We demonstrate that fluorous metal-organic frameworks (FMOFs) are highly hydrophobic porous materials with a high capacity and affinity to C(6)-C(8) hydrocarbons of oil components. FMOF-1 exhibits reversible adsorption with a high capacity for n-hexane, cyclohexane, benzene, toluene, and p-xylene, with no detectable water adsorption even at near 100% relative humidity, drastically outperforming activated carbon and zeolite porous materials. FMOF-2, obtained from annealing FMOF-1, shows enlarged cages and channels with double toluene adsorption vs FMOF-1 based on crystal structures. The results suggest great promise for FMOFs in applications such as removal of organic pollutants from oil spills or ambient humid air, hydrocarbon storage and transportation, water purification, etc. under practical working conditions.

A fluorous metal−organic framework, FMOF-1, is obtained by reaction of Ag(I) with 3,5-bis(trifluoromethyl)-1,2,4-triazolate, giving rise to a neutral, hydrogen-free, extended 3D nanotubular porous framework consisting of tetranuclear clusters [Ag4Tz6] connected by three-coordinate Ag(I) centers. The fluoro-lined channels and cavities of the framework show hysteretic adsorption of H2 with a volumetric capacity of 41 kg/m3 at 77 K and 64 bar. The framework also exhibits very high adsorptions for O2 and N2 with volumetric uptake of ∼550 and 400 kg/m3 at 77 K even at very low pressures (<10-2 bar).

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Playing accordion: Cooling a single crystal of a microporous fluorous metal-organic framework under ambient atmosphere leads to very large breathing upon gas adsorption, during which multiple N(2) molecules are filled into channels and cages (see picture). While the framework exhibits remarkable positive thermal expansion under vacuum, a gigantic apparent negative thermal expansion takes place when the crystal is exposed to N(2) at ambient pressure.

Water cluster formation and methane adsorption within a hydrophobic porous metal organic framework is studied by in situ vibrational spectroscopy, adsorption isotherms, and first-principle DFT calculations (using vdW-DF). Specifically, the formation and stability of H2O clusters in the hydrophobic cavities of a fluorinated metal-organic framework (FMOF-1) is examined. Although the isotherms of water show no measurable uptake (see Yang et al. J. Am. Chem. Soc. 2011 , 133 , 18094 ), the large dipole of the water internal modes makes it possible to detect low water concentrations using IR spectroscopy in pores in the vicinity of the surface of the solid framework. The results indicate that, even in the low pressure regime (100 mTorr to 3 Torr), water molecules preferentially occupy the large cavities, in which hydrogen bonding and wall hydrophobicity foster water cluster formation. We identify the formation of pentameric water clusters at pressures lower than 3 Torr and larger clusters beyond that pressure. The binding energy of the water species to the walls is negligible, as suggested by DFT computational findings and corroborated by IR absorption data. Consequently, intermolecular hydrogen bonding dominates, enhancing water cluster stability as the size of the cluster increases. The formation of water clusters with negligible perturbation from the host may allow a quantitative comparison with experimental environmental studies on larger clusters that are in low concentrations in the atmosphere. The stability of the water clusters was studied as a function of pressure reduction and in the presence of methane gas. Methane adsorption isotherms for activated FMOF-1 attained volumetric adsorption capacities ranging from 67 V(STP)/V at 288 K and 31 bar to 133 V(STP)/V at 173 K and 5 bar, with an isosteric heat of adsorption of ca. 14 kJ/mol in the high temperature range (288-318 K). Overall, the experimental and computational data suggest high preferential uptake for methane gas relative to water vapor within FMOF-1 pores with ease of desorption and high framework stability under operative temperature and moisture conditions.

CommunicationsVisible-light excitation of the europium complex shown leads to characteristic red emission from the Eu III center. A spectroscopic study shows the nature of the sensitization process and accounts for why the complex can be excited at these longer wavelengths.

A new cyclic gold(I) triazolate trimer, [Au(3,5-i-Pr2Tz)]3 (1), exhibits fully overlapping aurophilically bonded dimer-of-trimer units that lead to multiple phosphorescence bands in both the solid state and solution. The conformation of the hexanuclear unit exhibits reversible interconversion between C2 and D3 effective symmetries, depending on the crystal temperature or solution concentration, the variation of which leads to isoemissive and isosbestic points. Solutions of 1 exhibit remarkable quenching properties that demonstrate molecular recognition with high selectivity and hypersensitivity for some reagents, as influenced by protonation via Brønsted acids, pi intercalation, and/or energy transfer. The quenched phosphorescence of 1 by acetic acids can be regenerated by NEt3.