A series of regioisomeric Janus-type polyhedral oligomeric silsesquioxanes (POSS) with multiple, mixed surface functional groups has been successfully synthesized based on the cubic T8 -POSS framework in two consecutive thiol-ene reactions. The first thiol-ene addition of β-mercaptoethanol leads to a statistical mixture of multi-adducts where the regioisomers of bis-adducts (ortho, meta, and para isomers) can be isolated at synthetically useful quantities by flash column chromatography. Then, the second thiol-ene reaction readily installs a variety of functional groups onto the remaining vinyl groups of each regioisomer, providing an easy access to precisely defined, hetero-bifunctional Janus POSS nano-building blocks. The configurations and structures of the products have been unambiguously proven by using (1) H, (13) C, and (29) Si NMR spectroscopy as well as MALDI-TOF mass spectrometry.

The adsorption property of hydrogen molecules on YmSi@Al12 (m=13) cluster is investigated using the density functional theory. The results show that yttrium atoms do not suffer from clustering on the Si@Al12 cluster. The 18-electron rule can be used to design these systems, and Si@Al12 cluster coated with three yttrium atoms can adsorb 16 H2 molecules with a gravimetric density of up to 5.0 wt%. The calculated adsorption energy of 0.324-0.527 eV/H2 molecule is suited for reversible hydrogen storage in near-ambient conditions.

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