Gao Wen Yang

Three new manganese(II) coordination complexes based on tetrazole carboxylate ligands

AbstractReactions of three tetrazole carboxylate ligands, namely 5-(4-pyridyl)tetrazole-2-acetic acid (Hpytza), 1,3,5-tris(tetrazol-5-yl)benzene-N2,N2′,N2″-triacetic acid (H3tzpha) and 5-aminotetrazole-1-propanoic acid (Hatzpa) with Mn(NO3)2·6H2O in the presence of KOH afforded three new complexes, [Mn(pytza)2] (1), [Mn3(tzpha)2(H2O)12]·2CH3OH·10H2O (2) and [Mn(atzpa)2(H2O)2] (3), respectively. These complexes were characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Complex 1 displays a three-dimensional network while 2 and 3 show one-dimensional chains. Furthermore, the luminescence properties of these complexes were investigated at room temperature in the solid state.

Photochemical property of a Ru(II) compound based on 3-(2-pyridyl)pyrazole and 2,2′-bipyridine for ablation of cancer cells

Ru(II) compounds are potential candidates for photodynamic therapy (PDT). In the present study, a Ru(II) compound based on 3-(2-pyridyl)pyrazole (Hpypz) and 2,2′-bipyridine has been prepared and characterized. This compound can self-assemble to form nanoparticles (NPs) by nanoprecipitation in distilled water. These NPs with a mean size of 92 nm have good passive targeting by enhanced permeability and retention effect (EPR). In vitro studies on HeLa cells show that these NPs have high phototoxicity and a low IC50 (half-maximal inhibitory concentration) of only 8 μg mL−1 (12 μM), but they also have negligible dark toxicity. Moreover, such NPs can inhibit the migration of HeLa cells, indicating their potential to interfere with the transfer of tumors in vivo. Furthermore, in vivo investigations on nude mice demonstrate that such NPs can effectively inhibit the growth of the tumor. After treatment for 10 cycles, an obvious decrease in the tumor volume can be observed and in addition, the main organs (heart, liver, spleen, lung and kidney) suffer no damage, which indicates the high phototoxicity, low toxicity and excellent biocompatibility of these NPs.

Synthesis, crystal structure and luminescence of two barium(II) compounds: from mono- to bis-tetrazole carboxylic acids

Tetrazole carboxylates are acknowledged as bifunctional ligands for the construction of new coordination architectures. Two new coordination compounds, [Ba(atzpa)2(H2O)3]n·2nH2O (1) and [Ba2(dtzpda)(H2O)]n (2) have been prepared by solvothermal reactions of BaCl2·2H2O with Hatzpa or H4dtzpda, respectively (Hatzpa = 5-aminotetrazole-1-propanoic acid, H4dtzpda = 3,3-di(1H-tetrazol-5-yl)pentanedioic acid). The X-ray diffraction results reveal that compound 1 is a linear chain in which atzpa acts as a tridentate ligand to bridge adjacent Ba2+ ions in a µ1,1,3-COO mode. In contrast, compound 2 is a three-dimensional network where dtzpda4− acts as a dode-dentate ligand to bridge various Ba2+ ions. Furthermore, the luminescence of Hatzpa, H4dtzpda, compounds 1 and 2 in the solid state at room temperature were investigated.

Four new samarium(III) compounds based on different tetrazole–carboxylate ligands

Abstract Tetrazole–carboxylate ligands with both rigid tetrazole ring and flexible carboxylate group have a great potential in the construction of coordination architectures. Here, we report four new samarium(III) compounds based on four tetrazole–carboxylate ligands 5-(2-pyrimidyl)tetrazole-2-acetic acid (Hpmtza), 5-aminotetrazole-1-propanoic acid (Hatzpa), 5-(4-pyridyl)tetrazole-2-acetic acid (Hpytza), and 3,3-di(1H-tetrazol-5-yl)pentanedioic acid (H4dtzpda), namely mononuclear [Sm(pmtza)2(H2O)6]Cl·3H2O (1), binuclear [Sm2(atzpa)4(H2O)8](NO3)2·2H2O (2), one-dimensional [Sm(pytza)3(H2O)2]·2H2O (3) and [Sm(Hdtzpda)(H2O)4]·4H2O (4). The effect of different counter anion (ClO4−, Cl−, NO3−) on the formation of such compounds was also investigated. Furthermore, the luminescence of compounds 1–4 shows intraligand emission, whereas the characteristic peaks of Sm3+ may be overlapped.Graphical Abstract

