Highly-sensitive simultaneous detection of lanthanide(III) ions as kinetically stable aromatic polyaminocarboxylato complexes via capillary electrophoresis using resolution enhancement with carbonate ion

An aromatic polyaminocarboxylate ligand, 1-(4-aminobenzyl)ethylenediamine-N,N,N,N-tetraacetate (ABEDTA), is proposed as a complexing reagent in the pre-capillary mode so as to form kinetically inert Ln(III) complexes, meaning that no added ligand is necessary in alkaline carrier buffer solutions. In addition, highly-sensitive detection is possible through a light-absorbing moiety of an aminobenzyl group in the ligand. The fine-tuning of the electrophoretic mobilities of the Ln-abedta complexes is successfully achieved by adding an auxiliary carbonate ion ligand which alters the charge-to-size ratio of the complexes through fast exchange equilibria in a carrier buffer. In fact, all of the complexes are detectable with very similar analytical sensitivity and acceptable resolution (except for Ln=Sm, Eu, Gd) by using NaOH-borate carrier buffer solution at pH 12.35 with 20 mM of Na₂CO₃. A typical detection limit for Tb(III) ion (to 3) is as low as 0.94 M, which translates to an absolute amount of 9.4 fmol in a 1.0×10^–8 dm^-3 (10 nL) injection.     

Two new [Ni(tren)2]2+ complexes: [Ni(tren)2]Cl2 and [Ni(tren)2]WS4

Both title compounds, bis­[tris(2‐amino­ethyl)­amine]­nickel(II) dichloride, [Ni(tren)₂]Cl₂, (I), and bis­[tris(2‐amino­ethyl)­amine]­nickel(II) tetra­thio­tungstate, [Ni(tren)₂]WS₄, (II), contain the [Ni(tren)₂]²⁺ cation [tren is tris(2‐amino­ethyl)­amine, C₆H₁₈N₄]. The tren mol­ecule acts as a tridentate ligand around the central Ni atom, with the remaining primary amine group not bound to the central atom. In (I), Ni²⁺ is located on a centre of inversion surrounded by one crystallographically independent tren mol­ecule. In the [Ni(tren)₂]²⁺ cation of (II), the Ni atom is bound to two crystallographically independent tren mol­ecules. The Ni atoms in the [Ni(tren)₂]²⁺ complexes are in a distorted octahedral environment consisting of six N atoms from the chelating tren mol­ecules. The counter‐ions are chloride anions in (I) and the tetrahedral [WS₄]^2? anion in (II). Hydro­gen bonding is observed in both compounds.     

Ruthenium(II)-catalyzed selective intramolecular [2 + 2 + 2] alkyne cyclotrimerizations

In the presence of a catalytic amount of Cp*RuCl(cod), 1,6-diynes chemoselectively reacted with monoalkynes at ambient temperature to afford the desired bicyclic benzene derivatives in good yields. A wide variety of diynes and monoynes containing functional groups such as ester, ketone, nitrile, amine, alcohol, sulfide, etc. can be used for the present ruthenium catalysis. The most significant advantage of this protocol is that the cycloaddition of unsymmetrical 1,6-diynes with one internal alkyne moiety regioselectively gave rise to meta-substituted products with excellent regioselectivity. Completely intramolecular alkyne cyclotrimerization was also accomplished using triyne substrates to obtain tricyclic aromatic compounds fused with 5-7-membered rings. A ruthenabicycle complex relevant to these cyclotrimerizations was synthesized from Cp*RuCl(cod) and a 1,6-diyne possessing phenyl terminal groups, and its structure was unambiguously determined by X-ray analysis. The intermediary of such a ruthenacycle intermediate was further confirmed by its reaction with acetylene, giving rise to the expected cycloadduct. The density functional study on the cyclotrimerization mechanism elucidated that the cyclotrimerization proceeds via oxidative cyclization, producing a ruthenacycle intermediate and subsequent alkyne insertion initiated by the formal [2 + 2] cycloaddition of the resultant ruthenacycle with an alkyne.     

