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Photoactivatable probe-based fluorescent imaging has become an efficient and attractive technique for spatiotemporal microscopic studies of biological events. However, almost all previously reported photoactivatable organic probes have been based on hydrosoluble precursors, which have produced water-soluble active fluorophores able to readily diffuse away from the photocleavage site, thereby dramatically reducing spatial resolution. Hydroxyphenylquinazolinone (HPQ), a small organic dye known for its classic luminescence mechanism through excited-state intramolecular proton transfer (ESIPT), shows strong light emission in the solid state, but no emission in solution. In this work, HPQ was employed as a precursor to develop a localizable, photoactivatable two-photon probe (PHPQ) for spatiotemporal bioimaging applications. After photocleavage, PHPQ releases a precipitating HPQ fluorophore which shows both one-photon and two-photon excited yellow-green fluorescence, thereby producing a localizable fluorescence signal that affords high spatial resolution for bioimaging, with more than 200-fold one-photon and 150-fold two-photon fluorescence enhancement. [ABSTRACT FROM AUTHOR]

We prepared CoFe2O4-RGO (RGO: reduced graphene oxide) composites by ball-milling without using toxic chemical reagents and high-temperature heat treatment. The exfoliation and reduction of graphite oxide and anchoring of CoFe2O4 nanoparticles on graphene sheets were accomplished in one step. The microstructure of the heterophotocatalyst was characterized by X-ray diffraction, Fourier transform infrared, Raman and transmission electron microscopy methods. The photocatalyst exhibited desirable photocatalytic performance with excellent recycling stability for the degradation of methylene blue, rhodamine B and methyl orange under visible-light irradiation. In addition, the CoFe2O4-RGO photocatalyst can be easily separated by an external magnetic field. The simple and efficient one-step ball-milling strategy for preparing the photocatalysts is more applicable to industrial production. [ABSTRACT FROM AUTHOR]

The design of artificial systems that mimic highly evolved and finely tuned natural photosynthetic systems is a subject of intensive research. We report herein a new approach to constructing supramolecular systems for the photocatalytic generation of hydrogen from water by encapsulating an organic dye molecule into the pocket of a redox-active metal--organic polyhedron. The assembled neutral Co4L4 tetrahedron consists of four ligands and four cobalt ions that connect together in alternating fashion. The cobalt ions are coordinated by three thiosemicarbazone NS chelators and exhibit a redox potential suitable for electrochemical proton reduction. The close proximity between the redox site and the photosensitizer encapsulated in the pocket enables photoinduced electron transfer from the excited state of the photosensitizer to the cobalt-based catalytic sites via a powerful pseudo-intramolecular pathway. The modified supramolecular system exhibits TON values comparable to the highest values reported for related cobalt/fluorescein systems. Control experiments based on a smaller tetrahedral analogue of the vehicle with a filled pocket and a mononuclear compound resembling the cobalt corner of the tetrahedron suggest an enzymatic dynamics behavior. The new, well-elucidated reaction pathways and the increased molarity of the reaction within the confined space render these supramolecular systems superior to other relevant systems. [ABSTRACT FROM AUTHOR]

An N-annulated indenoperylene electron- donor decorated with photochemically inactive segments is synthesized and further conjugated via triple bond with electron-acceptor benzothiadiazolylbenzoic acid for a metal-free donor/acceptor dye. Without use of any coadsorbate, the judiciously tailored indenoperylene dye achieves a high-power conversion efficiency of 12.5% under irradiance of 100 mW cm-2 AM1.5G sunlight. [ABSTRACT FROM AUTHOR]

Traditionally, optical titrations of inorganic ions are based on a rapid and visible color change at the end point with water-soluble organic dyes as indicators. Adequate selectivity is required for both the indicator and the complexing agent, which is often limited. We present here alternative, heterogeneous ionophore-based ion-selective nanospheres as indicators and chelators for optical titrations. The indicating nanospheres rely on a weaker extraction of the analyte of interest by ion-exchange, owing to the additional incorporation of a lipophilic pH indicator in the nanosphere core. Ca2+ titration was demonstrated as a proof-of-concept. Both the chelating and the indicating nanospheres showed good selectivity and a wide working pH range. [ABSTRACT FROM AUTHOR]

A diversity-orientedone-pot synthesis of a series of membrane-permeableBF2-rigidified benz[c,d]indole N-heteroarene BBN and BBC dyes has beenachieved from the condensation of two commercial components (benz[c,d]indol-2-one and a set of N-heteroarene derivatives that can be selected from thousands of commerciallyavailable sources) and the subsequent in situ BF2complexationreaction. These dyes enjoy a set of excellent photophysical propertiesincluding the large Stokes shift, high solution and solid-state fluorescence,and excellent photostabilities. [ABSTRACT FROM AUTHOR]

Flexible microdisk whispering-gallery-mode (WGM) resonators with high quality factors were achieved through the controlled assembly of organic materials with an emulsion-solvent-evaporation method. The high material compatibility of the assembled microdisks enabled us to realize low-threshold WGM lasers by doping with organic dyes as gain media. Furthermore, the emulsion-assisted self-assembly provided a strategy for the one-step fabrication of microwire-waveguide-connected microdisk heterostructures, which can be utilized for the efficient output of the isotropic WGM lasers from the coupled waveguides. We hope that these results will pave an avenue for the construction of new types of flexible WGM-based components for photonic integration. [ABSTRACT FROM AUTHOR]

