Bi(OTf)3·xH2O is a powerful catalyst for the dehydration of tertiary alcohols into alkenes in apolar solvents. The reaction proceeds smoothly and selectively, with amounts as low as 0.01 mol % catalyst, in yields up to 93%. Moreover, in polar solvents, Bi(OTf)3·xH2O (0.1-1 mol %) selectively catalyzes the dimerization of the alcohols instead, forming new C-C bonds, in yields up to 96%. This mild, efficient, economic, and eco-friendly method is applicable across different chemical classes and amenable to several functional groups.

Tungsten disulfide (WS2) nanotubes are cylindrical, multiwall nanotubes with various diameters and wall numbers. They can exhibit various unique properties depending on their structures and thus preparing samples with uniform structures is important for understanding their basic properties and applications. However, most synthesis methods have difficulty to prepare uniform samples, and thus, a purification method to extract nanotubes with a selected diameter and wall number must be developed. Here, we demonstrate a solution-based purification of WS2 nanotubes using a surfactant solution. Stable dispersions of nanotubes were prepared using nonionic surfactants, which enabled us to sort the diameters and wall numbers of the nanotubes through a centrifugation process. By optimizing the conditions, we successfully obtained thin nanotubes with a mean diameter of 32 nm and mean wall number of 13 with relatively small distributions. Finally, we clarified the relationships between the structure and optical properties of the nanotubes.

Pyrimidines have always received considerable attention because of their importance in synthesis and elucidation of biochemical roles, in particular that of vitamin B1. Herein, we describe a reaction pathway in a Grignard reagent-based synthesis of substituted pyrimidines. A general synthesis of α-keto-2-methyl-4-amino pyrimidines and their C6-substituted analogues from 4-amino-5-cyano-2-methylpyrimidine is reported. The presence of the nitrile substituent in the starting material also results in an unusual reaction pathway leading to C6-substituted 1,2-dihydropyrimidines. Grignard reagents that give normal pyrimidine products under standard reaction conditions can be switched to give dihydropyrimidines by holding the reaction at 0 °C before quenching.

Fluorescent organic materials are commonly π-conjugated planar molecules. In the present work, however, we report a novel class of nonconjugated fluorescent molecular cages of trinuclear fluoroborate complexes (nine samples) with salicylaldehyde-based Schiff base ligands. Owing to the stress from lone pair electrons of N atom in the triethylamine bridge, these B(III) complexes exhibit unusual enantiomers with a tripodlike side-single-opening structure. They emit blue, green, and red emission with large Stokes shifts (up to 159 nm) and high fluorescence quantum yields in both solution (up to 0.24) and solid state (up to 0.25), which might contribute to their strong intramolecular hydrogen bonds and weak intermolecular and intramolecular π-π interactions. Combining their advantages of nonconjugation and biocompatibility, these flexible complexes have potential applications in living cell imaging and anion hosts. We have examined the inherent relationships between their chemical structures and emission properties and afforded a new stage for the design of nonconjugated fluorescent fluoroborate complexes.

The electrochemical systems of both grafted catechol as a pH-responsive electrophore and immobilized cytochrome c as a model redox protein are detected by cyclic voltammetry at an optimized lipid deposit-modified glassy carbon electrode. The catechol covalent grafting is successfully performed by the one-pot/three-step electrochemical reduction of 3,4-dihydroxybenzenediazonium salts generated in situ from 4-nitrocatechol. The resulting glassy carbon electrode electrochemically modified by grafted catechol species is evaluated as an efficient electrochemical pH sensor. The optimized molar ratio for the lipid deposit, promoting cytochrome c electrochemical activity in solution onto glassy carbon electrode, is reached for the lipid mixture composed of 75% 1,2-dioleoyl-sn-glycero-3-phosphocholine and 25% cardiolipin. Cytochrome c immobilization into the optimized supported lipid deposit is efficiently achieved by cyclic voltammetry (10 cycles) recorded at the modified glassy carbon electrode in a cytochrome c solution. The pH-dependent redox response of the grafted catechol and that of the immobilized cytochrome c are finally detected at the same lipid-modified glassy carbon electrode without alteration of their structure and electrochemical properties in the pH range 5-9.

