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941.
Corrigendum: Combined Two‐Photon Excitation and d→f Energy Transfer in a Water‐Soluble IrIII/EuIII Dyad: Two Luminescence Components from One Molecule for Cellular Imaging
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942.
C,C‐ and N,C‐Coupled Dimers of 2‐Aminotetraphenylporphyrins: Regiocontrolled Synthesis,Spectroscopic Properties,and Quantum‐Chemical Calculations
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Dr. Torsten Bruhn Dipl.‐Chem. Franziska Witterauf Dr. Daniel C. G. Götz Carina T. Grimmer Dipl.‐Chem. Max Würtemberger Prof. Dr. Udo Radius Prof. Dr. Gerhard Bringmann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(14):3998-4006
β,β′‐Bisporphyrins are intrinsically chiral porphyrin dimers with fascinating properties. The configurational stability at their axes can be directed by variation of the central metal atoms. Herein, we present a regioselective functionalization of the monomeric 2‐amino‐tetraphenyl‐porphyrin as a versatile substrate for dimerization by oxidative coupling. By simple variation of the reaction conditions (solvent and oxidant), the oxidation selectively gave either the axially chiral C,C‐coupled diaminobisporphyrin in high yields or, under Ullmann conditions, the twofold N,C‐linked achiral dimer, also in good yields. A generalized mechanism for the coupling reaction is proposed based on DFT calculations. The axially chiral β,β′‐coupled porphyrin dimers were isolated as racemic mixtures, but can be resolved by HPLC on a chiral phase. TDDFT and coupled‐cluster calculations were used to explain the spectroscopic properties of the aminoporphyrins and their dimers and to elucidate the absolute configurations of the C,C‐coupled bisporphyrins. 相似文献
943.
HP‐CsB5O8: Synthesis and Characterization of an Outstanding Borate Exhibiting the Simultaneous Linkage of All Structural Units of Borates
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Gerhard Sohr Daniel M. Többens Prof. Dr. Jörn Schmedt auf der Günne Prof. Dr. Hubert Huppertz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(51):17059-17067
The new cesium pentaborate HP‐CsB5O8 is synthesized under high‐pressure/high‐temperature conditions of 6 GPa and 900 °C in a Walker‐type multianvil apparatus. The compound crystallizes in the orthorhombic space group Pnma (Z=4) with the parameters a=789.7(1), b=961.2(1), c=836.3(1) pm, V=0.6348(1) nm3, R1=0.0359 and wR2=0.0440 (all data). The new structure type of HP‐CsB5O8 exhibits the simultaneous linkage of trigonal BO3 groups, corner‐sharing BO4 tetrahedra, and edge‐sharing BO4 tetrahedra including the presence of threefold‐coordinated oxygen atoms. With respect to the rich structural chemistry of borates, HP‐CsB5O8 is the second structure type possessing this outstanding combination of the main structural units of borates in one compound. The structure consists of corrugated chains of corner‐ and edge‐sharing BO4 tetrahedra interconnected through BO3 groups forming octagonal channels. Inside these channels, cesium is 13+3‐fold coordinated by oxygen atoms. 11B MQMAS NMR spectra are analyzed to estimate the isotropic chemical shift values and quadrupolar parameters. IR and Raman spectra are obtained and compared to the calculated vibrational frequencies at the Γ‐point. The high‐temperature behavior is examined by means of temperature‐programmed powder diffraction. 相似文献
944.
In Situ Electrodeposition of an Asymmetric Sol–Gel Membrane Based on an Octadecyltrimethoxysilane Langmuir Film
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Maria Hitrik Prof. Ovadia Lev Prof. Daniel Mandler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(38):12104-12113
The unique properties of Langmuir film formation were utilized in assembling a thin skin of an asymmetric membrane. An octadecyltrimethoxysilane (ODTMS) Langmuir monolayer was formed at the air–water interface and served as the substrate for growing a bulky sol–gel polymer in situ. The latter was based on the electrochemical deposition of tetramethoxysilane dissolved in the water subphase by means of horizontal touch electrochemistry. The resultant asymmetric layer that consisted of a thin hydrophobic ODTMS Langmuir film connected to a bulk hydrophilic sol–gel network was studied in situ and ex situ by using various techniques, such as cyclic voltammetry, electrochemical impedance spectroscopy (EIS), scanning electron microscopy, transmission electron microscopy (TEM), and goniometry. We found that a porous hydrophilic film grew on top of a hydrophobic layer as was evident from TEM, contact angle, and EIS analyses. The film thickness and film permeability could be controlled by changing the deposition conditions such as the potential window applied and its duration. Hence, this method offers an alternative approach for assembling asymmetric films for various applications 相似文献
945.
