Fig. 2: Water adsorption-induced reversible single-crystal to single-crystal transformation.
From: A spin-crossover framework endowed with pore-adjustable behavior by slow structural dynamics
a The conformational flexible prentrz molecules are employed as axial ligands. b The 2D network constructed from Fe−N( ≡ C − Pd) coordination bonds. The layer structures are further assembled into a 3D framework via interlaminar molecular interactions. c Single-crystal structure of the lcp phase 1·9/2H2O. d Single-crystal structure of the nqp phase 1·4/3H2O. The water adsorption-actuated reorientations and pedal rotations of the axial prentrz ligands repartition the lattice structure, manifesting as a narrow-pore to large-pore transformation accompanied by a rearrangement of the pore configuration from A’A’B’A’A’B’ mode in nqp phase 1·4/3H2O to ABABAB mode in lcp phase 1·9/2H2O (A: open channel, B: closed channel). Therefore, the opening (A’/B’ to A) and closing (A’ to B) of pores coincide during water adsorption. According to SC-XRD analyses, 4/3 H2O and 9/2 H2O per FeII ion accommodate in the pore of 1·4/3H2O and 1·9/2H2O, respectively. The dotted lines represent the hydrogen-bond interactions. Fe, orange; C, gray; N, blue; O, red. The hydrogen atoms were omitted for clarity.
