Thermally Stable Porous Hydrogen‐Bonded Coordination Networks Displaying Dual Properties of Robustness and Dynamics upon Guest Uptake

Two series of microporous lanthanide coordination networks of the general formula, {[Ln(ntb)Cl 3 ] ⋅ x  H 2 O} n (series 1 : monoclinic C 2/ c , Ln=Sm and Tb; series 2 : hexagonal P 3 1 / c , Ln=Sm and Eu; ntb=tris(benzimidazol‐2‐ylmethyl)amine, x =0–4) have been synthesized and characterized by IR, elemental analyses, thermal gravimetry, and single‐crystal and powder X‐ray diffraction methods. In both series, the monomeric [Ln(ntb)Cl 3 ] coordination units are consolidated by NH⋅⋅⋅Cl or CH⋅⋅⋅Cl hydrogen bonds to sustain three‐dimensional (3D) networks. However, the different modes of hydrogen bonding in the two series lead to crystallization of the same [Ln(ntb)Cl 3 ] monomers in different forms (monoclinic vs. hexagonal), consequently giving rise to distinct porous structures. The resulting hydrogen‐bonded coordination networks display high thermal stability and robustness in water removal/inclusion processes, which was confirmed by temperature‐dependent single‐crystal‐to‐single‐crystal transformation measurements. Adsorption studies with H 2 , CO 2 , and MeOH have been carried out, and reveal distinct differences in adsorption behavior between the two forms. In the case of MeOH uptake, the monoclinic network shows a normal type I isotherm, whereas the hexagonal network displays dynamic porous properties.