Dr. Damien Hudry Dr. Christos Apostolidis Dr. Olaf Walter Dr. Arne Janßen Dr. Dario Manara Dr. Jean‐Christophe Griveau Dr. Eric Colineau Dr. Tonya Vitova Tim Prüßmann Dr. Di Wang Dr. Christian Kübel Dr. Daniel Meyer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(33):10431-10438
Apart from its technological importance, plutonium (Pu) is also one of the most intriguing elements because of its non‐conventional physical properties and fascinating chemistry. Those fundamental aspects are particularly interesting when dealing with the challenging study of plutonium‐based nanomaterials. Here we show that ultra‐small (3.2±0.9 nm) and highly crystalline plutonium oxide (PuO2) nanocrystals (NCs) can be synthesized by the thermal decomposition of plutonyl nitrate ([PuO2(NO3)2] ? 3 H2O) in a highly coordinating organic medium. This is the first example reporting on the preparation of significant quantities (several tens of milligrams) of PuO2 NCs, in a controllable and reproducible manner. The structure and magnetic properties of PuO2 NCs have been characterized by a wide variety of techniques (powder X‐ray diffraction (PXRD), X‐ray absorption fine structure (XAFS), X‐ray absorption near edge structure (XANES), TEM, IR, Raman, UV/Vis spectroscopies, and superconducting quantum interference device (SQUID) magnetometry). The current PuO2 NCs constitute an innovative material for the study of challenging problems as diverse as the transport behavior of plutonium in the environment or size and shape effects on the physics of transuranium elements. 相似文献
946.
María José Heras‐Ojea Daniel Reta Mañeru Lidia Rosado Dr. Juan Rubio Zuazo Dr. German R. Castro Subrata Tewary Dr. Gopalan Rajaraman Dr. Guillem Aromí Dr. Erika Jiménez Dr. E. Carolina Sañudo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(33):10439-10445
The new diimine fluorescent ligand ACRI‐1 based on a central acridine yellow core is reported along with its coordination complex [Co2( ACRI‐1 )2] ( 1 ), a fluorescent weak ferromagnet. Due to the strong fluorescence of the acridine yellow fluorophore, it is not completely quenched when the ligand is coordinated to CoII. The magnetic properties of bulk complex 1 and its stability in solution have been studied. Complex 1 has been deposited on highly ordered pyrolitic graphite (HOGP) from solution. The thin films prepared have been characterized by AFM, time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS), grazing incidence X‐ray diffraction (GIXRD), X‐ray absorption spectroscopy (XAS), X‐ray magnetic circular dichroism (XMCD) and theoretical calculations. The data show that the complex is robust and remains intact on the surface of graphite. 相似文献
947.
Synthesis and Biological Evaluation of a Class of Mitochondrially‐Targeted Gadolinium(III) Agents
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Dr. Daniel E. Morrison Dr. Jade B. Aitken Dr. Martin D. de Jonge Dr. Fatiah Issa Prof. Hugh H. Harris Prof. Louis M. Rendina 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(50):16602-16612
A structure–activity relationship study of a library of novel bifunctional GdIII complexes covalently linked to arylphosphonium cations is reported. Such complexes have been designed for potential application in binary cancer therapies such as neutron capture therapy and photon activation therapy. A positive correlation was found between lipophilicity and cytotoxicity of the complexes. Mitochondria uptake was determined by means of inductively coupled plasma mass spectrometry (ICP‐MS), and Gd uptake was determined by means of quantification using synchrotron X‐ray fluorescence (XRF) imaging. A negative correlation between lipophilicity and tumour selectivity of the GdIII complexes was demonstrated. This study highlights the delicate balance required to minimise in vitro cytotoxicity and optimise in vitro tumour selectivity and mitochondrial localisation for this new class of mitochondrially‐targeted binary therapy agents. We also report the highest in vitro tumour selectivity for any Gd agent reported to date, with a T/N (tumour/normal cell) ratio of up to 23.5±6.6. 相似文献
948.
