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Synthetic dyes are widely used in various industries, which inevitably leads to increased water pollution. One of the recognized and waste-free techniques for water treatment is photocatalytic purification using semiconductor nanoparticles. However, the debate on how photocatalytic properties can be tuned through structural and morphological parameters using nanoparticle synthesis procedures remains open. In the present work, an approach to regulate UV-light-driven photocatalytic activity of spherical SnO2 nanoparticles using different structural parameters is demonstrated for the first time. Complex characterization of nanoparticles was provided using physicochemical methods with the help of computational methods. Special attention was paid to the development of a protocol of oxygen vacancy accounting within computer calculations for more realistic modeling of the interaction energy between nanoparticle surfaces and organic dye molecules of different natures. The photocatalysis mechanism was investigated according to the developed protocol, including the study of dye mixture kinetic degradation, dye-photocatalyst complex formation, and the ratio of oxygen vacancies and defects. It was shown that 93% of single dye decomposed in 7 min, and degradation of the dye mixture in a real water sample from Neva River achieved 60% after 40 min. It was possible to establish that this proof-of-concept study based on the combination of experimental and computational approaches can help develop the strategy of the rational design of photocatalysts promising for purification of real water samples. [ABSTRACT FROM AUTHOR]

The design of efficient photocatalysts for dye degradation is a challenging task for the scientific community. Semiconductor-based photocatalysts such as g-C3N4 and oxides, utilizing solar energy, have been proven to be effective and promising approaches to resolve this issue to some extent. Constructing Z-scheme heterostructures by coupling g-C3N4 with suitable oxide semiconductors has shown substantial enhancement of the photocatalytic performance. In this article, perovskite-type CeMnO3 (5, 15, 25%) nanoparticle-decorated g-C3N4 nanosheets are fabricated as heterostructures, using a hydrothermal synthesis process, for efficient photocatalysis of organic dyes. The formations of heterostructures are confirmed through structural, microstructural, and elemental state analysis. Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH) characterization techniques exhibited enhanced surface area and pore sizes, respectively. Ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy (DRS), Mott–Schottky, and linear sweep voltammetry (LSV) analyses along with density functional theory (DFT) calculations predicted a p–n junction heterostructure. Electron paramagnetic resonance (EPR) studies revealed a broad spectrum with sextet hyperfine lines corresponding to Mn4+ and Mn2+ ions and enhanced intensity as compared to the parent ones, signifying the creation of oxygen vacancies in the heterostructure. The CeMnO3 (25 wt %)/g-C3N4 heterostructure showed highly efficient photocatalytic degradation of methylene blue under direct sunlight irradiation, with up to 99% degradation achieved in 120 min and excellent recyclability. The robustness of this photocatalyst was tested by adopting a similar process for methylene orange dye degradation, exhibiting 94% yield in 120 min. A tentative degradation mechanism is proposed based on the enhanced photodegradation efficiency and results obtained from electrochemical impedance (EIS), photoluminescence (PL), LSV, and first principal studies, which provides more insights into the photogenerated charge separation, enhanced photocurrent, and interfacial transfer efficiency through the Z-scheme charge transfer process. This study offers opportunities for designing high-performance Z-scheme hybrid photocatalysts for environmental remediation. [ABSTRACT FROM AUTHOR]

Organic dyes in wastewater jeopardize aquatic ecosystems and biodiversity, besides having several concerns of health hazards. Nanostructured materials of controlled textural features with active surface functionalities are gaining immense interest as effective adsorbents for wastewater treatment. The present work addresses a facile approach to synthesize fibrous aerogel-templated nanostructured boron carbon oxynitride (BCNO). The surface functionalities, structural heterogeneity, crystalline phases, and morphological features of BCNO are probed by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman, X-ray diffraction, and high-resolution transmission electron microscopy analyses. The nanostructured BCNO showed preferential and remarkably high adsorption of cationic dyes with a removal capacity of 1258 mg g–1 for malachite green (MG) dye. The adsorption of MG dye by nanostructured BCNO is carried out at different pH, ionic strength, and temperature to emphasize the influence of environmental factors. The spectroscopic analyses suggested multiple adsorption pathways, viz. electrostatic, π–π, hydrogen, and Lewis acid–base interactions for unprecedentedly higher adsorption of cationic dyes by BCNO. Batch-mode findings promise the potential of nanostructured BCNO for wastewater treatment applications. [ABSTRACT FROM AUTHOR]

The same carbon-based nanomaterials have shown their potential photocatalytic applications toward environmental and energy-related problems based on their excellent light absorption abilities. Herein, we summarized the findings associated with visible light and sunlight-induced photocatalysis, specifically using carbon dots (CD), doped-CD, and their nanocomposite as an advanced photocatalytic material. Doped-CD and CD-based composite have improved light absorption abilities compared to bare CD, which is the essential parameter for photocatalysis applications. Various parameters, such as fabrication methodologies, efficiency, and stability, have also been discussed. The possible mechanistic insights involving the photocatalysis method applied in multiple chemical reactions have been discussed in detail, including degradation of organic dye, reduction of higher toxic oxidation states of metal ions, CO2 conversion, water splitting, organic transformation reaction, and NOx removal, etc. [ABSTRACT FROM AUTHOR]

Adsorption is a promising technique for the effective removal of dyes from dyeing wastewater resulting from the paper, textile, and leather industries. Herein, we report a facile strategy for preparing adsorption membrane-based aminated ultrathin polyacrylonitrile (UPAN-N) nanofibers to effectively remove the synthetic dyes from wastewater. The UPAN-N nanofibers were synthesized using a mixed solution electrospinning procedure, followed by triethylenetetramine modification. After the amino modification, the surface of the obtained UPAN-N nanofiber membrane is rich in amino groups, which endows the resulting membrane with an ultrahigh adsorption capacity of more than 1800 mg/g for the organic dye DR23 and a rapid adsorption rate for DR23 solutions with the concentrations ranging from 20 to 100 mg/L. This work not only provides a feasible method for the preparation of high-capacity adsorbents but also offers the possibility of preparing nanofibers by a mixed solution electrospinning procedure. [ABSTRACT FROM AUTHOR]