Lanthanide-doped upconverting nanoparticles(UCNPs) are highlypromising candidates for bioimaging and for cellular nanothermometryas a novel diagnostic tool. Aiming for the diagnosis of diseases atvery early stages in order to optimize therapy and recovery of thepatient, it must be taken into account that thermal singularitiesare often one of the first indicators of a disease. It is thereforeour goal to develop a nanothermometer based on UCNPs that is suitableto detect the temperature at a subcellular level in the physiologicalrange. Thus, upconverting NaGdF4:Er3+,Yb3+nanoparticles that convert near-infrared (NIR) into visible(VIS) light are synthesized by thermal decomposition. Appropriatesurface modification with a thermoresponsive polymer pNIPAM (poly(N-isopropylacrylamide)) guarantees dispersibility in aqueousmedia required for biomedical applications. In a further step, thecombination of the obtained UCNPs with an organic dye (FluoProbe532A)provides potential donor-acceptor-pairs allowing for energy transferprocesses, whereas the light emitted by the Er3+ions (donors)is absorbed by the organic dye (acceptor). It has been demonstratedthat the dye-conjugated UCNPs undergo a temperature-dependent energytransfer process inducing a temperature-dependent increase in thethermal sensitivity when compared to unlabeled UCNPs. This resultindicates the great potential of the presented nanoprobes for applicationsin nanothermometry. [ABSTRACT FROM AUTHOR]

Four uranium(VI)-polycarboxylatesframeworks with honeycomb (6,3) nets have been assembled from solvothermalsystems, which contain different guest molecules (transition metalcomplexes and methyl viologen). These compounds exhibit photocatalyticactivities for the degradation of rhodamine B. Interestingly, themethyl viologen-containing one possesses the highest efficiency, whichcan be attributed to the electron acceptor nature of methyl viologenfor the stabilization of active peroxide anions. [ABSTRACT FROM AUTHOR]

The anionic Zn-2,5-thiophenedicarboxylate framework material (1) built from the connection of Johnson cages can perform Ag+-exchange to upgrade the uptakes of C2 hydrocarbons (C2s) and separation properties of C2s over methane (C1). Moreover, its activated phase (1a) can enrich organic dyes from ethanol and make a significant red-shift in photoluminescent spectra of Rhodamine B (Rh B) via varying the aggregation states of dye molecules. [ABSTRACT FROM AUTHOR]

Quantumdots (QDs) offer distinct advantages over organic dyes and fluorescentproteins forbiological imaging applications because of their brightness, photostability,and tunability. However, a major limitation is that single QDs emitfluorescent light in an intermittent on-and-off fashion called “blinking”.Here we report the development of blinking-suppressed, relativelycompact QDs that are able to maintain their favorable optical propertiesin aqueous solution. Specifically, we show that a linearly gradedalloy shell can be grown on a small CdSe core via a precisely controlledlayer-by-layer process, and that this graded shell leads to a dramaticsuppression of QD blinking in both organic solvents and water. A substantialportion (>25%) of the resulting QDs does not blink (more than 99%of the time in the bright or “on” state). Theoreticalmodeling studies indicate that this type of linearly graded shellnot only can minimize charge carrier access to surface traps but alsocan reduce lattice defects, both of which are believed to be responsiblefor carrier trapping and QD blinking. Further, we have evaluated thebiological utility of blinking-suppressed QDs coated with polyethyleneglycol (PEG)-based ligands and multidentate ligands. The results demonstratethat their optical properties are largely independent of surface coatingsand solvating media, and that the blinking-suppressed QDs can providecontinuous trajectories in live-cell receptor tracking studies. [ABSTRACT FROM AUTHOR]

We report discovery of a new efficientand robust antenna compositefor light harvesting. The organic dye hostasol red (HR) is stronglyluminescent in aprotic solvents but only weakly luminescent in potassiumzeolite L (ZL) at ambient conditions. We observed a dramatic increaseof the luminescence quantum yield of HR–ZL composites if someor all exchangeable potassium cations of ZL are substituted by anorganic imidazolium cation (IMZ+) and if the acceptor HRis embedded in the middle part of the channels, so that it is fullyprotected by the environment of the perylene dye tb-DXP. This ledto the discovery of a highly efficient donor,acceptor-ZL antenna materialwhere tb-DXP acts as donor and HR acts as acceptor. The material hasa donor-to-acceptor (D/A) absorption ratio of more than 100:1 anda nearly quantitative FRET efficiency. Synthesis of this host–guestmaterial is reported. We describe a successful procedure for achievingfull sealing of the ZL channel entrances such that the guests cannotescape. This new material is of great interest for applications inluminescent solar concentrator (LSC) devices because the efficiencykilling self-absorption is very low. [ABSTRACT FROM AUTHOR]

A structurally and compositionally well-defined and spectrally tunable artificial light-harvesting system has been constructed in which multiple organic dyes attached to a three-arm-DNA nanostructure serve as an antenna conjugated to a photosynthetic reaction center isolated from Rhodobacter sphaeroides 2.4.1. The light energy absorbed by the dye molecules is transferred to the reaction center, where charge separation takes place. The average number of DNA three-arm junctions per reaction center was tuned from 0.75 to 2.35. This DNA-templated multichromophore system serves as a modular light-harvesting antenna that is capable of being optimized for its spectral properties, energy transfer efficiency, and photostability, allowing one to adjust both the size and spectrum of the resulting structures. This may serve as a useful test bed for developing nanostructured photonic systems. [ABSTRACT FROM AUTHOR]

Historically, two-photon absorption (2PA) cross sections reported in the literature have been derived from solution-phase measurements. However, such techniques fail to grasp the implications of how these cross sections can be impacted by varying degrees of aggregation or in the condensed phase as bulk solids or thin films. For a precise determination of how aggregation impacts 2PA at a molecular level, computational methods present themselves as ideal. Herein, a series of quadrupolar π-conjugated dyes were simulated by molecular dynamics (MD) in the gas phase and condensed phase. In the condensed phase, their intermolecular interactions and electronic coupling behavior were fully characterized, both quantitatively and qualitatively. Using quadratic-response time-dependent density functional theory, 2PA cross sections of structures derived from MD trajectories were calculated. Comparisons are made between gas-phase and condensed-phase results, and enhancement factors are defined to show how certain dyes may experience changes in their respective 2PA cross sections as a function of aggregation. It was found that these cross sections depend heavily on conformational locking in the condensed phase and relative stacking arrangements. J-aggregates were associated with enhanced 2PA and H-aggregates with quenched 2PA activity. However, in a highly disordered aggregate, the effects of these stacking arrangements are averaged out of the bulk result, and the effects of conformational locking dominate.

