Partial Order-Disorder Transformation of Interpenetrated Porous Coordination Polymers

Abstract

Controlling interpenetration and flexibility behaviors is intriguing and fundamental for porous coordination polymers. We report exceptional interpenetration behaviors involving controllable partial order-disorder structural transformations. A new bis-benzotriazolate ligand (NaH2sbbta) with a twisted and anionic backbone was designed and synthesized. The solvothermal reaction of ZnCl2 and NaH2sbbta yielded (Et2NH2)3[Zn5Cl4(sbbta)3] 6DEF (2) possessing two-fold interpenetrated anionic pcu networks with symmetry, shape, and charge different from the known analogues. More interestingly, powder and single-crystal X-ray diffractions showed that 2 can undergo solvent-induced structural transformation to form a noninterpenetrated anionic pcu network with larger pores (1). Consequently, 1/2 can selectively adsorb/exchange cationic dyes fromneutral and anionic dyes with tunable size selectivity. However, since the transformations are reversible without obvious change of crystal sizes, the network that disappeared in X-ray crystallography should be mainly disordered rather than decomposed. Further, the structural transformations can be suppressed by thermal decomposition/removal of Et2NH2 +/Et2NH. Computational simulations indicate that the ordered and disordered structures are stabilized by relatively large and small solvent molecules, respectively.