The first example of a mono-helical complex of 2,2′: 6′,2″:6″,2‴:6‴,2â�—:6â�—,2â�—′-sexipyridine; preparation, crystal and molecular structure of bis(nitrato-O,O′)(2,2′: 6′,2″:6″,2‴:6‴,2â�—:6â�—,2â�—′-sexipyridine)europium( III ) nitrate

The hexadentate ligand 2,2′ : 6′,2″:6″,2‴:6‴,2â�—:6â�—,2â�—′-sexipyridine (spy) forms double-helical binuclear complexes with transition metals, but 1:1 complexes with lanthanides; the photoactive complex [Eu(spy)(NO3)2][NO3] is obtained from the reaction of spy with europium(III) nitrate and has been structurally characterised as a mono-helical ten-coordinate species with a helically twisted hexadentate spy ligand.