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Zhong-Xia Wang, Fen-Ying Kong, Wei Wang
Graphene quantum dots-like structures of highly enriched nitrogen-based dual-color single-functional polymer carbon nanosheets (GLNPCNs) with an average diameter as large as 170 nm (~5 layers) are prepared by a facile hydrothermal method. Intermolecular C5H5N5···C5H5N5 or/and C2H5OH chemical polymerization interactions in the liquid state of the peripheral crown ether-like "hole" decorated compound GLNPCNs lead to a fascinating 2D supramolecular polymer architecture, which exhibits near-ultraviolet (NUV) fluorescence, narrow full width at half maximum, and excellent practical application capability...
October 20, 2016: Chemistry: a European Journal
Narcis Avarvari, Thomas Biet, Kévin Martin, Jihane Hankache, Nora Hellou, Andreas Hauser, Thomas Bürgi, Nicolas Vanthuyne, Tal Aharon, Marco Caricato, Jeanne Crassous
Introduction of heterocycles in the helical skeleton of helicenes allows modulation of their redox, chiroptical and photophysical properties. Herein, we describe the straightforward preparation and structural characterization by single crystal X-ray diffraction of thiadiazole-[7]helicene, which has been resolved into (M) and (P) enantiomers by chiral HPLC, together with its S-shaped double [4]helicene isomer, as well as the smaller congeners thiadiazole-[5]helicene and benzothiadiazole-anthracene. A copper(II) complex with two thiadiazole-[5]helicene ligands has been structurally characterized and it shows the presence of both (M) and (P) isomers coordinated to the metal centre...
October 20, 2016: Chemistry: a European Journal
Salem A E Omar, Paul A Scattergood, Luke K McKenzie, Helen E Bryant, Julia A Weinstein, Paul I P Elliott
The complex [Os(btzpy)₂][PF₆]₂ (1, btzpy = 2,6-bis(1-phenyl-1,2,3-triazol-4-yl)pyridine) has been prepared and characterised. Complex 1 exhibits phosphorescence (λem = 595 nm, τ = 937 ns, φem = 9.3% in degassed acetonitrile) in contrast to its known ruthenium(II) analogue, which is non-emissive at room temperature. The complex undergoes significant oxygen-dependent quenching of emission with a 43-fold reduction in luminescence intensity between degassed and aerated acetonitrile solutions, indicating its potential to act as a singlet oxygen sensitiser...
October 18, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Xiang Lin, Qing Wang, Xilin Peng, Hui Li
Metandienone (MET) is an exogenous anabolic androgenic steroid. The interaction between MET and human serum albumin (HSA) was investigated by molecular modeling and different optical techniques. There was no possibility of energy transfer, and the fluorescence quenching of HSA induced by MET was mainly due to the complex formation. The differences of binding ability between MET and compounds 1-5 were significantly caused by space steric hindrance. The single crystallographic data of two steroids (compounds 4 and 5) were obtained in the methanol at the first time...
October 20, 2016: Journal of Biochemical and Molecular Toxicology
Yongming Guo, Lianfeng Zhang, Fengpu Cao, Yumin Leng
A facile, simple and low-cost approach for synthesizing highly fluorescent carbon quantum dots (CQDs) from thermal treatment of sustainable hair has been developed. The resultant CQDs exhibited strong blue emission with a quantum yield of 10.75%, excellent photostability and high stability in high salt conditions. As the fluorescence of CQDs can be efficiently quenched by Hg(2+), the CQDs can be constructed as a nanosensor for Hg(2+) with good sensitivity and selectivity. And as low as 10 nM Hg(2+) can be successfully detected...
October 20, 2016: Scientific Reports
Haisheng He, Jian Zhang, Yunchang Xie, Yi Lu, Jianping Qi, Ejaj Ahmad, Xiaochun Dong, Weili Zhao, Wei Wu
One of the biggest challenges in bioimaging of nanoparticles is how to identify integral particles from bulk signals of probes. Signals of free probes are always mistakenly counted into total signals of particles. In this study, in vivo fate of intravenous polymeric micelles (PMs, mPEG2.5k-PDLLA2.5k) was explored using a highly sensitive near-infrared environment-responsive fluorescent probe. This probe is able to emit fluorescence when embedded in nanocarriers but quench spontaneously and absolutely upon release into water, based on the aggregation-caused quenching effect, which means that the interference generated by free probes can be completely diminished...
October 19, 2016: Molecular Pharmaceutics
Rui-Cheng Gao, Fu-Sheng Guo, Nan-Nan Bai, Yun-Long Wu, Fan Yang, Ji-Ye Liang, Zhen-Jing Li, Yao-Yu Wang
Two new three-dimensional isostructural lanthanide metal-organic frameworks (Ln(III)-MOFs), [LnL(H2O)3]·3H2O·0.75DMF (1-Ln; Ln = Dy(III) and Eu(III) ions, H3L = biphenyl-3'-nitro-3,4',5-tricarboxylic acid, DMF = N,N'-dimethylformamide), were synthesized and characterized. The appearance of temperature-dependent out-of-phase (χ″M) signal reveals that complex 1-Dy displays slow magnetic relaxation behavior with the energy barrier (ΔUeff) of 57 K and a pre-exponential factor (τ0) of 3.89 × 10(-8) s at 1200 Oe direct current field...
