A novel zinc() metal-organic framework with a diamond-like structure: synthesis, study of thermal robustness and gas adsorption properties

• Published in: Dalton transactions : an international journal of inorganic chemistry 2016-01, Vol.45 (3), p.1233-1242
• Main Authors: Almáši, Miroslav, Zele ák, Vladimír, Zukal, Arnošt, Kuchár, Juraj, ejka, Ji í
• Format: Article
• Language: English
• Subjects: Adsorption; Carbon dioxide; Diffraction; Hydrogen storage; Mathematical analysis; Metal-organic frameworks; Metalorganic compounds; Surface chemistry; X-rays
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c5dt02437d

A solvothermal reaction of Zn( ii ) salt with methanetetrabenzoic acid (H 4 MTB) and 1,4,8,11-tetraazacyclotetradecane (cyclam, CYC) created a new microporous metal-organic framework {[Zn 2 (μ 4 -MTB)(κ 4 -CYC) 2 ]·2DMF·7H 2 O} n (DMF = N , N ′-dimethylformamide). Single crystal X-ray diffraction showed that the complex exhibits a four-fold interpenetrated diamond-like structure topology with 1D jar-like channels with sizes about 14.1 × 14.1 and 2.4 × 2.4 Å 2 . The stability of the framework and activation conditions of the compound have been studied by high-energy powder X-ray diffraction during in situ heating, thermogravimetric analysis coupled with mass spectrometry and infrared spectroscopy performed at different temperatures. The gas adsorption behaviour of {[Zn 2 (μ 4 -MTB)(κ 4 -CYC) 2 ]·2DMF·7H 2 O} n was studied by adsorption of Ar, N 2 , CO 2 and H 2 . Nitrogen and argon adsorption showed that the activated sample exhibits Brunauer-Emmet-Teller (BET) specific surface areas of 644 m 2 g −1 (N 2 ) and 562 m 2 g −1 (Ar). The complex adsorbs carbon dioxide with a maximum storage capacity of 10.5 wt% at 273 K and 101 kPa. The observed hydrogen uptake was 1.27 wt% at 77 K and 800 Torr, which is the highest value reported for the compounds containing a MTB 4− linker. The adsorption heats of carbon dioxide and hydrogen, calculated according to the Clausius-Clapeyron equation, were in the range 22.8-22.4 kJ mol −1 for CO 2 and 8.9-3.2 kJ mol −1 for H 2 , indicating weak interactions of the gases with the framework. A novel 3D metal-organic framework with a diamond-like structure has been synthesised and structurally characterized. Adsorption of Ar, CO 2 , H 2 and N 2 has been studied. Heats of CO 2 and H 2 adsorption were calculated according to the Clausius-Clapeyron equation.