Diverse Rotational Flexibility of Substituted Dicarboxylate Ligands in Functional Porous Coordination Polymers

The radical polymerization in the channels of porous coordination polymers (PCPs) composed of different dicarboxylate ligands has been reported as a promising approach to control the tacticity of product polymers. However, it is still elusive how the different ligands contribute to control the tacticity. Here we anticipate an important role of the rotation of the dicarboxylate ligands in the control and have investigated the geometrical structure, stability, potential energy curves, and rotational energy barriers of the rotational groups of a series of PCPs considering a model system. Both the dispersion-uncorrected and corrected density functional theory methods with the correlation consistent double-C quality basis set have been applied. We have revealed the ligand-dependent equilibrium planar and nonplanar structures and a wide range of rotational barriers, from rigid 57.74 to flexible 10.45 kJ mol(-1). By fitting the force field parameters of the dicarboxylate ligands to the obtained rotational behaviors, future molecular dynamics simulation studies with the flexible PCP models will provide molecular insights into the mechanism of the control of tacticity.