Temperature plays a fundamental role in all fields of science; hence the development methods for measuring this property remains vogue. Within vast field, fluorescent thermometry appears as simple, noninvasive and cost-effective method providing good spatial, temporal thermal resolution both solid liquid phases, even distant or inaccessible environments. Here we describe properties two-component system comprised Fe(II)-triazole type spin-crossover nanoparticles (temperature sensor) an...

Kinetic modeling using nonlinear differential equations is proposed to analyze the spontaneous generation of enantiomeric excess in autocatalytic addition diisopropylzinc prochiral pyrimidine carbaldehydes (Soai reaction). Our approach reproduces experimentally observed giant chiral amplification from an initial <10 –6 % >60%, high sensitivity and positive response presence minute amounts initiator at concentrations –14 M, absolute asymmetric synthesis achiral starting conditions. From...

Abstract Reducing the size of upconversion nanoparticles (UCNPs) down to a few nm yields luminescent materials containing very small number emitters. Considering bottom limit one activator per particle ultrasmall UCNPs offer an unprecedented platform study contributions different energy transfers at play in luminescence. Maintaining detectable emission despite limited emitting ions and high surface‐to‐volume ratio requires suitable architectures. Na(Gd‐Yb)F 4 :Tm 3+ emissive sub‐3 diameter...

The photochromic behavior of 2,2-di(4-fluorophenyl)-6-methoxy-2H-1-chromene has been investigated by 19F NMR spectroscopy. Photocoloration under UV irradiation at low temperature led to the formation three interconverting photoisomers including two merocyanines and an unprecedented allenyl-phenol isomer. Photobleaching with visible light, which was known lead reversion initial closed chromene, shown increase concentration. Thermal relaxation preirradiated system also studied various...

A comprehensive kinetic analysis of three prototypical autocatalytic cycle models based on the absolute asymmetric Soai reaction is presented. The models, which can give rise to amplification enantiomeric excess and mirror-image symmetry breaking, vary by their monomeric, dimeric or trimeric order assumed catalytic species. Our numerical approach considered entire chiral combinatorics diastereomeric interactions in as well multiplicity coupled reversible reactions without applying fast...

The present study quantitatively analyses the gated photochromism and acidity photomodulation properties of a diacid dithienylethene compound. Photoisomerisation between open closed isomers was investigated by UV/visible (1)H NMR spectroscopy. It found that photocyclisation quantum yield form remarkably high (around 90%). Partial neutralisation isomer revealed as mono- dianion were 50 67%, respectively. A considerable observed: is more acid than one pK(a) unit. This effect has been shown to...

The kinetics of spiropyran photochromic systems in solution a stirred batch reactor continuously irradiated with monochromatic light was studied by UV/visible spectrophotometry. plots absorbance vs time were analyzed, and the desired parameters (quantum yields, spectrum unstable photomerocyanine, ...) extracted from an iterative computation which fitted calculated curves to experimental ones on basis representative model reaction mechanism. method applied...

The photochromic and solvatochromic behaviour of 17 variously substituted spiroindoline naphthoxazines has been investigated in cyclohexane, toluene, acetonitrile methanol fluid solution. Specific parameters such as the wavelengths molar absorption coefficients closed spiro- open merocyanine forms, together with photocoloration photobleaching quantum yields, rate constants activation energies thermal fading have determined under continuous monochromatic irradiation. It shown that most these...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNonlinear dynamics, multiple steady states, and oscillations in photochemistryB. Borderie, D. Lavabre, J. C. Micheau, P. LaplanteCite this: Phys. Chem. 1992, 96, 7, 2953–2961Publication Date (Print):April 1, 1992Publication History Published online1 May 2002Published inissue 1 April 1992https://pubs.acs.org/doi/10.1021/j100186a035https://doi.org/10.1021/j100186a035research-articleACS PublicationsRequest reuse permissionsArticle...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTQuantitative analysis of continuous-variation plots with a comparison several methods: Spectrophotometric study organic and inorganic 1:1 stoichiometry complexesE. Bruneau , D. Lavabre G. Levy J. C. Micheau Cite this: Chem. Educ. 1992, 69, 10, 833Publication Date (Print):October 1, 1992Publication History Received3 August 2009Published online1 October 1992Published inissue 1 1992https://doi.org/10.1021/ed069p833Request reuse permissionsArticle...

The Diels–Alder reaction kinetics between diphenylfulvene and maleimide using mechanochemistry in liquid state is described. This was carried out solid a modified vibratory ball-mill with temperature control solution toluene as solvent. effect of temperature, ball mass, material, additives, aging were studied. We reported for the first time mechanochemical depending on ratio mass/mass reagent. A new kinetic model has been established that corresponds well to our experimental data allows an...

The photochromic and solvatochromic behavior of four phenanthroline-containing spirooxazines bearing various alkyl long-chain substituents has been investigated in different polar nonpolar solvents at temperatures. These derivatives always appeared an equilibrium mixture spiro forms open merocyanines. Depending on the solvents, percentage spontaneous merocyanine form ranged from less than 10% to more 30%. results have corroborated by independent NMR photokinetic analysis. main spectroscopic,...

Periodic Marangoni convective instability has been observed in a biphasic system during the mass transfer of cetyltrimethylammonium bromide (CTAB) from an aqueous to dichloromethane organic phase. Visualization fluxes was possible thanks CTAB crystals that are formed phase at temperature below Krafft point. Surface tension and electrical potential oscillations have shown be correlated with fluid motion. measurements, representative adsorption state, showed fast stage, followed by slower...

Study of the interactions between a cationic laser-dye (rhodamine 6G or R6G) and an anionic surfactant (sodium dodecyl sulfate SDS) in aqueous solution has demonstrated that so-called premicellar effect on absorbance fluorescence occurring oppositely charged dye/surfactant systems is associated with slow ion-pair aggregation/precipitation process. The red-shift UV/visible band broadening which occurs during precipitation process been attributed to formation nanoparticles size-dependent...

Adsorption isotherms have been determined at the water/oil interface for five biphasic systems involving surfactants (non-ionic and ionic) present in both phases partition equilibrium. The studied were polyoxyethylene(23)lauryl ether (Brij35) water/hexane four ionic surfactants, hexadecyltrimethylammonium bromide (CTAB), a series of three tetraalkylammonium dodecylsulfate (TEADS, TPADS, TBADS) water/CH 2Cl 2. Interfacial tension measurements performed water/air interfaces provided all...

Spectral properties and photochromic behavior of a series novel 1',3',3'-trimethyl-1,2-tetramethylenespiro[7H-furo(3,2-f)-(2H-1)-benzopyran-7,2'-indolines] 1-4 have been studied. The mechanism the photoinitiated ring-opening reaction involves formation an acoplanar cis-cisoid intermediate, lifetime which in case 6-(tert-butyl) derivative 4 is long enough to observe its absorption fluorescence spectra under conditions continuous irradiation. occurrence intermediate on paths thermal...

The photophysical and photochemical properties of four 3,3-diphenyl-3H-naphtho[2,1- b]pyrans substituted, via an acetylenic junction, to (thiophene) n oligomers (n = 0-3 units) were investigated by transient absorption in the femtosecond microsecond time domain stationary fluorescence. decay initially produced excited S1(pi pi*) state is found occur three competing processes: fluorescence, intersystem crossing, a ring-opening reaction leading colored merocyanine product, with relative yields...