methyl ester protecting groups, respectively. The novel furyl-benzoxazol-5-yl-L-alanines were evaluated for the first time in the recognition of several transition metal cations with environmental, medicinal and analytical interest such as Co2+, Cu2+, Zn2+ and Ni2+, in acetonitrile solution. The spectrofluorimetric titrations showed that the novel benzoxazolyl-alanines 3a-g were sensitive, although not selective, fluorimetric chemosensors for the above mentioned cations, with the best result being obtained for N,N-diethylamino substituted alanine 3d in the sensing of Cu2+. The heterocyclic system at the side chain was identified as the key factor in the recognition event of the metal cations, through its electron donor atoms. The encouraging photophysical and metal ion sensing properties of these furyl-benzoxazolyl-alanines suggest that they can be used to obtain bioinspired fluorescent reporters for metal ions such as peptides/proteins with chemosensory/probing ability., Thanks are due to Fundação para a Ciência e Tecnologia (FCT) for a PhD grant to R. C. M. Ferreira (SFRH/BD/86408/2012), and FEDER (European Fund for Regional Development)-COMPETEQREN-EU for financial support through the Chemistry Research Centre of the University of Minho (Ref. UID/QUI/00686/2013 and UID/QUI/0686/2016). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased within the framework of the National Program for Scientific Re-equipment, contract REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT., info:eu-repo/semantics/publishedVersion

Three BODIPY derivatives substituted at meso position by aryl (phenyl or N,N-dimethylaminonaphthyl) groups and functionalized at position 2 with electron-withdrawing formyl or electron deficient benzimidazole heterocycle were synthesized and completely characterized by the usual spectroscopic techniques. A comprehensive photophysical study showed a remarkable enhancement of the singlet oxygen sensitization quantum yield for meso-substituted dimethylaminonaphthyl BODIPY with the decrease of the dielectric constant of the solvent (0.02–0.04 for dimethylsulfoxide vs. 0.84 in toluene). In toluene the triplet state formation for the aminonaphthyl substituted BODIPY's was found to be mediated by the intramolecular charge transfer state (ICT), whereas in polar solvents triplet state formation is hindered by fast recombination of the ICT state. Pump-probe transient absorption spectroscopy was used to characterize the photoinduced dynamics of the BODIPY derivatives from the femtosecond to the nanosecond time scale., FCT - Laserlab-Europe(REDE/1517/RMN/2005), This work was supported by the Fundação para a Ciˆencia e a Tec nologia (FCT), Portuguese Agency for Scientific Research, through the Coimbra Chemistry Centre projects UIDB/00313/2020 and UIDP/ 00313/2020 and through the Centro de Química (CQUM), project UID/ QUI/00686/2020. The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased within the framework of the National Program for Scientific Reequipment, contract REDE/ 1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT. Raquel C. R. Gonçalves acknowledges FCT for funding (SFRH/BD/ 05278/2020). The research leading to these results has received funding from Laserlab-Europe (grant agreement no. 284464, EC’s Seventh Framework Programme).

Photodynamic therapy (PDT) and photothermal therapy (PTT) are photo-mediated treatments with different mechanisms of action that can be addressed for cancer treatment. Both phototherapies are highly successful and barely or non-invasive types of treatment that have gained attention in the past few years. The death of cancer cells because of the application of these therapies is caused by the formation of reactive oxygen species, that leads to oxidative stress for the case of photodynamic therapy and the generation of heat for the case of photothermal therapies. The advancement of nanotechnology allowed significant benefit to these therapies using nanoparticles, allowing both tuning of the process and an increase of effectiveness. The encapsulation of drugs, development of the most different organic and inorganic nanoparticles as well as the possibility of surfaces’ functionalization are some strategies used to combine phototherapy and nanotechnology, with the aim of an effective treatment with minimal side effects. This article presents an overview on the use of nanostructures in association with phototherapy, in the view of cancer treatment.

