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521.
We give an alternative definition of Shannon and Kolmogorov-Sinai entropies based on the Boltzmann formula S = k log W. We prove the equivalence of those new definitions with the traditional ones using some tools from Information Theory such
as information function and empirical entropy.
Lecture held in the Seminario Matematico e Fisico on November 29, 2004 Received: April 2005 相似文献
522.
Insights into the Crystallization and Structural Evolution of Glycine Dihydrate by In Situ Solid‐State NMR Spectroscopy
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Dr. Paolo Cerreia Vioglio Dr. Giulia Mollica Marie Juramy Dr. Colan E. Hughes Dr. P. Andrew Williams Dr. Fabio Ziarelli Prof. Stéphane Viel Dr. Pierre Thureau Prof. Kenneth D. M. Harris 《Angewandte Chemie (International ed. in English)》2018,57(22):6619-6623
In situ solid‐state NMR spectroscopy is exploited to monitor the structural evolution of a glycine/water glass phase formed on flash cooling an aqueous solution of glycine, with a range of modern solid‐state NMR methods applied to elucidate structural properties of the solid phases present. The glycine/water glass is shown to crystallize into an intermediate phase, which then transforms to the β polymorph of glycine. Our in situ NMR results fully corroborate the identity of the intermediate crystalline phase as glycine dihydrate, which was first proposed only very recently. 相似文献
523.
2‐(4′‐Pyridyl‐N‐oxide)‐Substituted Hemithioindigos as Photoresponsive Guests for a Super Aryl‐Extended Calix[4]pyrrole Receptor
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We report the synthesis of two 2‐(4′‐pyridyl‐N‐oxide)‐substituted hemithioindigos (HTIs). We probed their photoisomerization by using UV/Vis and 1H NMR spectroscopy techniques. Light irradiation at λ=450 nm provoked the isomerization of the HTI Z isomer to the E counterpart to a large extent (≈80 % at the photostationary state). 1H NMR titration experiments revealed the formation of thermodynamically and kinetically stable 1:1 inclusion complexes of the (Z)‐HTI isomers with a super aryl‐extended host (association constant>104 m ?1). Photoirradiation at λ=450 nm of the inclusion complexes induced the isomerization of the bound HTI N‐oxide to afford the (E)‐HTI?calix[4]pyrrole complex. We determined accurate association constant values for the 1:1 inclusion complexes of the (Z)‐ and (E)‐HTI isomers by using isothermal titration calorimetry experiments. The results showed that the stability constants of the (E)‐HTI complexes were 2.2–2.8‐fold lower than those of the (Z)‐HTI counterparts, which explains the lack of light‐induced release of the former to the bulk solution. 相似文献
524.
Separation of intact proteins on γ‐ray‐induced polymethacrylate monolithic columns: A highly permeable stationary phase with high peak capacity for capillary high‐performance liquid chromatography with high‐resolution mass spectrometry
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Patrizia Simone Giuseppe Pierri Patrizia Foglia Giulia Mazzoccanti Anna Laura Capriotti Ornella Ursini Alessia Ciogli Aldo Laganà 《Journal of separation science》2016,39(2):264-271
Polymethacrylate‐based monolithic capillary columns, prepared by γ‐radiation‐induced polymerization, were used to optimize the experimental conditions (nature of the organic modifiers, the content of trifluoroacetic acid and the column temperature) in the separation of nine standard proteins with different hydrophobicities and a wide range of molecular weights. Because of the excellent permeability of the monolithic columns, an ion‐pair reversed‐phase capillary liquid chromatography with high‐resolution mass spectrometry method has been developed by coupling the column directly to the mass spectrometer without a flow‐split and using a standard electrospray interface. Additionally, the high working flow and concomitant high efficiency of these columns allowed us to employ a longer column (up to 50 cm) and achieve a peak capacity value superior to 1000. This work is motivated by the need to develop new materials for high‐resolution chromatographic separation that combine chemical stability at elevated temperatures (up to 75°C) and a broad pH range, with a high peak capacity value. The advantage of the γ‐ray‐induced monolithic column lies in the batch‐to‐batch reproducibility and long‐term high‐temperature stability. Their proven high loading capacity, recovery, good selectivity and high permeability, moreover, compared well with that of a commercially available poly(styrene‐divinylbenzene) monolithic column, which confirms that such monolithic supports might facilitate analysis in proteomics. 相似文献
525.
Cover Picture: Topological Polymer Chemistry Enters Surface Science: Linear versus Cyclic Polymer Brushes (Angew. Chem. Int. Ed. 50/2016)
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526.
Magnetic “Molecular Oligomers” Based on Decametallic Supertetrahedra: A Giant Mn49 Cuboctahedron and its Mn25Na4 Fragment
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Dr. Maria Manoli Sofia Alexandrou Dr. Linh Pham Dr. Giulia Lorusso Dr. Wolfgang Wernsdorfer Dr. Marco Evangelisti Prof. George Christou Dr. Anastasios J. Tasiopoulos 《Angewandte Chemie (International ed. in English)》2016,55(2):679-684
Two nanosized Mn49 and Mn25Na4 clusters based on analogues of the high‐spin (S=22) [MnIII6MnII4(μ4‐O)4]18+ supertetrahedral core are reported. Mn49 and Mn25Na4 complexes consist of eight and four decametallic supertetrahedral subunits, respectively, display high virtual symmetry (Oh), and are unique examples of clusters based on a large number of tightly linked high nuclearity magnetic units. The complexes also have large spin ground‐state values (Mn49: S=61/2; Mn25Na4: S=51/2) with the Mn49 cluster displaying single‐molecule magnet (SMM) behavior and being the second largest reported homometallic SMM. 相似文献
527.
