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
r
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.
OIH sol-gel materials based on Jeffamine THF-170 and GPTMS, doped with triarylimidazole, were synthesized. The
r
obtained for the OIH doped samples ranged between 11 and 19. The OIHs are thermally stable for fresh concrete purposes.
The demand for new fluorophores for different biological target imaging is increasing. Benzo
phenoxazine derivatives are fluorochromophores that show promising optical properties for bioimaging, ...namely fluorescent emission at the NIR of the visible region, where biological samples have minimal fluorescence emission. In this study, six new benzo
phenoxazinium chlorides possessing sulfonamide groups at 5-amino-positions were synthesized and their optical and biological properties were tested. Compared with previous probes evaluated using fluorescence microscopy, using different
strains, these probes, with sulfonamide groups, stained the vacuole membrane and/or the perinuclear membrane of the endoplasmic reticulum with great specificity, with some fluorochromophores capable of even staining the plasma membrane. Thus, the addition of a sulfonamide group to the benzo
phenoxazinium core increases their specificity and attributes for the fluorescent labeling of cell applications and fractions, highlighting them as quite valid alternatives to commercially available dyes.
Water security and industrial wastewater treatment are significant global concerns. One of the main issues with environmental contamination has been the discharge of dye wastewater from the textile ...and dye industries, contributing to an ever-growing problem with water pollution, poisoning water supplies, and harming the ecosystem. The traditional approach to wastewater treatment has been found to be inefficient, and biosorption techniques and mechanisms have been proven to be a successful replacement for conventional methods. Recent developments have led to the recognition of fibrous materials as an environmentally friendly option with broad application in several industries, including wastewater treatment. This review explores the potential of fibrous materials produced by the electrospinning technique as adsorbents for wastewater treatment, while at the same time, for the removal of adsorbates such as oil, dyes, heavy metals, and other substances, as reported in the literature. Textile wastewater filtering structures, produced by electrospinning, are summarized and the use of synthetic and natural polymers for this purpose is discussed. The limitations of electrospun textile wastewater filtering structures are also mentioned. Electrospun nanofibrous membranes appear to be a very promising route to filter textile wastewater and therefore contribute to water reuse and to reducing the contamination of water courses.
Organic-inorganic hybrids (OIHs) are a type of material that can be obtained using the sol-gel process and has the advantages of organic and inorganic moieties in a single material. Polyetheramines ...have been widely used in the preparation of this type of material, particularly in combination with epoxy-based alkoxysilanes. Nevertheless, epoxyciclohexylethyltrimethoxysilane (ECHETMS) is a promising alkoxysilane with an epoxy terminal group that is quite unexplored. In this work, four novel OIH materials were synthesized using the sol-gel method. The OIHs were based on Jeffamines® of different molecular weights (D-230, D-400, ED-600, and ED-900), together with ECHETMS. The materials were characterized using multinuclear solid state NMR, FTIR, BET, UV/Vis spectroscopy, EIS, and TGA. The influence of the Jeffamine molecular weight and the suitability of these materials to act as a supporting matrix for heteroaromatic probes were assessed and discussed. The materials show interesting properties in order to be applied in a wide range of sensing applications.
The search for benzo a phenoxazines, Nile Blue derivatives, with high antifungal activity and cell labelling capacity based on our previously published work on this type of compounds led us to the ...design of compounds with specific substituents in the polycyclic system. Thus, in the present work, four new benzo a phenoxazinium chlorides, possessing at the 5-position amino or (3-aminopropyl) amino groups and at the 9-position propylamino or dipropylamino groups, were synthesized. Another analogue, with a (3-aminopropyl) amino group at the 5-position, an ethyl amino group at the 9-position and a methyl group at the 10-position of the polycyclic system, was also synthesized for comparison in the studies performed. The fundamental photophysics (absorption and fluorescence emission) was studied in absolute ethanol, water, and other aqueous solutions of different pH values, relevant for the potential biological applications of these compounds. The antiproliferative activity of the synthesized benzo a phenoxazinium chlorides was determined using Saccharomyces cerevisiae PYCC 4072 and the microdilution method described for antifungal susceptibility tests in yeast. All compounds revealed antifungal activity, the most active being the one possessing an amino group at the 5-position and an aminopropyl group at the 9-position. The potential as fluorescent probes was evaluated by fluorescence microscopy, using S. cerevisae as a model system of eukaryotic cells, and it was found that the benzo a phenoxazinium chlorides stained the cells with preferential accumulation that seems to appear at the vacuolar membrane and/or the perinuclear membrane of the endoplasmatic reticulum.
