due to orbital degeneracy imposed by symmetry resulting from the equivalence of the monomers (Figures ). For the TRI-Ph molecule, the experimental singlet-triplet energy gap of 2 meV data is available and closely matches our calculation of the J value (Table ). For the systems sharing the same building units, similar ΔEspin are observed, manifesting the spin-polarization is principally defined by the elementary monomer (Table ). We also observe that the molecules bridged by -C ≡ C-have stronger magnetic coupling than those bridged by -C≡C-C≡C-, indicating the locality of magnetic interactions despite being mediated by the conjugated linkages. However, the directly-linked dimers do not necessarily have stronger J than the -C≡C-linked ones due to loss of conjugation across their twisted dimer linkages. The spin ladder of all the dimer molecules is shown in Figure .