Crown Ethers as Building Blocks for Carbohydrate Receptors

2006 ◽  
Vol 8 (5) ◽  
pp. 855-858 ◽  
Author(s):  
Monika Mazik ◽  
Matthias Kuschel ◽  
Willi Sicking
Keyword(s):  
Crown Ethers ◽  
Building Blocks

scholarly journals Flat Crown Ethers with Planar Tetracoordinate Carbon Atoms

2020 ◽  
Author(s):  
Venkatesan Thimmakondu ◽  
Krishnan Thirumoorthy
Keyword(s):  
Carbon Atom ◽  
Crown Ether ◽  
Crown Ethers ◽  
In Silico ◽  
Alkaline Earth ◽  
Experimental Studies ◽  
Building Blocks ◽  
Binding Energies ◽  
High Symmetry ◽  
Structural Rigidity

Novel flat crown ether molecules have been characterized in silico using DFT hybrid and hybrid-meta functionals. Monomer units of Si2C3 with a planar tetracoordinate carbon atom have been used as building blocks. Alkali (Li+, Na+, K+, Rb+, and Cs+) and alkaline-earth (Ca2+, Sr2+, and Ba2+) metals, and uranyl (UO2+ 2 ) ion selective complexes have also been theoretically identified. The high symmetry and higher structural rigidity of the host molecules may likely to impart higher selectivity in chelation. Theoretical binding energies have been computed and experimental studies are invited.

Luminescent liquid crystalline hybrid materials by embedding octahedral molybdenum cluster anions with soft organic shells derived from tribenzo[18]crown-6

2018 ◽  
Vol 47 (40) ◽  
pp. 14340-14351 ◽  
Author(s):  
Philipp Ehni ◽  
Kevin Guy ◽  
Max Ebert ◽  
Stuart Beardsworth ◽  
Korinna Bader ◽  
...  
Keyword(s):  
Crown Ethers ◽  
Hybrid Materials ◽  
Liquid Crystalline ◽  
Building Blocks ◽  
Cluster Anions ◽  
Supramolecular Materials ◽  
Molybdenum Cluster

Crown ethers and their derivatives are versatile building blocks for the design of supramolecular materials.

scholarly journals Polyhalides as scaffolds for supramolecular, ion-conducting crown ether stacks

2014 ◽  
Vol 70 (a1) ◽  
pp. C634-C634
Author(s):  
Katharina Fromm ◽  
Aurélien Crochet ◽  
Cyrille Dagri ◽  
Yvens Chérémond
Keyword(s):  
Solid State ◽  
Single Crystal ◽  
Crown Ethers ◽  
Halogen Bonding ◽  
Building Blocks ◽  
Channel Formation ◽  
One Dimensional ◽  
Naoh Solution ◽  
Ion Conducting

"Crown ethers, such as dibenzo-18-crown-6 (DB18C6) are in principle perfect building blocks to be stacked on top of each other for one-dimensional (1D) channel formation. However, in the more than 1000 publications on crown ethers in the solid state, only one case was of channel formation described, but not as main focus of research.[1] We now present a way to systematically induce the stacking of DB18C6 with the help of polyhalides, which play the roles of scaffolds via halogen bonding.[2] These compounds can be considered as ""supramolecular straws"". Using for example potassium as couter ion for triiodide for example, we obtained a solid which contains three differently filled, parallel channels in the solid state, which are arranged between the polyhalide anions. Exchanging potassium with sodium by immersion of a single crystal into NaOH solution leads to a single-crystal-to-single-crystal transformation into a compound with two channel types. This transition from a system crystallizing initially in the P2-space group to yield a compound in Pccn is only possible under these very special conditions. We will further present how the ion transport through these channels can be quantified and which process is involved in ion exchange. The role of the polyhalide anions, which cannot be replaced by other linear anions, will be emphasized as well. "

scholarly journals Organomagnesium Crown Ethers and Their Binding Affinities with Li+, Na+, K+, Be2+, Mg2+, and Ca2+ Ions - a Theoretical Study