Isomer directed assembly of two Ca(II) compounds based on 5-(n-pyridyl)tetrazole-2-isopropanoic acid (n = 2, 3) and action against Hela cells

Abstract Isomers sometimes play a fundamental role in the formation of coordination architectures. In this article, bifunctional 5-(n-pyridyl)tetrazole-2-isopropanoic acid (n = 2, 3) has been designed and prepared. Then, reactions of Ca(NO3)2·4H2O with isomeric 5-(n-pyridyl)tetrazole-2-isopropanoic acid (denoted as Hn-pytzipa, n = 2, 3) afforded mononuclear [Ca(2-pytzipa)2(H2O)4] (1) and one-dimensional [Ca(3-pytzipa)2(H2O)2]n (2), respectively. In 1, 2-pytzipa is a bidentate ligand which chelates one Ca(II) via the nitrogen atoms of the pyridine and tetrazole rings while in 2, 3-pytzipa bridges adjacent Ca(II) centers in a μ1,1,3-COO mode. PEG-5000 (poly(ethyleneglycol-5000)) coated [Ca(2-pytzipa)2(H2O)4] (1) and [Ca(3-pytzipa)2(H2O)2]n (2) nanoparticles (NPs) show toxicity towards Hela cells, but the ligands are non-toxic in nature and 2 is superior to 1. Furthermore, cell migration across a 2D artificial gap indicates that both NPs can inhibit the migration of Hela cells. GRAPHICAL ABSTRACT

A new Ce(III) compound based on 5-aminotetrazole-1-propanoic acid for ablation of HeLa cells

Abstract Developing new drugs for the treatment of cancer is of great significance. Coordination compounds based on tetrazole-carboxylates are the potential candidates for cancer treatment. In this article, [Ce2(atzpa)4(H2O)8](NO3)2·2H2O based on 5-aminotetrazole-1-propanoic acid (Hatzpa) and Ce(NO3)3·6H2O has been designed and prepared. Single-crystal X-ray diffraction reveals that the compound is binuclear in which atzpa acts as a bridging ligand. In order to improve the water dispersity of this compound, PEG-5000 (poly(ethyleneglycol-5000)) was coated on [Ce2(atzpa)4(H2O)8](NO3)2·2H2O to prepare the nanoparticles (NPs) in distilled water. In vitro study on HeLa cells shows that Hatzpa is nontoxic itself, while [Ce2(atzpa)4(H2O)8](NO3)2·2H2O NPs show high toxicity. Such NPs have a low half-inhibitory concentration (IC50) of 24 μg mL−1 (2.0 × 10−5 M). In addition, such NPs are able to inhibit the migration of HeLa cells even at a low concentration effectively, showing their potential to inhibit the transfer of tumors in vivo. GRAPHICAL ABSTRACT

Isomer Directed Synthesis of Two 3D Cadmium(II) Compounds: Structure Variation and Energetic Performance

Bifunctional tetrazole-carboxylates, 5-(n-pyridyl)tetrazole-2-isopropionic acid (denoted as Hn-pytzipa, n = 2, 3) have been selected to be reacted with CdCl2·2.5 H2O under solvothermal conditions, [Cd3(2-pytzipa)2(MeOH)2Cl4]n (1) and [Cd(3-pytzipa)2]n (2) were obtained. In compound 1, 2-pytzipa is a pentadentate ligand to bridge adjacent Cd(II) centers to generate a fascinating 3D dinodal 4-connected, 5-connected net with point symbol of (42·84)(43·64·73). In 2, each 3-pytzipa bridges three Cd(II) atoms in a μ1,3-COO syn-anti mode to generate a fascinating 3D one-nodal 6-connected net with point symbol of (42·52·66·75). Photoluminescence properties of compounds 1 and 2 in the solid state show enhanced ligand centered emission. Furthermore, thermogravimetric-differential (TG-DTG) and differential scanning calorimetry (DSC) were used to evaluate the thermal decomposition behavior of compounds 1 and 2, showing that the decomposition process of compound 2 is much more intense than that of compound 1. The thermal parameters (∆S, ∆H and ∆G) of the decomposition of compound 2 were calculated, as well.