Coordination-driven [2+2] metallo-macrocycles isomers: conformational control and photophysical properties

Coordination-driven [2+2] metallo-macrocycles isomers: conformational control and photophysical properties PDF Author: Yunting Zeng
Publisher: OAE Publishing Inc.
ISBN:
Category : Science
Languages : en
Pages : 12

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Book Description
In recent years, fluorescent supramolecular materials have received significant attention due to their wide application prospects. However, the relationship between the conformation of supramolecules and their photophysical properties remains an open question. In this study, two rhomboidal metallacycle isomers, SA and SB, self-assembled with trans- and cis-isomers of tetraphenylethylene-based ditopic pyridyl ligands (LA and LB), and a 120° di-platinum (II) acceptor were prepared. Compared with metallacycle SB constructed by cis- tetraphenylethylene (TPE)-based ligand LB, the curved rhomboidal metallacycle SA constructed with trans-TPE-based ligand LA can restrict molecular motions of the aromatic groups on TPE and exhibits better light-emitting properties. Moreover, curved SA also exhibited better fluorescence stability than isomer SB towards molecules with strongly electron-withdrawing groups. This work provides a new platform to explore the relationship between conformation and the corresponding photophysical properties.

Coordination-driven [2+2] metallo-macrocycles isomers: conformational control and photophysical properties

Coordination-driven [2+2] metallo-macrocycles isomers: conformational control and photophysical properties PDF Author: Yunting Zeng
Publisher: OAE Publishing Inc.
ISBN:
Category : Science
Languages : en
Pages : 12

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Book Description
In recent years, fluorescent supramolecular materials have received significant attention due to their wide application prospects. However, the relationship between the conformation of supramolecules and their photophysical properties remains an open question. In this study, two rhomboidal metallacycle isomers, SA and SB, self-assembled with trans- and cis-isomers of tetraphenylethylene-based ditopic pyridyl ligands (LA and LB), and a 120° di-platinum (II) acceptor were prepared. Compared with metallacycle SB constructed by cis- tetraphenylethylene (TPE)-based ligand LB, the curved rhomboidal metallacycle SA constructed with trans-TPE-based ligand LA can restrict molecular motions of the aromatic groups on TPE and exhibits better light-emitting properties. Moreover, curved SA also exhibited better fluorescence stability than isomer SB towards molecules with strongly electron-withdrawing groups. This work provides a new platform to explore the relationship between conformation and the corresponding photophysical properties.

Anion Receptor Chemistry

Anion Receptor Chemistry PDF Author: Jonathan L Sessler
Publisher: Royal Society of Chemistry
ISBN: 1847552471
Category : Science
Languages : en
Pages : 431

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Book Description
Anion recognition plays a critical role in a range of biological processes, and a variety of receptors and carriers can be found throughout the natural world. Chemists working in the area of supramolecular chemistry have created a range of anion receptors, drawing inspiration from nature as well as their own inventive processes. This book traces the origins of anion recognition chemistry as a unique sub-field in supramolecular chemistry while illustrating the basic approaches currently being used to effect receptor design. The combination of biological overview and summary of current synthetic approaches provides a coverage that is both comprehensive and comprehensible. First, the authors detail the key design motifs that have been used to generate synthetic receptors and which are likely to provide the basis for further developments. They also highlight briefly some of the features that are present in naturally occurring anion recognition and transport systems and summarise the applications of anion recognition chemistry. Providing as it does a detailed review for practitioners in the field and a concise introduction to the topic for newcomers, Anion Receptor Chemistry reflects the current state of the art. Fully referenced and illustrated in colour, it is a welcome addition to the literature.

