  In this report we give a brief introduction on the occurrence of
topologically protected one-dimensional electronic states in group IV
two-dimensional graphene-like materials. We discuss the effect of spin-orbit
coupling on the electronic band structure and show that these materials are
potential candidates to exhibit the quantum spin Hall effect. The quantum spin
Hall effect is characterized by a gapped interior and metallic
counter-propagating spin-polarized topologically protected edges states. We
also elaborate on the electric-field induced formation of a hexagonal network
of one-dimensional topologically protected electronic states in small-angle
twisted bilayer graphene.
