Prompted by the small increase in conductance observed for BC connection mode on moving from mono-to di-and tri-radicals, we calculated the current-voltage (I -V ) characteristics. Figure shows calculated total current (spin up + spin down) versus the bias voltage upto ±1.5 V for mono-, di-and tri-radicals in BC and BD connection modes. In general, increasing a bias voltage makes the energy window in which the transmission peak contributes to the current wider, thereby changing the available density of states nearby and tri-radicals in junction in both forward and reverse bias regions. This is analogous to negligible difference observed in transmission spectra as shown in Figure .