The equilibrium geometries and electronic properties of all 2D layered structures were investigated through dispersion-corrected unrestricted hybrid Density Functional Theory. The exchange-correlation functional was defined through the Heyd-Scuseria-Ernzerhof 2006 (HSE06) hybrid functional. Weak, long-range interactions (vdW and London dispersion forces) were taken into consideration through Grimme's third-order dispersion correction (-D3). All 2D COFs have P6m2 hexagonal symmetry, which was constrained throughout the optimization of atomic positions and lattice parameters. All structures were fully optimized in atomic positions and lattice parameters. Calculations were performed using the CRYSTAL17 code, which uses atom-centered Gaussian basis sets to describe atomic orbitals, allowing an efficient implementation of Post-Hartree-Fock methods (such as hybrid DFT). To avoid self-interactions due to periodic boundary conditions in the slabs, we have considered a vacuum space of 500 Å, resulting in essentially no periodicity in the z-direction. This is possible due to the use of localized Gaussian Type Orbitals (GTOs). GTOs present an advantage over plane wave basis sets, as the latter become significantly more resource-intensive with the addition of vacuum space. Triple-zeta valence with polarization (TZVP) quality basis sets were used for all atoms in the 2D COF calculations. The threshold used to evaluate the self consistent field (SCF) energy convergence, root mean squared (RMS) forces, maximum forces, RMS atomic displacements, maximum atomic displacments, and between-geometry convergence energies were set to 2.72 × 10 -6 eV, 1.54 × 10 -2 eV/Å, 2.31 × 10 -2 eV/Å, 6.35 × 10 -4 Å, 9.53×10 -4 Å, and 2.72×10 -6 eV. Vibrational modes are highly sensitive to structural parameters so we set stricter convergence criteria for frequency calculations. The stricter thresholds for SCF energy convergence, RMS forces, maximum forces, RMS atomic displacements, maximum atomic displacments, and between-geometry convergence energies were set to 2.72 × 10 -10 eV, 1.54 × 10 -3 eV/Å, 2.31 × 10 -3 eV/Å, 6.35 × 10 -5 Å, 9.53 × 10 -5 Å, and 2.72 × 10 -10 eV. Unrestricted wave functions were considered due to the partially filled 3d orbital electrons of the TM atoms intercalated in the structures. Electronic spin states were allowed to relax in the unrestricted wave function calculations after a set amount of SCF steps, described in Section 2.2.