We investigate the electronic and magnetic properties of the proposed one-dimensional TMn(benzimidazole)(n+1) (TM = Sc, Ti, V, Cr, Mn) systems by means of density functional theory. We find that the rigid benzimidazole (Bzim) scaffold can stabilize the Ti, V, and Cr transition metal (TM) atoms, while still retaining the helical and one-dimensional characteristics of DNA. The strong coupling between the TM d-orbitals and the HOMO, HOMO-1, and LUMO orbitals of Bzim are found to govern the electronic and magnetic properties of these systems. Under the application of an external electric field, a robust half-metallic behavior is predicted for the V-8(Bzim)(9) system, which is traced back to the pinning of certain orbitals in the presence of an external field. The ease of attaching a thiol linker to the 5' and 3' ends of the DNA strands and formation of stable self-assembled monolayers (SAM) of DNA on metal substrates make these TMn(Bzim)(n+1) DNA constructs promising materials for advanced spintronics applications.