Synthesis and Catalytic Properties of New Metalloporphyrin‐Based Porous Organic Framework Materials with Single and Accessible Sites

Abstract

It is a big challenge to homogenize heterogeneous catalysts with molecular catalytic performance. With this target in mind, herein, we describe a facile strategy for direct incorporation of single catalytic sites in 3D open porous aromatic frameworks (PAFs). The synthesis of the PAF (denoted as PAF‐76) as well as its derivatives (PAF‐76‐M, M=Fe, Mn, Zn) was achieved by the use of tetrakis(4‐bromophenyl)methane as tetrahedral nodes and tetrakis(4‐bromophenyl)porphyrin as planar nodes. The connection of monomers into an extended network of PAF‐76 was monitored by 13C NMR and FTIR spectroscopies. The prepared PAF‐76s showed 3D porous structures with surface areas of 450–700 m2 g−1, pore volumes of 0.3–0.4 cm3 g−1, and pore sizes around 1.2 nm. The direct incorporation of metalloporphyrin components into the PAF‐76‐M frameworks has allowed the uniform distribution of metal ionic sites throughout the PAF‐76‐M particles. The combined merits of isolated metal sites and suitable pore size make PAF‐76 a good candidate for heterogeneous catalysis. The catalytic performances of the porphyrin/metalloporphyrin‐based active sites in the PAF‐76s were evaluated by aerobic oxidation reactions of styrene, which are usually carried out with homogeneous systems. Metal‐functionalized PAF‐76s (PAF‐76‐M) exhibit enhanced turnover frequencies for styrene conversion (16.9–50.9 mol mol(M)−1 h−1) compared with molecular catalysts (0–35.0 mol mol(M)−1 h−1), and improved selectivity toward phenylacetaldehyde (85.7–99 %) in contrast to their corresponding monomers (0–75.5 %). The robustness of PAF‐76 in terms of high thermal stability, good recyclability, and excellent solvent resistance showed that these PAF‐76 materials hold great promise for developing heterogeneous catalysts.

Porous Organic Polymers Containing Active Metal Centers as Catalysts for Synthetic Organic Chemistry

“…Among other methods used for the formation of metal-POPs are nucleophilic aromatic substitution between fluoride-functionalized porphyrins and linkers bearing hydroxy-groups 85,86 , nickelcatalyzed Ullmann coupling for polymerizing porphyrin moieties 87 , Suzuki cross-coupling between bromide-functionalized porphyrins and aryl boronic esters 88 An introduction to different polymerization techniques for synthesizing different POPs has been presented in the previous sections. However, in order to obtain a single-site metal catalyst, a metal has to be incorporated into the structure of the POP.…”

Porous Ru(bpy)32+-Linked Polymers for Recyclable Photocatalysis of Enantioselective Alkylation of Aldehydes

“…Flourier transform infrared spectra of Ru-POP-1 and Ru-POP-2 showed the absence of the C–B (around 1021 cm –1 ) or B–O (around 1324 cm –1 ) vibration absorptions of the borate group , (Figure S2, Supporting Information), indicating that most of the starting materials were consumed in the coupling reactions. The H-6’ atoms of complexes 4a in the 1 H NMR spectrum, which was assigned on the basis of a reported analogous complex, exhibited multisets of signals (Figure S3, Supporting Information), and 2D H–H COSY (Figure S4, Supporting Information), indicating that the complexes existed in different optical isomers.…”

Porous aromatic frameworks derived from tetrahedral units

“…http://engine.scichina.com/doi/10.1360/N972018-00265 评 述 图 8 (网络版彩色)PAF70-NH2, PAF70-thiourea [78] 和PAF70-Pd的合成路线图 [79] Figure 8 (Color online) Synthetic route of PAF70-NH2, PAF70-thiourea [78] and PAF70-Pd [79] 卟啉环与PAFs材料结合, 不仅提供了新的构筑基元, 也增加了材料的功能位点. 通过四硼脂四苯基甲烷 与 四 溴 四 苯 基 卟 啉 的 Suzuki 偶 联 反 应 合 成 了 PAF-76 [80] . 然后, 利用卟啉环与过渡金属离子的络 合作用将金属Fe, Mn, Zn离子引入到骨架中, 合成的 PAF-76s在苯乙烯催化氧化的实验中具有优异的催化 性能.…”