The convenient synthesis of a new class of conjugated aza-BODIPY derivatives from readily available precursors has been achieved. The new materials bear close structural similarity to BODIPYs but differ significantly in electronic configuration from known derivatives, leading to markedly different absorption and emission properties. [ABSTRACT FROM AUTHOR]

Hybrid materials based on photoactivemolecules confined into nanostructuredsubstrates are very promising for technological applications. However,little is known about the impact of organic dyes on the mechanicalproperties of the substrate, a key aspect for their practical implementation.In this work, we use atomistic simulation methods to investigate themechanical properties of two hybrid systems consisting on a clay matrix(laponite) loaded with two different cationic dyes (LDS-722 and pyroninY). We applied tensile and shear deformations to the layered hybridmaterials and characterize the key mechanism triggering their failure.It has been observed that the water and dye molecules located in theinterlaminar spaces are those involved in the deformation processes,while the structure of the laponite layers does not change. Furthermore,it has been also found that the incorporation of dye molecules modifiesthe hydrogen-bonding network of water in the interlaminar space, worseningthe mechanical properties of the hybrids with respect to the clay.The information obtained by molecular simulation help us to assessthe mechanical behavior of these materials, and to design materialswith tailored strength. [ABSTRACT FROM AUTHOR]

Three D–A−π–Aorganic dyes based on5,6-difluoro-2,1,3-benzothiadiazole (DFBTD) were synthesized by sequentialdirect arylation and characterized by spectroscopic and electrochemicaltechniques. Compared to 2,1,3-benzothiadiazole (BTD) analogue, thepresence of two fluorine atoms on DFBTD results not only in a significantincrease in the molar absorptivity but also in a blue shift of theonset of the absorption spectra. In the system of DFBTD-based sensitizers,replacing the thienyl unit bridge with disubstituted cyclopenta[1,2-b:5,4-b′]dithiophene (CPDT) furtherincreases molar absorptivity and decreases the oxidation potentialof the excited state E(s+/s*). Similarly,changing the indoline donor to 4-butoxy-N-(4-butoxyphenyl)-N-phenylaniline increases the optical band gap and decreasesthe oxidation potential of the excited state E(s+/s*)of the sensitizer. The correlation between the molecularstructure of these sensitizers and the photovoltaic performance ofthe dye cells were examined using current–voltage scan, incidentphoton to electron conversion efficiency (IPCE), femtosecond transientabsorption spectroscopy (TAS), and electrochemical impedance spectroscopy(EIS). The observed change of the photovoltage and photocurrent uponchanging the molecular structure of the sensitizers are discussedin terms of the charge injection from the excited state to the interbandgap states of TiO2and the charge recombination betweeninjected electrons into TiO2film and electrolyte. In all,it is found that the most efficient D–A−π–Adye achieved an open circuit voltage of 0.717 V, short circuit currentdensity of 18.8 mA/cm2, corresponding to an overall powerconversion efficiency of 9.1%. [ABSTRACT FROM AUTHOR]

A new synthetic strategy for indolo[2,3-b]carbazolevia a double-intramolecular Buchwald–Hartwig reaction has beenestablished. The N-alkylated indolo[2,3-b]carbazole then was adopted as the geometry-fixed core for the synthesisof a new molecule (ICZDTA) bearing two bithiophene π-bridged2-cyanoacrylic acid groups as the bidentate anchor. The bidentateanchoring together with efficient HOMO (indolo[2,3-b]carbazole) → LUMO (TiO2nanocluster) electrontransfer leads to the successful development of ICZDTA-based DSSC with a power conversion efficiency of 6.02%. [ABSTRACT FROM AUTHOR]

A novel triphenylamine-based organic dye, TTA, with an acrylic group is designed to graft TiO2 nanoparticles for sensitive and selective photoelectrochemical sensing. The synthesized TTA possesses a high molar absorption coefficient, leading to an enhanced photoelectron emission ability of the electron donor. The carboxyl group of TTA acts as not only an electron acceptor but also a linker to connect TTA to TiO2 nanoparticles. Under irradiation, TTA shows fast intramolecular charge transfer from triphenylamine to carboxyl group via the nbridge of thiophene moiety, thus producing a sensitive photocurrent response. Meanwhile, the acrylic moiety provides an active site for the Michael addition reaction, which would destroy the π-bridge and decrease the photocurrent response. Thus, a selective photoelectrochemical sensing strategy is proposed for detection of small biomolecules. Using cysteine as a model analyte, this sensing strategy shows a detectable range from 1 to 200 μM, without die interference from natural amino acids and various biological reducing reagents. This work offers a new photoelectrochemical route to highly selective and sensitive detection of biologically important small molecules. [ABSTRACT FROM AUTHOR]

Two new organic dyes(PTN1and NPT1)of the configuration D–A–π–A, based on 2H-[1,2,3]triazolo[4,5-c]pyridine(PT) as a central linker, have been synthesized and used as the sensitizersfor dye-sensitized solar cells. Compared with pyridal[2,1,3]thiadiazole-containingcongeners, the new dyes have conversion efficiencies nearly 1 orderhigher due to alleviation of charge trapping. The best conversionefficiency of the cell reaches 6.05% (under AM 1.5G irradiation).Upon addition of the coadsorbent CDCA, the efficiency is boosted to6.76%, which reaches ∼90% of the standard based on N719. [ABSTRACT FROM AUTHOR]

