Molecular simulations of the sorption and cosorption energetics and siting locations of M(CO)

adsorb without any chemical reaction. The UV-visible absorption indicates the occupancy of 2 BP per supercage at bulk loading higher than 4 BP per unit cell. The calculated BP vibrational densities of state deduced from MD calculations are in agreement with the frequency values deduced from the Raman bands. In the vibrational time scale occluded BP are undergoing rapid motions at room temperature. The rapid motions at low loading average the microenvironments and vibrational couplings as found in solution. Nevertheless, the BP mobility is hindered by the presence of numerous Na`cations and BP at high loading in the void space. These e †ects induce the broadening of some Raman bands.

The predictions of the sorption energy, sorption site, conformation, mobility, and vibrational spectra of biphenyl (BP, C 12 H 10 ) occluded in nonacidic faujasitic Y zeolites M n (SiO 2 ) 192-n (AlO 2 ) n (M n FAU, n ) 0 or 56 and M ) Na + , K + , or Cs + ) were carried out using Monte Carlo simulations (MC), molecular mechanics (MM), and molecular dynamics (MD) calculations. The zeolite-biphenyl interactions have been tuned by varying the aluminum content n, the charge-balancing cation M + of the zeolite, and the BP loading. No preferential sorption site was expected in purely siliceous FAU at 300 K, whereas well-defined location sites energetically favored were expected in M 56 FAU aluminated faujasite. BP lies in the cavity in a twisted conformation with one phenyl group facially coordinated to the SII cations and the other phenyl group engaged in the 12-ring windows. The accommodation of two BPs within the same supercage occurs at relatively low coverage (2 BP/UC) and is hindered by the M + size. The diffuse reflectance UV-visible absorption data indicate the occupancy of 2 BP per supercage at bulk loading higher than 1 BP/UC. Surprisingly, the BP mean-square displacements (MSD) was found to be slightly lower in FAU than in Na 56 FAU, although the intracage mobility was found to be higher, while the BP MSD was found to be lower with bulky M + cations. The calculated vibrational densities of states of the atoms of the framework, M + and BP, were found to be in reasonable agreement with the frequency values deduced from the IR absorption and Raman scattering spectra of BPloaded M n FAU, bare M n FAU, and free BP. These results indicate no marked constraint between host and guest even at high BP coverage. The BP rapid motions average the microenvironments and vibrational couplings as found in solution. The experimental conditions of the BP sorption and the Ar, He, or O 2 gas pressure do not induce significant changes of occluded BP characteristics.

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