Among recently synthesized isoreticular metal-organic frameworks (IRMOFs), interpenetrating IRMOFs show high hydrogen adsorption capacities at low temperature and under ambient pressure. However, little is known about the molecular basis of their hydrogen binding properties. In this work, we performed grand canonical Monte Carlo (GCMC) simulations to investigate the effect of catenation on the interactions between hydrogen molecules and IRMOFs. We identified the adsorption sites and analyzed the adsorption energy distributions. The simulation results show that the small pores generated by catenation can play a role to confine the hydrogen molecules more densely, so that the capacity of the interpenetrating IRMOFs could be higher than that of the non-interpenetrating IRMOFs.

A new class of silicon-containing poly(cyanoterephthalylidene) copolymers with a uniform π-conjugated segment was synthesized using the Knoevenagel reaction between the dialdehyde monomer and the appropriate diacetonitrile. The incorporation of organosilicon units with the flexible alkyl side group into the polymer rigid backbone would afford processable electroluminescent materials and interrupt the regular π-conjugated chains. The resulting polymers were highly soluble in common organic solvents. The M n and M w of the resulting polymers are in the range 3800−4200 and 5400−6000 with a polydispersity index range of 1.38−1.43, respectively. Their glass transition temperature was in the range of 82−87 °C. According to the molecular mechanical calculations for single chain models of SiBuPPV and SiBuCNPPV, trans conformations are more stable than cis conformations. The UV−visible absorbance of present polymers show strong absorption bands around 340−360 nm, since the π-conjugated system is regulated by organosilicon units. Their photoluminescence spectra appeared around 460−470 nm in the blue region. The threshold voltage of the SiHMCNPPV was about 7 V. Surprisingly, these polymers exhibit blue light-emitting diodes in the EL emissive band at 480 nm in the blue region, instead of red light-emitting diodes, when an operating voltage of higher than 7 V is applied. These copolymers show a relatively low operating voltage compared with a block copolymer having well-defined structures because the incorporation of electron-withdrawing cyano groups into the π-conjugated system increased the electron affinity of those polymers and decreased the LUMO energy level.

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