October 19, 2016: Inorganic Chemistry
Di Shu, Ionel Simbotin, Robin Côté
We investigate the energy dependence of inelastic processes in systemswhich possess Efimov states. We consider the three-body recombinationrate $K_3$ where three free atoms interact to produce anatom--dimer pair, and the relaxation rate $K_{\rm rel}$where an atom quenches a weakly bound state of a dimernear an Efimov resonance to more deeply bound levels.Using a modelcapturing the key features of the Efimov problem, weidentify new energy regimes for $K_3$, namely the NTR (NearThreshold Resonance) regime behavior $E^{-2}$ for negativescattering lengths and the NTS (Near Threshold Suppression) regimebehavior $E^2$ for positive scattering lengths...
October 19, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Mouritz N Svenson, Randall E Youngman, Yuanzheng Yue, Sylwester J Rzoska, Michal Bockowski, Lars R Jensen, Morten M Smedskjaer
The structure and properties of glass can be modified through compression near the glass transition temperature (Tg), and such modified structure and properties can be maintained at ambient temperature and pressure. However, once the compressed glass undergoes annealing near Tg at ambient pressure, the modified structure and properties will relax. The challenging question is how the property relaxation is correlated with both the local and the medium-range structural relaxation. In this paper, we answer this question by studying the volume (density) and structural relaxation of a sodium borate glass that has first been pressure-quenched from its Tg at 1 GPa, and then annealed at ambient pressure under different temperature-time conditions...
October 19, 2016: Physical Chemistry Chemical Physics: PCCP
Shuyun Wu, Minghua Lai, Jiahao Luo, Jingwen Pan, Li-Ming Zhang, Liqun Yang
To understand the mechanism responsible for the α-amylase inhibitory activity of tea polysaccharides, the interaction between α-amylase and an acidic branched tea polysaccharide (TPSA) was investigated using fluorescence spectroscopy and resonance light scattering analysis. TPSA, exhibiting inhibitory activity towards α-amylase (the maximum inhibition percentage of 65%), was isolated from green tea (Camellia sinensis) and characterized by nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, and gas chromatography...
October 15, 2016: International Journal of Biological Macromolecules
Nikolai N Sluchanko, Konstantin E Klementiev, Evgeny A Shirshin, Georgy V Tsoraev, Thomas Friedrich, Eugene G Maksimov
In Cyanobacteria, the Orange Carotenoid Protein (OCP) and Fluorescence Recovery Protein (FRP) are central to the photoprotective mechanism consisting in regulated quenching of phycobilisome (PBs) fluorescence. Due to a transient and flexible nature of the light-activated red quenching form, OCP(R), which is obtained from the stable dark-adapted orange form, OCP(O), by photoconversion, the detailed mechanism of photoprotection remains unclear. Here we demonstrate that our recently described W288A mutant of the Synechocystis OCP (hereinafter called OCP(W288A)) is a fully functional analogue of the OCP(R) form which is capable of constitutive PBs fluorescence quenching in vitro with no need of photoactivation...
October 15, 2016: Biochimica et Biophysica Acta
Anders Sandell, Davide Ragazzon, Andreas Schaefer, Mari Helene Farstad, Anne Borg
We present a dedicated synchrotron radiation photoelectron spectroscopy (SR-PES) study of a photochemical reaction on the surface of rutile TiO2(110). The photoreaction kinetics of carboxylate species (trimethyl acetate, TMA) upon irradiation by UV and soft x-rays were monitored and we show that it is possible to control the reaction rates from UV light and soft x-rays independently. We directly observe Ti4+ → Ti3+ conversion upon irradiation, attributed to electron trapping at Ti sites close to surface OH groups formed by deprotonation of the parent molecule, trimethyl acetic acid (TMAA)...
October 18, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Taeho Kim, Gary B Braun, Zhi-Gang She, Sazid Hussain, Erkki Ruoslahti, Michael J Sailor
A theranostic nanoparticle with biochemically triggered antibacterial activity is demonstrated. Metallic silver is deposited onto porous silicon nanoparticles (pSiNPs) by galvanic displacement. When aqueous diaminesilver ([Ag(NH3)2](+)) is used as a silver source, the pSiNPs template the crystalline silver as small (mean diameter 13 nm) and well-dispersed nanoparticles embedded within and on the larger (100 nm) pSiNPs. The silver nanoparticles quench intrinsic photoluminescence (PL) from the porous silicon matrix...
