Dinuclear terbium(III) complexes based on substituted aliphatic and aromatic acids derivatives: Synthesis and photophysical studies

The formation of 3-((9R,10S,11R,15S)-12,14-dioxo-9,10-dihydro-9,10-[3,4]epipyrroloanthracen-13-yl)propanoic acid (HL1) and 3-((9R,10S,11R,15S)-12,14-dioxo-9,10-dihydro-9,10-[3,4]epipyrroloanthracen-13-yl)benzoic acid (HL2) were achieved from the reaction between Diels-Alder adduct of anthracene and maleic anhydride with β-alanine and 3-aminobenzoic acid, respectively. Leaving HL1 and HL2 with terbium(III) nitrate in a mixture of water:acetone resulted the formation of pale yellow precipitate. Subsequent recrystallization of these crude products in dimethyl sulfoxide resulted the formation of pale yellow crystals, determined to be [Tb2(μ-L1)2(L1)4(H2O)3((CH3)2SO)3]‧(CH3)2SO‧8H2O (1) and [Tb2(μ-L2)2(L2)4(H2O)2((CH3)2SO)2]‧2H2O (2), respectively, from single crystal X-ray diffraction data. In both dinuclear complexes, all terbium(III) ions display a square antiprism geometry with [TbO8] core. Both complexes present a characteristic terbium green emission once irradiated with UV-light corresponding to the 5D4→7F5 transition.