Industrial activity has raised significant concerns regarding the widespread pollution caused by metal ions, contaminating ecosystems and causing adverse effects on human health. Therefore, the ...development of sensors for selective and sensitive detection of these analytes is extremely important. In this regard, an azo dye, Dabcyl 2, was synthesised and investigated for sensing metal ions with environmental and industrial relevance. The cation binding character of 2 was evaluated by colour changes as seen by the naked eye, UV-Vis and 1H NMR titrations in aqueous mixtures of SDS (0.02 M, pH 6) solution with acetonitrile (99:1, v/v). Out of the several cations tested, chemosensor 2 had a selective response for Pd2+, Sn2+ and Fe3+, showing a remarkable colour change visible to the naked eye and large bathochromic shifts in the UV-Vis spectrum of 2. This compound was very sensitive for Pd2+, Sn2+ and Fe3+, with a detection limit as low as 5.4 × 10−8 M, 1.3 × 10−7 M and 5.2 × 10−8 M, respectively. Moreover, comparative studies revealed that chemosensor 2 had high selectivity towards Pd2+ even in the presence of other metal ions in SDS aqueous mixtures.
Unnatural amino acids with enhanced properties, such as increased complexing ability and luminescence, are considered to be highly attractive building blocks for bioinspired frameworks, such as ...probes for biomolecule dynamics, sensitive fluorescent chemosensors, and peptides for molecular imaging, among others. Therefore, a novel series of highly emissive heterocyclic alanines bearing a benzo
oxazolyl unit functionalized with different heterocyclic π-spacers and (aza)crown ether moieties was synthesized. The new compounds were completely characterized using the usual spectroscopic techniques and evaluated as fluorimetric chemosensors in acetonitrile and aqueous mixtures in the presence of various alkaline, alkaline-earth, and transition metal ions. The different crown ether binding moieties as well as the electronic nature of the π-bridge allowed for fine tuning of the sensory properties of these unnatural amino acids towards Pd
and Fe
, as seen by spectrofluorimetric titrations.
Leishmaniasis and Human African trypanosomiasis pose significant public health threats in resource-limited regions, accentuated by the drawbacks of the current antiprotozoal treatments and the lack ...of approved vaccines. Considering the demand for novel therapeutic drugs, a series of BODIPY derivatives with several functionalizations at the
, 2 and/or 6 positions of the core were synthesized and characterized. The in vitro activity against
and
parasites was carried out alongside a human healthy cell line (MRC-5) to establish selectivity indices (SIs). Notably, the
-substituted BODIPY, with 1-dimethylaminonaphthalene (
) and anthracene moiety (
), were the most active against
, displaying IC
= 4.84 and 5.41 μM, with a 16 and 18-fold selectivity over MRC-5 cells, respectively. In contrast, the mono-formylated analogues
and
exhibited the highest toxicity (IC
= 2.84 and 6.17 μM, respectively) and selectivity (SI = 24 and 11, respectively) against
. Further insights on the activity of these compounds were gathered from molecular docking studies. The results suggest that these BODIPYs act as competitive inhibitors targeting the NADPH/NADP
linkage site of the pteridine reductase (PR) enzyme. Additionally, these findings unveil a range of quasi-degenerate binding complexes formed between the PRs and the investigated BODIPY derivatives. These results suggest a potential correlation between the anti-parasitic activity and the presence of multiple configurations that block the same site of the enzyme.
The use of benzothiazole as an electron-withdrawing group allows obtaining the fastest thermal isomerisation kinetics reported heretofore for neutral azo dyes (70 μs at 298 K). These green light ...activatable molecules are valuable candidates as molecular photoswitches since they tolerate thousands of working cycles with no sign of fatigue.
Fluorescence-based probes represent a powerful tool for noninvasive imaging of living systems in real time and with a high temporal and spatial resolution. Amongst several known fluorophores, ...3-difluoroborodipyrromethene (BODIPY) derivatives have become a cornerstone for innovative fluorescent labelling applications, mainly due to their advantageous features including their facile synthesis, structural versatility and exceptional photophysical properties. In this context, we report a BODIPY-based fluorescent probe for imaging of lysosomes in living cells. The BODIPY derivative displayed a remarkable fluorescence enhancement at low pH values with a pK
* of 3.1. In vitro studies by confocal microscopy in HeLa cells demonstrated that the compound was able to permeate cell membrane and selectively label lysosome whilst remaining innocuous to the cell culture at the maximum concentration tested. Herein, the BODIPY derivative holds the promise of investigating lysosomal dynamics and function in living cells through fluorescence imaging.