Expanded, Contracted & Isomeric Porphyrins

Expanded, Contracted & Isomeric Porphyrins PDF Author: J.L. Sessler
Publisher: Elsevier
ISBN: 0080535232
Category : Science
Languages : en
Pages : 533

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Book Description
The porphyrins are a class of naturally-occurring macrocycles and are ubiquitous in our world. As such, they have been called the Pigments of Life. This auspicious designation reflects their importance in numerous biological functions. Indeed, life as we understand it relies on the full range of biological processes that are either performed by or catalyzed by porphyrin-containing proteins. Chlorophyll-containing photosynthetic reaction centers in plants, for instance, convert light energy into chemical energy while producing oxygen along the way. It is this oxygen, evolved from photosynthesis, that is transported, stored, and reduced by heme-containing proteins in many organisms, including mammals. Not surprisingly, therefore, these molecules remain of fundamental interest to chemists and biochemists. Indeed, they continue to be intensely investigated by researchers world-wide.Inspired by the importance of the porphyrins, a new research direction has emerged in recent years that is devoted to the preparation and study of non-porphyrin polypyrrole macrocycles. Here, the principal objectives have been to generate completely synthetic systems that bear some structural resemblance to naturally-occurring porphyrin derivatives while being quite different in their specific chemical makeup. Within this context, three different research directions have evolved, namely those involving the syntheses of contracted, isomeric, and expanded porphyrins, respectively. It is the chemistry of these systems that is the subject of this book. Because of the newness of the field, the emphasis of this book will be on synthesis and characterization (all work on porphyrin isomers and much of that associated with expanded porphyrins has only appeared in the last 10 years). One chapter on applications has, however, been included. Also, in the context of the preparative portions of the text, some efforts have been made to explain why various porphyrin analogue targets are of interest.

Supramolecular Chemistry in the 3rd Millennium

Supramolecular Chemistry in the 3rd Millennium PDF Author: Catherine E. Housecroft
Publisher: MDPI
ISBN: 3036514635
Category : Science
Languages : en
Pages : 264

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Book Description
This Special Issue is one of the first for the new MDPI flagship journal Chemistry (ISSN 2624-8549) which has a broad remit for publishing original research in all areas of chemistry. The theme of this issue is Supramolecular Chemistry in the 3rd Millennium and I am sure that this topic will attract many exciting contributions. We chose this topic because it encompasses the unity of contemporary pluridisciplinary science, in which organic, inorganic, physical and theoretical chemists work together with molecular biologists and physicists to develop a systems-level understanding of molecular interactions. The description of supramolecular chemistry as 'chemistry beyond the molecule' (Jean-Marie Lehn, Nobel Lecture and Gautam R. Desiraju, Nature, 2001, 412, 397) addresses the wide variety of weak, non-covalent interactions that are the basis for the assembly of supramolecular architectures, molecular receptors and molecular recognition, programed molecular systems, dynamic combinatorial libraries, coordination networks and functional supramolecular materials. We welcome submissions from all disciplines involved in this exciting and evolving area of science.

Beauty in Chemistry

Beauty in Chemistry PDF Author: Luigi Fabbrizzi
Publisher: Springer Science & Business Media
ISBN: 3642283411
Category : Science
Languages : en
Pages : 180

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Book Description
The Beauty of Chemistry in the Words of Writers and in the Hands of Scientists, by Margherita Venturi, Enrico Marchi und Vincenzo Balzani Living in a Cage Is a Restricted Privilege, by Luigi Fabbrizzi Inner and Outer Beauty, by Kenneth N. Raymond und Casey J. Brown The Mechanical Bond: A Work of Art, by Carson J. Bruns und J. Fraser Stoddart The Beauty of Knots at the Molecular Level, by Jean-Pierre Sauvage und David B. Amabilino

An Ion Exchange Study of Possible Hybridized 5f Bonding in the Actinides

An Ion Exchange Study of Possible Hybridized 5f Bonding in the Actinides PDF Author: R. M. Diamond
Publisher:
ISBN:
Category : Actinide elements
Languages : en
Pages : 46

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Book Description
A study has been made of the elution behavior of curium(III), americium(III), plutonium(III), actinium(III), plutonium(IV), neptunium(IV), uraniuM(IV), thorium(IV), neptunium(V), plutonium (VI), uranium (VI), lanthanum(III), cerium(III), europium(III), ytterbium(III), ytterium(III), strontium(II), barium(II), radium(II), cesium(I) with 3.2 M, 6.2 M, 9.3 M, and 12.2 M HCl solutions from Dowex-50 cation exchange resin columns. These elutions show that in high concentrations of hydrochloric acid the actinides form complex ions with chloride ion to a much greater extent than the lanthanides. The strengths of the tripositive actinide complex ions apparently go in the order plutonium > americium> curium, although their ionic radii also decrease in this same order. To explain these results, a partial covalent character may be ascribed to the bonding in the transuranium complex ions. It is shown that a reasonable structure for such covalent bonding involves hybridization of the 5f orbitals in the actinide elements.

