Bis(2-chloro-1,10-phenanthroline-κN,N')(thio-cyanato-κN)zinc (2-chloro-1,10-phenanthroline-κN,N')tris-(thio-cyanato-κN)zincate.

The asymmetric unit of the title compound, [Zn(NCS)(C(12)H(7)ClN(2))(2)][Zn(NCS)(3)(C(12)H(7)ClN(2))], contains two cations and two anions. In the cations, the Zn(II) ions have distorted trigonal-bipyramidal environments formed by four N atoms from two 2-chloro-1,10-phenanthroline (cphen) ligands and one N atom from a thio-cyanate ligand. The Zn(II) atoms in the complex anions also have distorted trigonal-bipyramidal environments, formed by two N atoms from a cphen ligand and three N atoms from three thio-cyanato ligands. The crystal packing exhibits π-π inter-actions between the rings of the cphen ligands [shortest centroid-centroid distance = 3.586 (5) Å] and short inter-molecular S⋯Cl [3.395 (5) Å] and S⋯S [3.440 (4) Å] contacts.

[2,9-Bis(3,5-dimethyl-1H-pyrazol-1-yl-κN)-1,10-phenanthroline-κN,N'](methanol-κO)(nitrito-κO,O')cadmium(II) perchlorate.

In the title complex, [Cd(NO(2))(C(22)H(20)N(6))(CH(3)OH)]ClO(4), the Cd(II) ion is in a distorted penta-gonal-bipyramidal CdN(4)O(3) coordination geometry. The dihedral angles formed between the mean planes of the pyrazole rings and the phenanthroline ring system are 4.37 (19) and 5.84 (21)°. In the crystal, the anions and cations are connected by inter-molecular O-H⋯O hydrogen bonding, while pairs of weak inter-molecular C-H⋯O hydrogen bonds connect the cations into centrosymmetric dimers. In addition, there is a π-π stacking inter-action involving two symmetry-related benzene rings, with a centroid-centroid distance of 3.437 (3) Å.

[2-(3,5-Dimethyl-1H-pyrazol-1-yl-κN)-1,10-phenanthroline-κN,N']bis-(nitrito-κO,O')cadmium(II).

In the title complex, [Cd(NO(2))(2)(C(17)H(14)N(4))], the Cd(II) ion assumes a distorted monocapped octa-hedral coordination geometry defined by an N(3)O(4) donor set. The crystal structure is stabilized by π-π stacking inter-actions [shortest centroid-centroid distance = 3.5537 (18) Å].

Bis[2-(1H-1,2,4-triazol-1-yl-κN)-1,10-phenanthroline-κN,N']zinc(II) bis-(perchlorate).

In the title complex, [Zn(C(14)H(9)N(5))(2)](ClO(4))(2), 2-(1H-1,2,4-triazol-1-yl)-1,10-phenanthroline functions as a tridentate ligand and the Zn(II) ion assumes a distorted octa-hedral ZnN(6) coordination geometry. There is a weak π-π stacking inter-action between symmetry-related triazolyl rings with a centroid-centroid distance of 3.802 (4) Šand a perpendicular distance of 3.413 Šbetween the rings.

[2-(3,5-Dimethyl-1H-pyrazol-1-yl-κN)-1,10-phenanthroline-κN,N']bis-(thio-cyanato-κN)cadmium(II).

In the title complex, [Cd(NCS)(2)(C(17)H(14)N(4))], the Cd(II) ion is in a distorted trigonal-bipyramidal CdN(5) coordination geometry. In the crystal structure, there is a π-π stacking inter-action involving a pyrazole ring and a symmetry-related pyridine ring with a centroid-centroid distance of 3.578 (3) Å.

Di-µ-nitrito-κO:O,O';κO,O':O-bis-{[2,6-bis-(pyrazol-1-yl-κN)pyridine-κN](nitrito-κO,O')cadmium(II)}.

In the title centrosymmetric binuclear complex, [Cd(2)(NO(2))(4)(C(11)H(9)N(5))(2)], the unique Cd(II) ion is in a distorted dodeca-hedral CdN(3)O(5) coordination environment. The two inversion-related Cd(II) ions are separated by 3.9920 (6) Šand are bridged by two O atoms from two nitrite ligands. There are two types of π-π stacking inter-actions involving symmetry-related pyrazole rings, with centroid-centroid distances of 3.445 (2) and 3.431 (2) Å.

Tetra-µ-acetato-κO:O'-bis[(N,N-di-methyl-pyrazin-2-amine-κN)copper(II)].

