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electron transfer

Jin-Le Hou, Peng Huo, Zheng-Zhen Tang, Li-Na Cui, Qin-Yu Zhu, Jie Dai
The use of multiple sensitizers in dye sensitized solar cells has been attractive as a promising way to achieve highly efficient photovoltaic performance. However, except for the complementary absorption, synergistic effects among the dye components have not been well understood. Herein, using ferrocene-1-carboxylate (FcCO2 ) and catechol (Cat) as dye ligands, two titanium oxo clusters (TOCs), [Ti3 O(Oi Pr)6 (Cat)(FcCO2 )2 ] (1) and [Ti7 O4 (Oi Pr)8 (Cat)5 (FcCO2 )2 ] (2), were synthesized and structurally characterized...
May 24, 2018: Inorganic Chemistry
Eric R Kennehan, Grayson S Doucette, Ashley R Marshall, Christopher Grieco, Kyle T Munson, Matthew C Beard, John B Asbury
Observations of the hot-phonon bottleneck, which is predicted to slow the rate of hot carrier cooling in quantum confined nanocrystals, have been limited to date for reasons that are not fully understood. We used time-resolved infrared spectroscopy to directly measure higher energy intraband transitions in PbS colloidal quantum dots. Direct measurements of these intraband states permitted detailed analysis of the electronic overlap of the quantum confined states that may influence their relaxation processes...
May 24, 2018: ACS Nano
Bin Yang, Youai Qiu, Jan-E Bäckvall
Oxidation reactions play a central role in organic synthesis, and it is highly desirable that these reactions are mild and occur under catalytic conditions. In Nature, oxidation reactions occur under mild conditions via cascade processes, and furthermore, they often occur in an enantioselective manner with many of them involving molecular oxygen or hydrogen peroxide as the terminal oxidant. Inspired by the reactions in Nature, we have developed a number of Pd(II)-catalyzed cascade reactions under mild oxidative conditions...
May 24, 2018: Accounts of Chemical Research
Alexander S Mikherdov, Mikhail A Kinzhalov, Alexander S Novikov, Vadim P Boyarskiy, Irina A Boyarskaya, Margarita S Avdontceva, Vadim Yu Kukushkin
The reaction of cis-[PdCl2 (CNXyl)2 ] (Xyl = 2,6-Me2 C6 H3 ) with the aminoazoles [1 H-imidazol-2-amine (1), 4 H-1,2,4-triazol-3-amine (2), 1 H-tetrazol-5-amine (3), 1 H-benzimidazol-2-amine (4), 1-alkyl-1 H-benzimidazol-2-amines, where alkyl = Me (5), Et (6)] in a 2:1 ratio in the presence of a base in CHCl3 at RT proceeds regioselectively and leads to the binuclear diaminocarbene complexes [(ClPdCNXyl)2 {μ-C(N-azolyl)N(Xyl)C═NXyl}] (7-12; 73-91%). Compounds 7-12 were characterized by C, H, N elemental analyses, high-resolution ESI+ -MS, Fourier transform infrared spectroscopy, 1D (1 H, 13 C) and 2D (1 H,1 H-COSY, 1 H,1 H-NOESY, 1 H,13 C-HSQC, 1 H,13 C-HMBC) NMR spectroscopies, and X-ray diffraction (XRDn)...
May 24, 2018: Inorganic Chemistry
Shue Mei Ng, Xiangyang Wu, M Faisal Khyasudeen, Pawel Jacek Nowakowski, Howe-Siang Tan, Bengang Xing, Edwin K L Yeow
A highly sensitive and selective probe for Vancomycin (Van) in aqueous and serum samples is developed in this study. The probe is based on a triad consisting of a near-infrared squaraine dye (Seta-640) conjugated to two anthraquinone molecules via Lys-D-Ala-D-Ala peptides. In the absence of Van, the close proximity and efficient electron-transfer from the excited Seto-640 dye to anthraquinone result in significant fluorescence quenching of the dye ("off"-state). When Van is added, the antibiotic molecules bind with high affinity to the -D-Ala-D-Ala ligands in a 2:1 stoichiometry (Van:triad); resulting in fluorescence recovery that is as high as 30-times ("on"-state)...