Four imidazoanthraquinone derivatives (2a–d) were synthesized and characterized and their coordination behavior against selected anions and cations tested. Acetonitrile solutions of probes showed ...charge-transfer absorptions in the 407–465 nm range. The four probes emitted in the 533–571 nm interval. The recognition ability of 2a–d was evaluated in the presence of F–, Cl–, Br–, I–, OCN–, BzO–, ClO4 –, AcO–, HSO4 –, H2PO4 –, and CN–. Only F–, AcO–, and H2PO4 – induced a new red-shifted absorption band that was attributed to a deprotonation process involving the amine moiety of the imidazole ring. Moreover, upon increasing quantities of F–, AcO–, and H2PO4 –, moderate quenching was induced in the emission of 2a–d together with the appearance of a new red-shifted band. The UV–visible and emission behavior of the four probes in the presence of Cu2+, Co2+, Mg2+, Fe3+, Ba2+, Fe2+, Ni2+, Ca2+, Zn2+, Pb2+, Cd2+, Cr3+, Al3+, K+, and Li+ was also assessed. Only addition of Fe3+, Cr3+, and Al3+ caused a new blue-shifted band in 2a–d that was ascribed to a preferential coordination with the acceptor part of the probes. Moreover, an important quenching of the emission was observed which was ascribed to the interaction between these trivalent cations and 2a–d.
Optical chemosensors are a practical tool for the detection and quantification of important analytes in biological and environmental fields, such as Cu2+ and Fe3+. To the best of our knowledge, a ...BODIPY derivative capable of detecting Cu2+ and Fe3+ simultaneously through a colorimetric response has not yet been described in the literature. In this work, a meso-triphenylamine-BODIPY derivative is reported for the highly selective detection of Cu2+ and Fe3+. In the preliminary chemosensing study, this compound showed a significant color change from yellow to blue–green in the presence of Cu2+ and Fe3+. With only one equivalent of cation, a change in the absorption band of the compound and the appearance of a new band around 700 nm were observed. Furthermore, only 10 equivalents of Cu2+/Fe3+ were needed to reach the absorption plateau in the UV-visible titrations. Compound 1 showed excellent sensitivity toward Cu2+ and Fe3+ detection, with LODs of 0.63 µM and 1.06 µM, respectively. The binding constant calculation indicated a strong complexation between compound 1 and Cu2+/Fe3+ ions. The 1H and 19F NMR titrations showed that an increasing concentration of cations induced a broadening and shifting of the aromatic region peaks, as well as the disappearance of the original fluorine peaks of the BODIPY core, which suggests that the ligand–metal (1:2) interaction may occur through the triphenylamino group and the BODIPY core.
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.
We report herein the synthesis and chromo-fluorogenic behaviour of a new probe 1 containing a boron-dipyrromethene (BODIPY) unit electronically connected with a dithia-dioxa-aza macrocycle. ...Acetonitrile and water–acetonitrile 95 : 5 v/v solutions of the probe showed an ICT band in the visible zone and are nearly non-emissive. When acetonitrile was used as a solvent, addition of Hg( ii ) and trivalent metal cations induced an hypsochromic shift of the absorption band and moderate emission enhancements. A highly selective response was obtained when using competitive media such as water–acetonitrile 95 : 5 v/v. In this case only Hg( ii ) induced a hypsochromic shift of the absorption band and a marked emission enhancement.
Three series of novel push–pull 5‐arylthieno3,2‐bthiophene derivatives functionalized with potent electron‐withdrawing terminal moieties have been synthesized in moderate to excellent yields by ...Suzuki coupling followed by Knoevenagel condensation. These novel chromophores show intense absorption in the near‐UV region through to the orange visible region, related to a strong intramolecular charge‐transfer transition. By combining a strong donor and acceptor, large fluorescence quantum yields were achieved as well as large two‐photon absorption responses. Interestingly, due to the improved rigidity and electronic delocalization provided by the thienothiophene moiety (as compared with the bithiophene unit), higher one‐ and two‐photon brightness values have been achieved. As a result, several new fluorescent dyes showing enhanced brightness and tunable fluorescence (ranging from the blue to the NIR region) have been obtained that have potential for bioimaging applications.
Fusion makes it better! Push–pull compounds built from a thienothiophene π‐connector have been synthesized. Due to improved rigidity and conjugation, derivatives with strong donor end groups have been shown to combine strong and tunable fluorescence with large two‐photon absorption in the NIR region. These dyes provide a route towards bright fluorophores spanning the visible region to the NIR.
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