Elucidating phase transformation of Eu-based metal organic framework with intermediate isolation and theoretical calculations

Abstract

Self assembly between 2,5-difluoro-3,6-dimercaptoterephthalic acid (H₄dfdmt) and Eu(III) centers under solvothermal conditions gave a 3D reddish-brown metal–organic framework (MOF, Eu-dfdmt-RB) that managed to transit to a 2D black analogue (Eu-dfdmt-B) by extending the reaction time. The putative intermediate (dfdmt-INT) for this transformation was isolated and crystallographically characterized. Theoretical calculation shows that Eu-dfdmt-RB is thermodynamically less stable than Eu-dfdmt-B and hence dissolutes to form dfdmt-INT, which finally repreciptates as Eu-dfdmt-B with an extended reaction time.