May 24, 2018: ACS Sensors
Soham Samanta, Senjuti Halder, Gopal Das
Two, cyanine based fluorescent probes L [(E)-2-(4-(diethylamino)-2-hydroxystyryl)-3-ethyl-1,1-dimethyl-1H-benzo[e]indol-3-ium iodide] and L1 [(E)-3-ethyl-1,1-dimethyl-2-(4-nitrostyryl)-1H-benzo[e]indol-3-ium iodide] have been designed and synthesized. Among these two probes; TICT (twisted intramolecular charge transfer) based probe L can preferentially self-assemble to form nanoaggregates. L displayed a selective TURN-ON fluorescence response towards HSA and BSA in ~100% aqueous PBS buffer medium which is noticeable through naked eye whereas L1 failed to sense these albumin proteins...
May 24, 2018: Analytical Chemistry
Michael W Ratzloff, Jacob H Artz, David W Mulder, Reuben T Collins, Thomas E Furtak, Paul W King
The [FeFe]-hydrogenases ([FeFe] H2 ases) catalyze reversible H2 activation at the H-cluster, which is composed of a [4Fe-4S]H subsite linked by a cysteine thiolate to a bridged, organometallic [2Fe-2S] ([2Fe]H ) subsite. Profoundly different geometric models of the H-cluster redox states that orchestrate the electron/proton transfer steps of H2 bond activation have been proposed. We have examined this question in the [FeFe] H2 ase I from Clostridium acetobutylicum (CaI) by Fourier-transform infrared (FTIR) spectroscopy with temperature annealing and H/D isotope exchange to identify the relevant redox states and define catalytic transitions...
May 23, 2018: Journal of the American Chemical Society
Eun-Tae Yun, Jeong Hoon Lee, Jaesung Kim, Hee-Deung Park, Jaesang Lee
Select persulfate activation processes were demonstrated to initiate oxidation not reliant on sulfate radicals, though the underlying mechanism has yet to be identified. This study explored singlet oxygenation and mediated electron transfer as plausible nonradical mechanisms for organic degradation by carbon nanotube (CNT)-activated peroxymonosulfate (PMS). The degradation of furfuryl alcohol (FFA) as a singlet oxygen (1O2) indicator and the kinetic retardation of FFA oxidation in the presence of L-histidine and azide as 1O2 quenchers apparently supported a role of 1O2 in the CNT/PMS system...
May 23, 2018: Environmental Science & Technology
Brian J Cook, Gianna N Di Francesco, Matthew T Kieber-Emmons, Leslie J Murray
Oxygenation of a tricopper(I) cyclophanate (1) affords reactive transients competent for C-H bond activation and O atom transfer to various substrates (including toluene, dihydroanthracene, and ethylmethylsulfide) based on 1 H NMR, gas chromatography/mass spectrometry (MS), and electrospray ionization (ESI)/MS data. Low product yields (<1%) are determined for C-H activation substrates (e.g, toluene, ethylbenzene), which we attribute to competitive ligand oxidation. The combined stopped-flow UV/visible, electron paramagnetic resonance, ESI/MS, 1 H NMR, and density functional theory (DFT) results for reaction of 1 with O2 are consistent with transient peroxo- and di(oxo)-bridged intermediates...