In recent years, controlling and manipulating the materials' surface charges have gained significant attention because of efficient application in various fields such as catalysis, dye adsorption, chromatography, etc. In this study, we have controlled the surface charge of ZnIn2S4 nanomaterials (NMs) by loading Zn2+ ions on the surface of materials. The ζ-potential studies revealed that the average surface charge of the NMs was successfully controlled from −30.3 to +31.4 mV. The X-ray diffraction patterns suggested that the phase of the NMs is changed from hexagonal ZnIn2S4 to cubic ZnIn2S4 with slight trigonal ZnS moieties. Further, the electron microscopy results displayed that the morphology of the NMs gradually changed from a sheetlike structure to a hybrid of sphere/petals and finally a very small flakelike structure with an increasing loading concentration of Zn2+ ions. Moreover, the nanosheet micrograph showed the different numbers of sheet layers, which are composed of 2–6 layers. The Brunauer–Emmett–Teller analysis indicated that the specific surface area is increased from 48.2 to 118.6 m2 g–1 after the loading of Zn2+ ions. The obtained NMs displayed a high adsorption selectivity performance for organic dyes. A separation factor (α21) of 95% was obtained for anionic Congo red (CR) over positively charged nanoflakes and 85% for cationic methylene blue (MB) dyes on negatively charged nanosheet. The as-prepared nanosheet and nanoflakes also showed efficient adsorption behavior toward two different kinds of antibiotics such as tetracycline and ciprofloxacin. The adsorption process followed the Langmuir isotherm model for the MB, CR, and ciprofloxacin, whereas tetracycline adsorption obeyed the Freundlich isotherm model. The adsorbents displayed a pseudo-second-order rate kinetic model. The recyclability of the best adsorbents was found up to five times without significant loss of removal efficiency. [ABSTRACT FROM AUTHOR]

Iron single-atom catalysts (Fe SACs) hold great promise for peroxymonosulfate (PMS) activation and degradation of organic pollutants in wastewater. However, insights into crucial catalytic sites and activation mechanisms of biochar-based Fe SACs for PMS remain a challenge. Herein, cotton stalk-derived biochar-based Fe SACs (Fe SACs-BC) with an asymmetric Fe-N/O-C configuration were prepared, and their PMS activation and acid orange 7 (AO7) degradation mechanisms were investigated. The results showed that the removal efficiency of the Fe SACs-BC catalyst with Fe-N 3 O-C configuration for AO7 and other five investigated organic dyes reached 95-99% within 15 min. The EPR spectrums, quenching experiments, electrochemical analysis, masking experiments, XPS, and theoretical calculations indicated that degradations of organic dyes were dominated by singlet oxygen, which was generated by direct PMS conversion at the electron-deficient carbon and iron sites in the Fe-N 3 O-C configuration. The Fe SACs-BC/PMS exhibited high removal efficiency and strong tolerance in different water matrices with a wide pH range, various coexisting anions and interfering substances, showing great potential and applicability for efficient treatment of actual textile wastewaters.

Facet-engineered anatase TiO2 with NiO nanoparticles heterocontacts were successfully prepared by selective photodeposition of NiO nanoparticles onto the {101} facet of the top-truncated bipyramidal TiO2 anatase nanocrystals coexposed with {001} and {101} facets. The morphology and electronic properties of the resulting 0.1-10 wt % NiO-decorated TiO2 were investigated by X-ray diffraction, high-resolution electron microscopy, N2 sorption analysis, and UV-vis spectroscopy. Furthermore, a careful determination of the energy band alignment diagram was conducted by a model experiment using XPS and UPS to verify charge separation at the interface of the NiO-TiO2 heterostructure. The model experiment was performed by stepwise deposition of NiO onto oriented TiO2 substrates and in-situ photoelectron spectroscopy measurements without breaking vacuum. Core levels showed shifts of 0.58 eV toward lower binding energies, meaning an upward band bending in TiO2 at the NiO-TiO2 interface. Furthermore, 0.1 wt % NiO-TiO2 exhibited 50% higher activities than the pure TiO2 for methylene blue (MB) photodecomposition under UV irradiation. This enhanced photocatalytic activity of NiO- TiO2 nanocomposites was related to the internal electric field developed at the p-n NiO-TiO2 heterojunction, leading to vectorial charge separation. Finally, mechanistic studies conducted in the presence of carrier or radical scavengers revealed that holes dominantly contributed to the photocatalytic reactions in the case of NiO- TiO2 photocatalysts while electrons played the main role in photocatalysis for the pure TiO2 materials. [ABSTRACT FROM AUTHOR]

microRNAs (miRNAs) have been a class of promising disease diagnostic biomarkers and therapeutic targets for their important biological functions. However, because of the high homology, interference from precursors (pri-miRNA, pre-miRNA), as well as limitations in the current assay technologies, it poses high demand and challenge for a specific, efficient, and economic miRNA assay method. Here, we propose a new miRNA detection method based on a labelfree probe and a small organic dye with sequence dependence, realizing the sequence-specific and colorimetric detection of target miRNA. What is pleasantly surprising, only one enzyme is enough to propel the whole miRNA assay process, greatly simplifying the reaction component and detection process. Together with PCR amplification for the high enough sensitivity and three checks for specificity control, a detection limit of 5 fM was obtained and even one mutation could be discriminated visually. Overall, the new method makes much progress in convenience and economy of PCR-based miRNA assay method so that miRNA assay is going to be more friendly and affordable. [ABSTRACT FROM AUTHOR]

