Flexible metal-organic frameworks (MOFs) are considered as fascinating materials due to their unique characteristics which have dynamic pore system and reversible structural transition upon external stimuli. The flexibility originated from breathing, swelling, linker rotation, and subnetwork displacement are useful to gas storage, separation, and sensing applications because it is led by selective adsorption of specific molecules via host-guest interaction. Thus, rational design of flexible MOFs is very intriguing research to bring selectivity and specificity to MOFs. In this works, five kinds of flexible MOFs, denoted flexMOF(CH3), flexMOF(CH2),
flexMOF(CN)-I, flexMOF(CN)-II, and flexMOF(OH), are successfully synthesized by using macrocycle containing different types of dangling functional groups and H4BPTC ligand including many rotational sites. Those flexible MOFs show different sorption behaviors, gate-opening and breathing phenomenon triggered by CO2 molecules depending on the functional groups. To elucidate those different flexible behaviors, we analyzed the single-crystal diffraction (SCD) data and calculated the rotational energies and interaction sites with regard to functional groups through computational simulations.