Metal-organic coordination polymers (CPs) have attracted great research interest because they are easy to prepare, porous, flexible in composition, and designable in structure. Their applications in biosensor development, drug delivery, and catalysis have been explored. Lanthanides and nucleotides can form interesting CPs, although most previous works have focused on a single type of metal ligand. In this work, we explored mixed nucleotides and studied their DNA adsorption properties using fluorescently labeled oligonucleotides. Adenosine monophosphate (AMP) and guanosine monophosphate (GMP) formed negatively charged CP nanoparticles with most lanthanides, and thus a salt was required to adsorb negatively charged DNA. DNA adsorption was faster and reached a higher capacity with lighter lanthanides. Desorption of pre-adsorbed DNA by inorganic phosphates, urea, proteins, surfactants, and competing DNA was successively carried out. The results suggested the importance of the DNA phosphate backbone, although hydrogen bonding and DNA bases also contributed to adsorption. The AMP CPs adsorbed DNA more strongly than the GMP ones, and using mixtures of AMP and GMP, continuous tuning of DNA adsorption affinity was achieved. Such CPs were also used as a sensor for DNA detection based on the different affinities of single- and double-stranded DNA, and a detection limit of 0.9 nM target DNA was achieved. Instead of tuning DNA adsorption by varying the length and sequence of DNA, the composition of CPs can also be controlled to achieve this goal.

Herein, we report the preparation of graphene oxide dots (GO dots) by fine-tuning the carbonization degree of citric acid. The structure of GO dots was characterized by absorption spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, as well as high-resolution scanning electron microscopy and transmission electron microscopy analyses. The typical particle size of the GO dots was 42 nm. The fluorescent characteristics of the GO dots were analyzed by fluorescence spectroscopy. Once excited at 360 nm, the GO dots were fluorescent in the range of 450-550 nm, which was dependent on the excitation wavelength. Further, GO dots were effectively utilized for multifarious applications such as photoinduced electron transfer and detection of explosives and biomolecules. The emission property of GO dots was competently quenched by viologens, picric acid (PA), and bilirubin (BR). The mechanism of quenching by viologens and explosives/biomolecules was found to be due to photoinduced electron transfer and the internal filter effect, respectively. Intriguingly, the detection minimum of PA is in the nanomolar level. Toward commercialization, the economic test strips have also been introduced for the identification of PA. Furthermore, the GO dots have been applied as an efficient luminescent bioprobe for a selective and perceptive finding of BR.

Steady development on photophysical behaviors for a variety of organic fluorophores inspired us to generate anthracene-based fluorescent molecules with a strong acceptor and a significantly weak donor through a π-spacer. Such molecules are found to have substantial twisted conformational orientations in the solid state and enhanced apolar character because of the attachment of tolyl or mesityl group with an anthracenyl core. Upon exposure to a variety of solvents, strong solvatochromism was noticed for 4-nitro compound (84 nm red shift) in contrast to the cyano analogue (18 nm red shift). Both these probes were highly emissive in apolar solvents while nitro-analogue, in particular, could discriminate the solvents of E T(30) (a measure of microscopic solvent polarity) ranging from 31 to 37. Thus, 4-nitro compounds can be successfully employed to detect and differentiate the apolar solvents. On the contrary, the 2-nitro analogue is almost nonemissive for the same range of solvents perhaps because of favorable excited-state intramolecular proton-transfer process. The fundamental understanding of solvatochromic properties through the formation of twisted intramolecular charge-transfer (TICT) state is experimentally analyzed by synthesizing and studying the π-conjugates linked to only benzene in place of nitro or cyanobenzene, which exhibits no solvatochromism and that helped finding the possible emission, originated from the locally excited state. Moreover, the molecular structures for these compounds are determined by the single-crystal X-ray diffraction studies to examine the change in emission properties with molecular packing and alignment in the aggregated state. The measurement of dihedral angles between the substituents and anthracenyl core was helpful in finding the possible extent of electronic conjugations within the system to decipher both solvatochromism and aggregation enhanced emission (AEE)-behavior. The cyano analogue exhibited prominent AEE-behavior, whereas nitro analogues showed the aggregation-caused quenching effect. The reason behind such dissimilarity in solvatochromism and AEE-behavior between cyano- and nitro-linked anthracenyl π-conjugates are also addressed through experimental outcomes.

