Chalcogenated (S)-(−)-nicotine derivatives as chiral linkers for 1D coordination polymers

Reactions of zinc(II) chloride with (S)-(−)-nicotine (Nic), cotinine, thionicotine and selenonicotine in 1:1 molar ratio yielded new metal complexes, which were characterized by elemental analysis, infrared, 13C and 1H NMR spectral methods. Single crystal X-ray diffraction studies of ZnCl2 complexes with thionicotine and selenonicotine revealed that the two complexes form isostructural crystals build of 1D coordination polymers (CP) and that coordination to metal centers alters the conformation of the parent organic ligand from syn to anti. Quantum chemical calculations indicate that in the isolated state the anti conformation of the uncoordinated chalcogen nicotine lactams is slightly more preferred energetically and it does not undergo substantial changes upon coordination to the metal center. The preference for the syn conformation in crystals of thio- and selenolactams of nicotine might be ascribed to their involvement in columnar stacking interactions, which do not operate in the isolated state and are also absent in crystals of their adducts with ZnCl2. This study has provided useful information regarding functionalization of (S)-(−)-nicotine molecule as a mixed-donor-atom ligand to enforce formation of 1D coordination polymers.

Bidentate bridging properties of (S)-(−)nicotine lactam, thiolactam and selenolactam ligands have been probed by complexation with ZnCl2.Figure optionsDownload as PowerPoint slide