2021 ◽  
Author(s):  
Krishnan Thirumoorthy ◽  
Uday Kumar Padidela ◽  
Pothiappan Vairaprakash ◽  
Venkatesan Thimmakondu
Keyword(s):  
Metal Ions ◽  
Crown Ethers ◽  
Density Functional ◽  
Building Blocks ◽  
Binding Energies ◽  
Binding Affinities ◽  
Free Energies ◽  
Delta G ◽  
Cluster Methods ◽  
First Time

Novel organomagnesium crown ether molecules have been computationally characterized for the first time using density functional theory (DFT). Monomer units of MgC6 have been used as building blocks. The potential energy surface of the parent elemental composition, MgC6H2, has been extensively explored using both DFT and coupled-cluster methods. It is concluded that the seven-membered ring isomer, 1-magnesacyclohept-4-en-2,6-diyne, is the thermodynamically most stable molecule at all levels. Thus, the latter has been used as the building block for organomagnesium crown ethers. Both alkali (Li+, Na+, and K+) and alkaline-earth (Be2+, Mg2+, and Ca2+) metal ions selective complexes have been theoretically identified. Binding energies (Delta E at 0 K) and thermally corrected Gibbs free energies (Delta G at 298.15 K) have<br>been computed for these metal ions with MgC6-9-crown-3 and MgC6-12-crown-4 to gauge their binding affinities.Novel organomagnesium crown ether molecules have been computationally characterized for the first time using density functional theory (DFT). Monomer units of MgC6 have been used as building blocks. The potential energy surface of the parent elemental composition, MgC6H2, has been extensively explored using both DFT and coupled-cluster methods. It is concluded that the seven-membered ring isomer, 1-magnesacyclohept-4-en-2,6-diyne, is the thermodynamically most stable molecule at all levels. Thus, the latter has been used as the building block for organomagnesium crown ethers. Both alkali (Li+, Na+, and K+) and alkaline-earth (Be2+, Mg2+, and Ca2+) metal ions selective complexes have been theoretically identified. Binding energies (Delta E at 0 K) and thermally corrected Gibbs free energies (Delta G at 298.15 K) have been computed for these metal ions with MgC6-9-crown-3 and MgC6-12-crown-4 to gauge their binding affinities.

scholarly journals Organomagnesium Crown Ethers and Their Binding Affinities with Li+, Na+, K+, Be2+, Mg2+, and Ca2+ Ions - a Theoretical Study

2021 ◽  
Author(s):  
Krishnan Thirumoorthy ◽  
Uday Kumar Padidela ◽  
Pothiappan Vairaprakash ◽  
Venkatesan Thimmakondu
Keyword(s):  
Metal Ions ◽  
Crown Ethers ◽  
Density Functional ◽  
Building Blocks ◽  
Binding Energies ◽  
Binding Affinities ◽  
Free Energies ◽  
Delta G ◽  
Cluster Methods ◽  
First Time

Novel organomagnesium crown ether molecules have been computationally characterized for the first time using density functional theory (DFT). Monomer units of MgC6 have been used as building blocks. The potential energy surface of the parent elemental composition, MgC6H2, has been extensively explored using both DFT and coupled-cluster methods. It is concluded that the seven-membered ring isomer, 1-magnesacyclohept-4-en-2,6-diyne, is the thermodynamically most stable molecule at all levels. Thus, the latter has been used as the building block for organomagnesium crown ethers. Both alkali (Li+, Na+, and K+) and alkaline-earth (Be2+, Mg2+, and Ca2+) metal ions selective complexes have been theoretically identified. Binding energies (Delta E at 0 K) and thermally corrected Gibbs free energies (Delta G at 298.15 K) have<br>been computed for these metal ions with MgC6-9-crown-3 and MgC6-12-crown-4 to gauge their binding affinities.Novel organomagnesium crown ether molecules have been computationally characterized for the first time using density functional theory (DFT). Monomer units of MgC6 have been used as building blocks. The potential energy surface of the parent elemental composition, MgC6H2, has been extensively explored using both DFT and coupled-cluster methods. It is concluded that the seven-membered ring isomer, 1-magnesacyclohept-4-en-2,6-diyne, is the thermodynamically most stable molecule at all levels. Thus, the latter has been used as the building block for organomagnesium crown ethers. Both alkali (Li+, Na+, and K+) and alkaline-earth (Be2+, Mg2+, and Ca2+) metal ions selective complexes have been theoretically identified. Binding energies (Delta E at 0 K) and thermally corrected Gibbs free energies (Delta G at 298.15 K) have been computed for these metal ions with MgC6-9-crown-3 and MgC6-12-crown-4 to gauge their binding affinities.

