Structures of S-(pyridin-2-yl) 4-nitro-benzo-thio-ate, S-(pyridin-2-yl) 4-methyl-benzo-thio-ate and S-(pyridin-2-yl) 4-meth-oxy-benzo-thio-ate: building blocks for low-symmetry multifunctional tetra-pyrroles. - Sample HC; Twamley B; Senge MO (Acta crystallographica. Section E, Crystallographic communications, 2023)