To systematically explore the effectof polynuclear complexes onphotocatalytic degradation of the organic dyes, a series of coordinationcomplexes containing CdIIclusters, formulated as {[Cd3L2(H2O)5]·H2O}n(1), {[Cd3L2(hbmb)(H2O)2]·2.5H2O}n(2), {[Cd3L2(btbb)(H2O)2]·2EtOH·1.5H2O}n(3), and {[Cd6L4(bipy)2(H2O)6]·3H2O}n(4) (H3L = 3,4-bi(4-carboxyphenyl)-benzoic acid, hbmb =1,1′-(1,6-hexane)bis(2-methylbenzimidazole), btbb = 1,4-bis(2-(4-thiazolyl)benzimidazole-1-ylmethyl)benzene,4,4′-bipy = 4,4′-bipyridine), have been designed andsynthesized. Complex 1based on trinuclear CdIIclusters exhibits a new (3,3,6)-connected 3D framework. 2belongs to a (3,3,8,8)-connected tfz-d topology net with pillar-layeredframeworks assembled by two kinds of trinuclear CdIIclusters. 3is a 3D pillar-layered framework, which features a (3,8)-connectedtfz-d net based upon one kind of trinuclear CdIIcluster. 4presents a new 3D (3,6,10)-connected framework with dinuclearand tetranuclear clusters. The photocatalytic properties of complexes 1–4have been studied in detail. Remarkably, 1–4all reveal good photocatalytic activityin MB/MO degradation. The optical energy gap calculated by the diffusereflectivity spectra of 1–4are consistentwith their degradation rates. Moreover, the experimental results furtherdemonstrate that the cluster complexes containing different kindsof nuclei may exert different impact on the decomposition of disparateorganic dyes. [ABSTRACT FROM AUTHOR]

Theorganic dye filters of conventional color image sensors achievethe red/green/blue response needed for color imaging, but have disadvantagesrelated to durability, low absorption coefficient, and fabricationcomplexity. Here, we report a new paradigm for color imaging basedon all-silicon nanowire devices and no filters. We fabricate pixelsconsisting of vertical silicon nanowires with integrated photodetectors,demonstrate that their spectral sensitivities are governed by nanowireradius, and perform color imaging. Our approach is conceptually differentfrom filter-based methods, as absorbed light is converted to photocurrent,ultimately presenting the opportunity for very high photon efficiency. [ABSTRACT FROM AUTHOR]

We show strong coupling involvingthree different types of resonances in plasmonic nanoarrays: surfacelattice resonances (SLRs), localized surface plasmon resonances onsingle nanoparticles, and excitations of organic dye molecules. Themeasured transmission spectra show splittings that depend on the moleculeconcentration. The results are analyzed using finite-difference time-domainsimulations, a coupled-dipole approximation, coupled-modes models,and Fano theory. The delocalized nature of the collective SLR modessuggests that in the strong coupling regime molecules near distantnanoparticles are coherently coupled. [ABSTRACT FROM AUTHOR]

New organic dyes containing fluorene functionalized with two imidazole chromophores as donors and cyanoacrylic acid acceptors have been synthesized and successfully demonstrated as sensitizers in nanocrystalline TiO2-based dye-sensitized solar cells (DSSCs). The monoimidazole analogues were also synthesized for comparison. The Sommelet reaction of bromomethylated 2-bromo-9,9-diethyl-9H-fluorene produced the key precursor 7-bromo-9,9-diethyl-9H-fluorene-2,4-dicarbaldehyde required for the preparation of imidazole-functionalized fluorenes. Since the dyes possess weak donor segment, the electron-richness of the conjugation pathway dictated the optical, electrochemical, and photovoltaic properties of the dyes. The dyes served as sensitizers in DSSC and exhibited moderate efficiency up to 3.44%. The additional imidazole present on the fluorene has been found to retard the electron recombination due to the bulkier hydrophobic environment and led to high open-circuit voltage in the devices. [ABSTRACT FROM AUTHOR]

A hapten-grafted graphene-based biosensor by integrating both the graphene nanosheets and immunoassay sensing technologies was developed for ultrasensitive homogeneous competitive immunoassay of small molecules. The structure of hapten-grafted graphene avoids the activity loss of biomolecules immobilized onto the graphene surface and is beneficial to preserve the binding affinity between small molecule and its specific antibody. The sandwich structure formed between hapten-grafted graphene nanosheets and fluorescence-labeled antibody increases the quenching efficiency of the organic dye, thereby resulting in high signal-to-background ratios and improved sensitivity for Bisphenol A (BPA) detection. On the basis of fluorescence resonance energy transfer (FRET) and homogeneous competitive immunoassay mechanism, high BPA concentrations in the sample reduce the amount of fluorescence-labeled anti-BPA antibody bound to graphene-BPA nanosheets, thus resulting in remarkable fluorescence signals. The linear quantification of BPA over concentration ranges from 0.5 to 50 nM with a detection limit determined as 0.12 nM. These findings show that the proposed method provides a powerful tool for the rapid and sensitive detection of small molecules in biological and environmental samples. [ABSTRACT FROM AUTHOR]

Iron(III)–alginatefiber complex was prepared through thecoordination of alginate fiber with Fe(III) ions and characterizedusing Fourier transform infrared, X-ray diffraction, X-ray photoelectronspectroscopy, and diffuse reflectance UV–vis spectra, respectively.Effect of Fe(III) initial concentration and reaction temperature onthe Fe content of the obtained complex was also investigated. It wasthen tested as a heterogeneous Fenton photocatalyst for dye degradationwith H2O2. The results indicated that the carboxylgroups from alginate fiber successfully reacted with Fe(III) ionsto form the complex. Higher Fe(III) ion concentration or elevationof temperature led to a proportional increase in the Fe content ofthe complex. Moreover, Fe(III)–alginate fiber complex couldeffectively catalyze the dye mineralization in the dark or under lightirradiation in a wide pH range of 3–9. Its catalytic activitywas hardly affected by Na2SO4or NaCl in wastewater.The stable catalytic performance was observed in its reuse processes. [ABSTRACT FROM AUTHOR]

Circularly polarized luminescence (CPL) in simple (small, nonaggregated, nonpolymeric) O-BODIPYs (R)-1 and (S)-1 by irradiation with visible light is first detected as proof of the ability of a new structural design to achieve CPL from inherently achiral monochromophore systems in simple organic molecules. The measured level of CPL (∣glum∣) in solution falls into the usual range of that obtained from other simple organic molecules (10-5-10-2 range), but the latter having more complex architectures since axially chiral chromophores or multichromophore systems are usually required. The new design is based on chirally perturbing the acting achiral chromophore by orthogonally tethering a single axially chiral 1,1'-binaphtyl moiety to it. The latter does not participate as a chromophore in the light-absorption/emission phenomenon. This simple design opens up new perspectives for the future development of new small-sized CPL organic dyes (e.g., those based on other highly luminescent achiral chromophores and/or chirally perturbing moieties), as well as for the improvement of the CPL properties of the organic molecules spanning their use in photonic applications. [ABSTRACT FROM AUTHOR]