We demonstrate a solution-based fabrication of centimeter-size free-standing films assembled from organic nanocrystals based on common organic dyes (perylene diimides, PDIs). These nanostructured films exhibit good mechanical stability, and thermal robustness superior to most plastics, retaining the crystalline microstructure and macroscopic shape upon heating up to 250-300 °C. The films show nonlinear optical response and can be used as ultra filtration membranes. The macroscopic functional materials based on small molecules can be alternative or complementary to materials based on macromolecules. [ABSTRACT FROM AUTHOR]

Nucleophilic addition of phosphinic acid, phosphites, sodium dialkyl phosphites, phosphoramidites, phosphinites, and phosphonites to highly polarized or cationic fluorophores, followed by oxidation, results in new "PONy" dyes with auxochromic phosphinate, phosphonate, or phosphonamidate groups. The reaction was applied to a wide variety of coumarins, (thio)pyronins, and N-alkylacridinium and 5,6-dihydrobenzo[c]xanthen-12-ium salts as well as a meso-chlorinated BODIPY to provide compact dyes with red-shifted absorption and emission bands and Stokes shifts up to 8200 cm-1. [ABSTRACT FROM AUTHOR]

We herein present a rarely seen (3,4)-connected non-interpenetrated anionic uranium-organic framework with tbo topology (FJI–H-U1), which is constructed from two kinds of ultralarge nanocages. More importantly, FJI–H-U1 can selectively adsorb positively charged organic dyes Ethyl Violet, Janus Green B, and Rhodamine B over the anionic organic dye Methyl Orange due to the nature of its anionic framework. [ABSTRACT FROM AUTHOR]

The fluorescence quenching property of graphene oxide (GO) has been newly demonstrated and applied for fluorescence imaging and biosensing. In this work, a new nanostructure was designed for effectively studying the quenching ability of GO. The key element in this design is the fabrication of a layer of rigid and thickness adjustable silica spacer for manipulating the distance between the GO and fluorophores. First, a silica core modified with organic dye molecules was prepared, followed by the formation of a silica shell with a tunable thickness. Afterward, the GO was wrapped around silica nanoparticles based on the electrostatic interaction between the negatively charged GO and positively charged silica. The quenching efficiency of GO to different dye molecules was studied at various spacer thicknesses and varying concentrations of GO. Fluorescence lifetime of fluorophores was measured to determine the quenching mechanism. We found that the quenching efficiency of GO was still around 30% when the distance between dyes and GO was increased to more than 30 nm, which indicated the long-distance quenching ability of GO and confirmed the previous theoretical calculation. The quenching mechanisms were proposed schematically based on our experimental results. We expected that the proposed nanostructure could act as a feasible model for studying GO quenching property and shed light on designing GO-based fluorescence sensing systems. [ABSTRACT FROM AUTHOR]

The synthesis of multicomponent mesocrystals represents an emerging strategy for obtaining nanomaterials with unique functionalities as a result of combining porosity and crystallographic order. This study presents the first synthesis of multicomponent Sb-Nb:TiO2 mesocrystals (Sb-mesoNb/TO) by using a microwave-assisted nonaqueous sol-gel method. Structural and chemical analyses, carried out using various transmission electron microscopy techniques, show that Sb-mesoNb/TO are 25-35 nm in size and composed of crystallographically aligned Nb:TiO2 subunits, embedded in a porous amorphous Sb-rich scaffold (Sb-scaffold). On the basis of the characterization of the intermediate products, the formation mechanism is proposed, involving a kinetically controlled particle-based assembly process. The latter is triggered by the occurrence of the Sb-scaffold in the early reaction stages, acting as a support for heterogeneous nucleation of Nb:TiO2 subunits. Subsequently, Nb:TiO2 subunits grow and assemble in a mutual crystallographic direction, while the Sb-scaffold prevents their complete fusion, hence leading to porosity in the final Sb-mesoNb/TO. Photocatalytic tests were performed by measuring the degradation of organic dyes under solar and visible light. [ABSTRACT FROM AUTHOR]

This study describes a bottom-up assembly route for monodisperse carbon dots (CDs) into different sizes of CD aggregates through the control of the concentration of fatty acids. The highly monodisperse CDs were prepared via solvent--thermal treatment of edible soybean oil, which generated glycerol-based polymer as a carbon source and fatty acid as a surface capping in the synthetic process. The as-synthesized CDs exhibited small particle size variation (2.7 ± 0.2 nm) and narrow emission bands (full width at half-maximum <20 nm). The monodisperse CDs can self-assemble into blue-, green-, yellow-, and red-emitting CD aggregates by tuning the concentration of fatty acids. Compared to commercially available organic dyes and semiconductor quantum dots, the CD aggregates provided a 10-7000-fold improvement in brightness. Additionally, their emission wavelength was tunable across the entire visible spectrum by tuning the excitation wavelength. Because of their high brightness, fluorescence imaging of a single carbon dot and CD aggregate was simply achieved using filter-free dark-field fluorescence microscopy (DFM). We also demonstrate the use of filter-free DFM to dynamically image cellular uptake of the monodisperse CDs in MCF-7 cells and Huh-7 liver cancer cells. Without the conjugation of the fluorophore to the CDs, the particle aggregation-induced red-shifted emission enables the development of the CD-based ratiometric sensor for FeIII ions and pyrophosphate based on FeIII -induced aggregation of the monodisperse CDs. [ABSTRACT FROM AUTHOR]