The title binuclear complex, [Cu(2)(C(2)H(3)O(2))(4)(C(6)H(9)N(3))(2)], lies on an inversion center with four acetate ligands bridging two Cu(II) ions and two monodentate N,N-dimethyl-pyrazine-2-amine ligands coordinating each Cu(II) ion via N atoms, forming slightly distorted square-pyramidal environments.

Aqua-(propane-dioato-κO,O)[2-(1H-pyrazol-1-yl-κN)-1,10-phenanthroline-κN,N']nickel(II) trihydrate.

In the title mononuclear complex, [Ni(C(3)H(2)O(4))(C(15)H(10)N(4))(H(2)O)]·3H(2)O, the metal center is coordinated in a distorted NiN(3)O(3) geometry. In the crystal structure, inter-molecular O-H⋯O hydrogen bonds link the components into a two-dimensional network. In addition, there are weak π-π stacking inter-actions between symmetry-related phenanthroline rings, with a centroid-centroid distance of 3.6253 (17) Å.

Bis[mu-1-(1,10-phenanthrolin-2-yl)-2-pyridone]bis{aqua[1-(1,10-phenanthrolin-2-yl)-2-pyridone]cadmium(II)} tetrakis(perchlorate).

In the title centrosymmetric binuclear complex, [Cd2(C17H11N3O)4(H2O)2](ClO4)4, the Cd(II) ion assumes a distorted octahedral geometry. There are pi-pi stacking interactions between the pyridine and 1,10-phenanthroline ring systems of adjacent ligands at the same Cd(II) centre. Intermolecular hydrogen bonds between the coordinated aqua ligand and the O atom of a keto group connect adjacent complex cations into extended chains. Hydrogen bonds also exist between the complex cations and the perchlorate anions. Compared with the fluorescence spectrum of the organic ligand, the complex displays strong fluorescent emission and an ipsochromic shift of the emission peaks, which may be attributed to the structural character.

2,3-Bis(pyrazin-2-yloxyimino)butane.

The title mol-ecule, C(12)H(12)N(6)O(2), lies on a crystallographic inversion center with all non-H atoms essentially coplanar.

Poly[tris-[µ(2)-2-(pyrazol-1-yl)pyrazine]hexa-µ(1,3)-thio-cyanato-tricadmium(II)].

The asymmetric unit of the title crystal structure, [Cd(3)(NCS)(6)(C(7)H(6)N(4))(2)](n), contains two independent Cd(II) ions, one of which is located on a crystallographic inversion center. Each independent Cd(II) ion is in a slightly distorted octa-hedral coordination environment, but the disortion from ideally octa-hedral is greater in the environment of the Cd(II) ion on a general position. Both thio-cyanate ligands act as bridges connecting independent Cd(II) ions, and the 2-(pyrazol-1-yl)pyrazine ligands chelate one Cd(II) ion in a bidentate mode while the remaining N atom of the pyrazine ring coordinates to a symmetry-related Cd(II) ion, forming a two-dimensional structure parallel to (211).

Pair Interaction of Catalytical Sphere Dimers in Chemically Active Media.

We study the pair dynamics of two self-propelled sphere dimers in the chemically active medium in which a cubic autocatalytic chemical reaction takes place. Concentration gradient around the dimer, created by reactions occurring on the catalytic sphere surface and responsible for the self-propulsion, is greatly influenced by the chemical activities of the environment. Consequently, the pair dynamics of two dimers mediated by the concentration field are affected. In the particle-based mesoscopic simulation, we combine molecular dynamics (MD) for potential interactions and reactive multiparticle collision dynamics (RMPC) for solvent flow and bulk reactions. Our results indicate three different configurations between a pair of dimers after the collision, i.e., two possible scenarios of bound dimer pairs and one unbound dimer pair. A phase diagram is sketched as a function of the rate coefficients of the environment reactions. Since the pair interactions are the basic elements of larger scale systems, we believe the results may shed light on the understanding of the collective dynamics.

Polynitrile-bridged two-dimensional crystal: Eu(III) complex with strong fluorescence emission and NLO property.

The first polynitrile coordinated lanthanide complex ([Eu(cda)3(H2O)3].H2O) infinity (cda = carbamyldicyanomethanide anion) has been synthesized and the two-dimensional structure coordination polymer exhibits strong fluorescence emission and strong powder second harmonic generation efficiency (16.8 times that of urea).

π-π stacking, spin density and magnetic coupling strength.