Gold Chemistry

Gold Chemistry PDF Author: Fabian Mohr
Publisher: John Wiley & Sons
ISBN: 3527320865
Category : Science
Languages : en
Pages : 425

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Book Description
Written by world-class authors, this most recent major book on the topic highlights new and current trends as well as future directions. It is comprehensive in its scope, covering all aspects of gold chemistry -- from homogeneous to heterogeneous catalysis, from supramolecular assemblies to sensors and medicinal applications. The result is an invaluable work for both organic and inorganic chemists working in universities and industry, as well as material scientists.

Macromolecular Metal Carboxylates and Their Nanocomposites

Macromolecular Metal Carboxylates and Their Nanocomposites PDF Author: Anatolii D. Pomogailo
Publisher: Springer Science & Business Media
ISBN: 3642105742
Category : Technology & Engineering
Languages : en
Pages : 311

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Book Description
Data on the synthesis and physicochemical studies of salts of mono- or dibasic unsaturated carboxylic acids and macromolecular metal carboxylates are generalised and described systematically in this monograph. The structures and properties of the COO group in various compounds and characteristic features of the structures of carboxylate are analysed. The main routes and kinetics of polymerisation transformations of unsaturated metal carboxylates are considered. The attention is focused on the effect of the metal ion on the monomer reactivity and the polymer morphology and structure. The possibility of stereochemical control of radical polymerisation of unsaturated metal carboxylates is demonstrated. The electronic, magnetic, optical, absorption and thermal properties of metal (co)polymers and nanocomposites and their main applications are also considered.

Molecular Devices and Machines

Molecular Devices and Machines PDF Author: Vincenzo Balzani
Publisher: John Wiley & Sons
ISBN: 3527605347
Category : Science
Languages : en
Pages : 511

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Book Description
The miniaturization of bulky devices and machines is a process that confronts us on a daily basis. However, nanoscale machines with varied and novel characteristics may also result from the enlargement of extremely small building blocks, namely individual molecules. This bottom-up approach to nanotechnology is already being pursued in information technology, with many other branches about to follow. - Written by a team of experienced authors headed by Vincenzo Balzani, one of the pioneers in the development of molecular machines - Covers such diverse aspects as sensors, memory components, solar energy conversion, biomolecules as molecular machines, and much more - Presented in a lucid style and didactically structured, with both the expert and the newcomer in mind - Includes a glossary of terms and numerous references to the recent literature Be among the first to explore the fascinating possibilities of this future-oriented technology! A must-have for every chemist and materials scientist with an interest in nanotechnology.

Data Mining in Crystallography

Data Mining in Crystallography PDF Author: D. W. M. Hofmann
Publisher: Springer
ISBN: 3642047599
Category : Science
Languages : en
Pages : 181

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Book Description
Humans have been “manually” extracting patterns from data for centuries, but the increasing volume of data in modern times has called for more automatic approaches. Early methods of identifying patterns in data include Bayes’ theorem (1700s) and Regression analysis (1800s). The proliferation, ubiquity and incre- ing power of computer technology has increased data collection and storage. As data sets have grown in size and complexity, direct hands-on data analysis has - creasingly been augmented with indirect, automatic data processing. Data mining has been developed as the tool for extracting hidden patterns from data, by using computing power and applying new techniques and methodologies for knowledge discovery. This has been aided by other discoveries in computer science, such as Neural networks, Clustering, Genetic algorithms (1950s), Decision trees (1960s) and Support vector machines (1980s). Data mining commonlyinvolves four classes of tasks: • Classi cation: Arranges the data into prede ned groups. For example, an e-mail program might attempt to classify an e-mail as legitimate or spam. Common algorithmsinclude Nearest neighbor,Naive Bayes classi er and Neural network. • Clustering: Is like classi cation but the groups are not prede ned, so the algorithm will try to group similar items together. • Regression: Attempts to nd a function which models the data with the least error. A common method is to use Genetic Programming. • Association rule learning: Searches for relationships between variables. For example, a supermarket might gather data of what each customer buys.