On the modeling of arginine-bound carboxylates: a case study with Pyruvate Formate-Lyase

High level ab initio and density functional calculations have been employed to determine the most appropriate manner in which to truncate an arginine-bound carboxylate motif, using the substrate mechanism of Pyruvate Formate-Lyase as a case study. The results show that, both qualitatively and quantitatively, a neutral carboxylic acid provides a more realistic approximation to the salt bridge arrangement than does a bare anionic carboxylate substituent.     

A New Two-dimensional Copper(Ⅱ)Complex with p-PhDTA Bridges

A new p-PhDTA bridged Cu(Ⅱ) complex [Cu2(p-PhDTA)(DMSO)2]·4DMSO (pPhDTA = p-phenylenediamine-N,N,N,N'-tetraacetic acid) has been synthesized and structurally characterized.The crystal belongs to orthorhombic, space group Pca21 with a = 19.572(4), b=19.552(4), c = 10.156(2)(A), C26H48N2O14Cu2S6, Mr = 932.10, V = 3886.4(13)(A)3, Z = 4, Dc = 1.593 g/cm3, F(000) = 1936, λ(MoKα) = 0.71073 (A),μ= 1.480, R = 0.0487 and wR = 0.1151 for 8464 observed reflections (I ＞2σ(I)).In the complex, the oxygen atoms of carboxylate of p-PhDTA connect the Cu atoms in a syn-anti type, giving one-dimensional chains which are further linked by the benzene groups of p-PhDTA to form a novel two-dimensional structure.     

Synthesis of benzylpalladium complexes through C-O bond cleavage of benzylic carboxylates: Development of a novel palladium-catalyzed benzylation of olefins

Benzylic carboxylates were found to react with Pd(0) complexes bearing tertiary phosphines to give benzylpalladium(II) carboxylate complexes with cleavage of the benzyl-oxygen bond. The benzylpalladium complexes having the trifluoroacetato ligand react with olefins such as ethyl acrylate to give olefin benzylation products. On the basis of these studies a novel palladium-catalyzed benzylation of olefins was developed without using organic halides as the starting materials. The method has another advantage of requiring no base as in the conventional Mizoroki-Heck process using organic halides. The catalytic cycle is proposed to be constituted of elementary processes of (a) oxidative addition of a benzyl carboxylate with C-O bond cleavage to a Pd(0) complex to give a benzylpalladium carboxylate, (b) olefin insertion into the benzylpalladium bond to give an alkylpalladium complex, and (c) β-H abstraction to liberate the benzylated olefin.     

New cobalt and iron pivalate complexes with 2,2′:6′,2″-terpyridine: synthesis, structure, and magnetic properties

The mononuclear complexes (η³-terpy)M(Piv)²·MeCN (M = Fe ⁱⁱ (3) and Co ⁱⁱ (4), and Piv is the pivalate anion) were synthesized by the reactions of polymeric iron(ii) and cobalt(ii) pivalates with 2,2′:6′,2″-terpyridine (terpy). The oxidation of compound 3 affords the pentanuclear heterospin iron(ii,iii) complex (η³-terpy)Fe₅(μ₄-O)(μ₃-OH)(μ-OH)₂(μ-Piv)₇(η¹-Piv)₂ (5). All compounds were characterized by X-ray diffraction. Dedicated to the 90th anniversary of the L. Ya. Karpov Institute of Physical Chemistry. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1186–1190, June, 2008.     

π–π stacking motifs in dialkylbis{5‐[(E)‐2‐aryldiazen‐1‐yl]‐2‐hydroxybenzoato}tin(IV) complexes

The diorganotin(IV) complexes of 5‐[(E)‐2‐aryldiazen‐1‐yl]‐2‐hydroxybenzoic acid are of interest because of their structural diversity in the crystalline state and their interesting biological activity. The structures of dimethylbis{2‐hydroxy‐5‐[(E)‐2‐(4‐methylphenyl)diazen‐1‐yl]benzoato}tin(IV), [Sn(CH₃)₂(C₁₄H₁₁N₂O₃)₂], and di‐n‐butylbis{2‐hydroxy‐5‐[(E)‐2‐(4‐methylphenyl)diazen‐1‐yl]benzoato}tin(IV) benzene hemisolvate, [Sn(C₄H₉)₂(C₁₄H₁₁N₂O₃)₂]·0.5C₆H₆, exhibit the usual skew‐trapezoidal bipyramidal coordination geometry observed for related complexes of this class. Each structure has two independent molecules of the Sn^IV complex in the asymmetric unit. In the dimethyltin structure, intermolecular O—H…O hydrogen bonds and a very weak Sn…O interaction link the independent molecules into dimers. The planar carboxylate ligands lend themselves to π–π stacking interactions and the diversity of supramolecular structural motifs formed by these interactions has been examined in detail for these two structures and four closely related analogues. While there are some recurring basic motifs amongst the observed stacking arrangements, such as dimers and step‐like chains, variations through longitudinal slipping and inversion of the direction of the overlay add complexity. The π–π stacking motifs in the two title complexes are combinations of some of those observed in the other structures and are the most complex of the structures examined.     