The effect of thedonor in an organic dye on the electron lifetimeof dye-sensitized solar cells (DSSCs) employing a cobalt redox electrolytewas investigated. We synthesized organic dyes with donor moietiesof carbazole, coumarin, triphenylamine, and N-phenyl-carbazoleand measured the current–voltage characteristics and electronlifetimes of the DSSCs with these dyes. The cell with the triphenylaminedonor dye produced the highest open circuit voltage and longest electronlifetime. On the other hand, the lowest open circuit voltage and shortestelectron lifetime was obtained with coumarin donor dye, suggestingthat the coumarin attracted the cobalt redox couples to the surfaceof the TiO2layer, thus increasing the concentration ofcobalt complex. On the other hand, the longest electron lifetime withtriphenylamine was attributed to the blocking effect by steric hindranceof the nonplanar structure of the donor. [ABSTRACT FROM AUTHOR]

Azo dyes are the most commonly used type of dye, accounting for 60-70% of all organic dye production worldwide. They are used as direct dyes in the textile, leather, printing ink, and cosmetic industries. The aim of this study was to assess the lethal and sublethal effects of the disazo dye Disperse Yellow 7 (DY7) in frogs to address a knowledge gap regarding mechanisms of toxicity and the potential for endocrine disrupting properties. Larvae of Silurana tropicalis (Western clawed frog) were exposed to DY7-contaminated water (0 to 22 μg/L) and sediment (0 to 209 μg/g) during early larval development. The concentrations used included the range of similar azo dyes found in surface waters in Canada. A significant decrease in tadpole survivorship was observed at 209 μg/g while there was a significant increase in malformations at the two highest concentrations tested in sediment. In the 209 μg/g treatment, DY7 significantly induced hsp70 (2.5-fold) and hsp90 (2.4-fold) mRNA levels, suggesting that cells required oxidative protection. The same treatment also altered the expression of two androgen-related genes: decreased ar (2-fold) and increased srd5a2 (2.6-fold). Furthermore, transcriptomics generated new hypotheses regarding the mechanisms of toxic action of DY7. Gene network analysis revealed that high concentrations of DY7 in sediment induced cellular stress-related gene transcription and affected genes associated with necrotic cell death, chromosome condensation, and mRNA processing. This study is the first to report on sublethal end points for azo dyes in amphibians, a growing environmental pollutant of concern for aquatic species. [ABSTRACT FROM AUTHOR]

This article describes the new multidimensional spectroscopy technique triply resonant sum frequency spectroscopy, a four-wave mixing technique sharing advantages of both 2D-IR and resonance Raman experiments. In this technique, lasers with three independent frequencies interact coherently within a sample and generate an output frequency at their triple summation. The output intensity depends on coupled electronic and vibrational resonances in the sample. We use an organic dye as a model system to demonstrate fully resonant, fully coherent multidimensional spectroscopy using two independently tunable mid-infrared vibrational interactions and one visible electronic interaction. When the pulses are time ordered, the method has a single coherence pathway, eliminating interference between pathways. Fundamental vibrational transitions appear on one axis and overtones and combinations bands on the other, allowing anharmonicities of the modes to be determined easily and conveying molecular coupling information. The experiments demonstrate coupling between seven vibrational ring modes and an electronic state, the resolution of a Fermi resonance, detection of low concentrations, elimination of excitation pulse scattering and fluorescence, background suppression of solvent and co-solutes, and observation of coherence dephasing dynamics. The electronic resonance enhancements used in this methodology are similar to the enhancements responsible for resonance Raman spectroscopy and can be considered resonance 2D-IR spectroscopy. [ABSTRACT FROM AUTHOR]

A SPASER,short for surface plasmon amplification by stimulatedemission of radiation, is key to accessing coherent optical fieldsat the nanoscale. Nevertheless, the realization of a SPASER in thevisible range still remains a great challenge because of strong dissipativelosses. Here, we demonstrate that room-temperature SPASER emissioncan be achieved by amplifying longitudinal surface plasmon modes supportedin gold nanorods as plasmon nanocavities and utilizing laser dyesto supply optical gain for compensation of plasmon losses. By choosinga particular organic dye and adjusting the doping level, the resonantwavelength of the SPASER emission can be tuned from 562 to 627 nmwith a spectral line width narrowed down to 5–11 nm. This workprovides a versatile route toward SPASERs at extended wavelength regimes. [ABSTRACT FROM AUTHOR]

We have demonstrated a template-free large-scale synthesis of nanostructured CdxZn1-xS by a simple and a low-temperature solid-state method. Cadmium oxide, zinc oxide, and thiourea in various concentration ratios are homogenized at moderate temperature to obtain nanostructured CdxZn1-xS. We have also demonstrated that phase purity of the sample can be controlled with a simple adjustment of the amount of Zn content and nanocrystalline CdxZn1-xS (x = 0.5 and 0.9) of the hexagonal phase with 6-8 nm sized and 4-5 nm sized Cd0.1Zn0.9S of cubic phase can be easily obtained using this simple approach. UV-vis and PL spectrum indicate that the optical properties of as synthesized nanostructures can also be modulated by tuning their compositions. Considering the band gap of the nanostructured CdxZn1-xS well within the visible region, the photocatalytic activity for H2 generation using H2S and methylene blue dye degradation is performed under visible-light irradiation. The maximum H2 evolution of 8320 μmol h-1g-1 is obtained using nanostructured Cd0.1Zn0.9S, which is four times higher than that of bulk CdS (2020 μmol h-1 g-1) and the reported nanostructured CdS (5890 μmol h-1g-1). As synthesized Cd0.9Zn0.1S shows 2-fold enhancement in degradation of methylene blue as compared to the bulk CdS. It is noteworthy that the synthesis method adapted provides an easy, inexpensive, and pollution-free way to synthesize very tiny nanoparticles of CdxZn1-xS with a tunnable band structure on a large scale, which is quite difficult to obtain by other methods. More significantly, environmental benign enhanced H2 production from hazardous H2S using CdxZn1-xS is demonstrated for the first time. [ABSTRACT FROM AUTHOR]