May 23, 2018: Inorganic Chemistry
A T Ezhil Vilian, Rajamanickam Sivakumar, Yun Suk Huh, Ji Ho Youk, Young-Kyu Han
Metal nanoparticle-containing porous organic polymers have gained great interest in chemical and pharmaceutical applications owing to their high reactivity and good recyclability. In the present work, a palladium nanoparticle-decorated triazine-urea-based porous organic polymer (Pd@TU-POP) was designed and synthesized using 1, 3-bis (4-aminiphenyl) urea with cyanuric chloride and palladium acetate. The porous structure and physicochemical properties of this electrode material Pd@TU-POP were observed using a range of standard techniques...
May 23, 2018: ACS Applied Materials & Interfaces
Shiyuan Gao, Bin Wang, Xinyu Liu, Zhanhu Guo, Zhongqing Liu, Yichao Wang
Amorphous molybdenum sulfides (a-MoSx) have been demonstrated as economic and efficient hydrogen evolution catalysts for water splitting. Further improvements of their hydrogen evolution reaction (HER) activities could be achieved by coupling them with appropriate electron transfer intermediates via interfacial engineering. In this study, a novel ternary composite electrode comprising PbTe quantum dots (QDs), a-MoSx and TiO2 nanotube arrays (TNAs) was successfully fabricated by a facile combination of successive ionic layer adsorption and reaction (SILAR) and electrodeposition routes...
May 23, 2018: Nanoscale
Chun Tian, Jinyun Niu, Xuerui Wei, Yujie Xu, Lifen Zhang, Zhenping Cheng, Xiulin Zhu
The performance of functional polymer nanomaterials is a vigorously discussed topic in polymer science. We devoted ourselves to investigating polymer nanomaterials based on near-infrared (NIR) fluorescence imaging and polymer prodrug in this study. Aza-boron dipyrromethene (BODIPY) is an important organic dye, having characteristics such as environmental resistance, light resistance, high molar extinction coefficient, and fluorescence quantum yield. We incorporated it into our target monomer, which can be polymerized without changing its parent structure in a polar solvent and copolymerized with water-soluble monomer to improve the solubility of the dye in an aqueous solution...
May 23, 2018: Nanoscale
Peter S Sherin, Yuri P Tsentalovich, Eric Vauthey, Enrico Benassi
Kynurenines (KNs) are natural UV filters of the human eye lens, protecting the eye tissues from solar UV radiation. Key points of their effective protection are the intramolecular charge transfer (ICT) in the excited state and the fast dissipation of absorbed light energy into heat via the intermolecular H-bonds. Herein we report that the introduction of an unsaturated double bond in the amino acid side chain, operating as an ICT-enhancing electron donor group, drastically accelerates the internal conversion (IC) due to a conical intersection (CI) between the potential energy surfaces of the excited and ground states...
May 23, 2018: Physical Chemistry Chemical Physics: PCCP
N M AbouShabana, R AbdelKader, S Abdel-Rahman, H S Abdel-Gawad, A M Abdel-Galil
The current study was conducted to investigate the effect of ExcelMOS® in enhancing the immune system of Sparus aurata broodstock and their impact on offspring health through displaying the maternal transfer of immunity. Broodstock were divided into two groups: one was injected intraperitoneally with ExcelMOS® 1 month before spawning, while the other group was used as a control (without injection). Comprehensive increase in survival rate was observed for larvae hatched from ExcelMOS®-injected broodstock than those of the control (P ≤ 0...
May 22, 2018: Fish Physiology and Biochemistry
Jianguang Feng, Hongzhou Dong, Beili Pang, Feifei Shao, ChunKai Zhang, Liyan Yu, Lifeng Dong
The effects of four heteroatoms (B, N, P, and S) with three doping patterns on graphene quantum dots (GQDs) are systematically investigated using time-dependent density functional theory (TD-DFT). The absorption spectra and HOMO-LUMO gaps are quantitatively analyzed to study the correlations between the optical properties and heteroatom doping of doped GQDs. Heteroatom doping can endow GQDs with various new optical and structural properties, depending on the dopants and doping configurations. Compared with the absorption spectra of pristine GQD, both N and S surface doping demonstrate a slight blue shift, whereas B and P doping lead to a blue shift for edge-doped GQDs with heteroatoms in a pentatomic ring...