Synthesis,structure and biological activity of organotin derivatives with pyridylmethylthiobenzoic acid

Reaction of 2-(2-pyridylmethylthio)benzoic acid (1) with R₂SnO (R = Et or ⁿBu) in a 1:1 molar ratio gives the dimeric compounds {[(2-PyCH₂SC₆H₄CO₂)SnR₂]₂O}₂. A similar reaction of 2-(4-pyridylmethylthio)benzoic acid (2) with Et₂SnO yields an analogous result. However, treatment of 2 with ⁿBu₂SnO in a 1:1 molar ratio only gives the diorganotin dicarboxylate (4-PyCH₂SC₆H₄CO₂)₂Sn(ⁿBu)₂. X-ray crystal structure analyses indicate that the pyridyl nitrogen atoms do not coordinate to the tin atoms in the dimer, whilst in the diorganotin dicarboxylate the tin atom has a seven-coordinate distorted pentagonal-bipyramidal geometry, and this compound forms a linkage coordination polymer through the interactions of the pyridyl nitrogen atoms with the adjacent tin atoms. In addition, treatment of 1 or 2 with (Ph₃Sn)₂O in a 2:1 molar ratio affords triphenyltin carboxylates, in which the tin atoms also show different coordination environments. In the solid state, triphenyltin 2-(2-pyridylmethylthio)benzoate is a monomer and the pyridyl nitrogen atom does not participate in coordination to the tin atom either, while the interactions between the pyridyl nitrogen atoms and the adjacent tin atoms link triphenyltin 2-(4-pyridylmethylthio)benzoate into a coordination polymer. Preliminary in vitro tests for fungicidal activity show that all these compounds display good activity to Physolospora piricola in a low concentration. Moreover, the triphenyltin carboxylates show a higher inhibition percentage than the diorganotin carboxylates.     

化学发光免疫分析试剂吖啶酯的合成新路线

设计了一种化学发光免疫分析试剂吖啶酯的合成新路线,以二苯胺为原料合成吖啶-9-羧酸,经酰氯化后与3-(4-羟基苯基)-丙酸-N-羟基琥珀酰亚胺酯反应得4-(2-琥珀酰亚胺基氧羰基乙基)苯基-9-吖啶羧酸酯,最后与氟磺酸甲酯反应即得4-(2-琥珀酰亚胺基氧羰基)苯基-10-甲基吖啶-9-羧酸酯氟磺酸盐(俗称吖啶酯).     

Syntheses and Crystal Structures of Two Trinuclear Iron(Ⅲ) Carboxylate Complexes: [Fe3(μ3-O)(μ-O2CEt)6(H2O)3]Cl.3H2O and [Fe3(μ3-O)(μ-O2CEt)6Py3]Cl(Py=pyridine)

Two new oxo-centered trinuclear iron complexes [Fe3(μ3-O)(μ-O2CEt)6(H2O)3]Cl.3H2O 1 and [Fe3(μ3-O)(μ-O2CEt)6Py3]Cl 2 were prepared in non-aqueous solvent and their crystal structures have been determined. Crystal 1 is monoclinic, space group P21/n, a=9.909(3), b=24.467(8), c=14.542(7)(), β=107.85(4)° V=3356(4)()3, Z=4, Mr=765.52, Dc=1.52 g/cm3, μ=14.28 cm-1, F(000)=1588 and R=0.059, Rw=0.071 for 3745 unique reflections with I>3σ(I). Crystal 2 belongs to the monoclinic system with space group C2/c, a=13.750(3), b=18.439(4), c=16.696(3)(), β=93.42(3)°, V=4226(3)()3, Z=4, Mr=894.73, Dc=1.41 g/cm3, μ=11.4 cm-1, F(000)=2322 and R=0.058, Rw=0.062 for 2272 unique reflections with I>3σ(I). The two structures contain the same trimetal framework in which three iron(Ⅲ) atoms form a nearly equilateral triangle with a μ3-oxygen atom in the centre.     

双(三烃基锡)二元羧酸酯的合成、结构和农药活性普筛

合成了一系列双(三烃基锡)二元羧酸酯类化合物,表征了这些化合物的结构,并进行了农药活性普筛。结果表明,三环己基锡系列大多具有很好的杀螨和杀虫活性,三苯基锡系列则在除草和植物生物刺激方面有一定效果。同时,还发现农药活性同二元羧酸酯的骨架有关,邻苯二甲酸和丁烯二酸衍生物的效果优于脂肪二酸衍生物。