showing 17 related works from this author
Chromogenic Detection of Nerve Agent Mimics by Mass Transport Control at the Surface of Bifunctionalized Silica Nanoparticles
2010
Chemical warfare (CW) agents are toxic chemicals that have been used in several terrorist attacks in recent years. Among CW species, nerve agents are probably the most dangerous; their high toxicity and facile synthesis underscores the need to detect these lethal compounds with quick, reliable procedures. Analytical methods based on enzymatic assays and physical measurements have generally been used to detect these hazards. However, these protocols usually have limitations such as low selectivity, poor portability, and a certain level of complexity. In recent years, several chromogenic and fluorogenic sensors, and reagents for the detection of nerve agents have been described. For instance,…
Nerve agent simulant detection by using chromogenic triaryl methane cation probes
2012
Two triaryl methane cations have been used as probes for colorimetric detection of nerve agent simulants. Buffered mixed aqueous solutions of 1 and 2 showed bathochromic shifts in the presence of DCNP (diethylcyanophosphonate) and DCP (diethylchlorophosphate). The colour modulation can be observed to the naked eye. Appropriate mechanisms for the recognition event are proposed. © 2012 Elsevier Ltd.
Dipeptidyl Enoates As Potent Rhodesain Inhibitors That Display a Dual Mode of Action
2015
Dipeptidyl enoates were prepared through a high-yielding two-step synthetic route. They have a dipeptidic structure with a 4-oxoenoate moiety as a warhead with multiple reactive sites. Dipeptidyl enoates were screened against rhodesain and human cathepsins B and L, and were found to be potent and selective inhibitors of rhodesain. Among them (S,E)-ethyl 5-((S)-2-{[(benzyloxy)carbonyl]amino}-3-phenylpropanamido)-7-methyl-4-oxooct-2-enoate (6) was the most potent, with an IC50 value of 16.4 nm and kinact/Ki=1.6×106 m−1 s−1 against rhodesain. These dipeptidyl enoates display a reversible mode of inhibition at very low concentrations and an irreversible mode at higher concentrations. Inhibition…
Hg2+ and Cu2+ selective detection using a dual channel receptor based on thiopyrylium scaffoldings
2009
2,4,6-Triphenylthiopyrylium functionalized with an aza-oxa-thia macrocycle is able to selectively recognize Hg2+ cation by a color change and Cu2+ cation by a remarkable significant emission enhancement.
Synthesis and biological evaluation of cyclic derivatives of combretastatin A-4 containing group 14 elements
2018
Several tricyclic compounds inspired by the structure of combretastatin A-4 and bearing group 14 elements have been synthesized by homocoupling lithiated aryl fragments followed by ring-closing metathesis. These tricyclic compounds and their diolefin precursors were evaluated for their antiproliferative action on the tumor cell lines HT-29, MCF-7, HeLa and A-549 and on the non-tumor cell line HEK-293. In addition, their effects on the cell cycle were also measured. The tricyclic compounds show antiproliferative activity similar to that of combretastatin A-4, even though they are not so active in arresting the cell cycle. However, some diolefin precursors are able to cause accumulation of ce…
Chromogenic detection of nerve agent mimics
2008
The current rise in international concern over criminal terrorist attacks via chemical warfare (CW) agents has resulted in an increasing interest in the detection of these lethal chemicals. Among CW species, nerve agents are extremely dangerous and their high toxicity and ease of production underscore the need to detect these deadly chemicals via quick and reliable procedures. A number of detection systems have been developed, most of them based on enzymatic and physical methodologies. However, these usually show limitations such as low selectivity, lack of portability and a certain complexity in their use. An alternative to these classical methods that has been gaining interest in recent y…
Antiprotozoal and cysteine proteases inhibitory activity of dipeptidyl enoates
2018
A family of dipeptidyl enoates has been prepared and tested against the parasitic cysteine proteases rhodesain, cruzain and falcipain-2 related to sleeping sickness, Chagas disease and malaria, respectively. They have also been tested against human cathepsins B and L1 for selectivity. Dipeptidyl enoates resulted to be irreversible inhibitors of these enzymes. Some of the members of the family are very potent inhibitors of parasitic cysteine proteases displaying k2nd (M−1s−1) values of seven orders of magnitude. In vivo antiprotozoal testing was also performed. Inhibitors exhibited IC50 values in the micromolar range against Plasmodium falciparum, Trypanosoma brucei, Trypanosoma cruzi and ev…
Surfactant-assisted chromogenic sensing of cyanide in water
2009
Chromogenic cyanide recognition in water was achieved by the use of a hydrophobic dye in micellar containers.