The π-π stacking interaction, one of the main intermolecular forces, sometimes leads to amazing magnetic properties. Although the concept has been raised that spin density is one of the main factors that contribute to the magnetic coupling strength in intermolecular magnetic coupling systems, it has not been confirmed either experimentally or theoretically to date. Herein we present a study on the magnetostructural data of seven unpublished Cu(II) complexes and ten reported radicals. It is confirmed for the first time that the spin density on short contact atoms is a major factor that contributes to the π-π stacking magnetic coupling strength. Based on the reported data to date, when the short contact distance is larger than the default contact radius, medium or relatively strong magnetic coupling strength could be obtained only if the spin density on the short contact atoms is greater than 0.1350; when the C···C short contact is less than the default contact radius of 3.4 Å, but not less than 3.351 Å, and the spin density is less than 0.1, neither medium nor strong magnetic coupling strength could be observed. Further, when the short contact distance decreases with a temperature drop, the spin densities on the relevant short contact atoms increase. In the complexes reported the small spin densities on the relevant short contact atoms are the major factors that result in the weak π-π magnetic coupling strength.

π-π Stacking and ferromagnetic coupling mechanism on a binuclear Cu(II) complex.

The ferromagnetic couplings were observed in an unpublished crystal that consists of binuclear copper(II) complexes, namely, [Cu(2)(µ(1,3)-SCN)(2)(PhenOH)(OCH(3))(2)(HOCH(3))(2)] (PhenOH = 2-hydroxy-1,10-phenanthroline), and in the binuclear complex Cu(ii) ion assumes a distorted octahedral geometry and thiocyanate anion functions as a µ(1,3)-SCN(-) equatorial-axial (EA) bridging ligand. The analysis for the crystal structure indicates that there are three types of magnetic coupling pathways, in which two pathways involve π-π stacking between the adjacent complexes and the third one is the µ(1,3)-SCN(-) bridged pathway. The fitting for the data of the variable-temperature magnetic susceptibilities shows that there is a ferromagnetic coupling between adjacent Cu(II) ions with J = 50.02 cm(-1). Theoretical calculations reveal that the two types of π-π stacking resulted in ferromagnetic couplings with J = 4.16 cm(-1) and J = 2.75 cm(-1), respectively, and the bridged thiocyanate anions pathway led to a weaker ferromagnetic interaction with J = 0.88 cm(-1). The theoretical calculations also indicate that the ferromagnetic coupling sign from the two types of π-π stacking does not accord with McConnell I spin-polarization mechanism. The analysis for the Wiberg bond indexes that originate from the π-π stacking atoms indicates that the Wiberg bond indexes are relevant to the associated magnetic coupling magnitude and the Wiberg bond index is one of the key factors that dominates the associated magnetic coupling magnitude.

In vivo evaluation of 5-fluorouracil-containing self-expandable nitinol stent in rabbits: Efficiency in long-term local drug delivery.

This 5-fluorouracil (5-FU)-containing stent is fabricated by coating a film, composed of one 5-FU-containing ethylene-vinyl acetate (EVA) copolymer layer and one drug-free EVA protective layer, around a commercial self-expandable nitinol stent. The stents with various drug loadings were implanted into rabbit esophagus, and then 5-FU concentrations in the stent-touching and adjacent segments (including mucosa layer and muscle layer of each segment) of esophagus, serum, and liver were investigated throughout the experiment period. Quantitative analysis of 5-FU was performed by HPLC or LC-MS/MS, while the morphologies of esophageal mucosae by scanning electron microscopy (SEM). The results show that the 5-FU concentration in stent-touching esophageal tissue is overwhelmingly higher than that in serum or liver at all the investigation time points until 45 days. The 5-FU concentration in the stent-touching segment is higher than those in the other segments of esophagus, while the 5-FU concentration in mucosa layer is higher than that in muscle layer for the same segment. With the increase of drug loading, the drug concentrations in esophageal tissues and serum increase, and cellular desquamation of stent-touching epithelial surface become increasingly severe by SEM. Based on the results, the 5-FU-loaded esophageal stent operates long-term local drug delivery with great efficiency.

The magnetic study of a binuclear Cu(ii) complex with pi-pi stacking interactions.

An anomalous magnetic interaction is observed in a very common and unpublished binuclear copper(ii) complex, [Cu(2)(micro(2)-OOCCH(3))(2)(bpydiol-H)(2)(H(2)O)(2)] (bpydiol-H = mono deprotonated 2,2'-bypyridine-3,3'-diol). In the complex, the two Cu(ii) ions are bridged by two acetate anions and there is a pi-pi stacking interaction between the adjacent pyridine rings. Theoretical calculations reveal that the acetate bridge ligand leads to an antiferromagnetic coupling with 2J = -166.72 cm(-1), whereas the pi-pi stacking developed a ferromagnetic interaction with 2J = 21.0 cm(-1). The offset from the antiferromagnetic interaction and the ferromagnetic interaction may be one of main factors that resulted in the weaker magnetic coupling with experimental fitting 2J = -59.61 cm(-1). This is the first example using theoretical calculations that evaluate the magnetic coupling intensity for a pi-pi stacking system.

