Sorption of benzene vapors to flexible metal–organic framework [Zn2(bdc)2(dabco)]

The isotherms of benzene sorption by the metal–organic coordination polymer [Zn 2 (bdc) 2 (dabco)] were studied within the temperature range 25–90 °C at pressures up to 75 torr. The maximal benzene content in [Zn 2 (bdc) 2 (dabco)] at room temperature was demonstrated to correspond to the composition [Zn 2 (bdc) 2 (dabco)]·3.8C 6 H 6 . It was established that the process of benzene desorption from the substance under investigation occurs in three stages. (1) Evaporation of benzene from the phase of variable composition (phase C ) with compression and distortion of the unit cell (the composition of the phase C varies from [Zn 2 (bdc) 2 (dabco)]·3.8C 6 H 6 to [Zn 2 (bdc) 2 (dabco)]·3.2C 6 H 6 ). (2) The transformation of the phase C into phase P . The phase P has the same unit cell geometry as that for the empty framework. The maximal benzene content is [Zn 2 (bdc) 2 (dabco)]·1.0C 6 H 6 . (3) Benzene evaporation from the phase P of variable composition. We studied the temperature dependences of the equilibrium vapor pressure of benzene for the samples with compositions [Zn 2 (bdc) 2 (dabco)]·3.0(3)C 6 H 6 and [Zn 2 (bdc) 2 (dabco)]·2.0(3)C 6 H 6 within the temperature range 290–370 K. The thermodynamic parameters of benzene vaporization were determined for the latter compound ( ; ; ).