Hai-Tao Xia

Synthesis, crystal structure, and luminescence properties of [TbGd(NAA)6(phen)2] and [Tb2(NNA)6(phen)2] · 2C3H7NO

Lanthanide(III) heteronuclear and binuclear complexes [TbGd(NAA)6(phen)2] (1) and [Tb2(NAA)6(phen)2] · 2C3H7NO (2) (NAA = 1-naphthylacetic acid, phen = 1,10-phenanthroline) were prepared and their crystal structures were determined. In 1 and 2, each lanthanide is nine-coordinate by two bidentate-bridging and two tridentate chelating-bridging carboxylate groups, one bidentate chelating carboxylate and one phen molecule in a distorted monocapped square antiprism. The solid-state luminescence behavior and the antibacterial activities were studied. Complexes 1 and 2 exhibited characteristic emission of Tb(III) ion 5D4 → 7FJ (J = 6–0) under UV radiation at room temperature. A main excitation peak (359 nm) of 2 appears under red emission of 615 nm. By contrast, all emission peak intensities of 1 were enhanced by addition of gadolinium(III), and the 545 nm band is much stronger than the 615 nm band, attributed to, under perturbation of the ligand field, the probability of 5D4 → 7F3 transition of Tb(III) was greatly enhanced in 2. Because of perturbation of the ligand field by addition of gadolinium(III), the probability of 5D4 → 7F5 transition of Tb(III) was greatly enhanced in 1 and green fluorescence was observed. The antibacterial activity showed that the two complexes were active against Escherichia coli, Staphylococcus aureus and Bacillus subtilis.

Crystal structure and interaction with bovine serum albumin of the Cu(I/II) complex [C20H32Cu2I3N4] n

[C20H32Cu2I3N4] n was synthesized and characterized by elemental analysis, ESI-MS spectrometry, and IR spectra. The crystal structure was determined by X-ray single-crystal diffraction. The binding of the complex with bovine serum albumin (BSA) was studied by fluorescence spectroscopy under simulated physiological conditions. The binding constant (K b), the number of binding sites (n), and the corresponding thermodynamic parameters ΔH, ΔS, ΔG were calculated based on the van’t Hoff equation. The complex had strong ability to quench the fluorescence from BSA, and the quenching mechanism of this complex to BSA was static quenching. Hydrogen bonds and van der Waals forces are the interactions between the Cu(I/II) complex and BSA. According to the Förster non-radiation energy transfer theory, the binding average distance between the donor (BSA) and the acceptor (Cu(I/II) complex) was obtained. The effect of the complex on the BSA conformation was also studied by using synchronous fluorescence spectroscopy.

Di-μ-chlorido-bis­[chlorido(N,N′-dibenzyl­propane-1,2-diamine-κ2N,N′)copper(II)]

In the title complex, [Cu2Cl4(C17H22N2)2], the CuII cation is coordinated by a N,N′-dibenzylpropane-1,2-diamine ligand and two Cl− anions, and a Cl− anion from an adjacent molecule further bridges to the CuII cation in the apical position, with a longer Cu—Cl distance of 2.9858 (18) Å, forming a centrosymmetric dimeric complex in which each CuII cation is in a distorted square-pyramidal geometry. Intramolecular N—H⋯Cl hydrogen bonding is observed in the dimeric complex.

4‐Bromo‐N‐(3,4‐methylenedioxybenzyl)aniline

In the title compound, C14H12BrNO2, the molecules are linked by one C—H...Br hydrogen bond, so forming a C(13) chain running parallel to the [010] direction, and these chains are linked by further C—H...π and C—H...Br hydrogen bonds, resulting in a three-dimensional network structure.

The dinuclear copper(II) complexes di-μ-chlorido-bis{[N,N′-bis(4-chlorobenzyl)propane-1,2-diamine]chloridocopper(II)} and di-μ-chlorido-bis{[N,N′-bis(3,4-methylenedioxybenzyl)propane-1,2-diamine]chloridocopper(II)}

The two title dinuclear copper(II) complexes, [Cu2Cl4(C17H20Cl2N2)2], (I), and [Cu2Cl4(C19H22N2O4)2], (II), have similar coordination environments. In each complex, the asymmetric unit consists of one half-molecule and the two copper centres are bridged by a pair of Cl atoms, resulting in complexes with centrosymmetric structures containing Cu(mu-Cl)2Cu parallelogram cores; the Cu...Cu separations and Cu-Cl-Cu angles are 3.4285 (8) A and 83.36 (3) degrees, respectively, for (I), and 3.565 (2) A and 84.39 (7) degrees for (II). Each Cu atom is five-coordinated and the coordination geometry around the Cu atom is best described as a distorted square-pyramid with a tau value of 0.155 (3) for (I) and 0.092 (7) for (II). The apical Cu-Cl bond length is 2.852 (1) A for (I) and 2.971 (2) A for (II). The basal Cu-Cl and Cu-N average bonds lengths are 2.2673 (9) and 2.030 (2) A, respectively, for (I), and 2.280 (2) and 2.038 (6) A for (II). The molecules of (I) are linked by one C-H...Cl hydrogen bond into a complex [10 1] sheet. The molecules of (II) are linked by one C-H...Cl and one N-H...O hydrogen bond into a complex [100] sheet.

