author ="Pham, Tony and Forrest, Katherine and Mostrom, Matthew and Hunt, Joseph and Furukawa, Hiroyasu and Eckert, Juergen and Space, Brian",
title  ="The Rotational Dynamics of H2 Adsorbed in Covalent Organic Frameworks",
journal  ="Phys. Chem. Chem. Phys.",
year  ="2017",
pages  ="-",
publisher  ="The Royal Society of Chemistry",
doi  ="10.1039/C7CP00924K",
url  ="http://dx.doi.org/10.1039/C7CP00924K",
abstract  ="A combined inelastic neutron scattering (INS) and theoretical study was car- ried out on H2 adsorbed in two covalent organic framework (COF) materials: COF-1 and COF- 102. These COFs are synthesized from self-condensation reactions of 1{,}4-benzenediboronic acid (BDBA) and tetra(4-(dihydroxy)borylphenyl)methane (TBPM) molecules{,} respectively. Molecular simulations of H2 adsorption in COF-1 revealed that the H2 molecules occupy the region between two eclipsed layers of the COF. The most favorable H2 binding site in COF-1 is located between two B3O3 clusters of the eclipsed layers. Two distinct H2 binding sites were identified in COF-102 from the simulations: the B3O3 clusters and the phenyl rings of the tetraphenylmethyl units. Two- dimensional quantum rotation calculations for H2 adsorbed at the considered sites in both COFs resulted in rotational transitions that are in good agreement with those that appear in the corre- sponding INS spectra. Such calculations were important for interpreting the INS spectra in these materials. Calculation of the rotational potential energy surface for H2 bound at the most favor- able adsorption site in COF-1 and COF-102 revealed unusually high rotational barriers that are at- tributed to the nature of the B3O3 rings. The values for these barriers to rotation are greater than or comparable to those observed in some metal-organic frameworks (MOFs) that possess open-metal sites. This study demonstrates the power of using INS experiments in conjunction with theoretical calculations to gain valuable insights into the nature of the binding sites and{,} for the first time{,} the rotational dynamics of H2 adsorbed in COFs."}