“Chiral Polythiophenes: a promising material for the study of the Chiral Induced Spin Selectivity”

The synthesis of both the enantiomers of a cysteine substituted thiophene monomer is reported (1). Once polymerized these molecules gave access to self assembling polythiophenes able to organize itself in chiral superstructures, controlled by the sign of the cysteine chiral center. These polymers show an interesting behavior due to the inter-chains hydrogen bonding interactions, that causes the formation of helical architectures in the solid state. The two polymers have been characterized both in solution and in the solid state. These chiral polymers have been used as spin filters to investigate the existence of the Chiral Induced Spin Selectivity effect (2) in the microscale dimension. Micro- and nano-scale multilayered devices based on these chiral polythiophenes were prepared using different techniques, and characterized with electrical measurements under applied magnetic field. The alignment of the polymer chains in relation to the substrate surface has been deepened (3), since the orientation of the helical aggregates in the film influences the magnitude of the spin filtering effect. Studies of the effect of a strong applied electric field on the alignment of the polymer both in static and dynamic experiments were carried out, and the obtained films were characterized with various surface analysis techniques. (1) Mucci, A.; Parenti, F.; Schenetti, L. Macromolecular Rapid Communications. 2003, 24, 9, 547–550. (2) Göhler, B.; V. Hamelbeck; T. Z. Markus; M. Kettner; G. F. Hanne; Z. Vager; R. Naaman; H. Zacharias. Science. 2011, 331, 6019, 894–897. (3) Sugita, A.; Tasaka, S. Journal of Polymer Science Part B: Polymer Physics. 2004, 42, 24, 4433–4439