scholarly journals Thermodynamic and electrochemical study of tailor-made crown ethers for redox-switchable (pseudo)rotaxanes

2020 ◽  
Vol 16 ◽  
pp. 2576-2588
Author(s):  
Henrik Hupatz ◽  
Marius Gaedke ◽  
Hendrik V Schröder ◽  
Julia Beerhues ◽  
Arto Valkonen ◽  
...  
Keyword(s):  
Crown Ethers ◽  
Building Blocks ◽  
Binding Energies ◽  
Titration Calorimetry ◽  
Emergent Properties ◽  
Naphthalene Diimide ◽  
Redox Active ◽  
Voltammetric Techniques ◽  
Redox Switching ◽  
Redox Switches

Crown ethers are common building blocks in supramolecular chemistry and are frequently applied as cation sensors or as subunits in synthetic molecular machines. Developing switchable and specifically designed crown ethers enables the implementation of function into molecular assemblies. Seven tailor-made redox-active crown ethers incorporating tetrathiafulvalene (TTF) or naphthalene diimide (NDI) as redox-switchable building blocks are described with regard to their potential to form redox-switchable rotaxanes. A combination of isothermal titration calorimetry and voltammetric techniques reveals correlations between the binding energies and redox-switching properties of the corresponding pseudorotaxanes with secondary ammonium ions. For two different weakly coordinating anions, a surprising relation between the enthalpic and entropic binding contributions of the pseudorotaxanes was discovered. These findings were applied to the synthesis of an NDI-[2]rotaxane, which retains similar spectroelectrochemical properties compared to the corresponding free macrocycle. The detailed understanding of the thermodynamic and electrochemical properties of the tailor-made crown ethers lays the foundation for the construction of new types of molecular redox switches with emergent properties.

scholarly journals Towards a Real Knotaxane

Chemistry ◽  
2020 ◽  
Vol 2 (2) ◽  
pp. 305-321
Author(s):  
Torben Duden ◽  
Ulrich Lüning
Keyword(s):  
Binding Site ◽  
Crown Ethers ◽  
Click Reaction ◽  
Building Blocks ◽  
Ammonium Ions ◽  
Spectral Analyses ◽  
Interlocked Molecules ◽  
Click Reactions ◽  
Mass Spectral ◽  
The Subject

Two classes of mechanically interlocked molecules, [3]rotaxanes and knotted [1]rotaxanes, were the subject of this investigation. The necessary building blocks, alkyne-terminated axles containing two ammonium ions and azide-terminated stoppers, and azide-containing substituted macrocycles, have been synthesized and characterized. Different [3]rotaxanes were synthesized by copper-catalyzed “click” reactions between the azide stoppers and [3]pseudorotaxanes formed from the dialkyne axles and crown ethers (DB24C8). Methylation of the triazoles formed by the “click” reaction introduced a second binding site, and switching via deprotonation/protonation was investigated. In preliminary tests for the synthesis of a knotted [1]rotaxane, pseudorotaxanes were formed from azide-containing substituted macrocycles and dialkyne substituted diammonium axles, and copper-catalyzed “click” reactions were carried out. Mass spectral analyses showed successful double “click” reactions between two modified macrocycles and one axle. Whether a knotted [1]rotaxane was formed could not be determined.

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