Revealing the nature of chain packing in conjugated polymer nanoparticles (CPNs) is one of the important issues to polymer physics research. Surfactant-stabilized CPNs in water show significantly enhanced luminescence intensity in comparison to small molecular organic dyes and single polymer chains dissolved in solvents. The importance of the conjugated polymer structure in nanomaterials is undoubted. However, details of the relationship between alignment of conjugated polymer backbone in CPNs and its luminescent property have not been established. Furthermore, there are yet no methods that can predict the atom-resolved structure of conjugated polymer in the CPNs. Herein, we employ coarse-grained (CG) molecular dynamic simulations to investigate the structure of phase-separated film and the film shattering process for a mixture of poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) and 1,2-dioctanoyl-sn-glycero-3-phosphocholine (D8PC). The p-p stacked structure of PCPDTBT is significantly enhanced when the ratio of D8PC increases in both dried and water exposed film. We also show that the amount of D8PC is at least 2.5 times larger than that of PCPDTBT to wrap the conjugated polymer chain, and the direct retrieval of atomistic details is achieved through back-mapping from the morphology of CG. Finally, we confirmed that conjugated backbones inside the nanoparticles were completely shielded from the aqueous solution by the dense layers of alkyl chains, resulting in remarkably enhanced chain packing. These simulated results are correlated with experimentally observed structure through UV-vis-near-infrared (UV-vis-NIR) spectrometry, scanning electron microscopy (SEM), particle size analyzer (PSA), transmission electron microscopy (TEM), and grazing-incidence X-ray diffraction (GIXD). [ABSTRACT FROM AUTHOR]

Treatment of N,N-bis(diphenylphosphanylmethyl)-3-aminopyridine (3-bdppmapy) with AgX (X = Br, I, CN, SCN, dicyanamide (dca)) under different reaction conditions afforded seven mononuclear, dinuclear, and polymeric coordination complexes including [Ag4I4(3-bdppmapy)2] n (1), [Ag2I2(3-bdppmapy)3]·CH3OH (2·CH3OH), [Ag2Br(3-bdppmapy)3]Br·4CH3OH (3·4CH3OH), [Ag4(CN)4(3-bdppmapy)3]·2CH3OH (4·2CH3OH), [Ag(3-bdppmapy)2]SCN (5), [Ag(3-bdppmapy)2](dca) (6), and {[Ag4(dca)4(3-bdppmapy)2]·4DMF} n (7). Compound 1 contains a unique two-dimensional (2D) network in which chairlike [Ag4I4] units are interconnected by μ3-3-bdppmapy bridges. Compounds 2 and 4 hold a similar centrosymmetric framework in which two [(3-bdppmapy)AgI] (2) or [(3-bdppmapy)Ag2(CN)2] (4) units are linked by a μ-3-bdppmapy. Compound 3 has a batlike cationic structure in which two Ag/3-bdppmapy units are joined by a pair of μ-Br and μ-3-bdppmapy bridges. Compounds 5 and 6 have a similar cationic mononuclear structure in which the Ag(I) center is chelated by two 3-bdppmapy ligands. Compound 7 possesses a 2D layer structure in which each one-dimensional (1D) chain [Ag4(dca)4(3-bdppmapy)2]n is connected to its equivalent ones by μ3-dca bridges. Compound 1 as a representative example exhibited excellent catalytic activity toward the photodecomposition of a spectrum of 11 organic dyes in water under UV light irradiation and can be reused five times without noticeable decay of its catalytic efficiency. [ABSTRACT FROM AUTHOR]

An atom transfer radical addition elimination (ATRE) reaction of terminal alkenes with perfluoroalkyl halides under visible light is described. The photoredox catalysis with Eosin Y provides perfluoroalkenes in good yields. The reaction has been utilized for the late stage perfluoroalkenylation of an estrone-derived alkene. [ABSTRACT FROM AUTHOR]

The excellent oxidizing capability of acridinium-based organic dye (Acr+-Mes) is fully studied in photoredox catalysis. However, its reducing ability is always considered weak for organic transformation. The reducing ability of Acr+-Mes is developed by Selectfluor to achieve effective fluorination and oxidation of benzylic C(sp3)-H bonds under visible light irradiation, which is not available for the direct use of oxidizing ability of excited Acr+-Mes. Mechanistic insights provided strong evidence for the oxidative quenching of Acr+-Mes. [ABSTRACT FROM AUTHOR]

A novel anionic metal-organic framework, JUC-138, constructed by In(III) and a pyrene-based linker, H8TIAPy (H8TIAPy = 1,3,6,8-tetrakis(3,5-isophthalic acid)pyrene), has been synthesized by solvothermal reaction successfully. In JUC-138, only four carbonyl groups in each ligand connect to In3+ ions, while the others remain uncoordinated. However, each In3+ connects to four carbonyl groups in a bidentate chelate style, resulting in the formation of 2D square sheets in JUC-138. The 2D sheets interact with adjacent layers through the O-H···O hydrogen bonds between the uncoordinated carboxyl groups, thus generating the whole 3D supramolecular structure of JUC-138. UV-vis tests show the energy gap E g of JUC-138 is 3.34 eV, indicating the semiconductor nature of JUC-138. In addition, JUC-138 shows good photocatalytic activity in Azure B (AB) decolorization and could decompose 90% AB within 4 h. This photocatalytic property makes JUC-138 promising in environment governance. [ABSTRACT FROM AUTHOR]

Two new networks, namely, {[Cd(bpba)(H2bptc)1/2·H2O]}n (1), {[Co(bpba)(bdc)1/2]}n (2), where Hbpba = 3,5-bis(pyridin-4-ylmethoxy)benzoic acid, H4bptc = 3,3',5,5'-biphenyltetracarboxylate, H2bdc = 1,4-benzenedicarboxylate, have been synthesized hydrothermally and characterized. Compound 1 is a three-dimensional net with a rare jea topology. The flexible pyridyl arms may afford a dimension extension in the crystal structure. While for compound 2 the flexible pyridyl arms are not involved in coordination, the Co(II) paddle-wheel secondary building units are bridged by the mixed ligands, bpba- and bdc2-, to furnish a two-dimensional layer. In addition, their heterogeneous catalytic oxidation activities toward methyl orange, methyl blue, neutral red, methylene blue, and safranine T (ST) in the presence of H2O2 are investigated in aqueous solution. The results suggested that the photocatalytic efficiency of ST is found to be 100% for MOF-2. [ABSTRACT FROM AUTHOR]

