6s-3d {Ba₃Zn₄}–Organic Framework as an Effective Heterogeneous Catalyst for Chemical Fixation of CO₂ and Knoevenagel Condensation Reaction

Abstract

The exquisite combination of Ba 2+ and Zn 2+ with the aid of 2,4,6tri(2,4-dicarboxyphenyl)pyridine (H 6 TDP) under the condition of solvothermal selfassembly generates one highly robust [Ba 3 Zn 4 (CO 2 ) 12 (HCO 2 ) 2 (OH 2 ) 2 ]−organic framework of {[Ba 3 Zn 4 (TDP) 2 (HCO 2 ) 2 (OH 2 ) 2 ]•7DMF•4H 2 O} n (NUC-27), in which adjacent 2D layers are interlaced via hydrogen-bonding interactions to form a 3D skeleton with peapod-like channels and nano-caged voids. It is worth emphasizing that both Ba 2+ and Zn 2+ ions in NUC-27 display the extremely low coordination modes: hexa-coordinated [Ba(1)] and tetra-coordinated [Ba(2), Zn(1), and Zn(2)]. Furthermore, to the best our knowledge, NUC-27 is one scarcely reported 2Dbased nanomaterial with an unprecedented Z-shaped hepta-nuclear heterometallic cluster of [Ba 3 Zn 4 (CO 2 ) 12 (HCO 2 ) 2 (OH 2 ) 2 ] as SBUs, which not only has plentiful low-coordinated open metal sites but also has the excellent physicochemical properties including omni-directional opening pores, ultrahigh porosity, larger specific surface area, and the coexistence of Lewis acid-base sites. Just as expected, thanks to its rich active metal sites and pyridine groups as strong Lewis acid-base roles, completely activated NUC-27 displays high catalytic efficiency on the chemical transformation of epoxides with CO 2 into cyclic carbonates under mild conditions and effectively accelerates the reaction process of Knoevenagel condensation.

Nanochannel-based {BaZn}–organic framework for catalytic activity on the cycloaddition reaction of epoxides with CO2 and deacetalization-Knoevenagel condensation

“…In addition, NUC-51 has a common feature with previously reported {ZnCa}-TDP and M II Ln III -TDP (M II Ln III , M = Mn, Co, Ni, Zn; Ln = rare earth cations) heterometallic MOFs, [24][25][26][27] in which the 3d cation of Zn(II) displays a tetra-coordinated mode, which should be attributed to the synergetic coordination effect between the heterometallic ions and the structure-oriented polycarboxylic ligand of H 6 TDP. Meanwhile, judged by the structures of achieved heterometallic MOFs, the main structure-oriented factor of H 6 TDP should be ascribed to the fact that TDP 6− owns multiple αand γ-carboxyl groups with chelating tendency, especially the ones affected by the electron density of N pyridine atoms.…”

“…Furthermore, it is noteworthy that crystal configurations are greatly affected by the solvent proportion (Table S3 †). According to our recent report on the synthesis condition of nano-caged {Ba 3 Zn 4 }-TDP (NUC-27), 24 NUC-51 can be obtained only by changing the polarity of the reaction solvent. The isomerization phenomenon caused by this solvent change has also been found in some MOFs.…”

“…Nevertheless, with the employment of 1.0 mol% NUC-51a and 2.5 mol% n-Bu 4 NBr, the conversion of styrene oxide increased significantly with the final rate of 43.3%, which should be ascribed to the fact that n-Bu 4 NBr as one kind of recognized nucleophilic co-catalyst played an important role in the multistage reaction system (entry 4). [24][25][26][27] Then, based on the employment of NUC-51a and n-Bu 4 NBr, temperature verification tests were carried out. Just as shown in entries 5-7, along with reaction temperature ranging from 35 °C to 55 °C with the interval of 10 °C, the conversion rate of styrene oxide ascended from 58.3% to 92.2%, which proved that the reaction temperature had a significant effect on the reaction rate.…”

“…[21][22][23] We have recently reported a series of heterometallic MOFs with excellent physicochemical properties including honeycomb channels, large specific surface area, coexisting Lewis acid-base sites, and high chemical stability. [24][25][26][27] However, the inherent laws regarding the arrangement and coordination number of the involved metal ions in cluster SBUs are still uncovered.…”

Design, Synthesis and Photoluminescence Sensing Property of a Ni‐Organic Material Achieved from 2,6‐Di(1H‐imidazol‐1‐yl) Naphthalene and Carboxylic Acid Ligands

“…Therefore, it is urgent to seek an excellent analytical method for detecting acetone [12–15] . Compared with electrochemical method, atomic absorption spectrometry and spectrophotometry, luminescence sensing has the advantages of simple preparation, convenient operation, low cost, clear and stable luminescence signal, good selectivity and sensitivity [16] …”