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Cage Molecules (cage + molecule)
Selected AbstractsSelective Guest Encapsulation by a Cobalt-Assembled Cage MoleculeCHEMISTRY - A EUROPEAN JOURNAL, Issue 20 2005Roger 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] A path from Ih to C1 symmetry for C20 cage moleculeJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 12 2005Zhigang Wang Abstract The symmetry of the C20 cage is studied based on the intrinsical relationship among point groups (Bradley, C. J.; Cracknell, A. P. The Mathematical Theory of Symmetry in Solids; Claredon Press: Oxford, 1972). The structure of the C20 cage with Ih symmetry is constructed, as are eight other structures with subgroup symmetry. A path from Ih symmetry to C1 symmetry is obtained for the closed-shell electronic state, and the structure with D2h symmetry is the most stable on this path. Using the D2h structure the correlation energy correction is studied on the condition of restricted excitation space at the CCSD(T) level. We obtain curves on the relation between the orbital numbers and the total energy at the CCSD(T), CCSD, and MP2 level, respectively. The results of these curves obtained from MP2 and CCSD(T) methods have the same tendency, while the results of CCSD gradually diverge with an increase in orbital numbers. When the orbitals used in the calculation reach 460, the total energy is ,759.644 hartree at MP2 level and is ,759.721 hartree by the CCSD(T) method. From the calculation results, we find that a large basis set can improve the reliability of the MP2 method, and to restrict excitation space is necessary when using the CCSD(T) method. © 2005 Wiley Periodicals, Inc. J Comput Chem 12: 1279,1283, 2005 [source] WS2 and MoS2 Inorganic Fullerenes,Super Shock Absorbers at Very High Pressures,ADVANCED MATERIALS, Issue 12 2005Q. Zhu Superb antishock WS2 inorganic fullerenes (IF) can sustain shock pressures up to 25,GPa, suggesting that these IFs are probably the toughest cage molecules known. The Figure shows images of a) pre- and b) post-shock WS2 IF nanoparticles. These IFs may have great potential to withstand very high applied loads when used as solid-state lubricants. [source] Magnetization Transfer from Laser-Polarized Xenon to Protons with Spin-Diffusion QuenchingCHEMPHYSCHEM, Issue 4 2003Hervé Desvaux Position of the prisoner: Accurate location of xenon atoms in cage molecules (see picture) is derived by specific through-space magnetization transfer from laser-polarized gas to protons using a new NMR pulse sequence. [source] | ||||||||||