Synthesis, characterisation of a complex of Cu(II) with a multidentate macrocyclic ligand and its interactions with anions

Abstract A macrocyclic ligand possessing a donor set of {N 3 S 2 } synthesised via Cs + -templation, 4-(pyridin-2-ylmethyl)-1,7-dithia-4,10-diazacyclododecane ( L ) and its Cu(II) complex, [Cu L (NCMe)] 2+ ( 6 ), are described. This Cu(II) complex interacts with a range of anions, F − , Cl − , Br − , I − , HCOO − , AcO − , CO 3 2− , NO 3 − , C 2 O 4 2− , H 2 PO 4 − , SCN − , CN − , BF 4 − . Of the investigated anions, I − , SCN − , and CN − , show strong interaction with the Cu(II) centre as indicated by their spectral variations. The iodide particularly demonstrates distinct change in colour. This change originates from a newly appeared band at 471 nm upon iodide binding, which arises from the ligand (I − ) to Cu(II) charge transfer (LMCT) in the iodide-substituted Cu(II) complex, [Cu L I] + ( 7 ). All organic compounds are characterised by NMR spectroscopy and/or microanalysis. The identities of the two Cu(II) complexes are confirmed by using microanalysis and the complex 6 is crystallographically analysed.