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Mouton N.,CNRS Laboratory of Infrared and Raman Spectrochemistry | de Juan A.,Facultat de Quimica | Sliwa M.,CNRS Laboratory of Infrared and Raman Spectrochemistry | Ruckebusch C.,CNRS Laboratory of Infrared and Raman Spectrochemistry
Chemometrics and Intelligent Laboratory Systems | Year: 2011

This work tackles the problem of convolution of femtosecond spectrokinetic data with the instantaneous response function (IRF) of the measurement by hybrid hard- and soft-modeling multivariate curve resolution (MCR). Fitting the time-dependent concentration profiles obtained during the MCR iterative optimization by a kinetic model convoluted with a parametric description of the IRF, the approach benefits of the advantages of both hard- and soft-modeling. The performance of the method is first proven on synthetic data sets with overlap of pure time-dependent concentration and/or spectral profiles and presence of interfering contributions. The method is afterwards applied to the resolution of femtosecond transient absorption spectroscopy data probing ultrafast photoinduced processes implied in the photochromism of anils. An excited-state proton transfer appearing in ~. 80. fs is characterized using an instrumental system with a severe influence of the convoluted instrumental response function, defined by a time resolution of ~. 150. fs. © 2010 Elsevier B.V. Source


Sauca S.,Facultat de Quimica | Giamberini M.,Escola Tecnica Superior dEnginyeria Quimica | Reina J.A.,Facultat de Quimica
Polymer Degradation and Stability | Year: 2013

A new set of polymers, which could act as flame retardant additives by blending with "commodity" polymers, was synthesized by chemically modifying poly(vinyl alcohol) (PVA) through reaction with a phosphorous- containing reagent. The phosphorous-based moiety introduced was 1-oxo-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane, which has been reported to be a good flame retardancy promoter structure. For a larger application and better compatibility with thermoplastic polymers, we also introduced in the polymeric additives aliphatic (valeroyl group) or aromatic (benzoyl group) moieties. The structures and properties of the polymers obtained were studied by 1H, 13C and 31P NMR, infrared spectroscopy (FTIR-ATR), inherent viscosity, inductively coupled plasma-atomic emission spectrometry (ICP-AES), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). A detailed study of their thermal degradation was performed by thermogravimetry coupled with mass spectrometry (TG-MS) and pyrolysis. Their thermal behavior and high char yield at high temperatures make them promising candidates to act as flame retardant additives through the formation of protective barriers. © 2012 Elsevier Ltd. All rights reserved. Source


Mouton N.,University of Lille Nord de France | Devos O.,University of Lille Nord de France | Sliwa M.,University of Lille Nord de France | de Juan A.,Facultat de Quimica | Ruckebusch C.,University of Lille Nord de France
Analytica Chimica Acta | Year: 2013

The main advantage of multivariate curve resolution - alternating least squares method (MCR-ALS) is the possibility to act as multiset analysis method, combining data coming from different experiments to provide a complete and more accurate description of a chemical system. Exploiting the multiset side, the combination of experiments obtained from two photo-active systems with complementary pathways and monitored by femtosecond UV-vis transient absorption spectroscopy is presented in this work. A multiset hard- and soft-multivariate curve resolution model (HS-MCR) was built allowing the description of the spectrokinetic features of the entire system. Additionally, reaction quantum yields were incorporated in the hard-model in order to describe branching ratios for intermediate species.The photodynamics of salicylidene aniline (SA) was investigated as a case study. The overall reaction scheme involves two competitive and parallel pathways. On the one hand, a photoinduced excited state intramolecular proton transfer (ESIPT) followed by a cis-. trans isomerization leads to the so-called photochromic form of the molecule, which absorbs in the visible. The formation of the photochromic species is well characterized in the literature. On the other hand, a complex internal rotation of the molecule takes place, which is a competing reaction. The rotation mechanism is based on a trans-. cis isomerization. This work aimed at providing a detailed spectrokinetic characterization of both reaction pathways for SA. For this purpose, the photodynamics of two molecules of identical parent structures and different substituent patterns were investigated in femtosecond transient absorption spectroscopy. For SA, the mechanism described above involving the two parallel pathways was observed, whereas for the derivative form of SA, the photochromic reaction was blocked because of the replacement of an H atom by a methyl group. The application of MCR approaches enabled to obtain transient spectra for the different intermediate species involved and rate constants for the photochromic reaction, thus contributing to a comprehensive description of the photodynamics of SA. © 2013 Elsevier B.V. Source


Du M.,Tianjin Normal University | Du M.,CAS Fujian Institute of Research on the Structure of Matter | Zhang Z.-H.,Tianjin Normal University | Li C.-P.,Tianjin Normal University | And 3 more authors.
Inorganic Chemistry | Year: 2011

The reaction of copper(II) nitrate, oxamide, and an angular bridging ligand 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (4-bpo) under hydrothermal conditions affords a 3D pillared-layer coordination framework {[Cu2(4-bpo)(ox) 2](H2O)4}n (1) (ox = oxalate), featuring the unique zeolite-type NiP2 network and interesting properties. © 2011 American Chemical Society. Source

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