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71.
We experimentally demonstrate a new technique to control the type of frequency correlations of entangled photon pairs generated by spontaneous parametric downconversion. Frequency-correlated and frequency-anticorrelated photons are produced when a broadband pulse is used as a pump. The method is based on the control of the group velocities of the interacting waves and can be applied in any nonlinear medium and frequency band of interest. 相似文献
72.
73.
Peripherally and Axially Carboxylic Acid Substituted Subphthalocyanines for Dye‐Sensitized Solar Cells 下载免费PDF全文
Dr. Mine Ince Dr. Anaïs Medina Dr. Jun‐Ho Yum Dr. Aswani Yella Dr. Christian G. Claessens Dr. M. Victoria Martínez‐Díaz Prof. Michael Grätzel Dr. Mohammad K. Nazeeruddin Prof. Tomás Torres 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(7):2016-2021
A series of subphthalocyanines (SubPcs) bearing a carboxylic acid group either at the peripheral or axial position have been designed and synthesized to investigate the influence of the COOH group positions on the dye‐sensitized solar cell (DSSC) performance. The DSSC devices based on SubPcs with axially substituted carboxylic acid groups showed low photovoltaic performance, whereas peripherally substituted one exhibited higher power conversion efficiency owing to improved injection from LUMO of SubPcs to the TiO2 conduction band. 相似文献
74.
Luís E. Sarto Iara M. R. Landre Gabriela F. Bozza Claudia Torres Eduardo T. de Almeida 《Transition Metal Chemistry》2014,39(5):495-500
Five new complexes of general formula [PdX2(p-diben)], where p-diben = N,N′-bis(4-dimethylaminobenzylidene)ethane-1,2-diamine) (1) and X = Cl (2), Br (3), I (4), N3 (5), or CNO (6), were synthesized and characterized by physicochemical and spectroscopic methods. The crystal structure of compound (5) was determined by single-crystal X-ray diffraction. Complexes 2–6 were characterized as N,N-chelated products. The crystal structure confirmed this formulation for [Pd(N3)2(p-diben)], besides showing the isomerism inversion of one of the C=N bonds, caused by Pd(II) coordination. 相似文献
75.
Luis M. Mateo Qiang Sun Shi‐Xia Liu Jesse J. Bergkamp Kristjan Eimre Carlo A. Pignedoli Pascal Ruffieux Silvio Decurtins Giovanni Bottari Roman Fasel Tomas Torres 《Angewandte Chemie (International ed. in English)》2020,59(3):1334-1339
On‐surface synthesis offers a versatile approach to prepare novel carbon‐based nanostructures that cannot be obtained by conventional solution chemistry. Graphene nanoribbons (GNRs) have potential for a variety of applications. A key issue for their application in molecular electronics is in the fine‐tuning of their electronic properties through structural modifications, such as heteroatom doping or the incorporation of non‐benzenoid rings. In this context, the covalent fusion of GNRs and porphyrins (Pors) is a highly appealing strategy. Herein we present the selective on‐surface synthesis of a Por–GNR hybrid, which consists of two Pors connected by a short GNR segment. The atomically precise structure of the Por–GNR hybrid has been characterized by bond‐resolved scanning tunneling microscopy (STM) and noncontact atomic force microscopy (nc‐AFM). The electronic properties have been investigated by scanning tunneling spectroscopy (STS), in combination with DFT calculations, which reveals a low electronic gap of 0.4 eV. 相似文献
76.
Marcos V. Foguel Angelica M. Balcarcel Mark A. Reed Percy Calvo‐Marzal Yulia V. Gerasimova Dmitry M. Kolpashchikov Karin Y. Chumbimuni‐Torres 《Electroanalysis》2020,32(4):835-841
One major challenge in nucleic acids analysis by hybridization probes is a compromise between the probe's tight binding and sequence‐selective recognition of nucleic acid targets folded into stable secondary structures. We have been developing a four‐way junction (4WJ)‐based sensor that consists of a universal stem‐loop (USL) probe immobilized on an electrode surface and two adaptor strands (M and F). The sensor was shown to be highly selective towards single base mismatches at room temperature, able to detect multiple targets using the same USL probe, and have improved ability to detect folded nucleic acids. However, some nucleic acid targets, including natural RNA, are folded into very stable secondary and tertiary structures, which may represent a challenge even for the 4WJ sensors. This work describes a new sensor, named MVF since it uses three probe stands M, V and F, which further improves the performance of 4WJ sensors with folded targets. The MVF sensor interrogating a 16S rRNA NASBA amplicon with calculated folding energy of ?32.82 kcal/mol has demonstrated 2.5‐fold improvement in a signal‐to‐background ratio in comparison with a 4WJ sensor lacking strand V. The proposed design can be used as a general strategy in the analysis of folded nucleic acids including natural RNA. 相似文献
77.
