Two sensitizers of Tb(III) constructed from alkaline earth metals and semi-rigid tripodal ligand

• Three alkaline earth compounds with different structures were synthesized.
• The luminescent spectra of compounds 1–3 exhibit different degree of redshift.
• Compounds 2 and 3 can sensitize Tb(III) ion to exhibit its characteristic emission.

Three alkaline earth (AE) coordination polymers, namely, [Mg(H2BCPBA)2(H2O)4]n (1), [Sr(HBCPBA)(H2O)2]n (2), [Ba(H2BCPBA)2]n (3), (H3BCPBA = 3,5-bi(4-carboxy-phenolxy)-ben-zoic acid) have been synthesized in mixed solvents under hydrothermal conditions. The single crystal analysis show 1 is mononuclear compound, which forms 3D supramolecular framework through H-bonding and π–π interaction. In compound 2, dinuclear Sr(II) subunits were connected by the tripod linkers to afford the 3D metal–organic framework. Compound 3 displays 3D structure and each Ba(II) center in the framework acts as a 4,8-connected binode to give a unique network with a Schläfli symbol of {44.62}2{48.618.82}. The solid-state luminescent spectra of complexes 1–3 reveals that all of them have different degree of redshift compared with free ligand. The experiments of sensitization to Eu(III) and Tb(III) are performed on these three compounds. The results show that 2 and 3 can sensitize Tb(III) ion to exhibit its characteristic green emission.

Three alkaline earth compounds with different structures were designed and synthesized through hydrothermal synthesis method. Their fluorescence emission spectra have some redshift compared with free ligand. Compounds 2 and 3 can be Tb3+ sensitizers.Figure optionsDownload as PowerPoint slide