RESUMEN
The present work is dedicated to the development of a lab-on-chip (LOC) device for water toxicity environmental analysis and more especially herbicide detection. The final goal is focused on the functional integration of three-electrode electrochemical microcells (ElecCell) and organic photodetectors (OPD) in order to perform simultaneously electrochemical and optical detection in the frame of algal metabolism monitoring. Considering three different algae, ie. Chlamydomonas reinhardtii, Pseudokirchneriella subcapitata and Chlorella vulgaris while dealing with photosynthesis, the multi-microsensor platform enables to measure the variations of microalgae fluorescence as well as oxygen production. It is applied to study the Diuron herbicide influences on algal metabolism, evidencing fluorescence enhancement and oxygen production inhibition for concentrations as low as few tens of nanomoles. These results are performed with unconcentrated and six time concentrated algae solutions respectively, to estimate the ability of this dual-sensor system to conduct measurements without any sample preparation. Thus, according to the obtained results, the proposed LOC device is fully adapted to the electrochemical/optical dual detection for on-site pollutant analysis, ie. without sample pre-treatment.
Asunto(s)
Técnicas Biosensibles/instrumentación , Diurona/análisis , Herbicidas/análisis , Dispositivos Laboratorio en un Chip , Contaminantes Químicos del Agua/análisis , Chlamydomonas reinhardtii/metabolismo , Chlorella vulgaris/metabolismo , Diurona/metabolismo , Técnicas Electroquímicas/instrumentación , Diseño de Equipo , Fluorescencia , Herbicidas/metabolismo , Microalgas/metabolismo , Oxígeno/metabolismo , Fotosíntesis , Contaminantes Químicos del Agua/metabolismoRESUMEN
The abundance and low toxicity of iron with respect to ruthenium would certainly make it valuable for photophysical applications if one could circumvent its tendency to make high-spin compounds and the kinetic lability of its polypyridine complexes, both related to the presence of low-lying quintet metal-centered excited states. The aim of this study was to probe the photophysical potential of six cyclometallated Fe(ii) polypyridine complexes by means of ground state DFT and TDDFT calculations. Quantitative and qualitative indicators were extracted from such calculations and bring us to the conclusion that two complexes should display promising photophysical properties: Fe(NCN)(NNC) and Fe(NNC)2.
RESUMEN
By means of Delta-SCF and time-dependent density functional theory (DFT) calculations on [Ru(LL)3]2+ (LL = bpy = 2,2'-bipyridyl or bpz = 2,2' -bipyrazyl) complexes, we have found that emission of these two complexes could originate from two metal-to-ligand charge-transfer triplet states (3MLCT) that are quasi-degenerate and whose symmetries are D3 and C2. These two states are true minima. Calculated absorption and emission energies are in good agreement with experiment; the largest error is 0.14 eV, which is about the expected accuracy of the DFT calculations. For the first time, an optimized geometry for the metal-centered (MC) state is proposed for both of these complexes, and their energies are found to be almost degenerate with their corresponding 3MLCT states. These [RuII(LL)(eta1-LL)2]2+ MC states have two vacant coordination sites on the metal, so they may react readily with their environment. If these MC states are able to de-excite by luminescence, the associated transition (ca. 1 eV) is found to be quite different from those of the 3MLCT states (ca. 2 eV).