Hyper-cross-linked polynaphthalene nanoparticles (PNNs) capable of catalyzing the degradation of organic pollutants upon exposure to visible light have been developed. The nascent and metal-free PNNs with a porous structure, high specific surface area, and narrow bandgap are chemically and thermally stable in the catalytic system, which make it promising as a kind of excellent photocatalytic material compared to conventional photocatalysts. The photocatalytic activity of the as-obtained PNNs exhibits remarkable photocatalytic performance for the degradation of rhodamine B (RhB) and methyl blue (MB) under the irradiation of visible light. The easy preparation, high catalytic activity, and recyclability of the PNNs open new opportunities in the visible-light-promoted degradation of organic pollutants. [ABSTRACT FROM AUTHOR]

We describe the synthesis, computational analysis, photophysics, electrochemistry and electrochemiluminescence (ECL) of a series of compounds formed of two triphenylamines linked by a fluorene or spirobifluorene bridge. The phenylamine moieties were modified at the para-position of the two external rings by electron-withdrawing or electron-donating substituents. These modifications allowed for fine-tuning of the photoluminescence (PL) and ECL emission from blue to green, with an overall wavelength span of 73 (PL) and 67 (ECL) nm, respectively. For all compounds, we observed a very high PL quantum yield (79-89%) and formation of stable radical ions. The ECL properties were investigated by direct annihilation of the electrogenerated radical anion and radical cation. The radical-ion annihilation process is very efficient and causes an intense greenish-blue ECL emission, easily observable even by naked eye, with quantum yield higher than the standard 9,10-diphenylanthracene. The ECL spectra show one single band that almost matches the PL band. Because the energy of the annihilation reaction is higher than that required to form the singlet excited state, the S-route is considered the favored pathway followed by the ECL process in these molecules. All these features point to this type of molecular system as promising for ECL applications. [ABSTRACT FROM AUTHOR]

Water-soluble organic dyes such as fluorescein are widely used, mainly for coloration of, e.g., biological samples and groundwater tracing, and they are not obviously amphiphilic by molecular structure like surfactants. Here, we show that the dyes alone stabilize oil-in-water emulsions. Exemplarily, fluorescein is compared with the classical surfactant sodium dodecyl sulfate (SDS) by means of surface/interfacial tension, concentration of stabilizer and electrolyte, as well as pH. The principle can be extended to further classes of water-soluble dyes, which keep up with or exceed SDS by efficiency. Various organic liquids of different polarities can be employed and be polymerized in the case of styrene as disperse phase. Thus, surfactant free latex solely stabilized by water-soluble dyes is accessible. The emulsions can be destabilized by absorption of the dyes to hydrogels, and their complete removal is easily followed visually. The stabilization mechanisms are different for SDS and the dyes: The latter stabilize droplets not as monomers but by their aggregates as molecular scale Pickering stabilizers, which is a new concept of stabilization. [ABSTRACT FROM AUTHOR]

Fluorescent bioprobes have been regarded as promising tools for bioimaging in recent years due to their excellent properties. However, the aggregation-caused quenching of emissions is a big limitation in practice for this strategy. Organic dyes with aggregation-induced emission (AIE) feature can effectively solve this problem. Herein, stable fluorescent nanoparticles were prepared by supramolecular assembling of carbon dots (CDs) and hydrophobic AIEgen. The formulated CDsG-AIE 1 exhibits superior physical and photo stability than AIE self-assembling nanoparticles in various physiology conditions. On the other hand, the formulated CDsG-AIE 1 also showed advanced features such as large Stokes shift, good biocompatibility, high emission efficiency, and strong photobleaching resistance. More importantly, the CDsG-AIE 1 can be readily internalized by HeLa cells, and strong red fluorescence from the nanoparticles can still be clearly observed after six generations over 15 days. In addition, the CDsG-AIE 1 also exhibits superior long-term imaging ability in vivo. These incredible features make the AIE nanoparticles to be an ideal fluorescent probe for noninvasive long-term tracing and imaging applications. This work highlights the potential of using carbon dots to assemble AIEgen for the preparation of nanoscale AIEgen-contained particles for desirable bioimaging and diagnostic. [ABSTRACT FROM AUTHOR]

A wide variety of organic dyes form, under certain conditions, clusters know as J- and H-aggregates. Cyanine dyes are such a class of molecules where the spatial proximity of several dyes leads to overlapping electron orbitals and thus to the creation of a new energy landscape compared to that of the individual units. In this work, we create artificial H-aggregates of exactly two Cyanine 3 (Cy3) dyes by covalently linking them to a DNA molecule with controlled subnanometer distances. The absorption spectra of these coupled systems exhibit a blue-shifted peak, whose intensity varies depending on the distance between the dyes and the rigidity of the DNA template. Simulated vibrational resolved spectra, based on molecular orbital theory, excellently reproduce the experimentally observed features. Circular dichroism spectroscopy additionally reveals distinct signals, which indicates a chiral arrangement of the dye molecules. Molecular dynamic simulations of a Cy3-Cy3 construct including a 14-base pair DNA sequence verified chiral stacking of the dye molecules. [ABSTRACT FROM AUTHOR]

An Au-Fe2O3@mesoporous SiO2 nanoreactor with a multiyolks/shell structure was synthesized through a multistep method. In this nanoreactor, the spindle Fe2O3 and Au nanoparticles were inside the same mesoporous SiO2 shell as the yolks but in a noncontact manner. The noncontact synergistic effect between Au nanoparticles and the Fe2O3 spindle was studied with a Fenton-like reaction. The catalytic activity of the Au-Fe2O3@mesoporous SiO2 nanoreactor to the Fenton-like reaction for the degradation of organic dyes was dramatically enhanced by the noncontact synergistic effect. [ABSTRACT FROM AUTHOR]

