Structures of <i>S</i>-(pyridin-2-yl) 4-nitrobenzothioate, <i>S</i>-(pyridin-2-yl) 4-methylbenzothioate and <i>S</i>-(pyridin-2-yl) 4-methoxybenzothioate: building blocks for low-symmetry multifunctional tetrapyrroles
Acta crystallographica. Section E, Crystallographic communications