Mechanistische Untersuchungen zur Ligandenfluktuation in den Sandwich-Komplexen [M([12]Krone-4)2]++ / Mechanistic Studies on the Ligand Fluctuations in the Sandwich Complexes [M([12]crown-4)2]++

1984 ◽  
Vol 39 (12) ◽  
pp. 1755-1758 ◽  
Author(s):  
Franz L. Dickert ◽  
Walter Gumbrecht ◽  
Manfred Waidhas
Keyword(s):  
Crown Ether ◽  
Metal Ions ◽  
Reaction Order ◽  
Outer Sphere ◽  
High Symmetry ◽  
Mechanistic Studies ◽  
Sandwich Complexes ◽  
Associative Mechanism ◽  
M 12 ◽  
Very High

The metal ions Co++ , Ni++ , Mg++ , and Zn++ form the sandwich complexes [M([12]crown-4)2]++ with [12]crown-4 in CD3NO2. From the reaction order of the crown ether exchange a strong outer sphere association between complex and ligand can be inferred. Ligand fluctuation processes occur via an intramolecular associative mechanism from which a very high symmetry of the complexes results.

Enhanced performance in gas adsorption and Li ion batteries by docking Li+ in a crown ether-based metal–organic framework

2016 ◽  
Vol 52 (14) ◽  
pp. 3003-3006 ◽  
Author(s):  
Linyi Bai ◽  
Binbin Tu ◽  
Yi Qi ◽  
Qiang Gao ◽  
Dong Liu ◽  
...  
Keyword(s):  
Crown Ether ◽  
Metal Ions ◽  
Gas Adsorption ◽  
Metal Organic Framework ◽  
Metal Organic Frameworks ◽  
Li Ion Batteries ◽  
Metal Organic ◽  
Li Ion ◽  
Organic Framework

Incorporating supramolecular recognition units, crown ether rings, into metal–organic frameworks enables the docking of metal ions through complexation for enhanced performance.

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.

Metallo-oxidase Enzymes: Design of their Active Sites

2011 ◽  
Vol 64 (3) ◽  
pp. 231 ◽  
Author(s):  
Zhiguang Xiao ◽  
Anthony G. Wedd
Keyword(s):  
Metal Ions ◽  
Active Sites ◽  
Specific Binding ◽  
Large Family ◽  
Outer Sphere ◽  
Transition Metal Ions ◽  
Substrate Oxidation ◽  
Cellular Functions ◽  
Domains Of Life ◽  
Low Valent

Multi-copper oxidases are a large family of enzymes prevalent in all three domains of life. They couple the one-electron oxidation of substrate to the four-electron reduction of dioxygen to water and feature at least four Cu atoms, traditionally divided into three sites: T1, T2, and (binuclear) T3. The T1 site catalyzes substrate oxidation while a trinuclear cluster (comprising combined T2 and T3 centres) catalyzes the reduction of dioxygen. Substrate oxidation at the T1 Cu site occurs via an outer-sphere mechanism and consequently substrate specificities are determined primarily by the nature of a substrate docking/oxidation (SDO) site associated with the T1 Cu centre. Many of these enzymes ‘moonlight’, i.e. display broad specificities towards many different substrates and may have multiple cellular functions. A sub-set are robust catalysts for the oxidation of low-valent transition metal ions such as FeII, CuI, and MnII and are termed ‘metallo-oxidases’. They play essential roles in nutrient metal uptake and homeostasis, with the ferroxidase ceruloplasmin being a prominent member. Their SDO sites are tailored to facilitate specific binding and facile oxidation of these low-valent metal ions and this is the focus of this review.

Donor-acceptor Stenhouse Adducts with Three Orthogonally Controlled Intrisic Stationary States

2020 ◽  
Author(s):  
Yongli Duan ◽  
Haiquan Zhao ◽  
GuoDong Xue ◽  
Ze Wang ◽  
Chaoyue Xiong ◽  
...  
Keyword(s):  
Crown Ether ◽  
Metal Ions ◽  
Smart Materials ◽  
Green Light ◽  
Supramolecular Structures ◽  
The Other ◽  
Van Der Waals Interactions ◽  
Stationary States ◽  
Complex Stimuli ◽  
Donor Acceptor

Abstract Photoresponsive molecules with more than two intrinsic stationary states are very Interesting. Here, we demonstrate a series of crown ether (CE) substituted donor-acceptor Stenhouse adducts (DASAs) that can be switched between three stationary states under orthogonal control of light and metal ions. DASA-CE molecules are self-assembled into 1:1 head-to-tail supramolecular structures to form di-linear states due to strong van der Waals interactions between electron-donating and -withdrawing moieties. Furthermore, treatment with metal ions (Na+ or K+) switches the di-linear back to the linear state, which is reversible after adding free crown ether. On the other hand, green light irradiation induces linear-to-cyclic isomerization of DASA-CE, while the photoisomerization from di-linear to cyclic state is inhibited. The reverse cyclic-to-linear isomerization can occur under heating in the dark. All in all, the orthogonal switching of DASA-CE between di-linear, linear and cyclic states enables the development of smart materials in environments with complex stimuli.

Trimeric uranyl(vi)–citrate forms Na+, Ca2+, and La3+ sandwich complexes in aqueous solution

2020 ◽  
Vol 56 (86) ◽  
pp. 13133-13136
Author(s):  
Jerome Kretzschmar ◽  
Satoru Tsushima ◽  
Björn Drobot ◽  
Robin Steudtner ◽  
Katja Schmeide ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Metal Ions ◽  
Sandwich Complexes ◽  
Oxygen Atoms

Under the uranyl citrate umbrella: metal ions are extremely shielded from water upon coordination by six uranyl(vi) oxygen atoms.

Sign in / Sign up

Export Citation Format

Share Document