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101.
We prove an elementary formula about the average expansion of certain products of 2 by 2 matrices. This permits us to quickly
re-obtain an inequality by M. Herman and a theorem by Dedieu and Shub, both concerning Lyapunov exponents. Indeed, we show
that equality holds in Herman’s result. Finally, we give a result about the growth of the spectral radius of products.
Financial support from Pronex-Dynamical Systems, CNPq 001/2000 and from Faperj is gratefully acknowledged. 相似文献
102.
Artur MichalakMarek Nawrocki 《Indagationes Mathematicae》2002,13(2):185-195
In the paper we describe the Banach envelopes of Hardy spaces of analytic functions of several variables on polydiscs taking values in quasi-Banach spaces. 相似文献
103.
104.
105.
Guest‐Induced Transformation of a Porphyrin‐Edged FeII4L6 Capsule into a CuIFeII2L4 Fullerene Receptor
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Daniel M. Wood Dr. Wenjing Meng Dr. Tanya K. Ronson Dr. Artur R. Stefankiewicz Prof. Jeremy K. M. Sanders Prof. Jonathan R. Nitschke 《Angewandte Chemie (International ed. in English)》2015,54(13):3988-3992
The combination of a bent diamino(nickel(II) porphyrin) with 2‐formylpyridine and FeII yielded an FeII4L6 cage. Upon treatment with the fullerenes C60 or C70, this cage was found to transform into a new host–guest complex incorporating three FeII centers and four porphyrin ligands, in an arrangement that is hypothesized to maximize π interactions between the porphyrin units of the host and the fullerene guest bound within its central cavity. The new complex shows coordinative unsaturation at one of the FeII centers as the result of the incommensurate metal‐to‐ligand ratio, which enabled the preparation of a heterometallic cone‐shaped CuIFeII2L4 adduct of C60 or C70. 相似文献
106.
Controlled Light‐Mediated Preparation of Gold Nanoparticles by a Norrish Type I Reaction of Photoactive Polymers
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Florian Mäsing Dr. Artur Mardyukov Carsten Doerenkamp Prof. Dr. Hellmut Eckert Ursula Malkus Harald Nüsse Prof. Dr. Jürgen Klingauf Prof. Dr. Armido Studer 《Angewandte Chemie (International ed. in English)》2015,54(43):12612-12617
Gold nanoparticles (AuNPs) are subjects of broad interest in scientific community due to their promising physicochemical properties. Herein we report the facile and controlled light‐mediated preparation of gold nanoparticles through a Norrish type I reaction of photoactive polymers. These carefully designed polymers act as reagents for the photochemical reduction of gold ions, as well as stabilizers for the in situ generated AuNPs. Manipulating the length and composition of the photoactive polymers allows for control of AuNP size. Nanoparticle diameter can be controlled from 1.5 nm to 9.6 nm. 相似文献
107.
Surface Trapping and STM Observation of Conformational Isomers of a Bis(Terpyridine) Ligand from Metallosupramolecular Grids
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Sujoy Karan Dr. Christian Hamann Dr. Hao Tang Dr. Artur R. Stefankiewicz Prof. Jean‐Marie Lehn Prof. Richard Berndt 《Chemphyschem》2015,16(7):1370-1373
Tetranuclear Co‐grid complexes incorporating bis‐tridentate ligands, namely 4,6‐bis(2,2′‐bipyrid‐6‐yl)‐2‐phenylpyrimidine, were electrosprayed onto a Au(111) substrate under an ultrahigh vacuum. Fragmentation occurs leaving the ligands in four different conformations. Most ligands are found to form H‐bonded dimers. The most abundant conformer of the ligand on the Au surface is an asymmetric form, which has not been observed before. The present results indicate that the fragmentation of coordination compounds during the deposition process, in principle, allows for surface trapping, identification, and investigation of high energy, out‐of‐equilibrium conformations of the ligand molecules at low temperatures, which otherwise would not be observable. 相似文献
108.
Inside Back Cover: Surface Trapping and STM Observation of Conformational Isomers of a Bis(Terpyridine) Ligand from Metallosupramolecular Grids (ChemPhysChem 7/2015)
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109.
Enhanced Photocatalytic Activity of MIL‐125 by Post‐Synthetic Modification with CrIII and Ag Nanoparticles
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Reda M. Abdelhameed Prof. Dr. Mário M. Q. Simões Prof. Dr. Artur M. S. Silva Prof. Dr. João Rocha 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(31):11072-11081
NH2‐MIL‐125, [Ti8O8(OH)4(bdc‐NH2)6] (bdc2?=1,4‐benzene dicarboxylate) is a highly porous metal–organic framework (MOF) that has a band gap lying within the ultraviolet region at about 2.6 eV. The band gap may be reduced by a suitable post‐synthetic modification of the nanochannels using conventional organic chemistry methods. Here, it is shown that the photocatalytic activity of NH2‐MIL‐125 in the degradation of methylene blue under visible light is remarkably augmented by post‐synthetic modification with acetylacetone followed by CrIII complexation. The latter metal ion extends the absorption from the ultraviolet to the visible light region (band gap 2.21 eV). The photogenerated holes migrate from the MOF’s valence band to the CrIII valence band, promoting the separation of holes and electrons and increasing the recombination time. Moreover, it is shown that the MOF’s photocatalytic activity is also much improved by doping with Ag nanoparticles, formed in situ by the reduction of Ag+ with the acetylacetonate pendant groups (the resulting MOF band gap is 2.09 eV). Presumably, the Ag nanoparticles are able to accept the MOF’s photogenerated electrons, thus avoiding electron–hole recombination. Both, the Cr‐ and Ag‐bearing materials are stable under photocatalytic conditions. These findings open new avenues for improving the photocatalytic activity of MOFs. 相似文献
110.
Artur Vashurin Vladimir Maizlish Ilya Kuzmin Oleg Petrov Mikhail Razumov Svetlana Pukhovskaya Oleg Golubchikov Oscar Koifman 《Journal of inclusion phenomena and macrocyclic chemistry》2017,87(1-2):37-43
The influence of the size of conjugated π-system on catalytic activity of cobalt complex with β-octaphenylporphyrin and its tetraaza-, tetrabenzo and tetrabenzotetraaza derivatives was studied in present work. It is found that catalytic activity for oxidation of sulfur-containing compounds increases under extension of conjugated macrocycle system according to the following series CoP < CoBP ≤ CoPz < CoPPz ? CoPc. 相似文献