| Autor: |
Rudzevich, Valentyn, Rudzevich, Yuliya, B�hmer, Volker |
| Předmět: |
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| Zdroj: |
Synlett; 2009, Issue 12, p1887-1904, 18p |
| Abstrakt: |
Calix[4]arenes, substituted at their wide rim by four urea functions, form hydrogen-bonded dimeric capsules. Covalent connection of adjacent urea functions within a calixarene molecule creates compounds with one to four loops. They show selective dimerization, since an overlap of loops is not possible within a dimer, and the urea substituent of the partner must be able to penetrate the loop. These selectivities can be developed into a sorting scheme for eleven tetraureas, where only six of potentially 35 dimeric combinations are realized. Together with the similar dimerization of triureas derived from triphenylmethane and the formation of tetramers from triurea monoacetamide calix[4]arenes, it is possible to design building blocks that form dendritic assemblies uniform in size and structure. 1 Introduction 1.1 Self-Assembly: General Points 1.2 Dimerization of Tetraureas Derived from Calix[4]arenes 1.3 Properties 1.3.1 Stability 1.3.2 Guest Exchange 1.3.3 Symmetry 2 Synthesis of Tetraurea Calix[4]arenes 2.1 General Pathways and Compounds with Identical Urea Groups 2.2 Selective Syntheses 2.2.1 Protective Groups 2.2.2 Stepwise Syntheses 2.3 Tetraurea Derivatives with Loops 2.3.1 Conventional Synthesis 2.3.2 Olefin Metathesis and Template Syntheses 3 Selective Dimerization 3.1 Early Examples 3.2 The Use of Loops and Bulky Groups 3.2.1 Urea Groups Connected by Loops 3.2.2 Urea Groups with Bulky Substituents 3.2.3 Bulky Substituents in Combination with Loops 3.3 Proofs for Selectivity 4 Self-Sorting 4.1 General Rules 4.2 A Sorting Scheme for Programmed Self-Assembly 4.3 Experimental Proofs 4.3.1 NMR Spectroscopy 4.3.2 Mass Spectrometry 5 Self-Assembly to Dendrimers 5.1 General Idea 5.2 Additional Assemblies 5.2.1 Dimers of Triurea Triphenylmethanes 5.2.2 Tetramers of Triurea Monoacetamides 5.3 Examples of Dendritic Assemblies 6 Outlook [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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