Xiushang Xu Rafael Muñoz-Mármol Serhii Vasylevskyi Andrea Villa Giulia Folpini Francesco Scotognella Giuseppe Maria Paternò Akimitsu Narita 《Angewandte Chemie (International ed. in English)》2023,62(14):e202218350
We report the synthesis of a hexabenzoperihexacene (HBPH) with two incorporated octacene substructures, which was unambiguously characterized by single-crystal X-ray analysis. The theoretical isomerization barrier of the (P,P)-/(P,M)-forms was estimated to be 38.4 kcal mol−1, and resolution was achieved by chiral HPLC. Notably, the enantiomers exhibited opposite circular dichroism responses up to the near-infrared (NIR) region (830 nm) with a high gabs value of 0.017 at 616 nm. Moreover, HBPH demonstrated NIR emission with a maximum at 798 nm and an absolute PLQY of 41 %. The excited-state photophysical properties of HBPH were investigated by ultrafast transient absorption spectroscopy, revealing an intriguing feature that was attributed to the rotational and/or conformational dynamics of HBPH after excitation. These results provide new insight into the design of chiral nanographene with NIR optical properties for potential chiroptical applications. 相似文献
528.
Dr. Linda Cerofolini Kristian Vasa Elisa Bianconi Maria Salobehaj Giulia Cappelli Alice Bonciani Giulia Licciardi Dr. Anna Pérez-Ràfols Luis Padilla-Cortés Sabrina Antonacci Dr. Domenico Rizzo Prof. Dr. Enrico Ravera Prof. Dr. Caterina Viglianisi Prof. Dr. Vito Calderone Prof. Dr. Giacomo Parigi Prof. Claudio Luchinat Prof. Dr. Antonio Macchiarulo Prof. Stefano Menichetti Prof. Dr. Marco Fragai 《Angewandte Chemie (International ed. in English)》2023,62(31):e202303202
Several protein-drug conjugates are currently being used in cancer therapy. These conjugates rely on cytotoxic organic compounds that are covalently attached to the carrier proteins or that interact with them via non-covalent interactions. Human transthyretin (TTR), a physiological protein, has already been identified as a possible carrier protein for the delivery of cytotoxic drugs. Here we show the structure-guided development of a new stable cytotoxic molecule based on a known strong binder of TTR and a well-established anticancer drug. This example is used to demonstrate the importance of the integration of multiple biophysical and structural techniques, encompassing microscale thermophoresis, X-ray crystallography and NMR. In particular, we show that solid-state NMR has the ability to reveal effects caused by ligand binding which are more easily relatable to structural and dynamical alterations that impact the stability of macromolecular complexes. 相似文献
529.
Bernardinelli G Seidel TM Kündig EP Prins LJ Kolarovic A Mba M Pontini M Licini G 《Dalton transactions (Cambridge, England : 2003)》2007,(16):1573-1576
A novel, mononuclear Ti(IV) amine triphenolate complex obtained by reaction of Ti(OiPr)(4) with tris(2-hydroxy-3-phenylbenzyl)amine bearing phenyl ortho-substituents affords quantitatively and spontaneously the corresponding heterochiral micro-oxo dinuclear compound whereas an analogous chiral, enantiopure complex maintains its mononuclear structure even in the presence of an excess of water. 相似文献
530.
Beobide G Wang WG Castillo O Luque A Román P Tagliabue G Galli S Navarro JA 《Inorganic chemistry》2008,47(12):5267-5277
A series of manganese(II) coordination polymers containing the bridging ligand pyrimidine-4,6-dicarboxylate (pmdc) have been prepared. The stoichiometries and structural features of these materials, which range from the one-dimensional (1D) chains in ([Mn(mu-pmdc)(H2O)3].2H2O)n (1) and ([Mn2(mu-pmdc)2(H2O)5].2H2O)n (2) to the two-dimensional layers in ([Mn(mu3-pmdc)(H2O)].H2O)n (3) or the three-dimensional porous network in ([Mn(pmdc)].2H2O)n (4), are extremely dependent on the synthetic conditions (i.e., temperature and solvent). In spite of the structural diversity of these systems, crystallographic studies revealed that the pmdc ligand typically displays a tetradentate mu-(kappaO,kappaN:kappaO',kappaN') coordination mode with the carboxylate groups almost coplanar with the pyrimidine ring [as in compounds 1 and 2 and compound 5 described below)]. In compound 3, the pmdc moiety adopts a pentadentate mu3-(kappaO,kappaN:kappaO',kappaN':kappaO) coordination mode. The thermal, magnetic, and adsorption properties of these systems were also studied. The results showed that these compounds behave as antiferromagnets as a consequence of efficient magnetic exchange through the pmdc bridges. Compound 4 possesses permanent porosity, as proved by gas sorption data (N2 at 77 K and CO2 at 293 K). Finally, the heteronuclear iron(II)/manganese(II) compound ([FeMn(mu-pmdc)2(H2O)5].2H2O)n (5), which is isomorphous to 2, was also prepared and fully characterized. 相似文献