Cationic assembly of metal complex aggregates: structural diversity, solution stability, and magnetic properties

Real-time and visual sensing devices based on pH-control assembled lanthanide-barium nano-cluster

Real-time and visual monitoring of pollutants in the air is of great importance since they are usually cannot be seen, smelled, or touched. Lanthanide nano-cluster is a kind of luminescent sensor for various species. However, controlling synthesis of lanthanide nano-cluster remains experimentally challenging. In this work, four series of lanthanide-barium (Ln-Ba) nano-clusters of Dy₂Ba (1), Tb₂Ba₂ (2), Ln₄Ba₃ (Ln = Tb, 3a; Eu, 3b), Tb₄Ba₄ (4) were assembled through precisely controlling the pH of the reactant solutions. The work features the first example that the number of cluster's nuclei changes regularly with the pH. Moreover, investigation reveals that nano-cluster 3a is a highly selective and sensitive sensor towards acetylacetone (acac) and aniline. Interestingly, easy-to-use sensing devices of test paper, agarose gel, and five kinds of film on CaCO₃, polyfoam, coin, mask, and wall that based on 3a were fabricated by facile methods. The seven sensing devices showed remarkable ability to sense aniline and acac vapors with visibility to the naked eyes. This is the first work on multiple real-time and visual sensing devices based on the lanthanide nano-cluster.

The first three-dimensional Fe(III)-Sr(II) heterometallic coordination polymer: poly[[diaquatetrakis(μ3-pyridine-2,3-dicarboxylato)diiron(III)strontium(II)] dihydrate]

The title compound, poly[[diaqua-1κ(2)O-tetrakis(μ3-pyridine-2,3-dicarboxylato)-2:1:2'κ(10)N,O(2):O(2'),O(3):O(3');2:1:2'κ(8)O(3):O(3'):N,O(2)-diiron(III)strontium(II)] dihydrate], {[Fe2Sr(C7H3O4)4(H2O)2]·2H2O}n, which has triclinic (P-1) symmetry, was prepared by the reaction of pyridine-2,3-dicarboxylic acid, SrCl2·6H2O and Fe(OAc)2(OH) (OAc is acetate) in the presence of imidazole in water at 363 K. In the crystal structure, the pyridine-2,3-dicarboxylate (pydc(2-)) ligand exhibits μ3-η(1),η(1):η(1):η(1) and μ3-η(1),η(1):η(1),η(1):η(1) coordination modes, bridging two Fe(III) cations and one Sr(II) cation. The Sr(II) cation, which is located on an inversion centre, is eight-coordinated by six O atoms of four pydc(2-) ligands and two water molecules. The coordination geometry of the Sr(II) cation can be best described as distorted dodecahedral. The Fe(III) cation is six-coordinated by O and N atoms of four pydc(2-) ligands in a slightly distorted octahedral geometry. Each Fe(III) cation bridges two neighbouring Fe(III) cations to form a one-dimensional [Fe2(pydc)4]n chain. The chains are connected by Sr(II) cations to form a three-dimensional framework. The topology type of this framework is tfj. The structure displays O-H...O and C-H...O hydrogen bonding.

Seven novel Sr(II)-Sm(III) and Sr(II)-Dy(III) coordination polymers: construction of five classes of structural topologies using different amounts of imidazole

The employment of pyridine-2,6-dicarboxylic acid (H2pda) and imidazole (im) in the synthesis of Sr(II)-Sm(III) and Sr(II)-Dy(III) coordination polymers has been reported. Seven novel heterometallic coordination polymers of compositions, [Dy3Sr3(pda)7(Hpda)(H2O)9]·6H2O (1), [LnSr(pda)3(H2O)5]·Him·H2O (Ln = Sm(2), Dy(3)), [Ln2Sr(pda)6(H2O)5]·4Him·C2H5OH·nH2O (Ln = Sm(4), n = 4; Dy(5), n = 5), [Sm2Sr2(pda)5(H2O)9]·2H2O (6) and [DySr(pda)3(H2O)4]·Him·3H2O (7), have been prepared and characterized. Complexes 1, 2-3, and 6 display three varieties of 2-D structures. 4-5 and 7 exhibit two types of 1-D chain structures. The structures of the complexes could be controlled via choosing appropriate starting materials and tuning the amount of imidazole. The photo-luminescent properties of these complexes have been investigated. The results show the exclusive luminescence emission bands being characteristic of Sm(III) and Dy(III).

