Insight into the Construction of (3,6)-Connected rtl, ant, and Chiral anh Nets Based on Structural Investigation of Several MOFs via Steric Tuning of Linkers.

Six cobalt-organic frameworks (1-6) were solvothermally constructed with a tritopic pyridine-carboxylate linker (L-H) and its methyl- and methoxy-functionalized derivatives (L-OCH3 and L-CH3). Due to incorporated multiple substituents with various steric hindrances, the tritopic linkers adopt different molecular configurations, Y-shaped and T-shaped, which further combine octahedral or trigonal-prismatic inorganic nodes to afford diverse (3,6)-connected nets. Consequently, 1 and 2 are rtl nets and 3 and 4 are ant nets. Notably, 5 and 6 present rarely observed chiral anh (flu-3) networks with left-handed double helical chains. The structural investigation indicates that the steric tuning of linkers may essentially dictate the resulting diverse MOF structures. Furthermore, the MOFs presented here can be regarded as an ideal structural platform for a better understanding of the assembly of (3,6)-connected rtl, ant, and chiral anh nets, which are closely related to the shape and geometric configuration/conformation of tridentate organic nodes as well as inorganic building nodes.