Laboratoire de Photophysique et Photochimie Supramoléculaires et Macromoléculaires

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLinear and Nonlinear Optical Properties of Photochromic Molecules and MaterialsJacques A. Delaire and Keitaro NakataniView Author Information Laboratoire de Photophysique et de Photochimie Supramoléculaires et Macromoléculaires (PPSM, UMR 8531 of CNRS), Ecole Normale Supérieure de Cachan, 94235 Cachan Cedex, France Cite this: Chem. Rev. 2000, 100, 5, 1817–1846Publication Date (Web):March 10, 2000Publication History Received2 September 1999Published online10 March 2000Published inissue 1 May 2000https://pubs.acs.org/doi/10.1021/cr980078mhttps://doi.org/10.1021/cr980078mresearch-articleACS PublicationsCopyright © 2000 American Chemical SocietyRequest reuse permissionsArticle Views9682Altmetric-Citations1074LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Molecules,Nonlinear optics,Optical properties,Polarization,Polymers Get e-Alerts

8-Hydroxyquinoline (8-HQ), referred as to oxine in analytical chemistry, is a fluorogenic ligand. Its lack of fluorescence in water and alkanes, and its low quantum yield in many other organic solvents, are rationalized in the present study in terms of photoinduced formation of a nonfluorescent tautomeric form 8-HQ(T*). In water, intermolecular proton transfers with surrounding water molecules are expected, but intrinsic intramolecular proton transfer between the −OH and ⩾N functions cannot be ruled out because the presence of a weak internal H bond can be inferred from the ground-state properties of 8-HQ such as pKa values or solubility. In organic solvents, vapor pressure osmometry measurements in conjunction with infrared spectra allow us to show that (i) in alkane solvents, a very stable dimer is formed in the ground state (Kdim = 7 × 107 at 25 °C); biprotonic concerted proton transfers are then expected to occur within the dimer upon excitation, as was previously reported for 7-azaindole; (ii) in chlorinated solvents (CH2Cl2, CHCl3), hydration by residual water molecules likely leads to a nonnegligible fraction of hydrated open structures where excited-state proton transfer is impaired; a weak fluorescence can then be observed (ΦF ≈ 4 × 10-3).

A detailed study on the photophysical and complexing properties of calixarenes bearing two and four dansyl derivatives (Calix-DANS2 and Calix-DANS4) in a CH3CN/H2O mixture (60:40 v/v) is reported. Calix-DANS2 shows a high selectivity towards Hg2+ over interfering cations (Na+, K+, Ca2+, Cu2+, Zn2+, Cd2+ and Pb2+) and a sensitivity in the 10(-7) mol L(-1) concentration range. The complexation of mercury ion induces a strong fluorescence quenching due to a well-defined electron transfer process from the fluorophore to the metal center. Calix-DANS4 exhibits an extremely high affinity for Pb2+ with a high selectivity over various competing ions. The unprecedented detection limit (4 microg L(-1)) is fully compatible with the level defined by the World Health Organisation. The affinity of Calix-DANS4 for Pb2+ can be rationalized by the activation of the inert pair of electrons on Pb2+. The number of fluorophores involved in the complexation can be determined from a careful time-resolved fluorescence characterization.

Two new anil molecules exhibiting photochromism in the crystalline state, N-(4-hydroxy)-salicylidene-amino-4-(methylbenzoate) (2) and N-(3,5-di-tert-butylsalicylidene)-4-aminopyridine (3), are obtained. Upon irradiation in the UV, the yellow crystals change color to red, owing to enol-keto intramolecular tautomerism. The red color disappears, when crystals are left in the dark or irradiated with visible light. 3 has the most stable keto form among all anil-type photochromic compounds (τ = 460 days at room temperature). Both exhibit nonlinear optical (NLO) properties and show powder second harmonic generation (SHG) of respectively 10 and 3 times vs urea. X-ray diffraction shows acentric structures where molecules line up "head-to-tail" through hydrogen bonds for 2 (space group Pc), or form a chiral helix 3 (space group P32). Evidence of reversible structural change is given for 3, and we demonstrate the functionality of this crystal as an NLO switching material, as SHG can be photomodulated by about 30%.

With the aim of optical sensing of Hg2+ in water, a calixarene bearing two dansyl fluorophores was grafted on a large pore mesoporous silica material (SBA-15) via two long alkyl chains containing triethoxysilane groups. The characterization of the obtained material 2-SBA-15 shows that the organized structure is preserved after the post-grafting procedure. A detailed study of the complexing and fluorescence properties of 2-SBA-15 is reported. The functionalized material is able to reversibly detect Hg2+ with a response time of a few seconds and a detection limit of 3.3 × 10−7 mol L−1 in water. Furthermore, this system offers a high selectivity over several interfering cations (Na+, K+, Ca2+, Cu2+, Cd2+, Pb2+).