Polyaniline@graphene/nickel oxide (Pani@GN/NiO), polyaniline/graphene (Pani/GN), and polyaniline/nickel oxide (Pani/NiO) nanocomposites and polyaniline (Pani) were successfully synthesized and tested for ammonia sensing. Pani@GN/NiO, Pani/NiO, Pani/GN, and Pani were characterized using X-ray diffraction, UV-vis spectroscopy, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. The as-prepared materials were studied for comparative dc electrical conductivity and the change in their electrical conductivity on exposure to ammonia vapors followed by ambient air at room temperature. It was observed that the incorporation of GN/NiO in Pani showed about 99 times greater amplitude of conductivity change than pure Pani on exposure to ammonia vapors followed by ambient air. The fast response and excellent recovery time could probably be ascribed to the relatively high surface area of the Pani@GN/NiO nanocomposite, proper sensing channels, and efficaciously available active sites. Pani@GN/NiO was observed to show better selectivity toward ammonia because of the comparatively high basic nature of ammonia than other volatile organic compounds tested. The sensing mechanism was explained on the basis of the simple acid-base chemistry of Pani.

We probe the role of surface functionalization and physical properties of nanoinclusions in thermal conductivity enhancement during liquid-solid phase transition in a hexadecane-based phase change material (PCM). Hexadecane-based PCM is loaded with six different nanoinclusions: carbon black nanopowder (CBNP), nickel nanoparticles (NiNPs), copper nanoparticles, silver nanowires (AgNWs), multiwalled carbon nanotubes, and graphene nanoplatelets (GNPs). The nanoinclusions CBNP, NiNP, AgNW, and GNP are surface-functionalized with oleic acid. Nanoinclusion-loaded PCM showed a large enhancement in thermal conductivity, which was more prominent in the solid state. Interestingly, a maximum thermal conductivity enhancement of ∼122% was observed in the solid state for the PCM loaded with 0.01 wt % CBNP. Higher thermal conductivity enhancement in the solid state is attributed to the formation of a nanocrystalline network structure during freezing of the PCM, consisting of a needlelike microstructure, which is confirmed by optical phase contrast microscopy. During solidification, the nanoinclusions are driven toward the grain boundaries, thereby forming a quasi-two-dimensional network of percolating structures with high thermal transport efficiency due to the enhancement of phonon-mediated heat transfer and near-field radiative heat transfer. Thermal conductivity increases with the increased loading of the nanoinclusions due to the formation of more interconnecting aggregates. Among the carbon-based nanoinclusions, the highest thermal conductivity enhancement is obtained for the PCM loaded with CBNP, which is attributed to the low fractal dimensions and volume-filling capability of CBNP aggregates. In the case of metallic nanoinclusions, the highest thermal conductivity enhancement is obtained for the PCM loaded with AgNW, which is due to the large aspect ratio of AgNW. The carboxylic group of oleic acid attached to the nanoinclusions is found to provide better steric stability with insignificant aggregation and improved thermal stability, which are beneficial for practical applications. Our results indicate that the initial thermal conductivity of carbon-based nanoinclusions has an insignificant role in the thermal conductivity enhancement of the PCM but the volume-filling capability of the nanoinclusion has a prominent role. The findings from the present study will be beneficial for tailoring the properties of nanoinclusion-loaded organic PCM for thermal energy storage and reversible thermal switching applications at room temperature.