New tetradentate Schiff bases of 2,2-dimethyl-1,3-diaminopropane and acetylacetone derivatives and their vanadyl complexes

A series of new VO(IV) complexes with two new tetradentate Schiff base of 4,4'-(2,2-dimethylpropane-1,3-diyl)-bis(azan-1-yl-1-yldene)dipent-2-en-2-ol) [H(2)L(1)] and 3,3'-(2,2-dimethylpropane-1,3-diyl)azan-1-yl-1-ylidene)-bis(1-phenylbut-1-en-1-ol) [H(2)L(2)] (which have been derived from 2,2-dimethyl-1,3-diaminopropan, and diketones of acetylacetone and benzoylacetone) were synthesized and characterized by (1)H NMR, (13)C NMR, FT-IR, mass and UV-Vis spectrophotometry. The electrochemical properties of the vanadyl complexes were investigated by means of cyclic voltammetry. The oxidation potentials are increased by increasing the electron-withdrawing properties of functional groups of the Schiff base ligands according to the trend of Me<Ph. The thermogravimetry (TG) and differential thermoanalysis (DTA) of the VO(IV) complexes were carried out in the range of 20-700°C. The complexes were decomposed in two stages. Also, decomposition of the synthesized complexes is related to the Schiff base characteristics. The thermal decomposition of the studied reactions was first order. The kinetic parameters for the decomposition steps in vanadyl complexes thermograms have been calculated.

Metallation of tetradentate N2O2 Schiff base with Mn(II), Co(II), Cu(II) and Zn(II): synthesis, characterization and formation constants measurement

Four Schiff base ligands, salabza-H2 = N,N′-bis(salicylidene)-2-aminobenzylamine, were synthesized by condensation of one mole of 2-aminobenzylamine and two moles of salicylaldehyde and/or two moles of substituted salicylaldehyde (5-OMe, 5-Br, 5-NO2). All the four Schiff bases and their Mn(II), Co(II), Cu(II) and Zn(II) complexes are characterized by UV-Vis, FT-IR, 1H NMR spectroscopy, mass spectrometry and elemental analysis. The formation constants and the Gibbs free energies were measured spectrophotometrically for 1:1 complexes in methanol in constant ionic strength (I = 0.1 mol dm−3 NaClO4) and at 25°C. The data refinement was carried out with the SQUAD program. The trend of formation constants of H2L1 with M(II) follows the order: Mn(II) (3.97) Also, the trend of formation constants of ligand toward a given metal (for example Mn) is as follows: H2L1 (p-OMe) (3.97) &gt; H2L2 (p-H) (3.65) &gt; H2L3 (p-Br) (3.37) &gt; H2L4 (p-NO2) (3.04)

Lithium, Titanium, and Zirconium Complexes with Novel Amidinate Scorpionate Ligands

The reaction of bis(3,5-dimethylpyrazol-1-yl)methane (bdmpzm) with BunLi and carbodiimide derivatives, namely, N,N'-diisopropyl, dicyclohexyl, and 1-tert-butyl-3-ethyl carbodiimides, enables the preparation of new heteroscorpionate ligands in the form of the lithium derivatives [Li(NNN)(THF)] (NNN = pbpamd (1) (pbpamd = N,N'-diisopropylbis(3,5-dimethylpyrazol-1-yl)acetamidinate); cbpamd (2) (cbpamd = N,N'-dicyclohexylbis(3,5-dimethylpyrazol-1-yl)acetamidinate); and tbpamd (3) (tbpamd = N-ethyl-N'-tert-butylbis(3,5-dimethylpyrazol-1-yl)acetamidinate)), although a similar process with N,N'-dimethylcarbodiimide gave the dinuclear complex [Li(bpzii)(THF)]2 (4) (bpzii = N-(dimethylamino)-N'-[(dimethylamino)bis(3,5-dimethylpyrazol-1-yl)methylimino]imino). When this last reaction was carried out in an air atmosphere, the cluster complex [Li8(mu4-O)2(mu4-OH)2(mu4-pz)2(kappa2-bpziLi)2(bpzCN)2(THF)4] (5) (bpziLi = dimethylaminobis(3,5-dimethylpyrazol-1-yl)methyliminolithium, bpzCN = bis(3,5-dimethylpyrazol-1-yl)acetonitrile) was isolated and characterized by X-ray analysis. Finally, when the same process was carried out in the presence of water the amidine-scorpionate (bpzan) (6) (bpzan = N,N-dimethylbis(3,5-dimethylpyrazol-1-yl)acetamidine) was obtained. Compounds 1 and 3 reacted with [TiCl4(THF)2] or [ZrCl4] to give complexes of stoichiometry [MCl3((kappa3-NNN))] (M = Ti, Zr) (7-10). The structures of the different compounds were determined by spectroscopic methods and, in addition, the X-ray crystal structures of 1, 3, 4, 5, and 6 were also established.

A one-pot synthesis of a paramagnetic high-nuclearity nickel(ii) cluster: an octadecanuclear NiII16NaI2metal aggregate

An unusual Ni(II)(16)Na(I)(2) cluster which features formate as a bridging clamp between two octanuclear nickel cages is reported; preliminary magnetic studies exhibit paramagnetic low-lying states resulting from dominating antiferromagnetic interactions between the nickel(II) centers.