Simultaneous separation of anionic and cationic proteins by capillary electrophoresis using high concentration of poly(diallyldimethylammonium chloride) as an additive

The simultaneous separation of anionic and cationic proteins has been achieved by addition of high concentration of poly(diallyldimethylammonium chloride) (PDDAC) in capillary electrophoresis. A capillary was filled with PDDAC so that it would act as ion-pair reagents in the separation of anionic proteins. On the other hand, the PDDAC can also be used as coating additives for the analysis of cationic proteins. Increasing the concentration of PDDAC in the separation buffer had the ability to improve the separation efficiency, change the electrophoretic mobility, and alter the separation selectivity; however, this was not true in the case of analyzing proteins by using the PDDAC larger than 1.6%. By both using a buffer containing 1.6% PDDAC and applying pH-stepwise techniques, 13 proteins with a wide range of pI (4.7-11.1) and molecular masses (6.5-198.0 kDa) could be separated within 30 min in a single run. In addition to this separation, we observed not only more peaks from alpha-chymotrypsinogen A and aprotinin but also the bovine serum albumin (BSA) dimer and trimer. With the 50 nL protein injection sample, the limits of detections at signal-to-noise of 3 for proteins are in the range of 0.07-0.79 microM. Except for BSA, the relative standard derivation values of migration time and peak height for all proteins were <1.3 and <6.9%, respectively. We suggested that this proposed method is a promising approach for clinical diagnosis and proteomics applications.     

Hydrolysis of [Pt(dien)H2O]2+ and [Pd(dien)H2O]2+ complexes in water

The hydrolysis of the [Pt(dien)H₂O]²⁺ and [Pd(dien)H₂O]²⁺ complexes has been investigated by potentiometry at 298 K, in 0.1 mol dm^–3 aqueous NaClO₄. Least-squares treatment of the data obtained indicates the formation of mononuclear and -hydroxo-bridged dinuclear complexes with stability constants: log ₁₁ = –6.94 for [Pt(dien)OH]⁺, log ₁₁ = –7.16 for [Pd(dien)OH]⁺, and also log ₂₂ = –9.37 for [Pt₂(dien)₂(OH)₂]²⁺ and log ₂₂ = –10.56 for [Pd₂(dien)₂(OH)₂]²⁺. At pH values > 5.5, formation of the dimer becomes significant for the Pt^II complex, and at pH > 6.5 for the Pd^II complex. These results have been analyzed in relation to the antitumor activity of Pt^II complexes.     

Synthesis of C-arylglycosides via Ru(II)-catalyzed [2 + 2 + 2] cycloaddition

In the presence of catalytic amounts of Cp*RuCl(cod), the cycloaddition of 1,6-diynes with various C-alkynylglycosides proceeded at ambient temperature to afford C-arylglycosides in 46-93% yields.     

Tetraphosphinitoresorcinarene complexes: cationic silver(I) and copper(I) halide complexes as mercurate(II) anion receptors

The reactions of mercury(II) halides with the tetraphosphinitoresorcinarene complexes [P4M5X5], where M=Cu or Ag, X=Cl, Br, or I, and P4=(PhCH2CH2CHC6H2)4(O2CR)4(OPPh2)4 with R=C6H11, 4-C6H4Me, C4H3S, OCH2CCH, or OCH2Ph, have been studied. The reactions of the complexes with HgX2 when M=Ag and X=Cl or Br occur with elimination of silver(I) halide and formation of [P4Ag2X(HgX3)], but when M=Ag and X=I, the complexes [P4Ag4I5(HgI)] are formed. When M=Cu and X=I, the products were the remarkable capsule complexes [(P4Cu2I)2(Hg2X6)]. When M=Ag and X=I, the reaction with both CuI and HgI2 gave the complexes [P4Cu2I(Hg2I5)]. Many of these complexes are structurally characterized as containing mercurate anions weakly bonded to cationic tetraphosphinitoresorcinarene complexes of copper(I) or silver(I) in an unusual form of host-guest interaction. In contrast, the complex [P4Ag4I5(HgI)] is considered to be derived from an anionic silver cluster with an iodomercury(II) cation. Fluxionality of the complexes in solution is interpreted in terms of easy, reversible making and breaking of secondary bonds between the copper(I) or silver(I) cations and the mercurate anions.     

Two new lead(II) nitrite complexes,crystal structure of [Pb(phen)2(NO2)2] an eight-coordinate lead(II) complex

Two new lead(II) complexes containing nitrite, [Pb(L)₂(NO₂)₂], L?=?1,10-phenanthroline (phen) or 2,2′-bipyridine (bpy), have been synthesized and characterized. The crystal structure of [Pb(phen)₂(NO₂)₂] shows monomeric units. The coordination number is eight (four from “phen” ligands and four nitrite anions), weak interaction of lead(II) with oxygen atoms of adjacent molecules produce dimer units in the solid state. The arrangement of ligands exhibits a coordination hole around the lead(II), occupied possibly by a stereoactive lone pair of electrons on lead(II), and the coordination around lead is hemidirected. There is a π–π stacking interaction between the parallel aromatic rings that may help to increase the “gap” around lead(II).     