The overexpression of α-synuclein (α-syn) and its aggregation is the hallmark of Parkinson's disease. The α-syn aggregation results in the formation of Lewy bodies that causes neuronal cell death. Therefore, the small molecules that can protect neuronal cells from α-syn toxicity or inhibit the aggregation of α-syn could emerge as anti-Parkinson agents. Herein, a library of methoxy-stilbenes was screened for their ability to restore the cell growth from α-syn toxicity, using a yeast strain that stably expresses two copies of a chromosomally integrated human α-syn gene. Tetramethoxy-stilbene 4s, a nonantioxidant, was the most capable of restoring cell growth. It also rescues the more toxic cells that bear three copies of wild-type or A53T-mutant α-syn, from cell growth block. Its EC50 values for growth restoration of the 2-copy wild-type and the 3-copy mutant α-syn strains are 0.95 and 0.35 μM, respectively. Stilbene 4s mitigates mitochondrial membrane potential loss, negates ROS production, and prevents nuclear DNA-fragmentation, all hallmarks of apoptosis. However, 4s does not rescue cells from the death-inducing effects of Bax and βA4, which suggest that 4s specifically inhibits α-syn-mediated toxicity in the yeast. Our results signify that simultaneous use of multiple yeast-cell-based screens can facilitate revelation of compounds that may have the potential for further investigation as anti-Parkinson's agents.

A new efficient approach has been reported for the tritylation of primary alcohols over secondary alcohols using triphenyl methyl alcohol and 4-monomethoxyl trityl alcohols in the presence of imidazolium-based ionic liquid 1-ethyl-3-methylimidazolium tetrachloroaluminate as catalyst. At room temperature, 5 mol % of catalyst in dichloromethane and acetonitrile solvent has been shown to be excellent for the tritylation of benzyl alcohol and various other alcohols The method was compatible with Fmoc/acetyl protecting group of amino and tert-butyldiphenylsilyl ether protecting group of alcohol. Moreover, the catalyst was reused for three to four catalytic cycles with little loss of catalytic activity. Excellent yields, reusability, chemoselectivity, and easy workup are advantages of this protocol.

Hierarchical mesoporous TiO2 was synthesized via a solvothermal technique. The sonochemical method was adopted to decorate plasmonic nanoparticles (NPs) (Ag, Au) on the pores of mesoporous TiO2. The crystallinity, structure, and morphology were determined to understand the physicochemical nature of the nanocomposites. The catalytic efficiency of the plasmonic nanocatalysts was tested for the azo dyes (congo red, methyl orange, acid orange 10, and remazol red) under solar and visible light irradiations. The generation of hydroxyl radicals was also studied using terephthalic acid as a probe molecule. An attempt was made to understand the influence of size, work function and Fermi level of the metal NPs toward the efficiency of the photocatalyst. The efficiency of the nanocomposites was found to be in the order of P25 < mesoporous TiO2 < mesoporous Ag-TiO2 < mesoporous Au-TiO2 nanospheres under both direct solar light and visible light irradiation. The results indicated that the adsorption of dye, anatase phase, and surface plasmon resonance of NPs favored the effective degradation of dyes in aqueous solution. Further, the efficiency of the catalyst was also tested for xanthene (rose bengal), rhodamine (rhodamine B, rhodamine 6G), and thiazine (methylene blue) dyes. Both TiO2 and NPs (Ag & Au) possess a huge potential as an eco-friendly photocatalyst for wastewater treatment.

