Novel and Versatile Cobalt Azobenzene-Based Metal-Organic Framework as Hydrogen Adsorbent

A novel URJC-3 material based on cobalt and 5,5′-(diazene-1,2-diyl)diisophthalate ligand, containing Lewis acid and basic sites, has been synthesized under solvothermal conditions. Compound URJC-3, with polyhedral morphology, crystallizes in the tetragonal and P4₃2₁2 space group, exhibiting a three-dimensional structure with small channels along a and b axes. This material was fully characterized, and its hydrogen adsorption properties were estimated for a wide range of temperatures (77–298 K) and pressures (1–170 bar). The hydrogen storage capacity of URJC-3 is quite high in relation to its moderate surface area, which is probably due to the confinement effect of hydrogen molecules inside its reduced pores of 6 Å, which is close the ionic radii of hydrogen molecules. The storage capacity of this material is not only higher than that of active carbon and purified single-walled carbon nanotubes, but also surpasses the gravimetric hydrogen uptake of most MOF materials.     

Fourth virial coefficients for globular molecules

A binary mixture of hard rods with non-additive distances of contact, in one dimension, is studied. Special attention is paid to the case that two particles (hard rods) of the same species can come into contact in the presence of a particle of the other species between them. The system is treated by means of the ensemble which is specified by the total number of particles of one species, the chemical potential of the particles of the other species, the temperature and the pressure. The free energy in this ensemble is shown to be expressed by the eigenvalue with the smallest absolute value of an integral equation. The equation of state is obtained by numerical differentiation of the free energy.