Giulia Lavarda Daiki Shimizu Toms Torres Atsuhiro Osuka 《Angewandte Chemie (International ed. in English)》2020,59(8):3127-3130
Peripherally metalated porphyrinoids are promising functional π‐systems displaying characteristic optical, electronic, and catalytic properties. In this work, 5‐(2‐pyridyl)‐ and 5,10,15‐tri(2‐pyridyl)‐BIII‐subporphyrins were prepared and used to produce cyclometalated subporphyrins by reactions with [Cp*IrCl2]2, which proceeded through an efficient C?H activation to give the corresponding mono‐ and tri‐IrIII complexes, respectively. While the mono‐IrIII complex was obtained as a diastereomeric mixture, a C3‐symmetric tri‐IrIII complex with the three Cp*‐units all at the concave side was predominantly obtained in a high yield of 90 %, which displays weak NIR phosphorescence even at room temperature in degassed CH2Cl2, differently from the mono‐IrIII complexes. 相似文献
78.
Beatriz Lozano‐Torres Juan F. Blandez Irene Galiana Alba García‐Fernndez María Alfonso María D. Marcos Mar Orzez Flix Sancenn Ramn Martínez‐Mez 《Angewandte Chemie (International ed. in English)》2020,59(35):15152-15156
In vivo detection of cellular senescence is accomplished by using mesoporous silica nanoparticles loaded with the NIR‐FDA approved Nile blue (NB) dye and capped with a galactohexasaccharide ( S3 ). NB emission at 672 nm is highly quenched inside S3 , yet a remarkable emission enhancement is observed upon cap hydrolysis in the presence of β‐galactosidase and dye release. The efficacy of the probe to detect cellular senescence is tested in vitro in melanoma SK‐Mel‐103 and breast cancer 4T1 cells and in vivo in palbociclib‐treated BALB/cByJ mice bearing breast cancer tumor. 相似文献
79.
Dr. Juliana Arriel Torres Dr. Gelson T. S. T. Da Silva Dr. Fernando Barbosa de Freitas Silva Dr. Caue Ribeiro 《Chemphyschem》2020,21(21):2392-2396
Tin dioxide (SnO2) has intrinsic characteristics that do not favor its photocatalytic activity. However, we evidenced that surface modification can positively influence its performance for CO2 photoreduction in the gas phase. The hydroxylation of the SnO2 surface played a role in the CO2 affinity decreasing its reduction potential. The results showed that a certain selectivity for methane (CH4), carbon monoxide (CO), and ethylene (C2H4) is related to different SnO2 hydrothermal annealing. The best performance was seen for SnO2 annealed at 150 °C, with a production of 20.4 μmol g−1 for CH4 and 16.45 μmol g−1 for CO, while for SnO2 at 200 °C the system produced more C2H4, probably due to a decrease of surface −OH groups. 相似文献
80.
Thaís Silva da Rocha Alessandro de Lima Jurandy do Nascimento Silva Geni Rodrigues Sampaio Rosana Aparecida Manlio Soares Freitas Renan Danielski Adriano Costa de Camargo Fereidoon Shahidi Elizabeth Aparecida Ferraz da Silva Torres 《Molecules (Basel, Switzerland)》2022,27(3)
Jua (juá in Portuguese) is an underexplored fruit from Brazil’s northeast. This fruit is rich in antioxidant substances. However, there is a dearth of information about jua’s bioactive potential. The present study evaluated two extraction methods (continuous agitation and ultrasound-assisted extraction—UAE) and employed three different solvents (water, ethanol, and acetone) to efficiently recover soluble phenolic compounds. Aqueous extracts obtained by UAE showed the highest total phenolic content (TPC) and antiradical activity. Besides being an eco-friendly procedure, extraction and/or solubility in an aqueous medium is also important for food application. Ellagic acids were the predominant phenolics (80%) found in aqueous jua pulp extract obtained by UAE, as determined by HPLC, while its TPC was 405.8 gallic acid equivalent per gram of fruit. This extract also exhibited a higher scavenging activity towards peroxyl radicals when compared to that of several other fruits from the literature, including grape, strawberry, cranberry, and walnuts, which are known references in terms of antioxidants. This is the first report that demonstrates jua pulp’s potential as an alternative source of ellagic acid and other phenolic acids and flavonoids. Therefore, the outcome of this study provides new information that can be useful for functional food and nutraceutical industries. 相似文献