Since the introduction of acetyl cholinesterase inhibitors as the first approved drugs by the US Food and Drug Administration for Alzheimer's disease (AD) in clinics, less than satisfactory success in the design of anti-AD agents has impelled the scientists to also focus toward inhibition of Aβ aggregation. Considering the specific binding of fragments for their parent peptide, herein, we synthesized more than 40 new peptides based on a C-terminus tetrapeptide fragment of Aβ1-42. Initial screening by MTT cell viability assay and supportive results by ThT fluorescence assay led us to identify a tetrapeptide showing complete inhibition for Aβ1-42 aggregation. Peptide 20 displayed 100% cell viability at 20 μM concentration, while at lower concentrations of 10 and 2 μM 76.6 and 70% of cells were viable. Peptide 20 was found to restrict the conformational transition of Aβ1-42 peptide toward β-sheet structure. Inhibitory activity of tetrapeptide 20 was further evidenced by the absence of Aβ1-42 aggregates in electron microscopy. Peptide 20 and other significantly active tetrapeptide analogues could prove imperative in the future design of anti-AD agents.

The sluggish oxygen evolution reaction (OER) hinders the development of electrocatalytic water splitting for energy conversion and storage. Therefore, it is imperative to explore the cost-effective and highly efficient noble-metal-free electrocatalysts for OER. Herein, we are introducing such OER electrocatalyst based on Co, fabricated through an ionic-liquid-assisted one-step synthesis, where ionic liquid played a dual role as solvent cum structure-directing agent. Besides possessing large-accessible surface area and numerous active sites, the as-prepared stable CoO nanosheets exhibited excellent electrochemical activity through establishing an extensive contact with the electrolyte. Under alkaline conditions, the overpotential to achieve a current density of 10 mA cm-2 is only 320 mV, and the Tafel slope is as small as 70 mV dec-1. Thus, our work provides a new pathway for designing and engineering the highly efficient non-noble metal OER electrocatalysts by using ionic liquids.

Periphyton is a complex mixture of algae, microbes, inorganic sediment, and organic matter that is attached to submerged surfaces in most flowing freshwater systems. This natural community is known to absorb pollutants from the water column, resulting in improved water quality. However, the role of periphyton in the fate and transport of genetic fecal markers suspended in the water column remains unclear. As application of genetic-based methodologies continues to increase in freshwater settings, it is important to identify any interactions that could potentially confound water quality interpretations. A 16 week indoor mesocosm study was conducted to simultaneously measure genetic fecal markers in the water column and in the associated periphyton when subject to wastewater source loading. Treated wastewater effluent was pumped directly from a treatment facility adjacent to the experimental stream facility. Inflow and outflow surface water grabs were paired with the collection of periphyton samples taken from the mesocosm substrates on a weekly basis. Samples were analyzed with three genetic fecal indicator quantitative real-time polymerase chain reaction assays targeting Escherichia coli (EC23S857), enterococci (Entero1), and Bacteroidales (GenBac3), as well as, two human host-associated fecal pollution markers (HF183 and HumM2). In addition, periphyton dry mass was measured. During wastewater effluent loading, genetic markers were detected in periphyton at frequencies up to 100% (EC23S857, Entero1, and GenBac3), 59.4% (HF183), and 21.9% (HumM2) confirming sequestration from the water column. Mean net-flux shifts in water column inflow and outflow genetic indicator concentrations further supported interactions between the periphyton and water column. In addition, positive correlations were observed between periphyton dry mass and genetic marker concentrations ranging from r = 0.693 (Entero1) to r = 0.911 (GenBac3). Overall, findings support the notion that genetic markers suspended in the water column can be trapped by periphyton, further suggesting that the benthic environment in flowing freshwater systems may be an important factor to consider for water quality management with molecular methods.

