To further understand the electronic structure governing the contrasting β values in CSS and OSS state, the spatial distribution of frontier HOMO and LUMO orbitals and their energy gaps is shown in insets of As discussed above, in CSS state the HOMO-LUMO gap approaches towards gap closure with the increasing length, while in OSS state, the gap is an exchange gap between the spinsplit orbitals which is not strongly length dependent and saturates to a finite value. The decrease in delocalized nature of spin-split orbitals integrated with an increase of HOMO-LUMO gap in OSS state inhibits the efficient contact coupling in junction. This results in an emphatic decrease in conductance with the increasing diradical character along the series.