Diketo-Pyrrolo Pyrrole-Based Acceptor-Acceptor Copolymers with Deep HOMO and LUMO Levels Absorbing in the Near Infrared

A series of acceptor-acceptor (A-A') alternated copolymers based on dithienodiketopyrrolo pyrrole were synthesized by copolymerizing it with itself and other different electron-poor monomers. The experimental and computed optoelectronic properties of four DPP-based copolymers, P(DPP-DPP) (with linear and branched chains), copolymer with diazapentalene P(DPP-DAP) and also with dioxothienopyrrolebenzodifurandione P(DPP-BTPBF), as well as thermal characterizations were described. UV-visible spectrophotometry and cyclic voltammetry were used to estimate the optical and electrochemical bandgaps, and were found as very small: 1.3, 1.0, and 0.9 eV for P(DPP-DPP), P(DPP-DAP), and P(DPP-BTPBF), respectively. The BTPBF unit allowed a strong reduction of the bandgap, leading to a broad absorption in the visible and near infra-red regions from 650 to 1450 nm. These results were compared to analogous donor-acceptor (D-A) copolymers previously reported, in which DPP is replaced by DTS, P(DTS-DPP), P(DTS-DAP), and P(DTS-BTPBF). The same trend was observed. By comparing A-A' to D-A' copolymers analogues, it was shown that the bandgap remained the same while both HOMO and LUMO levels were lowered by roughly 0.2 eV.Technologie alternative pour les photodétecteurs infrarougeE2

Solubilite de la boehmite et speciation de l'aluminium dissous dans les solutions aqueuses a haute temperature (90-350deg.C). Determination experimentale et modelisation

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : T 81772 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

ETUDE EXPERIMENTALE DE LA COMPLEXATION AQUEUSE DES TERRES RARES AVEC LES IONS HYDROXYLES ET LES ANIONS ORGANIQUES LEGERS (25-150\C) (MODELISATION THERMODYNAMIQUE)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Etude expérimentale de l'adsorption des lanthanides sur une kaolinite et une montmorillonite à 25C

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Adsorption de Cs+, Ni2+ et des lanthanides sur une kaolinite et une smectite jusqu'à 150C (étude expérimentale et modélisation)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Experimental sorption of Ni2+, Cs+ and Ln3+ onto a montmorillonite up to 150°C

International audienceThe effect of temperature on the sorption of cations onto a dioctahedral smectite was investigated by running batch experiments at 25, 40, 80 and 150°C. We measured the distribution coefficient (Kd) of Cs+, Ni2+ and 14 lanthanides (Ln3+) between solutions and the montmorillonite fraction of the MX80 bentonite at various pH and ionic strengths. Up to 80°C we used a conventional experimental protocol derived from Coppin et al. (2002). At 150°C, the experiments were conducted in a PTFE reactor equipped with an internal filter allowing the sampling of clear aliquots of solution. The results show a weak but measurable influence of the temperature on the elements sorption. Kd?s for Ni2+ and Ln3+ increase by a factor 2 to 5 whereas temperature raises from 25 to 150°C. This effect seems higher at high ionic strength. The estimated apparent endothermic sorption enthalpies are 33 ± 10 kJ.mol?1 and 39 ± 15 kJ.mol?1 for Ni2+ and Eu3+, respectively. On the other hand, the temperature effect on Cs+ sorption is only evidenced at low ionic strength and under neutral conditions where the Kd decreases by a factor 3 between 25 and 150°C. Apparent exothermic sorption enthalpy for Cs+ on the montmorillonite is ?19 ± 5 kJ.mol?1. Experiments conducted at the four temperatures with the coexistence of all of the cations in the reacting solution (100 ppb of each element in the starting solution) or only one of them, produced similar values of Kd. This suggests the absence of competition between the sorbed cations, and consequently a low degree of saturation of the available sites. A fractionation of the lanthanides spectrum is also observed at high pH and high ionic strength whatever the temperature. The conclusion of this study is that the temperature dependence on sorption reflects, as the fractionation of REE or the pH and ionic strength effects, the chemical process which controls the overall reaction. In the case of an exchange dominated reaction (low pH and low ionic strength), the temperature effect is negligible. In the case of surface complexation (high pH and high ionic strength), the observed increase of Kd with temperature reflects either an increase of the sorption equilibrium constant with temperature or an endothermic property for reactions describing the montmorillonite surface chemistry

Halochromic Switch from the 1st to 2nd Near-Infrared Window of Diazapentalene–Dithienosilole Copolymers

International audienceHalochromic switch from the 1st to 2nd near-infrared window of diazapentalene–dithienosilole copolymers is reported. The diazapentalene repeat unit presents an imine group that can be either protonated by a Brønsted acid or coordinated with a Lewis acid. As a consequence, the wavelength of maximum absorbance was switched from 840 to 1070 nm. Experimental data obtained by spectrophotometry and cyclic voltammetry were combined with theoretical density functional theory calculations to explain the reversible halochromic behavior of these copolymers and the adducts that are formed during the reactions. As they can undergo analyte-induced absorption shifts in the near-infrared, these materials should prove useful as biological/chemical sensors

Economic impact of human-induced shrinkage of Posidonia oceanica meadows on coastal fisheries in the Gabes Gulf (Tunisia, Southern Mediterranean Sea)

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