Crystal chirality – cobalt complexes with thiazole based ligands

Abstract

Chirality is a striking property of the biological world. Many organic molecules, including the most biological amino acids are chiral and the DNA double helix in its standard form twists like a right-handed screw. The importance of chirality in biological systems was brought to light by the thalidomide tragedy [1]. On the other hand, there are many non-biological chiral crystals which have not been treated in terms of chirality, which include important enantioselective catalysts and sensing materials, as well as enenatioselective chromatographic materials. In dealing with chirality in relation to crystal structures it is essential to distinguish between three different objects that may be either chiral or achiral: 1) the molecular components of the crystal, 2) the crystal structure itself and 3) the symmetry group of the crystal structure. Chirality of crystals will be discussed taking cobalt complexes with thiazole based ligands as examples.

Hiralnost je izraženo svojstvo biološkog sveta. Mnogi organski molekuli su hiralni, uključujući većinu bioloških aminokiselina. Takođe, dvostruki heliks DNK u svom kanonskom obliku ima formu desnog zavrtnja. Međutim, značaj hiralnosti sagledan je tek nakon tragedije sa talidomidom [1]. S druge strane, postoje mnogi nebiološki hiralni kristali kojima nije razmatrana hiralnost, a oni uključuju važne enantioselektivne katalizatore i senzorske materijale, kao i enantioselektivne hromatografke materijale. Kada se radi o hiralnosti u kristalnim strukturama, važno je razlikovati tri različite grupe objekata koji mogu biti ili hiralni ili ahiralni: 1) molekulske komponente kristala, 2) same kristalne strukture, 3) simetrijske grupe kristalnih struktura. Hiralnost kristala će biti razmatrana na primerima kompleksa kobalta sa tiazolskim ligandima.