Regulation of deprotonation of 3,3-di(1H-tetrazol-5-yl)pentanedioic acid: Solvothermal synthesis of La(III) and heterometallic La(III)/Cu(II) compounds for ablation of A549 cells

3,3-di(1H-tetrazol-5-yl)pentanedioic acid (H(4)dtzpda) can display tunable valence when reacted with different metal ions because it has four acidic hydrogen atoms of both tetrazole rings and carboxylate groups. Solvothermal reactions of H(4)dtzpda with La(NO3)(2)center dot 6H(2)O or La(NO3)(3)center dot 6H(2)O/Cu(NO3)(2)center dot 6H(2)O afforded a one dimensional [La(Hdtzpda)(H2O)(4)]4H(2)O (1) and a three dimensional [La2Cu(dtzpda)(2)(H2O)(10)]center dot 4H(2)O (2), respectively, where only three acidic hydrogen atoms of H(4)dtzpda are deprotonated in compound 1 while all the four acidic ones are deprotonated in compound 2. In compound 1, Hdtzpda(3-) is a penta-dentate ligand to bridge La(III) centers via only oxygen atoms of the carboxylate group while in compound 2, dtzpda(4-) is a hepta-dentate one via not only the oxygen atoms of the carboxylate group but also the nitrogen atoms of the tetrazole rings. PEG-soon (poly(ethyleneglycol(-5000))) coated compound 1 or 2 nanoparticles (NPs) have good dispersity in water. Cytotoxicity study on A549 cells (human caucasian lung carcinoma) shows that compound 2 (half-maximal inhibitory concentration, IC50 similar to 18 mu g/mL) is superior to compound 1 (IC50 38 mu g/mL). Furthermore, both NPs of the two compounds are able to inhibit the migration of A549 cells, indicating their potential to inhibit the transfer of tumors in vivo.