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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 μ 1,1,3-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.

Evaluation of the potential for metal–metal (M–M) cooperation to enable catalysis requires access to specific polynuclear aggregates that display appropriate geometry and size. Here we demonstrate ion metathesis within pre-formed metal–organic frameworks (MOFs) to prepare metastable Pd2 tetracarboxylates sites., Evaluation of the potential for metal–metal (M–M) cooperation to enable catalysis requires access to specific polynuclear aggregates that display appropriate geometry and size. In many cases, exerting synthetic control over the aggregation of simple metal salts is a challenge. For example, Pd(ii) acetate self assembles as a trimer (i.e. Pd3(OAc)6) both in the solid state and in solution and does not feature close Pd–Pd interactions. Related carboxylate-supported Pd2 aggregates (i.e. Pd2(OAc)4), which would feature close Pd–Pd interactions, are thermodynamically metastable in solution phase and thus largely unavailable. Here we demonstrate ion metathesis within pre-formed metal–organic frameworks (MOFs) to prepare metastable Pd2 tetracarboxylates sites. The newly synthesized materials are characterized by elemental analysis, PXRD, SCXRD, EXAFS, XANES, and gas adsorption analysis. In addition, the critical role of network solvation on the kinetics of ion metathesis was revealed by coupled TGA-MS and ICP-MS experiments. The demonstration of templated ion metathesis to generate specific metastable coordination sites that are inaccessible in solution phase chemistry represents a new opportunity to interrogate the chemistry of specific polynuclear metal aggregates.

Isomers play a crucial role in the formation of coordination architectures. Herein we report two Sr(II) coordination compounds, mononuclear [Sr(2-pytzipa)2(H2O)4] (1) and 1D [Sr(3-pytzipa)2(H2O)2]n (2) derived from two isomers, 5-(n-pyridyl)tetrazole-2-isopropionic acid (Hn-pytzipa, n = 2, 3). Furthermore, differential scanning calorimetry and thermogravimetric-differential thermogravimetric analyses were applied to evaluate the thermal decomposition behavior of such compounds. The relevant thermodynamic parameters (ΔH, ΔS, and ΔG) of the decomposition process of 1 and 2 were calculated as well.

Mononuclear [Ce(pztza)2(H2O)6](pztza)·H2O (1) (pztza = 5-(2-pyrazinyl)tetrazole-2-acetato) has been prepared and characterized by IR, elemental analysis and single-crystal X-ray diffraction. PEG-5000 (poly(ethyleneglycol-5000)) coated [Ce(pztza)2(H2O)6](pztza)·H2O nanoparticles (NPs) can disperse into distilled water. In vitro study on Hela cells shows that Hpztza is nontoxic while [Ce(pztza)2(H2O)6](pztza)·H2O NPs show high toxicity with half-maximal inhibitory concentration (IC50) of 17 μg/mL (1.93 × 10−5 M). In addition, such NPs can inhibit the migration of Hela cells effectively.

3,3-di(1H-tetrazol-5-yl)pentanedioic acid (H4dtzpda) 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 H4dtzpda with La(NO3)2·6H2O or La(NO3)3·6H2O/Cu(NO3)2·6H2O afforded a one dimensional [La(Hdtzpda)(H2O)4]·4H2O (1) and a three dimensional [La2Cu(dtzpda)2(H2O)10]·4H2O (2), respectively, where only three acidic hydrogen atoms of H4dtzpda are deprotonated in compound 1 while all the four acidic ones are deprotonated in compound 2. In compound 1, Hdtzpda3- is a penta-dentate ligand to bridge La(III) centers via only oxygen atoms of the carboxylate group while in compound 2, dtzpda4- 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-5000 (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, IC50～18 μg/mL) is superior to compound 1 (IC50～38 μg/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.

pH is sometimes fundamental to the formation of coordination compounds. Here we report two new Zn(II)-tetrazole-carboxylate coordination compounds derived from Hatzipa, namely two dimensional [Zn(atzipa)2]n (1) and [Zn(atzipa)2(H2O)(EtOH)]n (2), where Hatzipa = 5-aminotetrazole-1-isopropanoic acid. The structures of the two compounds are controlled by pH value of the reaction system. Compound 1 crystallizes in an achiral space group while 2 in a chiral space group P2(1)2(1)2. Furthermore, nanoparticles (NPs) of the two compounds can be obtained by co-precipitation with PEG-5000 (Polyethylene Glycol-5000). And [Zn(atzipa)2]n (1) NPs with a relatively low IC50 (half-maximal inhibitory concentration) on Hela cells of 23 μg/mL (6.1 μM) is superior to [Zn(atzipa)2(H2O)(EtOH)]n (2) NPs (58 μg/mL, 13.2 μM). Both NPs of the two compounds can inhibit the migration of Hela cells and compound 1NPs can be used as a cell imaging agent. The results show that pH influences the resulting structures and [Zn(atzipa)2]n (1) NPs capable of inhibiting the growth of tumor in vitro may be a potential candidate against cancer.

