Counter anion and pH directed assembly of europium(III) compounds based on tetrazole containing carboxylic acids

•Htzpya, Hatzpa and Hpytza and their Eu3+ compounds were prepared.•The structures are controlled by the counter anion or pH value.•These compounds show both intraligand luminescence and characteristic peaks of Eu3+.

Counter anion and pH play important roles in the self-assembly process of coordination compounds. Tetrazole carboxylate ligands are outstanding candidates for construction of coordination architectures. Four new compounds based on Htzpya, Hatzpa, Hpytza and europium(III) salts, namely mononuclear [Eu(tzpya)2(H2O)5]Cl·4H2O (1), binuclear [Eu2(atzpa)4(H2O)8](NO3)2·2H2O (2), one dimensional [Eu(pytza)3(H2O)2]n·2nH2O (3) and [Eu(pytza)2(H2O)4]nCln (4) were obtained, where Htzpya = 3-(5-tetrazolyl)pyridine-1-acetic acid, Hatzpa = 5-aminotetrazole-1-propanoic acid and Hpytza = 5-(4-pyridyl) tetrazole-2-acetic acid. Different europium(III) salts EuX3·6H2O (X = Cl−, NO3−) and pH values were selected to investigate the influence of both the counter anions and the pH on the formation of such compounds. Furthermore, the luminescence properties of 1–4 in the solid state were also investigated at room temperature, showing both intraligand emission and characteristic peaks of Eu3+ for compounds 1–4.

Graphical abstractHtzpya, Hatzpa, Hpytza were selected to be reacted with different Eu3+ salts under different pH, and four new compounds were obtained. Counter anion and pH are important in the self assembly of such compounds. The luminescence shows both intraligand and characteristic peaks of Eu3+.Figure optionsDownload full-size imageDownload as PowerPoint slide