A major limitation of solid-statedye-sensitized solar cells isa short electron diffusion length, which is due to fast recombinationbetween electrons in the TiO2electron-transporting layerand holes in the 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene(Spiro-OMeTAD) hole-transporting layer. In this report, the sensitizingdye that separates the TiO2from the Spiro-OMeTAD was engineeredto slow recombination and increase device performance. Through thesynthesis and characterization of three new organic D-π-A sensitizingdyes (WN1, WN3, and WN3.1), the quantity and placement of alkyl chainson the sensitizing dye were found to play a significant role in thesuppression of recombination. In solid-state devices using Spiro-OMeTADas the hole-transport material, these dyes achieved the followingefficiencies: 4.9% for WN1, 5.9% for WN3, and 6.3% for WN3.1, comparedto 6.6% achieved with Y123 as a reference dye. Of the dyes investigatedin this study, WN3.1 is shown to be the most effective at suppressingrecombination in solid-state dye-sensitized solar cells, using transientphotovoltage and photocurrent measurements. [ABSTRACT FROM AUTHOR]

The placement of fluorophores in close proximity to metal nanoparticle surfaces is proposed to enhance several photophysical properties of the dyes, potentially leading to improved quantum yields and decreased photobleaching. It is difficult in practice, however, to establish and maintain the nanoscale distances that are required to maximize these effects. The type of metal, size, and shape of the nanoparticle, the physical distance separating the metal nanoparticle from the organic dye, and the spectral properties of the fluorophore itself are all proposed to influence the quantum yield and lifetime. This results in a complex behavior that can lead to either enhanced or quenched fluorescence in different contexts. In this report, we describe a well-defined system that can be used to explore these effects, while physically preventing the fluorophores from contacting the nanoparticle surfaces. The basis of this system is the spherical protein capsid of bacteriophage MS2, which was used to house gold particles within its interior volume. The exterior surface of each capsid was then modified with Alexa Fluor 488 (AF 488) labeled DNA strands. By placing AF 488 dyes at distances of 3, 12, and 24 bp from the surface of capsids containing 10 nm gold nanoparticles, fluorescence intensity enhancements of 2.2, 1.2, and 1.0 were observed, respectively. A corresponding decrease in fluorescence lifetime was observed for each distance. Because of its well-defined and modular nature, this architecture allows the rapid exploration of the many variables involved in metal-controlled fluorescence, leading to a better understanding of this phenomenon. [ABSTRACT FROM AUTHOR]

Two donor--acceptor organic dyes have been synthesized that differ only by a two-heteroatom change from oxygen to sulfur within the donor unit. The two dyes, (E)-3-(5-(4-(bis(4-(hexyloxy)phenyl)amino)phenyl)thiophen-2-yl)-2-cyanoprop-2-enoic acid (Dye-O) and (E)-3-(5-(4-(bis(4-(hexykhio)phenyl) amino)phenyl)thiophen-2-yl)-2-cyanoprop-2-enoic acid) (Dye-S), were tested in solar cell devices employing both I3-/I--based and [Co(bpy)3]3+/2+ redox mediators. Power conversion efficiencies over 6% under simulated AM 1.5 illumination (1 Sun) were achieved in both electrolytes. Despite similar optical and redox properties for the two dyes, a consistently higher open-circuit voltage (Voc) was measured for Dye-S relative to Dye-O. The improved efficiency observed with Dye-S in an iodide redox mediator is against the commonly held view that sulfur atoms promote charge recombination attributed to inner-sphere interactions. Detailed mechanistic studies revealed that this is a consequence of a 25-fold enhancement of the regeneration rate constant that enhances the regeneration yield under open circuit conditions. The data show that a high short circuit photocurrent does not imply optimal regeneration efficiency as is often assumed. [ABSTRACT FROM AUTHOR]

An amine-free oligothiophene-based dye (BTB) featuring a tailor-made dianchoring function, a spiro-configured central unit, and bulky end-capping TIPS groups to diminish intermolecular interactions and to suppress aggregation-induced self-quenching was synthesized to achieve efficient dye-sensitized solar cells with a high power conversion efficiency of 6.52%. [ABSTRACT FROM AUTHOR]

Understanding the role played by external factors onthe organizationof molecules has the potential to contribute greatly to fundamentalresearch and applications in fields as diverse as nanotechnology,medicine, material chemistry, etc. Countless studies involve the organizationof small organic molecules in environments rich in ionic species,yet their participation in molecular organization is often overlooked.Herein, we critically assess the organization in aqueous solutionof the cationic cyanine dye, thiazole orange, in the presence of differentmonovalent sodium salts. Our findings clearly indicate that not allions are identical with regards to the organization of thiazole orangemolecules and specific ions effects are at play. The conventionalDebye and Hückel model is not sufficient to explain our results,and the participation of ionic species in molecular organization isexplained in terms of the recent theory of water matching affinity.Herein, by choosing the right counterion with the appropriate size,we have shown that it is possible to either induce a simple shiftin the monomer–dimer equilibrium of thiazole orange or to turnon the formation of larger organized structures. [ABSTRACT FROM AUTHOR]

Two new organic dyes incorporating triphenylamine as a donor and oligothienylenevinylene as a bridge have been synthesized. The new dyes cover the entire visible region and have a power conversion of up to 6.25%. [ABSTRACT FROM AUTHOR]