Three different tetrazole-carboxylate ligands, monotetrazole-carboxylate H 2 tza (H 2 tza=1,5-tetrazole-diacetic acid), Hpztza (Hpztza=5-(2-pyrazinyl)tetrazole-2(1-methyl)acetic acid), ditetrazole-carboxylate H 2 tzpha (H 2 tzpha=1,3-di(tetrazole-5-yl)benzene-N2,N2′-diacetic acid) have been chosen to react with CdCl 2 ·6H 2 O, resulting in the formation of three new compounds [Cd 2 (tza) 2 ] ( 1 ), [Cd(pztza) 2 ] ( 2 ) and [Cd(tzpha)(CH 3 OH) 2 ] ( 3 ). The coordinate sites of the three ligands are major influenced by the different substituted group of tetrazole ring. These compounds have been characterized by elemental analysis, IR and single crystal X-ray diffraction. Compound 1 displays a complex 3D structure; compound 2 shows a 3D network and compound 3 features a 2D layer network. Furthermore, the luminescence properties investigated at room temperature in the solid state showed excellent ligand-centered luminescence. The obvious enhancement in luminescence makes these compounds potential materials for optical use. The differential scanning calorimetry (DSC) and thermogravimetric-differential thermogravimetric (TG-DTG) analyses were applied to evaluate the thermal decomposition behavior of such compounds, showing that compounds 2 and 3 can be used as potential energetic materials. The relevant thermodynamic parameters ΔH, ΔS and ΔG were calculated as well.

Two novel coordination compounds, [Sr(atzp)2(H2O)2]·CH3OH (1) and [Sr(dtzpha)(H2O)3]·4H2O (2) [Hatzp=5-aminotetrazole-1-propionic acid, H2dtzpha=1,3-di(tetrazol-5-yl)benzene-N2,N2′-diacetic acid)], have been generated by using 5-aminotetrazole-1-propionic acid and 1,3-di(tetrazol-5-yl)benzene-N2,N2′-diacetic acid to react with strontium salts, respectively. X-ray diffraction analysis reveals that carboxylic groups of two ligands show the same coordination mode (the μ 1,1,3-COO coordination mode), compound 1 displays a 1D structure while compound 2 shows a 2D structure, which implies the influence of the number of the carboxylic acid groups. Luminescence properties of 1 and 2 were investigated at room temperature in the solid state.

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.

[Sm(pztza)2(H2O)6]·pztza·3H2O has been prepared by the reaction of SmCl3·6H2O and 5-(pyrazin-2-yl)tetrazole-2-acetic acid (Hpztza) under the presence of potassium hydroxide. The compound has been structurally characterized by elemental analysis, IR, and single-crystal X-ray diffraction. The X-ray analysis demonstrates this complex displays a mononuclear structure. Furthermore, it shows an excellent catalytic property for polymerization of vinyl monomers and the polymerization shows controlled characteristics. It can be isolated from the reaction system and reused at least 10 times.

Reactions of two structure-relevant ligands, Hpytz [Hpytz = 5-(4-pyridyl)tetrazole] and its 2H-tetrazole-carboxylate substituted derivative Hpytza [Hpytza = 5-(4-pyridyl)tetrazole-2-acetic acid] with Pb(NO3)2 under the presence of potassium hydroxide, afforded a new mononuclear [Pb(pytz)2(H2O)4]·3H2O (1) and a two dimensional polymer [Pb(pytza)2]n (2) with (4,4) topology, respectively. The two compounds were characterized by elemental analysis, IR and single crystal X-ray diffraction. The luminescence properties of compounds 1 and 2 investigated at room temperature in the solid state show both intraligand emission and characteristic peak of Pb2+. Differential scanning calorimetry (DSC) and thermogravimetric-differential thermogravimetric (TG-DTG) analyses were applied to assess the thermal decomposition behavior of compounds 1 and 2. The DSC test indicates that compound 2 can be taken advantage of as a potentially explosive material.