The control of luminous radiation has extremely important implications for modern and future technologies as well as in medicine. In this Review, we detail chemical structures and their relevant photophysical features for various groups of materials, including organic dyes such as metalloporphyrins and metallophthalocyanines (and derivatives), other common organic materials, mixed metal complexes and clusters, fullerenes, dendrimeric nanocomposites, polymeric materials (organic and/or inorganic), inorganic semiconductors, and other nanoscopic materials, utilized or potentially useful for the realization of devices able to filter in a smart way an external radiation. The concept of smart is referred to the characteristic of those materials that are capable to filter the radiation in a dynamic way without the need of an ancillary system for the activation of the required transmission change. In particular, this Review gives emphasis to the nonlinear optical properties of photoactive materials for the function of optical power limiting. All known mechanisms of optical limiting have been analyzed and discussed for the different types of materials. [ABSTRACT FROM AUTHOR]

Organic dyes have been used as gain medium for lasers since the 1960s, long before the advent of today's organic electronic devices. Organic gain materials are highly attractive for lasing due to their chemical tunability and large stimulated emission cross section. While the traditional dye laser has been largely replaced by solid-state lasers, a number of new and miniaturized organic lasers have emerged that hold great potential for lab-on-chip applications, biointegration, low-cost sensing and related areas, which benefit from the unique properties of organic gain materials. On the fundamental level, these include high exciton binding energy, low refractive index (compared to inorganic semiconductors), and ease of spectral and chemical tuning. On a technological level, mechanical flexibility and compatibility with simple processing techniques such as printing, roll-to-roll, self-assembly, and soft-lithography are most relevant. Here, the authors provide a comprehensive review of the developments in the field over the past decade, discussing recent advances in organic gain materials, which are today often based on solid-state organic semiconductors, as well as optical feedback structures, and device fabrication. Recent efforts toward continuous wave operation and electrical pumping of solid-state organic lasers are reviewed, and new device concepts and emerging applications are summarized. [ABSTRACT FROM AUTHOR]

Three S-containing highly porous metal-organic frameworks, namely, [((CH3)2NH2)Cd(MIPA)]n.xG (n = 4 (1), 2 (2), 1 (3) G = guest of DMF/DMA and H2O), featuring with high adsorption capacities and high selectivity for methylene blue (MB), were successfully assembled by subtly varying the synthesis conditions including solvents and temperatures. Compounds 1-3 crystallize in P21/c, I2/a, and R3¯m, respectively. The anionic frameworks of them are homologues and multiple crystal phases of the {[Cd(MIPA)]n}n-. Compounds 1 and 2 demonstrate the same 3,6-connected binodal net (42.6)(48.64.83), encapulating ca. 18 Å × 18 Å hexagonal channels and three other types of micropous channels. Compound 3 shows a different topology of a 4,4-connected binodal net (43.62.8), which has the highest crystalline density, highest solvent-accessible void, and accessible special surface area, as well as the highest symmetry among them. Circular channel, ca. 13 Å × 13 Å, and two other types of micropore channels are found in six directions. The dye adsorption process for these homologues is proven to be charge-selective and size-selective, in which only the cationic guest (MB+) with a suitable size could enter the frameworks of them and exchange with the dimethylammonium cations. The MB maximum adsorption capacities are 395.1 mg g-1 for 1, 286.6 mg g-1 for 2, and 373.2 mg g-1 for 3, respectively. Moreover, for three kinds of dye mixtures, 3 exhibits the best adsorption kinetics, which is probably due to the suitable pore size, highest solvent-accessible void, and the moderate maximum adsorption capacity of MB. [ABSTRACT FROM AUTHOR]

Conspectus: The majority of organic reactions are commonly carried out inside a lab, under a fume hood. A particular case is that of photochemical reactions, a field where the pioneering experiments by Giacomo Ciamician demonstrated more than one century ago that different processes can be carried out outdoors, for example, on the balcony of his own department, upon exposure of the reacting mixtures to sunlight. The main problem related to this chemistry of the "window ledge" is that most organic compounds are colorless and their absorption in the solar light region is in most cases negligible. Recently, the impressive development in the use of visible light absorbing photocatalysts (e.g., RuII or IrIII complexes, as well as organic dyes) made light-induced processes convenient even for non-photochemistry practitioners. It is thus possible to easily perform the reactions by simply placing the reaction vessel in a sunny place outside the lab. However, most of these processes are based on single electron transfer (SET) reactions (photoredox catalysis). Other photocatalysts able to activate substrates via alternative paths, such as hydrogen atom transfer (HAT), are emerging. In the last years, we were deeply involved in the use of the decatungstate anion ([W10O32]4-, a polyoxometalate) in synthesis. Indeed, such a versatile species is able to promote the photocatalytic C-H activation of organic compounds via either SET or HAT reactions. Interestingly, though the absorption spectrum of [W10O32]4- does not extend into the visible region, it shows an overlap with solar light emission. In this Account, we provide an overview on the application of decatungstate salts as photocatalysts in window ledge chemistry. We initially discuss the nature of the photogenerated species involved in the mechanism of action of the anion, also supported by theoretical simulations. The first-formed excited state of the decatungstate anion decays rapidly to the active species, a dark state tagged wO, featuring the presence of electron-deficient oxygen centers. Next, we describe the main applications of decatungstate chemistry. A significant part of this Account is devoted to photocatalyzed synthesis (C-X bond formation, with X = C, N, O, and oxidations) carried out by adopting sunlight (or simulated solar light). This synthetic approach is versatile, and most of the reactions involved C-H activation in cycloalkanes, alkylaromatics, amides, ethers (1,4-dioxane, oxetane, benzodioxole, and THF), aldehydes, nitriles, and cyclopentanones, and the ensuing addition of the resulting radicals onto electron-deficient olefins. Finally, the increasing role of the decatungstate anion in water depollution and polymerization is briefly discussed. [ABSTRACT FROM AUTHOR]

