Search results for "Fluorophore"
showing 10 items of 71 documents
Synthesis and photophysical properties of dansyl-based polyamine ligands and their Zn(II) complexes
2007
The synthesis, potentiometric studies and photophysical properties of two new polyamine ligands (L1 and L2) possessing the dansyl chromophore were studied in aqueous 0.15 M NaCl. The compounds show the absorption and emissions bands characteristic of the dansylamide fluorophore and both present intramolecular excited state proton transfer at intermediate pH ranges. One of the ligands (L2) strongly coordinates Zn(II) leading to fluorescence quenching. A model compound (L3) of the dansyl moiety was also investigated. http://www.sciencedirect.com/science/article/B6TG5-4MB4DV1-2/1/45cafbcee9a8df7daddd765512437ca3
The Role of Polyvinylpyrrolidone as a Potential Fluorophore for the Detection of Nitroaromatic Explosives
2022
Background: Detection of explosives (Nitroaromatic compounds) is one of the major issues faced in global security and, to date, remains a challenge even though some materials are developed for their detection. This study introduces the use of polyvinylpyrrolidone (PVP), a nonconjugated conducting polymer, as a potential fluorophore for sensing nitroaromatics. The stimuliresponse of fluorescence of PVP on interaction with energetic nitroaromatics was investigated in the present study. Methods: Fluorescence quenching studies of 5% PVP was carried out by the addition of varying concentration of quenchers (m-dinitrobenzene, trinitrobenzene and 2,4,6-trinitrophenol). To study the effect of diff…
SiPM as miniaturised optical biosensor for DNA-microarray applications
2015
A miniaturized optical biosensor for low-level fluorescence emitted by DNA strands labelled with CY5 is showed. Aim of this work is to demonstrate that a Si-based photodetector, having a low noise and a high sensitivity, can replace traditional detection systems in DNA-microarray applications. The photodetector used is a photomultiplier (SiPM), with 25 pixels. It exhibits a higher sensitivity than commercial optical readers and we experimentally found a detection limit for spotted dried samples of ∼1 nM. We measured the fluorescence signal in different operating conditions (angle of analysis, fluorophores concentrations, solution volumes and support). Once fixed the angle of analysis, for s…
Addressing subphthalocyanines and subnaphthalocyanines features relevant to fluorescence imaging
2018
International audience; A series of new synthetic subphthalocyanines bear structural features aimed at allowing either fluorescence activation or a bathochromic shift of the absorption band towards the near-infrared window, relevant to optical imaging. X-ray diffraction studies of four subphthalocyanines are reported. Spectrofluorimetric studies on subnaphthalocyanines and activatable subphthalocyanine pro-fluorophores are reported.
Photoluminescence in Carborane–Stilbene Triads : A Structural, Spectroscopic, and Computational Study
2016
A set of triads in which o- and m-carborane clusters are bonded to two stilbene units through Ccluster -CH2 bonds was synthesized, and their structures were confirmed by X-ray diffraction. A study on the influence of the o- and m- isomers on the absorption and photoluminescence properties of the stilbene units in solution revealed no charge-transfer contributions in the lowest excited state, as confirmed by (TD)DFT calculations. The presence of one or two B-I groups in m-carborane derivatives does not affect the emission properties of the stilbenes in solution, probably due to the rather large distance between the iodo substituents and the fluorophore. Nevertheless, a significant redshift o…
Near-infrared emissive bacteriochlorin-diketopyrrolopyrrole triads: Synthesis and photophysical properties
2019
International audience; The synthesis of unprecedented energy transfer triads containing a near-infrared (NIR) emissive bacteriochlorin subunit and two diketopyrrolopyrrole (DPP) moieties linked to each other via ethynyl or zero-carbon spacers is presented. Their optical and fluorescence properties were determined in CHCl3 and toluene. These photophysical measurements highlight the ability of DPP scaffold to act as an effective energy donor, which once excited in the range 450-550 nm resulting nearly exclusively NIR emission of hydroporphyrin (ETE > 96%). Since DPP dyes are valuable structurally tunable fluorophores that may be used in the construction of high-performance multicomponent pho…
Site-specific near-infrared fluorescent labelling of proteins on cysteine residues with meso -chloro-substituted heptamethine cyanine dyes
2018
International audience; Near-infrared (NIR) fluorescence imaging is a promising new medical imaging modality. Associated with a targeting molecule, NIR fluorophores can accumulate selectively in tissues of interest and become valuable tools for the diagnosis and therapy of various pathologies. To facilitate the design of targeted NIR imaging agents, it is important to identify simple and affordable fluorescent probes, allowing rapid labelling of biovectors such as proteins, ideally in a site-specific manner. Here, we demonstrate that heptamethine cyanine based fluorophores, such as IR-783, that contain a chloro-cyclohexyl moiety within their polymethine chain can react selectively, at neutr…
Fluorescent-Cavity Host: An Efficient Probe to Study Supramolecular Recognition Mechanisms
2018
Using fluorometry to study the interactions between guests and host cavities is often challenging, especially for hosts with small cavities because the fluorophore may not be close to the binding site. Therefore, it is critical to overcome this hurdle to broaden the applicability of fluorometry in supramolecular chemistry. Herein, we designed a fluorescent-cavity host (H1) by conjugating the binding site of a pillar[5]arene cavity and studied its host-guest recognition mechanism in the cavity. Distinct fluorescent responses of H1 were observed for cyano homologues: the fluorescence was enhanced for succinonitrile but quenched for malononitrile. Such an unusual phenomenon with such subtle di…
Chemosensors displaying pH controlled multistage fluorescence emission
1999
A large number of systems displaying pH controlled multistages of fluorescence emission intensity, have not been recognized from this point of view. In this work we present two paradigmatic cases: (i) polyamine receptors linked to a fluorophore unit, in which the signal is modulated by an intra-molecular pH dependent electron transfer process, (ii) phenols presenting adiabatic excited state proton transfer. In the first example the chemosensors are constituted by a receptor unit containing a polyaza moiety suitable for binding protons (but also metal ions or anions). The receptor is linked to a benzene or naphthalene unit that acts as a fluorophore. The fluorescence signal is dependent on t…
Spectroscopic Methods for the Determination of Protein Interactions
2005
This unit provides guidelines on how to use steady-state fluorescence spectroscopy for the quantification of protein-protein interactions. The fluorescence of a protein is characterized by its excitation and emission spectra, quantum yield, and anisotropy. These parameters can change upon interaction with another protein and can be used to measure the extent of complex formation. The source of fluorescence can be an intrinsic fluorophore, such as tryptophan or tyrosine; a covalently attached fluorescent dye; or a fluorescent binding partner, such as a nucleotide or cofactor, that interacts specifically with the complex. Protocols are provided in this unit for determining affinity constants …