Dedicated to Professor Jean-Claude Bünzli on the occasion of his 65th birthday Two chelate ligands for europium(III) having minocycline (¼ (4S,4aS,5aR,12aS)-4,7-bis(dimethylamino)-1,4,4a,5,5a,6,11,12a-octahydro-3,10,12,12a-tetrahydroxy-1,11-dioxonaphthacene-2-carboxamide; 5) as a VIS-light-absorbing group were synthesized as possible VIS-light-excitable stable Eu 3þ complexes for protein labeling. The 9-amino derivative 7 of minocycline was treated with H 6 TTHA (¼ triethylenetetraminehexaacetic acid ¼ 3,6,9,12-tetrakis(carboxymethyl)-3,6,9,12-tetraazatetradecanedioic acid) or (minocycline-TTHA)] (13) was confirmed by UV-absorption semi-quantitative