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Flipping the switch: A new type of bipyridine-based ligand functionalized by phenyl- and dimethylaminophenyldithienylethene groups allows the preparation of photochromic dipolar zinc(II) complexes. For the first time, efficient on/off photoswitching of the NLO response of metallochromophores is observed. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2008/z704138_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Two N-pyrenylacetamide-substituted sugar-aza-crown ethers have been synthesized as new fluorescent chemosensors. The designed ligands 1 and 2 exhibit fluorescence characteristics of a pyrene monomer and a dynamic excimer emission when compared to N-pyrenylacetamide as a model compound. Both ligands displayed a Cu2+-sensitive fluorescence quenching with a 1:1 stoichiometry and high stability constants (log K = 6.7 for 1 and 7.8 for 2). The quenching effect was rationalized on the basis of photoinduced electron transfer from the excited pyrene to the complexed Cu2+ cation, while the changes in excimer-to-monomer ratio were explained by a conformational analysis through DFT calculations. The predicted structure suggests that the Cu2+ cation is coordinated with the two carbonyl groups and the sugar-aza-crown ethers which rigidified the complex structure and placed the two pyrene moieties far apart.

Noncentrosymmetric crystals of photochromic N-salicylidene-4-bromoaniline are obtained and studied for their second-order nonlinear optical properties. Second harmonic light is generated and can be seen by the naked eye. Moreover, photochromism in the bulk state yields totally reversible photoswitching of the second harmonic intensity.

This work reports the first structure-properties relationship study of ortho [2,1-c]-, meta [1,2-a]-, and para [1,2-b]dihydroindenofluorenes, highlighting the influence of bridge rigidification on the electronic properties. This study has made it possible to devise an extended π-conjugated molecule with both a high triplet state energy level and excellent thermal and morphological stability. As a proof of concept, dihydroindenofluorenes were used as the host in sky-blue phosphorescent organic light-emitting diodes (PhOLEDs) with high performance.

A new fluorescent molecular sensor based on a calix[4]arene bearing four dansyl groups exhibits very efficient binding in acetonitrile-water for lead and the changes of emission properties allows a detection limit of 4 microg L(-1).

Abstract New tetrazines substituted by heteroatoms have been synthesized and their electrochemical and photochemical properties investigated. All compounds are reversibly electroactive with standard potentials shifting cathodically according to the donor character of the substituent. The tetrazine derivatives are also fluorescent with maximum emission wavelengths in the range 550–575 nm. Some of them show very long fluorescence lifetimes (several tens of ns) and remain fluorescent in the solid state without major changes in the spectral features. The fluorescence of one of the derivatives can be efficiently quenched by the presence of electron‐rich compounds such as triphenylamines, phenol or anisole, which make them very promising compounds for sensor applications.

Original tetrazines substituted by heterocyclic rings have been prepared. Their syntheses, as well as their electrochemical and spectroscopic features, are described. Calculations have also been made on the cation radicals, anion radicals and neutral compounds and are in correct agreement with the experimental results. All compounds are electroactive, both in oxidation and reduction, and display two absorption bands in the UV and visible regions of the spectrum. Reduction potentials and maximum wavelengths are correlated with the electron-rich character of the heterocyclic substituent on the tetrazine ring. None of these compounds gives good quality polymers upon electro-oxidation, which was unexpected, especially for the bis(2-pyrrolyl) tetrazine. This latter result can be explained by the occurrence of a self-deprotonation equilibrium in the cation radical.