October 18, 2016: ACS Applied Materials & Interfaces
Boran Lee, Byung Gyu Park, Wansang Cho, Ho Yong Lee, András Olasz, Chun-Hsing Chen, Seung Bum Park, Dongwhan Lee
A series of air-stable boron complexes 1-5 were prepared by using N-aryl iminopyrrolide ligands. Designed as minimalist structural mimics of the privileged BODIPY motif, these new BOIMPY (BOron complexes of IMinoPYrrolide ligands) fluorophores feature low molecular symmetry that promotes emission from CT-type excited states with large Stokes shifts and little self-quenching. Through comparative studies on the homologous set of compounds 1-4, we have confirmed that a delicate interplay between conformational twisting and donor-acceptor interaction dictates the mechanism of de-excitation, which responds sensitively to solvent polarity as well as protonation states...
October 18, 2016: Chemistry: a European Journal
Yi Wang, Meiqing Zhu, Feng Liu, Xiangwei Wu, Dandan Pan, Jia Liu, Shisuo Fan, Zhen Wang, Jun Tang, Risong Na, Qing X Li, Rimao Hua, Shangzhong Liu
In the present study, 3-(fluorobenzylideneamino)-6-chloro-1-(3,3-dimethylbutanoyl)-phenyl-2,3-dihydroquinazolin-4(1H)-one (FDQL) derivatives have been designed and synthesized to study the interaction between fluorine substituted dihydroquinazoline derivatives with human serum albumin (HSA) using fluorescence, circular dichroism and Fourier transform infrared spectroscopy. The results indicated that the FDQL could bind to HSA, induce conformation and the secondary structure changes of HSA, and quench the intrinsic fluorescence of HSA through a static quenching mechanism...
October 14, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Jangsun Hwang, Mintai P Hwang, Moonhyun Choi, Youngmin Seo, Yeonho Jo, Jaewoo Son, Jinkee Hong, Jonghoon Choi
Heavy metal pollution has been a problem since the advent of modern transportation, which despite efforts to curb emissions, continues to play a critical role in environmental pollution. Copper ions (Cu(2+)), in particular, are one of the more prevalent metals that have widespread detrimental ramifications. From this perspective, a simple and inexpensive method of detecting Cu(2+) at the micromolar level would be highly desirable. In this study, we use porous silicon nanoparticles (NPs), obtained via anodic etching of Si wafers, as a basis for undecylenic acid (UDA)- or acrylic acid (AA)-mediated hydrosilylation...
October 18, 2016: Scientific Reports
Lin Ma, Feng Hao, Constantinos C Stoumpos, Brian T Phelan, Michael R Wasielewski, Mercouri G Kanatzidis
The dynamics of photoexcited lead-free perovskite films, CH3NH3SnI3, were studied using broadband transient absorption (TA) and time-resolved fluorescence (TRF) spectroscopy. Similar to its lead analogue CH3NH3PbI3, we show that free carrier (electrons and holes) recombination is also the dominant relaxation pathway in CH3NH3SnI3 films. The slow hot carrier relaxation time is 0.5 ps. Long carrier diffusion lengths for electrons (279 ± 88 nm) and holes (193 ± 46 nm) were obtained from fluorescence quenching measurements...
October 17, 2016: Journal of the American Chemical Society
Maximiliano L Agazzi, M Belén Ballatore, Eugenia Reynoso, Ezequiel D Quiroga, Edgardo N Durantini
Two cationic BODIPYs 3 and 4 were synthesized by acid-catalyzed condensation of the corresponding pyrrole and benzaldehyde, followed by complexation with boron and methylation. Compound 3 contains methyl at the 1,3,5 and 7 positions of the s-indacene ring and a N,N,N-trimethylamino group attached to the phenylene unit, while 4 is not substituted by methyl groups and the cationic group is bound by an aliphatic spacer. UV-visible absorption spectra of these BODIPYs show an intense band at ∼500 nm in solvents of different polarities and n-heptane/sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/water reverse micelles...
October 3, 2016: European Journal of Medicinal Chemistry
Ning Du, Jian Song, Shuang Li, Yu-Xian Chi, Feng-Ying Bai, Yong-Heng Xing
Hydrothermal reaction of the multidentate organic ligand (H6TTHA) with indium chloride (InCl3) produced a highly stable 3D luminescent indium-organic framework [In2(OH)2(H2TTHA)(H2O)2]n (1). Complex 1 exhibits remarkable luminescent properties, especially the multifunction sensitivity and selectivity for detecting Ru(3+), UO2(2+); as well as small biomolecules thiamines (TPP, TMP, and TCl) based on a "turn-off" manner. In particular, the pyrophosphate groups of TPP and the phosphate groups of TMP could further affect the quenching rate, leading to different luminescent responds...
October 17, 2016: ACS Applied Materials & Interfaces
Bert Conings, Aslihan Babayigit, Matthew T Klug, Sai Bai, Nicolas Gauquelin, Nobuya Sakai, Jacob Tse-Wei Wang, Johan Verbeeck, Hans-Gerd Boyen, Henry J Snaith
A robust and expedient gas quenching method is developed for the solution deposition of hybrid perovskite thin films. The method offers a reliable standard practice for the fabrication of a non-exhaustive variety of perovskites exhibiting excellent film morphology and commensurate high performance in both regular and inverted structured solar cell architectures.
October 17, 2016: Advanced Materials
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