Investigation of the Influence of Functionalization Strategy on Urea 2D MOF Catalytic Performance.

Urea-functionalized MOFs with unique properties have recently been used as efficient platforms to conduct organocatalytic reactions. To gain more insight into the key factors which govern an efficient organocatalytic reaction in urea-MOFs, two different urea-containing 2D MOFs TMU-58 ([Zn(L1)(oba)].CH3CN) and TMU-83 ([Zn(L2)(oba)].DMF), where L1 = (1E,5E)-1,5-bis(1-(pyridine-4-ylethylidene)carbonohydrazide, L2 = (1E,5E)-1,5-bis(1-(pyridine-4-ylmethylene)carbonohydrazide, and oba = 4,4'-oxybisbenzoic acid, with abundant accessible active sites, were selected and examined in the methanolysis of styrene oxide. TMU-58 with the ability to form a two-point H-bond with different substrates revealed a high organocatalytic efficiency in the regioselective ring opening of styrene oxide. The catalytic activation of epoxide oxygen by the urea N-H functional sites, followed by the nucleophilic attack of methanol at the benzylic carbon led to the formation of 2-methoxy-2-phenylethanol as the major product. DFT calculations were also performed to investigate the acidic strength of the urea hydrogens in both TMU-58 and TMU-83 structures as a major factor to conduct an efficient catalytic reaction. The results indicated the more acidic nature of the urea hydrogens in TMU-83; however, its catalytic efficiency was remarkably reduced due to the inappropriate orientation of the active interaction sites within the framework revealing the importance of proper orientation of the urea hydrogens in conducting an efficient organocatalytic reaction. The current study provides a comparative study on the function-property relationship in 2D MOF assemblies which has not been explored so far.

Impact of Pore Size and Defects on the Selective Adsorption of Acetylene in Alkyne-Functionalized Nickel(II)-Pyrazolate-Based MOFs.

C2 H2 /CO2 separation is a highly challenging process as a consequence of their similar physicochemical properties. In this work we have explored, by static and dynamic gas sorption techniques and computational modelling, the suitability of a series of two isoreticular robust Ni(II)pyrazolate-based MOFs, bearing alkyne moieties on the ligand backbones, for C2 H2 /CO2 separation. The results are consistent with high adsorption capacity and selectivity of the essayed systems towards C2 H2 molecules. Furthermore, a post-synthetic treatment with KOH ethanolic solution gives rise to linker vacancy defects and incorporation of extraframework potassium ions. Creation of defects is responsible for increased adsorption capacity for both gases, however, strong interactions of the cluster basic sites and extraframework potassium cations with CO2 molecules are responsible for a lowering of C2 H2 over CO2 selectivity.

Highest and Fastest Removal Rate of PbII Ions through Rational Functionalized Decoration of a Metal-Organic Framework Cavity.

To overcome the challenge of developing a multipurpose adsorbent for effective removal of toxic and carcinogenic PbII ions from aqueous solutions, a made-for-purpose functional group (N1 ,N2 -di(pyridine-4-yl)oxalamide) was rationally designed and incorporated into the cavities of a Zn metal-organic framework (MOF), namely, TMU-56. Large enough pore size along with high densities of strong metal chelating sites lead not only to the highest uptake capacity for PbII ions, but also the fastest removal rate that has ever been reported for functionalized MOFs, occurring in just 20 s. Moreover, high concentrations of lead ions favor the ion exchange reaction, resulting in a high degree of metal exchange. In addition, TMU-56 can be a practical adsorbent because of its notable performance in the simultaneous removal of several toxic and carcinogenic heavy metals from wastewater, which has rare precedence.

N,N'-Bis(3-phenyl-allyl-idene)biphenyl-2,2'-diamine.

In the title Schiff base, C(30)H(24)N(2), the complete molecule is generated by a crystallographic twofold axis; the aromatic rings of the biphenyl unit are twisted by 60.78 (1)°. The imine double bond has a trans configuration.