Calixarene-based fluoroionophores composed of tert-butylcalix[4]arenes with one or four appended naphthalene moieties, such as the one shown here, exhibit not only red shifts in the absorption and emission spectra upon complexation, but also drastic enhancement of the fluorescence quantum yields. Complexation studies show very high selectivities towards sodium in ethanol and ethanol–water mixtures. The syntheses and properties of two calixarene-based fluorescent molecular sensors are reported. These comprise tert-butylcalix[4]arene either with one appended fluorophore and three ester groups (Calix-AMN1), or with four appended fluorophores (Calix-AMN4). The fluorophore is 6-acyl-2-methoxynaphthalene (AMN), which contains an electron-donating substituent (methoxy group) conjugated to an electron-withdrawing substituent (carbonyl group); this allows photoinduced charge transfer (PCT) to occur upon excitation. The investigated fluoroionophores thus belong to the family of PCT fluorescent molecular sensors. In addition to the expected red shifts of the absorption and emission spectra upon cation binding, a drastic enhancement of the fluorescence quantum yield—in an “off–on” fashion comparable to that seen in photoinduced electron transfer (PET) molecular sensors—was observed. For Calix-AMN1, it increases from 10−3 for the free ligand to 0.68 for the complex with Ca2+. This exceptional behaviour can be interpreted in terms of the relative locations of the nπ* and ππ* levels, which depend on the charge density of the bound cation. For Calix-AMN4, in addition to the photophysical effects observed for Calix-AMN1, interactions between the chromophores by complexation with some cations have been found in the ground state (hypochromic effect) and in the excited state (excimer formation). Steady-state fluorescence anisotropy measurements for the system Na+⊂Calix-AMN4, show a depolarization effect due to energy transfer (homotransfer) between the fluorophores. Regarding the complexing properties, a high selectivity for Na+ over K+, Li+, Ca2+ and Mg2+ was observed in ethanol and ethanol–water mixtures. The selectivity (Na+/other cations) expressed as the ratio of the stability constants was found to be more than 400. Cet article présente la synthèse et lapos;étude des propriétés photophysiques et de complexation de deux nouvelles sondes fluorescentes à base de calixarène. Ces fluoroionophores sont constitués de tert-butylcalix[4]arenes liés de façon covalente à un fluorophore et trois groupes ester (Calix-AMN1) ou à quatre fluorophores (Calix-AMN4). Le fluorophore utilisé est composé dapos;un groupe methoxy (donneur) conjugué à un groupe carbonyle (accepteur), participant à la complexation du cation. Ainsi un transfert de charge photoinduit se produit lors de lapos;excitation lumineuse. La complexation du cation par le calixarène sapos;accompagne non seulement dapos;un déplacement bathochrome des spectres dapos;absorption et de fluorescence mais aussi dapos;une très forte augmentation du rendement quantique de fluorescence aussi importante que dans le cas de fluorionophores fonctionnant suivant le principe du transfert dapos;électron photoinduit (PET). Dans le cas du Calix-AMN1, le rendement quantique passe de ≈10−3 à 0.68 lors de la complexation avec le calcium. Ce phénomène remarquable peut sapos;expliquer par une modification des niveaux dapos;énergie relatifs des états singulets ππ* et nπ* (dépendant de la densité de charge du cation complexé). Dans le cas du Calix-AMN4, des intéractions entre les chromophores lors de la complexation de cations ont été mises en évidence aussi bien à lapos;état fondamental (effet hypochrome) quapos;à lapos;état excité (formation dapos;excimères). Dapos;autre part des mesures dapos;anisotropie de fluorescence sur le système Na+⊂Calix-AMN4 ont montré un effet de dépolarisation dû à lapos;existence dapos;un transfert dapos;énergie entre les chromophores (homotransfert). En ce qui concerne les propriétés de complexation, une excellente sélectivité de ces systèmes vis-à-vis du sodium par rapport aux autres cations a été obtenue dans des solvants protiques (éthanol et mélanges éthanol–eau). La sélectivité du sodium par rapport aux autres cations (exprimée par le rapport des constantes de stabilité) est supérieure à 400.

Small molecule-based amorphous materials involving unsymmetrical triarylamines exhibit multicolor emission as transparent thin films and nanoparticles under single UV wavelength excitation. Tuning of the emission originally stems from combined interbranch energy transfer and intramolecular charge transfer leading to blue to red outputs in the solid state.

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This article reviews the synthesis, structural and optical characterizations of some novel luminescent two dimensional organic-inorganic perovskite (2DOIP) semiconductors. These 2DOIP semiconductors show a self-assembled nano-layered structure, having the electronic structure of multi-quantum wells. 2DOIP thin layers and nanoparticles have been prepared through different methods. The structures of the 2DOIP semiconductors are characterized by atomic force microscopy and X-ray diffraction. The optical properties of theb DOIP semiconductors are characterized from absorption and photoluminescence spectra measured at room and low temperatures. Influences of different components, in particular the organic parts, on the structural and optical properties of the 2DOIP semiconductors are discussed.

Broad-frequency dielectric behaviors of multiwalled carbon nanotubes (MWCNTs) embedded in room temperature vulcanization silicone rubber (RT-SR) matrix were studied by analyzing alternating current (ac) impedance spectra, which would make a remarkable contribution for understanding some fundamental electrical properties in the MWCNT/RT-SR nanocomposites. Equivalent circuits of the MWCNT/RT-SR nanocomposites were built, and the law of polarization and mechanism of electric conductance under the ac field were acquired. Two parallel RC circuits in series are the equivalent circuits of the MWCNT/RT-SR composites. At different frequency ranges, dielectric parameters including conductivity, dielectric permittivity, dielectric loss, impedance phase, and magnitude present different behaviors.

A new fluorescent molecular sensor for Hg2+ based on the phosphane sulfide derivative exhibits a very low detection limit in an aqueous medium (3.8 nM) with a very high selectivity over other interfering cations. The reversibility of the complexation process was also examined and was found to be successful. [structure: see text]

The optical limiting effect induced by gold clusters was measured as a function of excitation wavelength. The limiting effect is most efficient below 530 nm, and decreases towards the red. Two different behaviors are seen in the time-resolved signals in the nanosecond and picosecond ranges. These behaviors have different time delays for the amplitude maxima and for the fluence thresholds where nonlinear effects are observed. This suggests that two types of scattering centers are responsible for the optical limitation. The fast mechanism, which reaches a maximum amplitude in less than 1 ns, occurs at relatively high fluence and for short pulses and is assigned to the vaporization of metal particles. It is more pronounced for large clusters where the absorbed light energy is primarily highly confined. The slow mechanism, which develops in a few nanoseconds, is assigned to the energy transfer from the gold particles to the surrounding solvent and to the formation of solvent bubbles. At lower fluence and for smaller size clusters, only the second mechanism is observed in the nanosecond range, because the efficient dissipation of energy from the small clusters to the solvent, which produces bubbles, precludes metal-particle vaporization.