Lead Structures for New Antibacterials: Stereocontrolled Synthesis of a Bioactive Muraymycin Analogue
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Daniel Wiegmann Dr. Stefan Boettcher Agnes Mihalyi Prof. Timothy D. H. Bugg Prof. Christian Ducho 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(47):15292-15297
Naturally occurring muraymycin nucleoside antibiotics represent a promising class of novel antibacterial agents. The structural complexity suggests the investigation of simplified analogues as potential lead structures, which can then be further optimized towards highly potent antimicrobials. Herein we report studies on muraymycin‐derived potential lead structures lacking an aminoribose motif found in most naturally occurring muraymycins. We have identified a 5′‐defunctionalized motif to be ideal in terms of stability and chemical accessibility and have synthesized a full‐length muraymycin analogue based on this structure using a novel fully stereocontrolled route. The obtained 5′‐deoxy analogue of the natural product muraymycin C4 showed good inhibitory properties towards the bacterial target protein MraY, sufficient pharmacokinetic stability and no cytotoxicity against human cells, thus making it a promising lead for antibacterial drug development. 相似文献
949.
Tao Wang Shuai Shi Daniel Pflästerer Eva Rettenmeier Dr. Matthias Rudolph Dr. Frank Rominger Prof. Dr. A. Stephen K. Hashmi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(1):292-296
The conversion of simple, easily available urea‐substituted 3‐phenylpropargyl alcohols catalyzed by a simple IPr–gold(I) catalyst in a gold(I)‐catalyzed cascade reaction composing of a gold‐catalyzed nucleophilic addition and a subsequent gold‐catalyzed substitution reaction delivers 1H‐imidazo[1, 5?a]indol‐3(2 H)‐ones. Other gold(I) catalysts or silver catalysts gave lower yields and often gave other side products. Gold(III) and copper(II) catalysts decomposed the starting material. Twelve examples, including donor and acceptor substituents on the distal nitrogen of the urea substructure, are provided. An X‐ray crystal structure analysis confirmed the structural assignment. The mechanistic investigation including isolation and further conversion of intermediates and reactions with enantiopure starting materials indicated that after the nucleophilic‐addition step, the substrate undergoes an SN1‐type benzylic substitution reaction at the indolyl alcohol intermediate or an intramolecular hydroamination reaction of the 2‐vinylindole intermediate. 相似文献
950.
Coverage‐ and Temperature‐Dependent Metalation and Dehydrogenation of Tetraphenylporphyrin on Cu(111)
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Michael Röckert Matthias Franke Quratulain Tariq Stefanie Ditze Michael Stark Patrick Uffinger Daniel Wechsler Upendra Singh Dr. Jie Xiao Dr. Hubertus Marbach Prof. Dr. Hans‐Peter Steinrück Dr. Ole Lytken 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(29):8948-8953
Using temperature‐programmed desorption, supported by X‐ray photoelectron spectroscopy and scanning tunneling microscopy, a comprehensive overview of the main reactions of 5,10,15,20‐tetraphenyl‐21H,23H‐porphyrin (2HTPP) on Cu(111) as a function of coverage and temperature is obtained. Three reactions were identified: metalation with Cu substrate atoms, stepwise partial dehydrogenation, and finally complete dehydrogenation. At low coverage the reactions are independent of coverage, but at higher coverage metalation becomes faster and partial dehydrogenation slower. This behavior is explained by a weaker interaction between the iminic nitrogen atoms and the Cu(111) surface in the high‐coverage checkerboard structure, leading to faster metalation, and the stabilizing effect of T‐type interactions in the CuTPP islands formed at high coverage after metalation, leading to slower dehydrogenation. Based on the amount of hydrogen released and the appearance in STM, a structure of the partially dehydrogenated molecule is suggested. 相似文献