Co(II), Ni(II) and Cu(II) complexes of new [1+1] and [2+2] macrocyclic ligands derived from 1,4-bis(2′-formylphenyl)-1,4-dioxabutane and cis-1,2-diaminocyclohexane

Two new macrocyclic ligands, L¹ (14-membered N₂O₂) and L² (28-membered N₄O₄) from [1+1] and [2+2] condensation, respectively, have been obtained in a one-pot synthesis starting from 1,4-bis(2′-formylphenyl)-1,4-dioxabutane and cis-1,2-diaminocyclohexane.     

Pyrazolate-based copper(II) and nickel(II) [2 x 2] grid complexes: protonation-dependent self-assembly, structures and properties

The pyrazole-based diamide ligand N,N'-bis(2-pyridylmethyl)pyrazole-3,5-dicarboxamide (H(3)L) has been structurally characterised and successfully employed in the preparation of [2 x 2] grid-type complexes. Thus, the reaction of H(3)L with Cu(ClO(4))2.6H(2)O or Ni(ClO(4))2.6H(2)O in the presence of added base (NaOH) affords the tetranuclear complexes [M(4)(HL(4))].8H(2)O (1: M = Cu, 2: M = Ni). Employment of a mixture of the two metal salts under otherwise identical reaction conditions leads to the formation of the mixed-metal species [Cu(x)Ni(4-x)(HL)(4)].8H(2)O (x相似文献   

Catalytic asymmetric addition of arylboronic acids to isatins using C2-symmetric cationic N-heterocyclic carbenes (NHCs) Pd2+ diaqua complexes as catalysts

A catalytic asymmetric addition of arylboronic acids to isatins has been achieved by using chiral cationic C(2)-symmetric N-heterocyclic carbene (NHC) Pd(2+) diaqua complexes as the catalysts. The reaction can be performed under convenient conditions to give the corresponding adducts in good to high yields (79-94%) and moderate to excellent enantioselectivities (up to 94% ee) in the presence of LiOAr as the promoter which was generated in situ.     

An octanuclear [Co(II)2-Co(III)2]2 interlocked grid--example of an inorganic [2]catenane

An oxalic dihydrazide based flexible polydentate amidrazone ligand undergoes spontaneous [2 x 2] grid assembly, followed by partial disassembly, and then reassembly in the presence of Co(NO3)2.6H2O and NH4(NCS) to form a unique octanuclear [Co(II)2-Co(III)2]2 interlocked, single braided 4 + 4 [2]catenane.     

Alkyl- and aryl-platinum(II) complexes from K2[PtCl4] and tetraorganotin compounds in dimethylsulphoxide. Preparation and reactions of complexes [PtR2(DMSO)2] and [PtR(C) (DMSO)2]

The reaction between K₂[PtCl₄] and a variety of tetraorganotin compounds SnMe₃R (R = Me, aryl) in DMSO gives the complexes cis-[PtR₂(DMSO)₂] and trans-[PtR(Cl)(DMSO)₂] in which the DMSO ligands are bound to Pt through S in the solid state. The DMSO ligands are easily displaced by a variety of N, P, As and Sb donors.     

Effect of substituents on DNA-binding behaviors of ruthenium(II) complexes: [Ru(dmb)2(dtmi)]2+ and [Ru(dmb)2(dtni)]2+

Two Ru(II) complexes [Ru(dmb)₂(dtmi)](ClO₄)₂ (1) (dmb = 4, 4′-dimethyl-2, 2′-bipyridine, dtmi = 3-(pyrazin-2-yl)-as-triazino[5, 6-f]-5-methoxylisatin) and [Ru(dmb)₂(dtni)](ClO₄)₂ (2) (dtni = 3-(pyrazin-2-yl)-as-triazino[5, 6-f]-5-nitroisatin) have been synthesized and characterized by elemental analysis, ES-MS, and ¹H NMR. DNA-binding behaviors of these complexes have been investigated by spectroscopic titration, viscosity measurements, and thermal denaturation. The results indicate that the two complexes interact with calf thymus DNA by intercalation.