A study of binding interactions between terpyridine derivatives and cucurbituril
The binding interactions of a series of 2,2′:6′,2″-terpyridine (TPY) derivatives and their metal complexes with cucurbituril (CB) were investigated by 1H NMR, UV/Vis, emission spectroscopy, and ESI mass spectrometry. 1H NMR titrations revealed CB could encapsulate methylated TPY (MTPY), and the binding ratio between guest MTPY and host was 1:1 and 2:1 via ESI-MS characterization. For the transition metal complexes composed of Fe(II) or Ru(II) or Rh(III) and TPY derivatives, the octahedral TPY−metal−TPY core can be included in the cavity of CB. Three binding modes (1:1, 1:2 and 1:3) have been detected for the binding of the metal−MPTY complexes with CB by ESI-MS.