There are various ways of immobilizing carbonic anhydrase (CA) on solid materials. One of the final aims is to apply immobilized CA for the catalytic hydration of carbon dioxide (CO2) as a first step in the conversion of gaseous CO2 into solid products. The immobilization method investigated allows a straightforward, stable, and quantifiable immobilization of bovine erythrocyte carbonic anhydrase (BCA) on silicate surfaces. The method is based on the use of a water-soluble, polycationic second-generation dendronized polymer with on average 1000 repeating units, abbreviated as de-PG21000. Several copies of BCA were first covalently linked to de-PG21000 through stable bisaryl hydrazone (BAH) bonds. Then, the de-PG21000-BAH-BCA conjugates obtained were adsorbed noncovalently either on microscopy glass coverslips, inside glass micropipettes, or in porous glass fiber filters. The apparent density of the immobilized BCA on the glass surfaces was about 8-10 pmol/cm2. In all three cases, the immobilized enzyme was highly active and stable when tested with p-nitrophenyl acetate as a model enzyme substrate at room temperature. The micropipettes and the glass fiber filters were applied as flow-through systems for continuous operation at room temperature. In the case of the glass fiber filters, the filters were placed inside a homemade flow-through filter holder which allows flow-through runs with more than one filter connected in series. This offers the opportunity of increasing the substrate conversion by increasing the number of BCA-containing filters.

The simpler the design, the better and more effective it is. Two novel conjugated triarylamine derivatives in donor-π-donor structure employing biphenyl core and pyrene core as π-bridges, which are termed as Bp-OMe and Py-OMe, have been synthesized and characterized and then applied to perovskite solar cells (PSCs) as hole-transport materials (HTMs) successfully. Using 2,2',7,7'-tetrakis(N,N-di-p-methoxy-phenylamine)-9,9'-spirobiuorene (spiro-OMeTAD) as a relative reference, Py-OMe-based PSCs showed the best power conversion efficiency (PCE) of 19.28% under AM 1.5 G illumination at 100 mW cm-2, which is comparable to that of PSCs based on spiro-OMeTAD with a best PCE of 18.57% with doping. Although Bp-OMe-based PSCs performed with relatively poor PCEs (best PCE of 15.06%) than those of Py-OMe-based PSCs, attributing to the poor planarity and hole mobility, taking the cost into consideration, Bp-OMe and Py-OMe are much more likely to be promising efficient HTMs for PSCs.

Herein, we demonstrate the fabrication of Bi(0)-doped bismuth oxyhalide solid solution films for the removal of trace organic pollutants (TrOPs) in water. With the advantage of a viscous AlOOH sol, very high loadings (75 wt %) of bismuth oxyhalides were embedded within the thin films and calcined at 500 °C to develop porous alumina composite coatings. Various concentrations of Bi(0) doping were tested for their photocatalytic activity. Seven TrOPs including iopromide (IPRM), iohexol (IHX), iopamidol (IPMD), sulfamethoxazole (SMX), carbamazepine, venlafaxine, and bezafibrate (BZF) were selected for this study based on their occurrence and detection in effluents and surface waters worldwide. In all tests, with the exception of IPRM, 3% Bi(0)-doped BiOCl0.875Br0.125 showed highest activity, which can be attributed to its unique, highly organized, and compact morphology besides its well-matched energy band positions. Although IPMD, IHX, IPRM, and SMX are susceptible to photolysis, still the photocatalytic activity significantly augmented the removal of all tested compounds. In addition, analysis of the surface charge excluded electrostatic interactions and confirmed the ion-exchange adsorption mechanism for the high degradation rate of BZF in the presence of bismuth oxyhalides.

We developed a spinning approach for a dope produced by treating softwood pulp with a deep eutectic solvent (DES). The DES enables formation of a sufficiently viscous spinnable gel-like suspension of fibers, which solidifies upon the removal of the DES. This solidification, however, requires a longer time compared to most conventional wet spinning processes. Consequently, the continuity of the spinning process has been constrained in previous work. Moreover, the ability to draw the incipient yarn to increase orientation has been limited. Here we present a continuous spinning approach where the fiber yarn properties and processability can be improved using an inclined channel. A combination of an air gap and an inclined ethanol stream transports and draws the incipient fiber yarn during spinning. The influence of syringe tip diameter, angle of the channel, ethanol flow rate, and twisting were studied experimentally. The improvements in the spinning process resulted in an increase in load bearing capability and ability to reduce the linear density of the fiber yarn.