In this paper, two 3D anionic metal-organic frameworks, [(CH3CH2)2NH2]·[Zn(BTC)1/3(PyC)]·1/2CH3CN·2H2O (NKU-102) and [(CH3CH2)2NH2]·[Zn2(BTC) (PyC)]·1.5H2O·DEF (NKU-103), were constructed from the same reaction system at different temperature. Though both are of anionic framework, NKU-102 possesses a sealed 3D framework based on octahedral cage and shows negligible adsorption capacity of organic dyes, whereas NKU-103 features an open triangular microchannel surrounded by two types of helical chains, and thus exhibits outstanding size-selective adsorption toward small cationic organic dyes. [ABSTRACT FROM AUTHOR]

Low rylene (R) and rylene diimides (RD) are important organic semiconductors and dyes. High R and RD with larger conjugated cores show different properties compared with their low counterparts. Herein, absorption spectra, frontier molecular orbitals, band gaps, inner-sphere reorganization energy (λi), ionization potential, electron affinity, and atomic charge population of 20 rylene compounds were calculated by the density functional theory method. The theoretical results agree well with experimental ones. We predict some unusual properties of some high rylene derivatives that are unknown compounds due to synthetic difficulties. The lowest unoccupied molecular orbital energy levels of RD compounds change slightly, from −3.61 to −3.79 eV, which makes them strong electron acceptors. The band gaps narrow with the size increase of conjugated cores, which makes high rylene derivatives near-infrared dyes. The rising highest occupied molecular orbital energy levels of high rylene derivatives makes them unstable in the air. The λi falls with the size increase of the conjugated core, and the size of RD-4 or R-4 is big enough for the small λi to favor charge transport. The charge population analysis indicates R and RD have different charge distribution under the effect of electron-withdrawing imide groups, which contributes to distinct properties. [ABSTRACT FROM AUTHOR]

Fluorescent silica nanoparticles (FSNPs) are synthesized through the Stöber method by incorporating silane-modified organic dye molecules. The modified fluorescent organic dye molecule is able to be prepared by allylation and hydrosilylation reactions. The optical properties of as-prepared FSNPs are shown the similar optical properties of PR254A (allylated Pigment Red 254) and have outstanding photostability. The polyvinylpyrrolidone (PVP) is introduced onto the surface of FSNP to enhance the binding affinity of PVP-coated FSNP for latent fingerprints (LFPs) detection. The simple preparation and easy control of surface properties of FSNPs show potential as a fluorescent labeling material for enhanced latent fingerprint detection on hydrophilic and hydrophobic substrates in forensic science for individual identification. [ABSTRACT FROM AUTHOR]

The past years have evidenced the rapid development of photochromic coordination compounds; however, the impact of coordination on the photochromic behavior of organic dyes has never been explored in the pyridinium derivative photochromic system. In this work, two new coordination compounds with a photoactive pyridinium-based inner salt, [Zn(H2O)6](PTA)·(CEbpy)2·2H2O (1, PTA = terephthalate, CEbpy = 1-carboxyethyl-4,4'-bipyridine) and [Zn(H2O)2(CEbpy)2]nBr2n·[Zn(H2O)4(PTA)]n (2), were selected as model compounds for this purpose. Compound 1 features an isolated structure, where uncoordinated photoactive CEbpy ligands connect to hexahydrated zinc ions through hydrogen bonds. Compound 2 features a 1-D chain structure with CEbpy ligands coordinating to zinc ions. Compound 1 shows faster coloration speed upon irradiation than 2, demonstrating that coordination of the electron donor in CEbpy is not in favor of photochromic behavior. Both compounds show significant photoluminescence quenching after coloration, and the intensity contrast before and after coloration for 1 is larger than that for 2. This finding will help to design and synthesize new photochromic compounds with high performance. [ABSTRACT FROM AUTHOR]

A conceptually new approach for an efficient removal of anionic organic dyes from wastewater using layered double hydroxides (LDHs) through their formation is presented. Acid yellow 25 (AY25) was used as anionic organic dye model molecules. As a result of the electrostatic induction, the removal mechanism involved a concurrent incorporation of AY25 molecules into the interlayer of LDHs during their structural arrangement, where Mg2+ and Al3+ ions were utilized to construct the base of LDHs in an alkaline solution. It was found that the molar stoichiometry of all precursors was a key factor affecting the removal efficiency. Within 5 min removal time, this method still maintained high removal efficiency of over 97% and provided a removal capacity of ~186 mg g-1, comparable to that of other LDH-based methods. Also, almost complete dye recovery was simply achieved by anionic exchange with common anions (Cl-, NO3-, and CO32-). Additionally, the present technique is straightforward, cost-effective, and environmentally friendly since it avoids the synthesis step of sorbents, thus significantly saving time, chemicals, and energy. Hence, this strategy not only exhibits the alternative exploitation of LDHs, but also provides new insights into the removal of contaminants from wastewater. [ABSTRACT FROM AUTHOR]

We report a platform for the ratiometric fluorescent sensing of endogenously generated gaseous transmitter H2S in its aqueous form (bisulfide or hydrogen sulfide anion) based on the alteration of Forster resonance energy transfer from an emissive semiconductor quantum dot (QD) donor to a dithiol-linked organic dye acceptor. The disulfide bridge between the two chromophores is cleaved upon exposure to bisulfide, resulting in termination of FRET as the dye diffuses away from the QD. This results in enhanced QD emission and dye quenching. The resulting ratiometric response can be correlated quantitatively to the concentration of bisulfide and was found to have a detection limit as low as 1.36 ± 0.03 µM. The potential for use in biological applications was demonstrated by measuring the response of the QD-based FRET sensor microinjected into live HeLa cells upon extracellular exposure to bisulfide. The methodology used here is built upon a highly multifunctional platform that offers numerous advantages, such as low detection limit, enhanced photochemical stability, and sensing ability within a biological milieu. [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.