Synthesis, crystal structure, magnetic properties and theoretical studies on a one-dimensional polynuclear copper(II) complex [Cu2(mu1,3-SCN)2(mu'1,3-SCN)2(MPyO)2]n.

A new one-dimensional polynuclear copper(II) complex [Cu(2)(mu(1,3)-SCN)(2)(mu'(1,3)-SCN)(2)(MPyO)(2)](n)(where MPyO = 4-methylpyridine N-oxide) has been synthesized and its crystal structure determined by X-ray crystallography. In the complex there exist two kinds of bridging coordination modes, namely, mu(1,3)-SCN(-) equatorial-equatorial (EE) bridging ligand and micro'(1,3)-SCN(-) equatorial-axial (EA) bridging ligand. Two micro(1,3)-SCN(-) EE bridging ligands coordinate two copper(II) ions in a binuclear unit, and the S atoms from the micro'(1,3)-SCN(-) EA bridging ligands as axial coordinated atoms link the binuclear units into one-dimensional chains. The ESR spectra have been investigated, and variable temperature (4-300 K) magnetic measurements were analyzed using a binuclear Cu(ii) magnetic interaction formula and indicate the existence of strong antiferromagnetic coupling with 2J=- 216.00 cm(-1) between bridged copper(II) ions. Density functional calculations have been carried out on this binuclear unit, yielding a similar singlet-triplet splitting. The mechanism of strong antiferromangetic interaction is revealed according to the calculations.

Magnetic study on a two-dimensional coordination polymer with mixed bridging ligands.

A two-dimensional coordination polymer, [Co(mu(1,3)-SCN)(2)(mu(1,6)-dmpzdo)](n)() (where dmpzdo = 2,5-dimethylpyrazine-1,4-dioxide), has been synthesized and its crystal structure determined by X-ray crystallography. In the complex, the adjacent Co(II) ions are coordinated by mu(1,3)-SCN(-) bridging ligands which forms a one-dimensional chain along the a axis; the one-dimensional chains are further connected by mu(1,6)-dmpzdo bridging ligands which leads to the formation of a two-dimensional layer on the ac plane. The theoretical calculations reveal that a ferromagnetic coupling exists between the mu(1,3)-SCN(-) bridging Co(II) ions and an anti-ferromagnetic interaction between the mu(1,6)-dmpzdo bridging Co(II) ions, and the anti-ferromagnetic interaction is stronger than the ferromagnetic interaction. The fitting of the variable-temperature (34-300 K) magnetic susceptibilities reveals that there is an anti-ferromagnetic coupling between the bridging Co(II) ions with the magnetic coupling constant J = -3.52 cm(-1).

Pharmacokinetic difference between S-(+)- and R-(-)-etodolac in rats.

AIM: To study whether etodolac enantiomers have pharmacokinetic difference after oral administration. METHODS: Fourteen rats, divided into two groups randomly, were orally given S-(+)- or R-(-)-etodolac at a single dose of 20 mg/kg, respectively. Blood samples were collected before and at 5, 10, 20, 30 min and 1, 3, 6, 12, 24, 48, 72 h after treatment. The plasma samples were analyzed with a high-performance liquid chromatographic method. RESULTS: The calibration curves were linear in the range of 0.5-50.0 mg/L (r=0.9999) to S-(+)-etodolac and 2.0-200.0 mg/L (r=0.9999) to R-(-)-etodolac, respectively. The main pharmacokinetic parameters of S-(+)- and R-(-)-etodolac were as follows: t1/2(lambdaz) 18+/-4 h vs 19.4+/-2.2 h, tmax 3.3+/-2.6 h vs 4+/-4 h; Cmax 29+/-6 mg/L vs 97+/-14 mg/L, AUC0-t 706+/-100 h.mg.L(-1) vs 2940+/-400 h mg.L(-1), CL(s) 0.030+/-0.006 L.kg(-1).h(-1) vs 0.0065+/-0.0010 L.kg(-1).h(-1) and V/F 0.25+/-0.22 L.kg(-1) vs 0.03+/-0.05 L.kg(-1). There was no significant difference in t1/2(lambdaz), and tmax between S-(+)- and R-(-)-etodolac (P>>0.05). The Cmax, and AUC0-t of R-(-)-etodolac were markedly higher (P<0.05), while the CL(s) and V/F were markedly lower than those of S-etolodac (P<0.05). CONCLUSION: There is pharmacokinetic difference between S-(+)- and R-(-)- etodolac enantiomers in rats after oral administration.