Syntheses, electrolytic behaviour and antifungal activities of Zn(II) complexes of isomers of 3,10-C-meso-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane (L). Crystal and molecular structure of [ZnLB(NO3)]NO3 (LB = a,e,a,e-L)

The isomeric cyclam ligands Me8[14]anes, designated by LA, LB and LC, produce, on reaction with zinc(II)nitrate, zinc(II)sulphate or zinc(II)chloride corresponding complexes, i.e. dinitrato/mononitrato-nitrate complexes [ZnL(NO3)2]/[ZnL(NO3)](NO3) (L = LA, LB or LC, where the indices A, B and C refer to differing orientations of the four methyl groups on secondary carbons of Me8[14]ane), the diaqua-sulphates [ZnL(H2O)2]SO4 (L = LA, LB or LC), and the diaqua dichloride and dichlorido complexes [ZnL(H2O)2]Cl2 (L = LA or LC) or [ZnLBCl2], respectively. The complexes have been characterised on the basis of elemental analyses, IR, UV–Vis, 1H and 13C NMR spectroscopies, magnetic and conductance data. The structure of [ZnLB(NO3)](NO3) has been determined by X-ray crystallography. The zinc centre is coordinated to a N4O donor set in a square-pyramidal geometry. The complexes show differing electrolytic behaviour in different solvents. In chloroform, the complexes are non-electrolytes, indicating that both anions are coordinated to Zn2+. Antifungal activity of the ligands and complexes against the phytopathogenic fungi Alternaria alternata and Colletotrichum corcolei have been investigated, and positive results were noted.

A series of zinc(II) compounds of three isomers of an octamethyl substituted tetraaza-macrocyclic ligand were thoroughly characterised. Some of them exhibited different electrolytic behaviour in different solvents. Some examples demonstrated significant antifungal activity.Figure optionsDownload as PowerPoint slideHighlights
► The cyclam ligands Me8[14]ane (LA, LB and LC) undergo complexation with Zn2+.
► The structure of [ZnLB(NO3)]NO3 has been confirmed by X-ray crystallography.
► Some complexes show differing electrolytic behaviour in different solvents.
► Studies on the activity against phytopathogenic fungi exhibit positive results.