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Toward a new Molecular Recognition System and its related Interlocked Molecules
No full text論文摘要
藉由大環分子與分子夾之間所形成之錯合體，我們設計且合成了一種新型的分子開關。在此系統中，分子的開關行為不僅可藉由K+/[2,2,2]cryptand 及NH4+/Et3N的二種模式控制。特別的是在此開關過程中，系統會產生肉眼可見的顏色變化。因此，此系統的作用模式就有如一個NOR的邏輯閘。
經由適當的設計我們構築另一個結構有別於一般冠醚的大環，此環狀分子主要由一個具有3個氧原子的diethylene glycol鏈, phenolic aromatic ring 及一個xylene 連接基所組成。雖然分子間的[N+-H…O]氫鍵作用力可能因氧原子數的減少而減弱但主客體之間良好的前置構型可能增加了[cation…pi], [N+-H…pi] 和 [N+C-H…pi等的非共價作用力，使得此大環分子與DBA+擁有相當強的結合力(Ka = 15000, CD3NO2)。此外，此系統亦可辨識bipyridinium ions且與其形成準車輪烷(pseudorotaxane)；為了證明此準車輪烷結構確實存在溶液中，我們亦合成了其相對應的車輪烷及環連體。Abstract
We have synthesized a new molecular switch—based on a macrocycle–clip complex—whose switching behavior not only can be controlled through the use of either K+/[2,2,2]cryptand or NH4+/Et3N systems but also provides color changes that are visible to the naked eye; consequently, this system operates as a two-input NOR functioning molecular logic gate.
We report a new host molecule in which one diethylene glycol chain (i.e., a loop possessing only three oxygen atoms) incorporated along with two phenolic aromatic rings is linked by a xylene spacer into a macroring. The design of the molecular structure of this macrocycle “amplifies” any potential [cation•••pi], [N+-H•••pi] and [N+C-H•••pi]interactions between the dibenzylammonium (DBA+) ion and the phenolic rings of the macrocycle; as such, these species display a very strong binding affinity in CD3NO2 (Ka = 15,000 M–1). The macroring also coordinates to bipyridinium ions in a [2]pseudorotaxane fashion, which makes it the smallest macrocycle (i.e., a 25-membered ring) known to complex both DBA+ and bipyridinium ions in solution. To confirm unambiguously that these pseudorotaxanes exist in solution, we synthesized their corresponding interlocked molecules, namely rotaxanes and catenanes.TABLE OF CONTENTS
List of schemes..........................................................................................iii
List of figures……………………………………………………………iv
Publications……………………………………………………………...vi
Abstract…………………………………………………………………vii
Chapter 1.
A Switchable Macrocycle—Clip Complex That Functions as a NOR Gate…………………………………………………………………1
Experimental section....................................15
References…………………………………………………………..22
Chapter 2.
Is [N+-H•••O] Hydrogen Bonding the Most Important Noncovalent Interaction in Macrocycle–Dibenzylammonium Ion Complexes?..24
Experimental section………………………………………….46
References…………………………………………………………….5
[3]Pseudorotaxane-Like Complexes Formed between Bipyridinium Dications and Bis-p-xylyl[26]crown-6
No full textA Macrocycle/Molecular-Clip Complex that Functions as a Quadruply Controllable Molecular Switch
No full textBis-p-xylyl[26]crown-6/pyridinium ion recognition: one-pot synthesis of molecular shuttles
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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