Three new metal-free organic dyes with the [1]benzothieno[3,2-b]benzothiophene (BTBT) p-bridge, having the structure donor-p-acceptor (D-π-A) and labeled as 19, 20 and 21, have been designed and synthesized for application in dye-sensitized solar cells (DSSC). Once the design of the π-acceptor block was fixed, containing the BTBT as the π-bridge and the cyanoacrylic group as the electron acceptor and anchoring unit, we selected three donor units with different electron-donor capacity, in order to assemble new chromophores with high molar extinction coefficients (ε), whose absorption features well reflect the good performance of the final DSSC devices. Starting with the 19 dye, which shows a molar extinction coefficient ε of over 14,000 M-1 cm-1 and takes into account the absorption maximun at the longer wavelength, the substitution of the BFT donor unit with the BFA yields a great enhancement of absorptivity (molar extinction coefficient ε > 42,000 M-1 cm-1), until reaching the higher value (ε > 69,000 M-1 cm-1) with the BFPhz donor unit. The good general photovoltaic performances obtained with the three dyes highlight the suitable properties of electron-transport of the BTBT as the π-bridge in organic chromophore for DSSC, making this very cheap and easy to synthesize molecule particularly attractive for efficient and low-cost photovoltaic devices. [ABSTRACT FROM AUTHOR]

An organic dye-modified organolead halide CH3NH3PbBr3 nanoparticle (cubic) is prepared successfully by using a perylenetetracarboxylic diimide (PDI) bearing an -NH3+ headgroup as the capping ligand. The nanopartilces are homogeneous with high crystallinity. The photoluminescence of perovskite is quenched completely by the chemically adsorbed PDI molecules. This efficient fluorescence quenching has confirmed that the PDI molecules are anchored on the surface of CH3NH3PbBr3 nanoparticle. The resulting nanoparticles can be dispersed in organic solvents, and the resulting dispersion remains stable for days. This result provides a general guideline for surface engineering of organolead halide CH3NH3PbBr3 nanoparticles. [ABSTRACT FROM AUTHOR]

Biocompatible organic dyes emitting in the near-infrared are highly desirable in fluorescence imaging techniques. Herein we report a synthetic approach for building novel small peri-guanidine-fused naphthalene monoimide and perylene monoimide chromophores. The presented structures possess near-infrared absorption and emission, high photostability, and good water solubility. After a fast cellular uptake, they selectively stain mitochondria with a low background in live and fixed cells. They can be additionally modified in a one-step reaction with functional groups for covalent labeling of proteins. The low cytotoxicity allows a long time exposure of live cells to the dyes without the necessity of washing. Successful application in localization super-resolution microscopy was demonstrated in phosphate-buffered saline without any reducing or oxidizing additives. [ABSTRACT FROM AUTHOR]

In this work a novel strategy is introduced to achieve thermally switchable emission from photon upconversion (UC) systems based on organic dyes. When these molecules were dissolved at low concentrations in phase-change media, a reversible, sharp, and nearly complete interconversion from blue upconverted emission to red luminescence was observed around the solid-to-liquid transition of the system. This result was rationalized in terms of dye aggregation, which selectively occurs in the solid state and dramatically enhances the inter-chromophoric energy transfer processes leading to UC. Notably, this behavior is extendable to different media and dyes, which allows an easy tuning of the switching temperature and emission colors. In addition, with proper selection of the phase-change medium, our strategy permits facile preparation of solid molecular materials showing photon UC at room temperature and even at sub-micromolar dye concentrations. [ABSTRACT FROM AUTHOR]

A new microporous luminescent coordination polymer [(CH3)2NH2]·[Cu2(CN)3] (1) with channels occupied by dimethylamine cations was synthesized due to the inducing effect of 2-(2'-pyridyl)imidazole. Complex 1 exhibits bright-green emission in the solid state, and its emission intensity would be significantly enhanced, especially by DMAc and cupric ion after immersing the as-synthesized crystals of 1 into common organic solvents or methanol solutions of various metal ions. In addition, 1 exhibits photocatalytic activity for the degradation of RhB and MB under natural light and is stable during the photocatalysis process. Thus, 1 can act as a multifunctional material for selectively sensing of Cu2+ and effectively photocatalytic degradation of dyes. [ABSTRACT FROM AUTHOR]

Nitrogen-basedheterocycles are important frameworks for pharmaceuticals,natural products, organic dyes for solar cells, and many other applications.Catalysis for the formation of heterocyclic scaffolds, like many C–Cand C–N bond-forming reactions, has focused on the use of rare,late transition metals like palladium and gold. Our group is interestedin the use of Earth-abundant catalysts based on titanium to generateheterocycles using multicomponent coupling strategies, often in one-potreactions. To be of maximal utility, the catalysts need to be easilyprepared from inexpensive reagents, and that has been one guidingprinciple in the research. For this purpose, a series of easily preparedpyrrole-based ligands has been developed. [ABSTRACT FROM AUTHOR]

Lanthanide-doped upconversion nanoparticleshold promises for bioimaging,solar cells, and volumetric displays. However, their emission brightnessand excitation wavelength range are limited by the weak and narrowbandabsorption of lanthanide ions. Here, we introduce a concept of multistepcascade energy transfer, from broadly infrared-harvesting organicdyes to sensitizer ions in the shell of an epitaxially designed core/shellinorganic nanostructure, with a sequential nonradiative energy transferto upconverting ion pairs in the core. We show that this concept,when implemented in a core–shell architecture with suppressedsurface-related luminescence quenching, yields multiphoton (three-,four-, and five-photon) upconversion quantum efficiency as high as19% (upconversion energy conversion efficiency of 9.3%, upconversionquantum yield of 4.8%), which is about ∼100 times higher thantypically reported efficiency of upconversion at 800 nm in lanthanide-basednanostructures, along with a broad spectral range (over 150 nm) ofinfrared excitation and a large absorption cross-section of 1.47 ×10–14cm2per single nanoparticle. Thesefeatures enable unprecedented three-photon upconversion (visible bynaked eye as blue light) of an incoherent infrared light excitationwith a power density comparable to that of solar irradiation at theEarth surface, having implications for broad applications of theseorganic–inorganic core/shell nanostructures with energy-cascadedupconversion. [ABSTRACT FROM AUTHOR]