BODIPY derivatives have been proving to be a key class of compounds as a tool for a wide range of research fields. Among the diverse applications of BODIPYs, the development of derivatives owning the ability to recognize and detect small organic molecules and metal ions have received great attention in the last years. Moreover, the BODIPY core can be chemically modified in order to improve the optical properties or add new functionalities as chemosensors, for example insertion of receptor groups selective to analytes. There are diverse cations with biological and environment relevance, such as Fe3+ as an important metal ion in several physiological process involving electron transfer, oxidation and also as an enzymatic cofactor for oxygen transport, DNA synthesis, etc. On the other hand, the accumulation of iron in the central nervous system has been implicated in a number of diseases. Therefore, the design of molecular systems for recognition of cations with ‘‘naked-eye’’ detection is an attractive goal.In continuation of our research group’s investigation developed in the field of chromofluorogenic sensors, we report in this work the synthesis, characterization and evaluation of a novel BODIPY derivative as a colorimetric chemosensor for Fe3+ recognition in acetonitrile solution.

Using the electrospinning technique nanofibers consisting of organic nonlinear optical 3-nitroaniline (3NA, C6H6N2O2) nanocrystals embedded in poly-epsilon-caprolactone (PCL) polymer, 3NA@PCL nanofibers, were produced. Polarimetry optical second harmonic generation and X-ray diffraction studies show that 3NA push-pull molecules crystallize inside the polymer fibers with a strong preferential orientation giving rise to an alignment of the molecular dipole moments along the nanofibers longitudinal axis. This alignment strongly enhances the second order nonlinear optical response of the fibers. Intense second harmonic generation emission was observed from a single nanofiber, corresponding to an effective second order susceptibility of 80 pm V-1, four times greater than the largest second order susceptibility tensor element (21 pm V-1) associated with a macroscopic 3NA crystal. Moreover, when subjected to a modest periodically applied force of 3 N, a piezoelectric current of 70 nA generated by a 4 cm(2) electrospun nanofiber mat amounted to 122 nW cm(-2) of instantaneous density power, sufficient to power a LCD display. The results show that the electrospinning technique is a powerful technique to fabricate organic functional materials with oriented nanocrystals made of highly polarizable molecules, embedded in a polymer matrix., The authors acknowledge funding from the FUNDACAO PARA A CIENCIA E TECNOLOGIA (FCT) for a post-doctoral grant to Rosa M. F. Batista (SFRH/BPD/79333/2011), a PhD grant to Cesar R. Bernardo (SHFR/BD/102616/2014) funding in the framework of the project PTDC/NAN-OPT/29265/2017, and FEDER (European Fund for Regional Development)-COMPETE-QREN-EU for financial support through the Physics Center of the Universities of Minho and Porto (Ref. UID/FIS/04650/2013 and UID/FIS/04650/2019) and the Chemistry Research Centre of the University of Minho (Ref. UID/QUI/00686/2013 and UID/QUI/0686/2016). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased within the framework of the National Program for Scientific Re-equipment, contract REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT.

Natural products such as epigallocatechin-3-gallate (EGCG) have been suggested for complementary treatments of cancer, since they lower toxic side effects of anticancer drugs, and possess anti-inflammatory and antioxidant properties that inhibit carcinogenesis. Their effects on cancer cells depend on interactions with the membrane, which is the motivation to investigate Langmuir monolayers as simplified membrane models. In this study, EGCG was incorporated in zwitterionic dipalmitoyl phosphatidyl choline (DPPC) and anionic dipalmitoyl phosphatidyl serine (DPPS) Langmuir monolayers to simulate healthy and cancer cells membranes, respectively. EGCG induces condensation in surface pressure isotherms for both DPPC and DPPS monolayers, interacting mainly via electrostatic forces and hydrogen bonding with the choline and phosphate groups of the phospholipids, according to data from polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). Both monolayers become more compressible upon interaction with EGCG, which may be correlated to the synergy between EGCG and anticancer drugs reported in the literature. The interaction with EGCG is stronger for DPPC, leading to stronger morphological changes in Brewster angle microscopy (BAM) images and higher degree of condensation in the surface pressure isotherms. The changes induced by blue irradiation on DPPC and DPPS monolayers were largely precluded when EGCG was incorporated, thus confirming its antioxidant capacity for both types of membrane.