Study on interaction of N,N′-(2-hydroxy-3-methoxybenzyl) diamine cerium(IV) with bovine serum albumin

Complexes of cerium(IV) with bis(N,N′-(2-hydroxy-3-methoxybenzyl) ethane-1,2-diamine, bis(2-hydroxy-3-methoxybenzyl) propane-1,2-diamine and bis(2-hydroxy-3-methoxybenzyl) propane-1,3-diamine were synthesized by reaction of cerium(IV) nitrate and the ligands. The obtained coordination compounds have also been characterized by elemental analysis, IR spectroscopy, and single crystal X-ray diffraction. The interactions of these complexes with bovine serum albumin (BSA) were investigated using fluorescence spectroscopy under the simulated physiological conditions. Fluorescence titration revealed that the complexes can quench the intrinsic fluorescence of BSA through static quenching mechanism. The static quenching constants, the binding constants, and the binding sites were also acquired according to the Stern–Volmer equation and the corresponding thermodynamic parameters ΔH, ΔS, and ΔG were calculated through the van’t Hoff equation. Hydrogen bonds and van der Waals forces were the predominant intermolecular forces between these complexes and BSA. The distances between BSA and these complexes were less than 8 nm, indicating that energy transfer between the donor and acceptor occurs with high probability. Synchronous fluorescence studies indicate that binding of these complexes with BSA changes the polarity around tyrosine residues rather than tryptophan residues.

Study on the interaction between rare earth complex [Er(C 18 H 22.5 N 2 O 4 ) 2 ] and bovine serum albumin

The interaction of rare earth complex [Er(C<inf>18</inf>H<inf>22.5</inf>N<inf>2</inf>O<inf>4</inf>)<inf>2</inf>] and bovine serum albumin (BSA) under physiological condition was studied by fluorescence spectrum. The experiment demonstrated that the fluorescence quenching of BSA by Er(III) complex is a result of the formation of ground state complex and the quenching mechanism is mainly static quenching. The corresponding binding constants between Er(III) complex and BSA were 5.17×10³ L.mol⁻¹(293K), and the binding sites were 1. According to the binding constants of the different temperatures, the thermodynamic parameters ΔH, ΔG, ΔS were calculated. From thermodynamic parameters it can be judged that the binding force between Er(III) complex and BSA is mainly H-bond and Van der Waals force. The effect of Er(III) complex on the conformation of BSA was analyzed by synchronous fluorescence spectrometry.

Fluorescence spectroscopic study on the interaction between praseodymium complex [Pr(C 18 H 22.5 N 2 O 4 ) 2 ] and bovine serum albumin

The interaction between praseodymium complex [Pr(C<inf>18</inf>H<inf>22.5</inf>N<inf>2</inf>O<inf>4</inf>)<inf>2</inf>] and bovine serum albumin (BSA) under physiological condition was investigated by fluorescence spectrum. The quenching mechanism of fluorescence was suggested as static quenching according to the Steru-Volmer equation. The binding constants between Pr(III) complex and BSA were 7.31×10⁴L·mol⁻¹(291K), and the binding sites were 1. The thermodynamic parameters ΔH, ΔS and ΔG were calculated at different temperatures indicated that the binding forces between Pr(III) complex and BSA were hydrogen bonds and van der Waals forces. According to the Förster non-radiation energy transfer theory, the binding average distance (r=2.84nm) between donor (BSA) and acceptor (Pr(III) complex) was obtained. Furthermore, the investigations of the synchromous fluorescence of the system reveal that the conformation of BSA is changed in the presence of Pr(III) complex.

Study on the interaction of N 1 -(1-phenylethyl) propane-1,2-diamine Nickel(II) complex and bovine serum albumin by fluorescence spectra

The binding reaction of the N1-(1-phenylethyl) propane-1,2-diamine nickel(II) complex with bovine serum albumin (BSA) was studied by fluorescence spectroscopy under the simulative physiological conditions. The experimental results show that the complex had a quite strong ability to quench the fluorescence from BSA and the quenching mechanism of this complex to bovine serum albumin was static quenching. The binding constants were 4.92×106 and 1.35×106 L·mol−1 at 293K and 303K with one binding site, respectively. The type of bonding forces was estimated by the calculation of thermodynamic parameters of the reaction of the complex with BSA at different temperatures, and the result showed that H-bond and Van der Waals are two main reactions between complex and BSA. The effect of the complex on the BSA conformation was also studied by using synchronous fluorescence spectrum.

Bis{6,6′-dimeth­oxy-2,2′-[ethane-1,2-diyl­bis(imino­methyl­ene)]diphenolato(1.5−)-κ4O,N,N′,O′}terbium(III)

The title compound, [Tb(C18H22.5N2O4)2], is isotypic with its Pr and Tb analogues. All interatomic distances, angles and the hydrogen bond geometry are very similar for the three structures.