Four different tetrazole–carboxylate ligands, monotetrazole–carboxylate Hatza (Hatza = 5-aminotetrazole-1-acetic acid), Hpytza (Hpytza = 5-(4-pyridyl)tetrazole-2-acetic acid), ditetrazole–carboxylate H2datza (H2datza = N,N-di(tetrazol-5-yl)amine-N2,N2′-diacetic acid) and tristetrazole–carboxylate, H3tzpha (H3tzpha = 1,3,5-tris(tetrazol-5-yl)benzene-N2,N2′,N2′′-trisacetic acid) have been chosen to be reacted with zinc salts, resulting in the formation of four novel compounds, [Zn(atza)2(H2O)4] (1), [Zn(pytza)2] (2), [Zn(datza)(H2O)2]·3H2O (3) and [Zn3(tzpha)2(H2O)12]·MeOH·EtOH·4H2O (4), whose structures are controlled by not only the number and different coordination modes of the tetrazole–carboxylate but also the complementary hydrogen bonds. These compounds have been characterized by elemental analysis, IR and single crystal X-ray diffraction. Compound 1 displays a simple zero dimensional mononuclear structure, 2 shows a classic 3D 8-connect (36, 416, 56) tsi network topology, 3 features a 1D ladder-like chain while 4 is a 1D beaded chain. Furthermore, the luminescence properties investigated at room temperature in the solid state show excellent ligand-centered luminescence.

Reactions of Hpytza (Hpytza = 5-(2-pyridyl)tetrazole-2-acetic acid) with M(NO3)2 (M = Co(II), Mg(II), Ca(II)) with the presence of KOH under hydrothermal conditions, produced three novel coordination compounds, [M(pytza)2(H2O)2] (M = Co(1), Mg(2), Ca(3)). These compounds were structurally characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Compound 1 shows mononuclear structure while 2 and 3 reveal 1D structures via bridging pytza as linker. Furthermore, the luminescence properties of 1–3 at room temperature in the solid state were investigated and the thermal stabilities of 1-3 were discussed, as well.

4,4′-Bipyridine phosphotungtic salt has been synthesized and used as a special catalyst for vinyl polymerization. This is a fast and smooth reaction, and high molecular weight polymers with narrow polydispersity are obtained within 60 min. The compound was structurally characterized by elemental analysis, IR spectroscopy and 1 H NMR spectroscopy. The electrochemical property was determined on a CHI 660 electrochemistry workstation. The polymerization initiated by 4,4′-bipyridine phosphotungtic salt showed controlled characteristics, the catalyst can be isolated from polymer product easily and reused for at least 10 times.

Reactions of 1H-tetrazolate-5-acetic acid(H2tza) with Nd(NO3)3·6H2O or Dy(NO3)3·6H2O with the presence of KOH under solvothermal conditions, produced two new coordination compounds, [M2(tza)3(H2O)6]·2H2O [M=Nd(1), Dy(2)]. Both compounds were structurally characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Compounds 1 and 2 reveal 1D structures via bridging tza as linker. Furthermore, the compounds 1 and 2 showed a specific and good catalytic behavior for the polymerization of styrene, and the polymerization showed controlled characteristics.

Reaction of MCl2·4H2O (M=Zn, Cd, Mn, Co, Ni ) with 2-(5-(pyrazin-2-yl)-2H-tetrazol-2-yl) acetic acid (Hpztza) yielded a set of new M(II)/pztza complexes, [Cd(pztza)2(H2O)6]·3H2O·(Hpztza) (1), [M(pztza)2(H2O)2] [M=Cd(2), Zn(7), Mn(9)], [Cd(pztza)2]·2(CH3OH) (3), [Co(pztza)2(H2O)2]·6H2O (4), [Co(pztza)(H2O)Cl] (6) and [M(pztza)2(H2O)2]·2H2O [M=Co(5), Zn(8), Ni(10)]. These compounds were structurally characterized by elemental analysis, IR spectroscopy and X-ray single-crystal diffraction. Complex 1 featured a mononuclear structure, complexes 4, 5, 7, 8, 10 showed 1D chains and complexes 2, 3, 6, 9 displayed 2D layer structures. Furthermore, the luminescence properties of 1–10 were investigated at room temperature in the solid state.

Reactions of CdSO4·6H2O and Hpytz [Hpytz = 5-(4-pyridyl)tetrazole] under high pH values produced a known compound, [Cd(pytz)2(H2O)4]·2H2O (1), which can be used to prepare [Cd(Hpytz)(SO4)(H2O)2] (2) by adjusting the pH to a lower level using sulfuric acid under hydrothermal conditions. These compounds were characterized by elemental analysis, IR spectroscopy, and single-crystal diffraction. X-ray analysis reveals that 1 features a mononuclear structure, while 2 affords a 1-D polymeric chain structure. Compound 1 displays a 2-D network, while 2 shows a 3-D network by hydrogen bonding interactions. Furthermore, the luminescent properties were investigated at room temperature in the solid state.