New phenothiazine based organic dyes were prepared for visible-light-driven organic transformations. The 3,7-disubstituted phenothiazine derivatives showed visible light absorption and reversible one-electron oxidation behavior. In the presence of 0.5 mol % of 3,7-disubstituted phenothiazines, primary benzylamines showed oxidative coupling under visible light irradiation from a blue LED. The electronic effect of substituents in phenothiazine dyes was observed in catalytic activities. The mechanistic pathway of oxidative coupling was discussed based on the detection of H2O2after the reaction. [ABSTRACT FROM AUTHOR]

Colloidal carbon nanospheres (CNS) with rich surfacefunctional groups of −OH and −COO–were prepared from glucose solution via hydrothermal reaction andactivated by NaOH solution. The nonporous CNS exhibited excellentadsorption performance toward basic dyes. High maximum adsorptioncapacities were obtained at 682 mg g–1for Methyleneblue, 395 mg g–1for Methyl violet 2B, and 310 mgg–1for Malachite green. Methylene blue with aninitial concentration of 94 mg L–1can be completelyremoved in 5 min at a dosage of 0.5 g L–1. Thiscan be associated with the low mass transfer resistance due to thenonporous structure and the abundant surface active sites. The adsorptionprocess is chemisorption in nature, while the kinetic data were wellfitted to pseudosecond-order kinetic model. This material presentedexcellent adsorption capacities toward basic dyes with maximum adsorptioncapacity of 682 mg g–1for Methylene blue B, 310mg g–1for Malachite green, and 395 mg g–1for Methyl violet 2B. Furthermore, the dye saturated CNS was regeneratedusing an advanced oxidation method using Co2 aqueoussolution as a homogeneous catalyst. After seven recycle runs, therewas still 96% of adsorption capacity retained. The low-cost CNS nanomaterialhas the potential to be applied as a new type of efficient adsorbentfor water treatment. [ABSTRACT FROM AUTHOR]

An organic dye containing two D-π-A branches linkedwitha thiophene unit has been designed and synthesized for efficient dye-sensitizedsolar cells (DSSCs). As compared to the rod-shape of the single D-π-Aanalogue dye, the cross shape of the double D-π-A branched dyeis favorable for reducing intermolecular interaction and retardingcharge recombination. Controlled intensity modulated photovoltagespectroscopy reveals that electron lifetime for the double D-π-Adye-based DSSC is 14-fold longer than that for the corresponding singleD-π-A dye-based DSSC. Linking two D-π-A branches witha thiophene unit increases open-circuit photovoltage by 100 mV andshort-circuit photocurrent by 4.10 mA cm–2. As aconsequence, power conversion efficiency is enhanced by about 2-fold.This work presents a new route to designing sensitizers with highsuppression ability of charge recombination toward high-performanceDSSCs. [ABSTRACT FROM AUTHOR]

A series of metal-free organic dyes exploiting different combinations of (hetero)cyclic linkers (benzene, thiophene, and thiazole) and bridges (4H-cyclopenta[2,1-b:3,4-b′]dithiophene (CPDT) and benzodithiophene (BDT)) as the central π-spacers were synthesized and characterized. Among them, the sensitizer containing the thiophene and CPDT showed the most broad incident photon-to-current conversion efficiency spectra, resulting in a solar energy conversion efficiency (η) of 6.6%. [ABSTRACT FROM AUTHOR]

The cobalt(II)-bicarbonate (HCO3–)complex is a very efficient catalyst for organic dye decolorizationwith H2O2as an oxidant, but its mineralizationdegree is very low. One interesting alternative is the combinationof the system with a subsequent biological step. With the aim of employingthe Co2+HCO3–system as apretreatment method to dye wastewater, a typical azo dye, reactivebrilliant red X-3B (X-3B), was selected as the model compound, andthe biodegradability enhancement of the dye was investigated. Theresults showed that X-3B was effectively degraded by the Co2+HCO3–system under various mild conditions,and the BOD5/COD ratio of the dye solution could markedlyincrease from 0.046 to higher than 0.46. The effluent treatment bythe system was efficiently post-treated in a batch biological reactorwith the COD removal around 44% after 8 h aeration, while a littledecrease of the COD value of the raw solution was observed. [ABSTRACT FROM AUTHOR]

Liquid/liquid interfaces play a crucial role in numerousareasof science. However, direct spectroscopic access to this thin (∼1nm) region is not possible with conventional optical methods. Aftera brief review of the most used techniques to perform interfacialoptical spectroscopy, we will focus on time-resolved surface secondharmonic generation, which allows the measurement of the excited-statedynamics of probe molecules at interfaces. By comparing these dynamicswith those measured in bulk solutions, precious information on theproperties of the interfacial region can be obtained. To illustratethis, several studies performed in our group will be presented. [ABSTRACT FROM AUTHOR]

Nanoporous SnO2--ZnO heterojunction nanocatalyst was prepared by a straightforward two-step procedure involving, first, die synthesis of nanosized SnO2 particles by homogeneous precipitation combined with a hydrothermal treatment and, second, the reaction of the as-prepared SnO2 particles with zinc acetate followed by calcination at 500 °C. The resulting nanocatalysts were characterized by X-ray diffraction (XRD), FTIR, Raman, X-ray photoelectron spectroscopy (XPS), nitrogen adsorption--desorption analyses, transmission electron microscopy (TEM), and UV--vis diffuse reflectance Timeinun) spectroscopy. The SnO2--ZnO photocatalyst was made of a mesoporous network of aggregated wurtzite ZnO and cassiterite SnO2 nanocrystallites, the size of which was estimated to be 27 and 4.5 nm, respectively, after calcination. According to UV--visible diffuse reflectance spectroscopy, the evident energy band gap value of the SnO2--ZnO photocatalyst was estimated to be 3.23 eV to be compared with those of pure SnO2 that is, 3.7 eV, and ZnO, that is, 3.2 eV, analogues. The energy band diagram of the SnO2--ZnO heterostructure was directly determined by combining XPS and the energy band gap values. The valence band and conduction band offsets were calculated to be 0.70 ± 0.05 eV and 0.20 ± 0.05 eV, respectively, which revealed a type-II band alignment. Moreover, the heterostructure SnO2--ZnO photocatalyst showed much higher photocatalytic activities for die degradation of methylene blue dian those of individual SnO2 and ZnO nanomaterials. This behavior was rationalized in terms of better charge separation and the suppression of charge recombination in the SnO2--ZnO photocatalyst because of the energy difference between the conduction band edges of SnO2 and ZnO as evidenced by the band alignment determination. Finally, this mesoporous SnO2--ZnO heterojunction nanocatalyst was stable and could be easily recycled several times opening new avenues for potential industrial applications. [ABSTRACT FROM AUTHOR]