May 23, 2018: Physical Chemistry Chemical Physics: PCCP
Daisuke Matsushita, Hirotaka Uji, Shunsaku Kimura
Electron transfer (ET) reactions via helical peptides composed of -(Aib-Pro)n- were studied in self-assembled monolayers and compared with -(Ala-Aib)n- peptides. Short Aib-Pro peptides showed slightly higher ET rates due to the better electronic coupling of the Pro residue. But, the 24mer Aib-Pro peptide showed a smaller ET rate than the corresponding Ala-Aib peptide. On the basis of DFT calculations, the deceleration of the ET rate of the longer Aib-Pro peptide is considered to be due to the smaller number of active modes of accordion-like oscillations than the Ala-Aib peptide, which has a strong influence on a long-range ET reaction...
May 23, 2018: Physical Chemistry Chemical Physics: PCCP
Ankita Joshi, C N Ramachandran
Using the dispersion-corrected density functional B97D and 6-31g(d,p) basis set, the structural, stability, electronic, optical and charge transport properties of the complexes formed by encapsulating indigo inside carbon nanotubes (CNTs) of varying diameters are investigated. Based on the stabilization energy of the complexes indigo@(n,n)CNT (where n = 6, 7 and 8), indigo@(7,7)CNT is shown to be the most stable owing to the ideal diameter of (7,7)CNT for encapsulating indigo. The nature of the interaction between the guest and the host is investigated by means of energy decomposition analysis employing the symmetry adapted perturbation theory...
May 23, 2018: Physical Chemistry Chemical Physics: PCCP
Junko Matsuda, Tatsuya Kawasaki, Shotaro Futamura, Tsutomu Kawabata, Shunsuke Taniguchi, Kazunari Sasaki
In situ transmission electron microscopy (TEM) observations of a Ni(O)-Sc2O3-stabilized ZrO2 (ScSZ; 10 mol% Sc2O3, 1 mol% CeO2, 89 mol% ZrO2) anode in a solid oxide fuel cell (SOFC) have been performed at high temperatures under a hydrogen/oxygen gas atmosphere using an environmental transmission electron microscope (ETEM); the specimens were removed from cross-sections of the real SOFC by focused ion beam milling and lifting. When heating the NiO-ScSZ anode under a hydrogen atmosphere of 3 mbar in ETEM, nano-pores were formed at the grain boundaries and on the surface of NiO particles at around 400°C due to the volume shrinkage accompanying the reduction of NiO to Ni...
May 19, 2018: Microscopy
Yau-Chung Hu, Meng-Han Chung, Tsung-Han Lee
Cytochrome c oxidase (COX) catalyzes the terminal oxidation reaction in the electron transfer chain (ETC) of aerobic respiratory systems. COX activity is an important indicator for the evaluation of energy production by aerobic respiration in various tissues. On the basis of the respiratory characteristics of muscle, we established an optimal method for the measurement of maximal COX activity. To validate the measurement of cytochrome c absorbance, different ionic buffer concentrations and tissue homogenate protein concentrations were used to investigate COX activity...
May 19, 2018: Analytical Biochemistry
Juan C Rojas, Kyle A Carey, Dana P Edelson, Laura R Venable, Michael D Howell, Matthew M Churpek
RATIONALE: Patients transferred from the intensive care unit (ICU) to the wards who are later readmitted to the ICU have increased length of stay, healthcare expenditure, and mortality compared to those who are never readmitted. Improving risk-stratification for patients transferred to the wards could have important benefits for critically ill hospitalized patients. OBJECTIVE: We aimed to use a machine-learning technique to derive and validate an ICU readmission prediction model with variables available in the electronic health record (EHR) in real-time and compare it to previously published algorithms...
May 22, 2018: Annals of the American Thoracic Society
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