Optical method based detection and wavelets based processing of acoustic waves
2020
Acoustic waves (AW) has been used for the testing of static and dynamic structures. They contain the signature about the performance of rotary machines such as cyclic fatigue, friction, turbulence and cavitation. Thus has been extensively used in the condition monitoring and material characterization. In this paper, we present an algorithm based on wavelets to process the transient AW in time and frequency domain both simultaneously to extract its the temporal (e.g. time duration) and spectral properties (e.g. emission frequency). Further, optical method based on optical feedback (OF) is presented for detection of AW providing powerful non-contact, non-destructive diagnostic capabilities, w…
A chalcone-based highly selective and sensitive chromofluorogenic probe for trivalent metal cations
2015
[EN] Anew chalcone-based probe for the chromofluorogenic sens-ing of trivalent (Al3 +,Fe3+,Cr3+,Ga3+,In3+and As3 +)overmono-and divalent cationsand anionsisreported. In the presence of trivalent metal cations,the probe was able to displayaremarkable color change from yellow to colorless that wasclearly visible to the naked eye. Also, the initial strongyellowemission was gradually quenched and substituted by aweaklyshifted band.
Current modulation induced stability in laser diode under high optical feedback strength
2021
The back-reflection of emitted laser beam (optical feedback, also know as selfmixing) from various external interfaces are sufficient to cause instability, and prohibiting its use in various fields such as communication, spectroscopy, imaging to name a few. So it is desirable to study the laser dynamics and the conditions causing it to be stable in spite of strong optical feedback. With the aid of mathematical formulation, simulation and backed by experimental evidences, it is demonstrated that the frequency deviation of the laser emission due to current (intensity) modulation alters the dynamic state and boundary conditions of the system such that even under large optical feedback strength…
Chromo-Fluorogenic Detection of Nerve-Agent Mimics Using Triggered Cyclization Reactions in Push-Pull Dyes
2010
A family of azo and stilbene derivatives (1-9) are synthesized, and their chromo-fluorogenic behavior in the presence of nerve-agent simulants, diethylchlorophosphate (DCP), diisopropylfluorophosphate (DFP), and diethylcyanophosphate (DCNP) in acetonitrile and mixed solution of water/acetonitrile (3:1 v/v) buffered at pH 5.6 with MES, is investigated. The prepared compounds contain 2-(2-N,N-dimethylaminophenyl)ethanol or 2-[(2-N,N-dimethylamino)phenoxy]ethanol reactive groups, which are part of the conjugated pi-system of the dyes and are able to give acylation reactions with phosphonate substrates followed by a rapid intramolecular N-alkylation. The nerve-agent mimic-triggered cyclization …
Multi-channel receptors based on thiopyrylium functionalised with macrocyclic receptors for the recognition of transition metal cations and anions.
2010
We report herein the synthesis and characterization of a family of ligands containing different cation binding sites covalently connected to a thiopyrylium signalling reporter. The receptors L1–L6 are able to signal the presence of certain metal cations via three different channels; i.e. electrochemically, fluorogenically and chromogenically. An acetonitrile solution of L1–L6 shows a bright blue colour due to a charge-transfer band in the 575–585 nm region. The colour variation in acetonitrile of L1–L6 in the presence of the metal cations Ag+, Cd2+, Cu2+, Fe3+, Hg2+, Ni2+, Pb2+ and Zn2+ has been studied. A selective hypsochromic shift of the blue band was found for the systems L4-Pb2+ and L…
Dyes That Bear Thiazolylazo Groups as Chromogenic Chemosensors for Metal Cations
2011
A family of dyes (L 1-L 6) that contain a thiazolylazo group as signalling subunit and several macrocyclic cavities with different ring sizes and type and number of heteroatoms as binding sites has been synthesized and characterized. Solutions of L 1-L 6 in acetonitrile show broad and structureless absorption bands in the 554-577 nm range with typicalmolar absorption coefficients that range from 20000 to 32000 M -1 cm -1. A detailed protonation study was carried out with solutions of L 1, L 2 and L 5 in acetonitrile. Addition of one equivalent of protons to L 1 and L 2 resulted in the development of a new band at 425 and 370 nm, respectively, which was ascribed to protonation in the aniline…
Aryl carbinols as nerve agent probes. Influence of the conjugation on the sensing properties
2012
Two new aryl carbinols (1 and 3) have been synthesised and characterised and their ability as OFF-ON probes for the chromogenic detection of the nerve agent simulant in acetonitrile has been tested. In addition compound 2 has been also studied. The carbinols suffered a phosphorylation reaction followed by an elimination process giving rise to the corresponding carbocations. This transformation of the carbinol into the carbocation is responsible for a significant color change. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2012.
Chromogenic and fluorogenic reagents for chemical warfare nerve agents' detection
2008
The ease of production, the extreme toxicity of organophosphorus-containing nerve agents, and their facile use in terrorism attacks underscores the need to develop accurate systems to detect these chemicals. Among different technologies we review here recent advances in the design of chromo-fluorogenic methods for the specific detection of nerve agents. Optical sensing (especially colorimetric detection) requires usually low-cost and widely used instrumentation and offers the possibility of so-called “naked eye detection”. Recent reported examples suggest that the application of chromo-fluorogenic supramolecular concepts for the chromogenic or fluorogenic sensing of nerve agents might be an…
Discrimination of nerve gases mimics and other organophosphorous derivatives in gas phase using a colorimetric probe array.
2012
A colorimetric array for the chromogenic discrimination of organophosphorous derivatives in gas phase has been developed. The array allows us to classify the nerve agent simulants DFP, DCP and DCNP.