Organic dye degradation was achieved via direct oxidation by bismuth silver oxide coupled with visible light photocatalysis by sodium bismuthate. Crystal violet dye decomposition by each reagent proceeded via two distinct pathways, each involving different active oxygen species. A comparison of each treatment method alone and in combination demonstrated that using the combined methods in sequence achieved a higher degree of degradation, and especially mineralization, than that obtained using either method alone. In the combined process direct oxidation acts as a pretreatment to rapidly bleach the dye solution which substantially facilitates subsequent visible light photocatalytic processes. The integrated sequential direct oxidation and visible light photocatalysis are complementary manifesting α > 100% increase in TOC removal, compared to either isolated method. The combined process is proposed as a novel and effective technology based on one primary material, sodium bismuthate, for treating wastewaters contaminated by high concentrations of organic dyes. [ABSTRACT FROM AUTHOR]

To overcome the drawback of catalytic wet air oxidation (CWAO) with high temperature and high pressure, the catalytic activity of Mo-Zn-Al-O catalyst for degradation of cationic red GTL under room temperature and atmospheric pressure was investigated. Mo-Zn-Al-O catalyst was prepared by coprecipitation and impregnation. XRD, TG-DTG, and XPS were used to characterize the resulting sample. Central composition design using response surface methodology was employed to optimize correlation of factors on the decolorization of cationic red GTL. The results show that the optimal conditions of pH value, initial concentration of dye and catalyst dosage were found to be 4.0, 85 mg/L and 2.72 g/L, respectively, for maximum decolorization of 80.1% and TOC removal of 50.9%. Furthermore, the reaction on the Mo-Zn-Al-O catalyst and degradation mechanism of cationic red GTL was studied by Electron spin resonance (ESR) and GC-MS technique. The possible reaction mechanism was that the Mo-Zn-Al-O catalyst can efficiently react with adsorbed oxygen/H2O to produce ·OH and 1O2 and finally induce the degradation of cationic red GTL. GC-MS analysis of the degradation products indicates that cationic red GTL was initiated by the cleavage of -N=N- and the intermediates were further oxidized by ·OH or 1O2. [ABSTRACT FROM AUTHOR]

The surface active derivative of the organic dye Acridine Orange (N-10-dodecyl-acridine orange (DAO)) has been included in mixed Langmuir monolayers with stearic acid (SA). The maximum relative content on DAO for a stable mixed monolayer is a molar ratio of XDAO= 0.5. Brewster angle microscopy (BAM) reveals a high homogeneity at the micrometer level for the mixed monolayer in equimolar proportion (XDAO= 0.5), whereas the appearance of domains occurs for lower content of DAO, i.e., XDAO= 0.2 and 0.1. The aggregation of the DAO headgroup leads to well-defined H-aggregates at the air/water interface for those mixed monolayers with a low content of DAO. However, for the mixed monolayers enriched in DAO, e.g., XDAO= 0.5, the molecular crowding prevents the formation of defined supramolecular structures. Molecular organization and tilting of the DAO headgroup is quantitatively analyzed by in situ UV–visible reflection spectroscopy. The formation of H-aggregates of the DAO headgroup can be reversibly tuned with the applied surface pressure. A molecular mechanism for the conformational rearrangement of the DAO molecule is proposed using RM1 quantum semiempirical calculations. [ABSTRACT FROM AUTHOR]

Fluorescent proteins (FPs) of the green fluorescent protein family blink and bleach like all fluorophores. However, contrary to organic dyes, the mechanisms by which transient losses of fluorescence occur in FPs have received little attention. Here, we focus on the photoactivatable IrisFP, for which a transient non-fluorescent chromophoric state with distorted geometry was recently reported (Adam, V.; et al. J. Am. Chem. Soc.2009, 131, 18063). We investigated the chemical nature of this blinked state by employing quantum chemical/molecular mechanical calculations. Our findings suggest two previously unidentified dark states that display similar distorted chromophores with a transiently ruptured π-electron system. Both are protonated at atom Cα of the chromophore methylene bridge. Transient protonation may occur via proton transfer from the nearby Arg66 either in the triplet state T1 after intersystem crossing or in an anionic radical (doublet) ground state. As Arg66 is conserved in green-to-red photoconvertible FPs, these dark states are predicted to be common to all these proteins. We also suggest that Cα protonated dark states may accelerate photobleaching by favoring decarboxylation of the fully conserved Glu212. [ABSTRACT FROM AUTHOR]

In this study, we presented the efficiently adsorptive removal of organic dye, methyl orange (MO), from aqueous solution with the hydrothermal synthesized Mg–Al layered double hydroxide (LDH). The as-obtained product was characterized by X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The adsorption characteristics of MO onto the Mg–Al LDH were evaluated in a batch adsorption process and systematically investigated by different experimental parameters, such as initial dye concentration, contact time, and solution pH. The adsorption kinetics were analyzed by pseudofirst-order, pseudosecond-order, Elovich, intraparticle diffusion, and Boyd models, which were well-described by the pseudosecond-order model. The equilibrium adsorption data were interpreted using the Langmuir, Freundlich, and Temkin isotherm models, which fitted well to both the Langmuir and Freundlich models. The monolayer adsorption capacity of the Mg–Al LDH toward MO was found to be 0.453 mol·kg–1. These findings suggested that the LDH could be regarded as a promising adsorbent for the removal of anionic dye in wastewaters. [ABSTRACT FROM AUTHOR]