Closed-pore crystal capable of adsorbing CO2 onto isolated cavities generated by disorderly mixing of substituents on host skeleton

Abstract

A single crystal adsorbent, [Rh(II)₂(bza)₄(2,3-empyz)]_n (2,3-empyz = 2-ethyl-3-methylpyrazine) (1), was synthesized by self-assembly reaction of a Rh₂ benzoate complex and substituted pyrazine linker. The compound consists of one-dimensional zigzag chains, which generated a closed-pore structure without channels. The cavities were statistically generated by the static disorder of substituents on pyrazine and are separated by long intervals within the crystal. The property of CO₂ absorption was characterized in this closed-pore system. The CO₂ inclusion structure was determined by single-crystal X-ray diffraction measurements. These studies suggest that CO₂ molecules were adsorbed and diffused in the nonporous crystal with the isolated cavities.