Dear Customers! We're out of the office from the 6th of October to the 11th of October. We sincerely apologize for the inconvenience. For WordPress 5.5.* related issues, please visit this article.
Metal-organic frameworks are a new class of heterogeneous catalysts that can easily achieve molecular-level control over the immediate and long-range chemical environment around the catalytic center. Here, the oxidation of cyclohexane to cyclohexanol and cyclohexanone was used as a model reaction to investigate the effects of the hydrophobic pore environment on product selectivity and catalyst stability in a series of iron-based frameworks. Specifically, extended analogs of Fe2(dobdc) (dobdc4- = 2,5-dioxy-1,4-benzenedicarboxylic acid) were synthesized and evaluated, including the biphenyl derivative Fe2(dobpdc) (H4dobpdc = 4,4'-dihydroxy-[1, 1'-biphenyl]-3,3'-dicarboxylic acid), the terphenyl derivative Fe2(dotpdc) (H4dotpdc = 4,4''-Dihydroxy-[1,1':4',1''-terphenyl]-3,3''-dicarboxylic acid), and three modified terphenyl derivatives whose central rings were substituted with tetrafluoro, tetramethyl, or di-tert-butylaryl groups. In these five materials, the alcohol:ketone (A:K) ratio can be significantly increased by three times and the turnover number can be increased by an order of magnitude by simply changing the framework pore size and installing nonpolar functional groups near the iron site. In a nitrogen-filled glove box, 4,4''-Dihydroxy-[1,1':4',1''-terphenyl]-3,3''-dicarboxylic acid (60 mg, 0.17 mmol, 1.0 eq.), FeCl2(60 mg, 0.47 mmol, 2.8 eq.), DMF (8.0 mL) and MeOH (1.0 mL) were mixed in a 20 mL scintillation vial. The vial was sealed with a Teflon-lined cap and heated to 140°C for 2 days. The resulting precipitate was filtered, washed with DMF (3×10 mL at 120°C) and MeOH (3×10 mL at 60°C), and dried under vacuum at 120°C for 2 h. To exchange the bound methanol molecules for CD3CN, the powder was immersed in 0.5 mL of CD3CN and exposed to vacuum at 120 °C for another 2 h to obtain 66 mg (70%) of yellow-green Fe2(dotpdc)·2CD3CN powder.
Metal-organic frameworks are a new class of heterogeneous catalysts that can easily achieve molecular-level control over the immediate and long-range chemical environment around the catalytic center. Here, the oxidation of cyclohexane to cyclohexanol and cyclohexanone was used as a model reaction to investigate the effects of the hydrophobic pore environment on product selectivity and catalyst stability in a series of iron-based frameworks. Specifically, extended analogs of Fe2(dobdc) (dobdc4- = 2,5-dioxy-1,4-benzenedicarboxylic acid) were synthesized and evaluated, including the biphenyl derivative Fe2(dobpdc) (H4dobpdc = 4,4'-dihydroxy-[1, 1'-biphenyl]-3,3'-dicarboxylic acid), the terphenyl derivative Fe2(dotpdc) (H4dotpdc = 4,4''-Dihydroxy-[1,1':4',1''-terphenyl]-3,3''-dicarboxylic acid), and three modified terphenyl derivatives whose central rings were substituted with tetrafluoro, tetramethyl, or di-tert-butylaryl groups. In these five materials, the alcohol:ketone (A:K) ratio can be significantly increased by three times and the turnover number can be increased by an order of magnitude by simply changing the framework pore size and installing nonpolar functional groups near the iron site.
In a nitrogen-filled glove box, 4,4''-Dihydroxy-[1,1':4',1''-terphenyl]-3,3''-dicarboxylic acid (60 mg, 0.17 mmol, 1.0 eq.), FeCl2(60 mg, 0.47 mmol, 2.8 eq.), DMF (8.0 mL) and MeOH (1.0 mL) were mixed in a 20 mL scintillation vial. The vial was sealed with a Teflon-lined cap and heated to 140°C for 2 days. The resulting precipitate was filtered, washed with DMF (3×10 mL at 120°C) and MeOH (3×10 mL at 60°C), and dried under vacuum at 120°C for 2 h. To exchange the bound methanol molecules for CD3CN, the powder was immersed in 0.5 mL of CD3CN and exposed to vacuum at 120 °C for another 2 h to obtain 66 mg (70%) of yellow-green Fe2(dotpdc)·2CD3CN powder.