70880-05-6Relevant articles and documents
Organic-inorganic hybrid mesoporous materials as regenerable sensing systems for the recognition of nitroaromatic explosives
Sarkar, Krishanu,Salinas, Yolanda,Campos, Inmaculada,Martinez-Manez, Ramon,Marcos, Maria D.,Sancenon, Felix,Amoros, Pedro
, p. 684 - 694 (2013)
Fluorescent organic-inorganic mesoporous hybrid materials have been prepared and characterised, and their behaviour against nitroaromatic explosives have been tested. MCM-41 silica was used as an inorganic scaffold and pyrene (P derivative containing trialkoxysilane moieties), dansyl and fluorescein (D and F derivatives also containing trialkoxysilane groups, respectively) fluorophores have been anchored on hybrid materials by a co-condensation method to obtain a homogenous distribution of dyes into the pores of the support. Six sensing materials have been prepared, of which SP, SD, SF were hydrophilic and SPh, SDh, SFh were hydrophobic. Template-free hydrophilic materials (SP, SD, SF) were obtained after repeated NH4NO3/ethanol extractions under temperature from as-synthesised (MP, MD and MF supports, respectively) solids. Hydrophobic materials (SPh, SDh, SFh) were prepared by using excess 1,1,1,3,3,3-hexamethyldisilazane with template-free hydrophilic (SP, SD and SF) materials. The six final materials displayed the typical emission bands of the grafted fluorophores. In particular, SP and SPh show the typical pyrene monomer (370-420 nm) and excimer (430-600 nm) emissions. SD and SDh exhibit the broad dansyl fluorescence band in the 450-600 nm range, whereas solids SF and SFh present sharp fluorescein emission centred at 525 nm. The fluorescent behaviour of the six final materials was tested in the presence of explosives (pentaerythritol tetranitrate (PETN), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), nitrobenzene (NB), 1,3,5-trinitrobenzene (TNB), 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), 2,4,6-trinitrophenylmethylnitramine (Tetryl) and picric acid (PA)). Only nitroaromatic compounds were able to induce emission quenching. As a general trend, the quenching degree depended on the nature of the final material. The best response was obtained with explosives PA and Tetryl, which were able to significantly quench the emission of the sensing supports. The observed quenching was ascribed to the π-π stacking interactions between the electron-donor fluorophores and the electron-withdrawing nitroaromatic explosives. When using SPh for Tetryl and PA, the limits of detection were 8.5 and 1.4 ppm, respectively, whereas they were 14.4 and 1.2 ppm for SDh. Principal component analysis algorithms were applied to the fluorescence measurements taken with the six hybrid materials and the seven explosives. The obtained score plot showed well-defined clusters for the seven explosives tested. Finally, solid SDh was applied to detect trace amounts of Tetryl in soil samples with good results. Copyright
Organic-inorganic molecular nano-sensors: A bis-dansylated tweezer-like fluoroionophore integrating a polyoxometalate core
Carraro, Mauro,Modugno, Gloria,Fiorani, Giulia,MacCato, Chiara,Sartorel, Andrea,Bonchio, Marcella
, p. 281 - 289 (2012)
Functionalization of the bis-lacunary Keggin polyoxotungstate [γ-SiW10O36]8- has been achieved with a two-step synthesis, by the covalent attachment of a 3-aminopropylsilane spacer and further linkage of the dansyl (5-dimethylamino-1-naphthalenesulfonyl-) residue. The resulting bis-decorated molecular hybrid [{{(CH3) 2N}C10H6SO2NH(CH2) 3Si}2O(γ-SiW10O36)] 4- has been isolated and characterized in solution and in the solid state by FTIR, multinuclear NMR, ESI-MS, UV/Vis, luminescence spectroscopy, dynamic light scattering (DLS), and Scanning Electron Microscopy (SEM). The inorganic polyoxometalate provides a molecular nano-surface where the dansyl fluorophores are anchored with a tweezer-type arrangement. The merging of the organic and inorganic domains of the bis-dansylated complex dictates its fluorescence features, which are observed in the range 375-600 nm, its amphiphilic properties, and the multi-site recognition/signaling of cationic analytes due to the complementary effect of the tungsten oxide polyanionic surface. Indeed, the interplay of the appended sulfonamide moieties and of the molecular metal oxide fosters an enhanced selectivity for Cu2+ and Pb2+ ion sensing, even in the presence of potentially interfering cations such as Co2+. These latter are preferentially captured by the inorganic platform. By virtue of its hybrid nature, the title fluoroionophore evolves to supramolecular architectures and extended systems in mixed organic solvent/aqueous environment, yielding spherical vesicles and macroporous thin films. Flat polymeric membranes incorporating the hybrid fluorophore can also be obtained, suggesting the generation of heterogeneous sensing devices that integrate both filtration and separation functionalities. Copyright
Surface modification of silica nanoparticles: A new strategy for the realization of self-organized fluorescence chemosensorst
Rampazzo, Enrico,Brasola, Elena,Marcuz, Silvia,Mancin, Fabrizio,Tecilla, Paolo,Tonellato, Umberto
, p. 2687 - 2696 (2007/10/03)
The self-organization of the proper subunits of a fluorescence chemosensor on the surface of silica nanoparticles allows the easy design and realization of new effective sensing systems. Commercially available silica particles (20 nm diameter) were functionalized with triethoxysilane derivatives of selective Cu(II) ligands and fluorescent dyes. Grafting of the sensor components to the particle surface ensures the spatial proximity between the sensor components and, as a consequence, binding of Cu(II) ions by the ligand subunits leads to quenching of the fluorescent units emission. In 9:1 DMSO-water solution, the coated silica nanoparticles (CSNs) selectively detect copper ions down to nanomolar concentrations. The operative range of the sensors can be tuned either by switching the ligand units or by modification of the components ratio. Sensors with the desired photophysical properties can be easily prepared by using different fluorescent dyes. Moreover, the organization of the network of sensor components gives rise to cooperative and collective effects: on one hand, the ligand subunits bound to the particle surfaces cooperate to form multivalent binding sites with an increased affinity for the Cu(II) ions; on the other hand, binding of a single metal ion leads to the quenching of several fluorescent groups producing a remarkable signal amplification. The Royal Society of Chemistry 2005.
