Two-photon Absorption Engineering of 5-(Fluorenyl)-1,10-phenanthroline-based Ru(II) Complexes

International audienceThis study deals with the fine tuning of the photophysical characteristics, and especially two-photon absorption (2PA) properties, of several homo- and heteroleptic ruthenium(II) complexes involving 5-substituted-1,10-phenanthroline ligands. The 2PA spectra of the complexes were determined in the 700-930 nm range by investigating their two-photon excited luminescence (2PEL). Structure - linear and nonlinear optical properties correlations are discussed, and potential applications (therapy and optical power limiting in the near infrared) can be anticipated

A Combined Experimental and Theoretical Study of Carboxylate Coordination Modes: A Structural Probe

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Enhanced two-photon absorption properties of weakly conjugated oligomers

International audienceThe theoretical study of two-photon absorption (TPA) properties of a non-conjugated dimer is related to cooperative effects between monomers. This effect leads to a strong increase of the TPA cross-section. This phenomenon is studied in the case of the three-level model

Synthesis of a pentaerythritol derivative bearing azo functions

International audienceA convenient strategy for synthesis of a pentaerythritol derivative diacetal containing azo functions is presented; NMR data are discussed and are in good agreement with the molecular structure

Optical properties of a donor–acceptor-substituted “hemi-cruciform” catechol derivative

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Self-Assembled Monolayers Based on Phenanthroline−Gold(111) Bonding

International audienceThe self-assembly of long-alkyl-chain substituted phenanthroline derivatives on highly oriented pyrolitic graphite (HOPG) and gold(111) is compared. Whereas the adsorption on HOPG is controlled by the affinity of alkyl chains for the substrate, which leads to flat-lying adsorbed molecules, alignments of upright-oriented molecules are formed on gold(111). This situation is explained by the bonding of chelating species with gold(111) surfaces and by the π-stacking interaction between conjugated moieties. This intermediate situation between strong thiol-like chemical bonding and the weak n-alkane-like physical adsorption opens the route toward laterally organized functional molecular assemblies

3MLCT excited states in Ru(II) complexes: Reactivity and related two-photon absorption applications in the near-infrared spectral range

This short review provides a concise summary of the current state of research on the population by two-photon absorption of the triplet metal-to-ligand 3MLCT excited state of ruthenium(II) complexes. Several effective and potential applications of this nonlinear optics phenomenon (optical power limiting in the near infrared, biological imagery and photodynamic therapy, PDT) and related linear effects will also be presented

Self-Assembled Monolayers of 1,10-Phenanthroline Based Bis-Bidentate Ligands on Au(111)

International audienceThe possibility for two bis-bidentate polypyridyle type ligands (TPPHZ and PEP) to form Self-Assembled Monolayers (SAMs) on Au(111) surfaces, has been investigated by Scanning Tunelling Microscopy (STM)

Induced effects of hedgerow networks on soil organic carbon storage within an agricultural landscape

International audienceHedgerow network landscapes or "bocages" are present throughout a large part of Western Europe [Baudry, J., Bunce, R.G.H. et al., 2000. Hedgerows: an international perspective on their origin, function and management. Journal of Environmental Management 60 (1), 7-22.]. These manmade landscapes are typically comprised of fields separated by boundaries, often marked by perennial vegetation (hedges or shelterbelts), yet little is known about the effect of these field margins on soil organic carbon (SOC) stocks and their dynamics, which offer large carbon sequestration potential [Walter, C., Mérot, P., Layer, B., Dutin, G., 2003. The effect of hedgerows on soil organic carbon storage in hillslopes. Soil Use and Management 19, 201-207.; Falloon, P., Powlson, D., Smith, P., 2004. Managing field margins for biodiversity and carbon sequestration: a Great Britain case study. Soil Use and Management 20, 240-247.]. In hedged landscapes, hedges induce a modification to the soil A-horizon geometry at the slope scale, as attributed to an anti-erosive effect, along with a local modification of the associated SOC stocks. Most studies undertaken within this context have been performed in two dimensions and under favourable conditions for soil accumulation with the hedges lying perpendicular to the steepest slope direction. Consequently, an extrapolation of these findings to the entire landscape can lead to overestimating SOC stocks at the landscape scale. The aims of this paper were to: quantify SOC stocks, describe their spatial variability in three dimensions, and identify the main determinants behind this variability within an agricultural hedgerow network landscape. To achieve these aims, we conducted a detailed field survey that took into account all three dimensions of the soil cover and anthropogenic structures. We then analysed the spatial distribution of SOC contents and stocks with respect to pedological and landscape parameters. Results show that SOC stocks may be locally significant in the vicinity of hedges with a median stock value of 16.6 kg C m − 2 , in comparison with stock at the landscape scale (13.3 kg C m − 2). This study has highlighted the need to incorporate the three dimensions of soil cover at the landscape scale in order to characterise SOC storage. This step will prevent the generalisation of local stocks at a landscape scale given the high variability of SOC stocks (1st quartile = 10.5 kg C m − 2 ; 3rd quartile = 18.5 kg C m − 2) induced by hedge structures

Polyfluorene Based Coordination Compounds for Nonlinear Absorption

International audienceWe report here the nonlinear absorption properties of different coordination compounds (M = Eu, Zn), based on the bifluorene system. Measurements were performed in chloroform between 450 and 650 nm for nanosecond time duration pulses. The nonlinear absorption is attributed to a three-photon absorption process involving a first two-photon absorption step followed by an excited state absorption process. The three-photon absorption efficiency of these complexes was shown to be similar to that of the bifluorene for a same concentration in bifluorene, with furthermore an excellent thermal stability