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Keywords:

  • aluminum terephthalate;
  • CAU-1;
  • metal–organic frameworks;
  • microwave chemistry;
  • X-ray diffraction

Abstract

Aluminium dihydroxyterephthalate [Al8(OH)4(OCH3)8(BDC(OH)2)6]x H2O (denoted CAU-1-(OH)2) was synthesized under solvothermal conditions and characterized by X-ray powder diffraction, IR spectroscopy, sorption measurements, as well as thermogravimetric and elemental analysis. CAU-1-(OH)2 is isoreticular to CAU-1 and its pores are lined with OH groups. It is stable under ambient conditions and in water, and it exhibits permanent porosity and two types of cavities with effective diameters of approximately 1 and 0.45 nm. The crystallization of CAU-1-(OH)2 was studied by in situ energy-dispersive X-ray diffraction (EDXRD) experiments in the 120–145 °C temperature range. Two heating methods—conventional and microwave—were investigated. The latter leads to shorter induction periods as well as shorter reaction times. Whereas CAU-1-(OH)2 is formed at all investigated temperatures using conventional heating, it is only observed below 130 °C using microwave heating. The calculation of the activation energy of the crystallization of CAU-1-(OH)2 exhibits similar values for microwave and conventional synthesis.