Anion sensing is a dynamic research field due to the biological and environmental importance of some organic or inorganic anions. Hydrazones show promising properties in the design of anion ...chemosensors due to the presence of proton donor and acceptor sites in their structure. In this work, two novel dinitrophenyl hydrazones, functionalized with a quinoline moiety, were synthesized and characterized by spectroscopic and spectrometric techniques. The interaction between the new compounds 3a–b with different organic and inorganic anions was assessed. The two compounds showed a change in color from light yellow to magenta in the presence of H2PO4−, CH3COO−, BzO−, CN−, and F−. The interactions were analyzed by spectrophotometric titrations and the stoichiometry of the interaction was assessed by the method of continuous variation. Compound 3b showed a remarkable sensitivity to CN−, with a limit of detection of 0.35 µM. The interaction of compound 3b with CN− and F− was also analyzed by 1H NMR titrations, showing that an increasing concentration of anions induce a deprotonation of the NH and OH groups.
Organic-inorganic hybrids (OIH) are materials that can be easily synthesized by the sol-gel method and combine the advantages of organic and inorganic moieties within a single polymeric matrix. ...Imidazole derivatives are versatile organic compounds that can change their optical properties with the variation of pH due to the protonation or deprotonation of the nitrogen atoms. This work reports the preparation of different OIHs doped with different contents of two imidazole compounds (
,
). The obtained materials were characterized structurally by FTIR, and the dielectric properties were studied by electrochemical impedance spectroscopy. The optical properties were studied by UV-Vis absorption and fluorescence spectroscopies. The FTIR analysis showed that the presence of the imidazole does not change the structural properties of the matrices. The normalized resistance values obtained for the doped matrices ranged between 8.57 and 9.32 Ω cm
, all being higher than the undoped matrix. The σ ranged between 9.49 and 10.28 S cm
, being all higher than the pure OIH samples. Compound
showed a maximum absorption peak at 390 nm, which is present in the OIH spectra, proving the presence of the compound. In the case of compound
, a maximum absorption wavelength at 412 nm was found, and the compound peak was not clear, which may indicate that an interaction between the compound and the matrix occurred. A synergetic effect between the intrinsic emission of the matrix and the fluorescence of
is found on the OIH-doped matrices.
Nowadays, concrete degradation is a major problem in the civil engineering field. Concrete carbonation, one of the main sources of structures' degradation, causes concrete's pH to decrease; hence, ...enabling the necessary conditions for corrosion reinforcement. An accurate, non-destructive sensor able to monitor the pH decrease resistant to concrete conditions is envisaged by many researchers. Optical fibre sensors (OFS) are generally used for concrete applications due to their high sensitivity and resistance to external interferences. Organic-inorganic hybrid (OIH) films, for potential functionalization of OFS to be applied in concrete structures, were developed. Polydimethylsiloxane (PDMS) based sol-gel materials were synthesized by the formation of an amino alcohol precursor followed by hydrolysis and condensation. Different ratios between PDMS and (3-aminopropyl)triethoxysilane (3-APTES) were studied. The synthesized OIH films were characterized by Fourier-transformed infrared spectroscopy (FTIR), UV-Vis spectroscopy, electrochemical impedance spectroscopy (EIS) and thermogravimetric analysis (TGA). The OIH films were doped with phenolphthalein (Phph), a pH indicator, and were characterized by UV-Vis and EIS. FTIR characterization showed that the reaction between both precursors, the hydrolysis and the condensation reactions occurred successfully. UV-Vis characterization confirmed the presence of Phph embedded in the OIH matrices. Dielectric and thermal properties of the materials showed promising properties for application in contact with a high alkaline environment.
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.
•Resistance are > 107 Ω cm2 therefore the OIHs are fit for alkaline environments.•Presence of phph in the OIH matrix does not affect the OIH dielectric properties.•TGA data proved that the produced ...OIHs were stable to be used in fresh concrete.•Release-retarding efficiency of the phph's encapsulation in the OIH was effective.
This work reports the synthesis of organic–inorganic hybrid (OIH) membranes for potential optical fibre sensors (OFS) functionalisation for pH monitoring of concrete and reinforced concrete structures (RCS). As precursors, 3-glycidyloxypropyltrimethoxysilane 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 as surfactant.
OIH membranes with pH sensing ability properties were successfully obtained. The dielectric properties of the resultant membranes were determined by electrochemical impedance spectroscopy. The logarithm of resistance obtained was 10.19 Ω cm2 for the undoped matrix and, 7.06 Ω cm2 for the doped one with phph. The results obtained in simulated concrete pore solutions, for the OIH produced, showed to be promising for application in fresh concrete. The transmittance of the synthesized OIH materials decreased after the doping with phph. The matrix showed intrinsic fluorescence and doping it only led to small deviations in the wavelength of the peak of maximum emission. Regarding thermal analysis, no significant changes were obtained on the thermal profile of the doped and undoped OIH membranes. The pH variation was detected by the OIH membrane colour change. Stability studies regarding the release of phph from the OIH matrix led to a mean dissolution time equal to 75.4 (±0.02) hours, indicating that the proposed system reveals long-term stability.
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