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Guest Encapsulation (guest + encapsulation)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Solid-State Anion,Guest Encapsulation by Metallosupramolecular Capsules Made from Two Tetranuclear Copper(II) Complexes

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 29 2007
Emilio Pardo
Abstract A new cationic tetranuclear copper(II) complex self-assembles from one 1,3-phenylenebis(oxamato) (mpba) bridging ligand and four CuII ions partially blocked with N,N,N,,N, -tetramethylethylenediamine (tmen) terminal ligands. In the solid state, two of these tetracopper(II) oxamato complexes of bowl-like shape and helical conformation then serve as a building block for the generation of either hetero- (MP) or homochiral (MM/PP) dimeric capsules depending on the nature of the encapsulated anion guest, perchlorate or hexafluorophosphate. The overall magnetic behaviour of these metallosupramolecular capsules does not depend on the nature of the encapsulated anion guest, but it is consistent with the dimer-of-dimer structure of the tetracopper(II) cation host, where the interdimer magnetic coupling through the meta -phenylenediamidate bridge is negligibly smallrelative to the reasonably strong intradimer one across the oxamato bridge.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Noncovalent Isotope Effect for Guest Encapsulation in Self-Assembled Molecular Capsules

CHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2010
Takeharu Haino Prof.
No abstract is available for this article. [source]

Selective Guest Encapsulation by a Cobalt-Assembled Cage Molecule

CHEMISTRY - A EUROPEAN JOURNAL, Issue 20 2005
Roger G. Harrison Prof.
Abstract Metal-assembled resorcinarene-based cages enclose space and entrap organic molecules from water. Addition of cobalt(II) ions to a neutral, aqueous solution of a resorcinarene that has iminodiacetic acids attached to its upper rim results in the formation of cages. These cages not only entrap organic molecules, but they do so in a selective manner. Guests with optimum size, shape, and polarity are preferentially entrapped. For example, selection of p -xylene is twenty thousand times more favorable than that of m -xylene. The enthalpy of resorcinarene deprotonation and cage formation was calculated by performing calorimetry studies and ranged from ,305 to ,348 kJ,mol,1. The change in enthalpy of guest encapsulation varied by as much as 43 kJ,mol,1. The differences in change in free energy of guest encapsulation varied by ,16 kJ,mol,1. The changes in enthalpy and free energy of guest encapsulation were used to calculate the changes in entropy, which ranged from ,97 to +37 J,mol,1,K,1. An enthalpy,entropy compensation of guest encapsulation was observed. [source]

Hydrophobic Chemistry in Aqueous Solution: Stabilization and Stereoselective Encapsulation of Phosphonium Guests in a Supramolecular Host

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 22 2004
Julia L. Brumaghim
Abstract Encapsulation of guest molecules inside supramolecular host assemblies provides a way to stabilize reactive species in aqueous solution. The stabilization of reactive phosphonium/ketone adducts of the general formula [R1MeC(OH)PR3]+ by encapsulation as guest molecules within a [Ga4L6]12, tetrahedral metal,ligand assembly is reported; although these cations decompose in aqueous solution, encapsulation inside the hydrophobic cavity of the assembly lengthens their lifetimes considerably, in some cases up to weeks. By varying the phosphane (PMe3, PEt3, PPhMe2, and PPh2Me) and ketone (acetone, methyl ethyl ketone, 1,1,1-trifluoroacetone, and fluoroacetone) which form these adducts, as well as the pD of the solutions, it was determined that the pH of the solution as well as the size and shape of the guest cations play an important role in the stability of these host,guest complexes. Encapsulation of chiral guests in the chiral [Ga4L6]12, assembly results in the formation of diastereomers, as characterized by 1H, 19F, and 31P NMR spectroscopy. Although the [Ga4L6]12, assembly is formed from non-chiral ligands, the assembly itself has ,,,, or ,,,, chirality around the metal centers. Due to the chirality of this assembly, diastereomeric selectivity is observed upon initial guest encapsulation (typical diastereomeric excesses are 30,50%). This initial diastereomeric selectivity decreases over time to reach an equilibrium but does not become 1:1, indicating both kinetic and thermodynamic processes promote selective guest encapsulation. These experiments demonstrate further the applications of nanoscale reaction vessels, self-assembled by design from non-chiral ligands, in providing a chiral and hydrophobic environment for guest molecules in aqueous solution. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

Selective Guest Encapsulation by a Cobalt-Assembled Cage Molecule

CHEMISTRY - A EUROPEAN JOURNAL, Issue 20 2005
Roger G. Harrison Prof.
Abstract Metal-assembled resorcinarene-based cages enclose space and entrap organic molecules from water. Addition of cobalt(II) ions to a neutral, aqueous solution of a resorcinarene that has iminodiacetic acids attached to its upper rim results in the formation of cages. These cages not only entrap organic molecules, but they do so in a selective manner. Guests with optimum size, shape, and polarity are preferentially entrapped. For example, selection of p -xylene is twenty thousand times more favorable than that of m -xylene. The enthalpy of resorcinarene deprotonation and cage formation was calculated by performing calorimetry studies and ranged from ,305 to ,348 kJ,mol,1. The change in enthalpy of guest encapsulation varied by as much as 43 kJ,mol,1. The differences in change in free energy of guest encapsulation varied by ,16 kJ,mol,1. The changes in enthalpy and free energy of guest encapsulation were used to calculate the changes in entropy, which ranged from ,97 to +37 J,mol,1,K,1. An enthalpy,entropy compensation of guest encapsulation was observed. [source]