One-pot synthetic approach to isolate a single isomer of bis(diethylenetriamine)cobalt(III) cation in bulk using benzoates and the isomeric effects of the cation on ion association with anions

Using a one-pot synthetic approach, a single isomer of bis(diethylenetriamine)cobalt(III) cation, [Co(dien)₂]³⁺ is obtained in bulk from the isomeric mixture (s-fac : u-fac : mer is 7 : 28 : 65) using sodium salts of benzoates (BBz-bromobenzoate, DNBz-dinitrobenzoate, MBz-methylbenzoate) in aqueous medium. Herein, we report the syntheses and characterization of three complexes of composition mer-[Co(dien)₂]Cl(p-BBz)₂·H₂O (1), s-fac-[Co(dien)₂](o,p-DNBz)₃·H₂O (2) and mer-[Co(dien)₂]Cl(p-MBz)₂·4H₂O (3) in the continuation of our earlier work, where benzoate (Bz), p-chlorobenzoate (CBz), p-nitrobenzoate (NBz) and p-aminobenzoate (ABz) were used. The isomeric identification of complex cation was initially made on the basis of spectroscopic characterization (UV–visible, IR and NMR). The binding properties of [Co(dien)₂]³⁺ with benzoates (p-BBz, o,p-DNBz, p-MBz, Bz, CBz, NBz or ABz) have been studied using standard UV–visible spectroscopic titrations in aqueous medium and comparison indicate ion association constants of s-fac > mer. The single-crystal X-ray diffraction structure analysis of 3 reveals the presence of discrete ions ([Co(dien)₂]³⁺, chloride, p-MBz) along with four lattice water molecules. The structure of 3, with formula [Co(dien)₂](p-MBz)₂Cl·4H₂O, consists of alternating layers made of benzoate ions and layers made of [Co(dien)₂]³⁺, chloride and water molecules. These layers result in the formation of their respective columns and intermolecular cohesion of p-MBz within the columns of [Co(dien)₂]³⁺ is achieved via electrostatic and H-bonding interactions.     

Synthesis,Electrochemical, and Optical Properties of a Novel PPV/PPE Block‐Copolymer

Summary: A novel poly(p‐phenylene vinylene) (PPV)/poly(p‐phenylene ethynylene) (PPE) block‐copolymer was synthesized by a cross‐coupling polycondensation with Pd(PPh₃)₂Cl₂ and a phase‐transfer catalyst, and was confirmed by ¹H NMR and IR spectroscopy and elemental analysis. The thermal, electrochemical, and photoluminescent properties of the new copolymer have been investigated. The incorporation of triple bonds into the cyano‐substituted PPV (CN‐PPV) backbone leads to higher oxidation and reduction potentials than poly(2‐methoxy‐5‐(2‐ethylhexyloxy)‐p‐phenylene vinylene) (MEH‐PPV) and CN‐PPV, potentially making the copolymer a good electron‐transporting material for use in a light‐emitting‐diode device.

The cyclic voltammogram of the novel poly(p‐phenylene vinylene) (PPV)/poly(p‐phenylene ethynylene) (PPE) block‐copolymer synthesized here.     

Bulk polymerization of p‐dioxanone using a cyclic tin alkoxide as initiator

Poly(p‐dioxanone) with an inherent viscosity of over 1 dL/g has been synthesized using the cyclic tin alkoxide 1‐di‐n‐butyl‐1‐stanna‐2,5‐dioxacyclopentane as initiator. Poly(p‐dioxanone) was synthesized in bulk and the results have been compared with polymerizations using tin (II) 2‐ethylhexanoate (Sn(Oct)₂) as catalyst. Sn(Oct)₂ has often been reported to be an effective catalyst for the synthesis of poly(p‐dioxanone), but here it is compared with an initiator which is less prone to catalyze transesterification reactions. The results demonstrate that the cyclic tin initiator is a promising alternative for the synthesis of poly(p‐dioxanone) with a high inherent viscosity. Poly(p‐dioxanone) is a polymer with mechanical properties and a degradation rate suitable for tissue engineering applications. Both the cyclic tin initiator and Sn(Oct)₂ gave, under some reaction conditions, inherent viscosities around 1 dL/g. The best polymer synthesized using the cyclic tin initiator had a strain‐at‐break of 515% and a stress‐at‐break of 43 MPa. The inherent viscosity of this polymer was 1.16 dL/g, while Sn(Oct)₂ resulted in a polymer with an inherent viscosity less than 0.4 dL/g under the same reaction conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5552–5558, 2007     

Construction and Properties of Two MOFs Based on 2‐p‐Bromophenyl Imidazole Dicarboxylate

To further explore the coordination ability of an multi‐functional ligand 2‐(p‐bromophenyl)‐1H‐imidazole‐4,5‐dicarboxylic acid (p‐BrPhH₃IDC), two metal‐organic frameworks [Mn(μ₂‐p‐BrPhH₂IDC)₂]_n ( I ) and {[Pb(μ₂‐p‐BrPhH₂IDC)₂] · H₂O}_n ( II ) were synthesized under hydro(solvo)thermal conditions and structurally characterized by elemental analyses, IR spectroscsopy, and single‐crystal X‐ray diffraction. Polymer I shows a 2D sheet structure. In polymer II , 1D octagonal channels are connected by the organic ligands to form a 3D architecture. Furthermore, the thermal characteristics of the two polymers and the coordination features of p‐BrPhH₃IDC were investigated.     

Synthesis and structural characterization of two cationic dinuclear cymene-ruthenium(II) complexes with thiolato and chloro bridges

Treatment of [(p-cymene)RuCl₂]₂ with HSp-Tol or HSCH₂Ph in the presence of K[PF₆] gave the cationic dinuclear cymene–ruthenium(II) complexes [(p-cymene)₂Ru₂(μ-Cl)(μ-Sp-Tol)₂][PF₆] (1) and [(p-cymene)₂Ru₂(μ-Cl)(μ-SCH₂Ph)₂][PF₆] (2), respectively, which have been characterized by IR, NMR spectroscopies and mass spectrometry along with microanalyses. Their crystal structures were determined by single-crystal X-ray diffraction analyses. The structures of the cationic complexes contain the unusual pseudo-trigonal-bipyramidal Ru₂S₂Cl framework without a ruthenium–ruthenium single bond. The two p-cymene–ruthenium units are held together by two bridging thiolates and one bridging chloride.     

Selective synthesis of poly(p‐oxybenzoyl) by fractional polycondensation: Enhancement of selectivity by shearing

The influence of shear flow, especially the timing for the application of shearing, was examined to enhance the selectivity for the preparation of poly(p‐oxybenzoyl) (Pp‐OB) by using hydrodynamically induced phase separation during polymerization of 4‐(4‐acetoxybenzoyloxy)benzoic acid (p‐ABAD) and m‐acetoxybenzoic acid (m‐ABA). The polymers containing few m‐oxybenzoyl (m‐OB) moieties were obtained as precipitates even at high content of m‐OB moiety in feed (χ_f) under shear flow. The content of m‐OB moiety in the precipitates (χ_p) prepared under shearing throughout the polymerization at the shear rate (γ) of 489 s^?1 was 6.3 mol % even at χ_f of 60 mol %. Especially, the Pp‐OB was obtained as the precipitates at χ_f of less than 50 mol %. The timing of the application of the shearing influenced the selectivity significantly, and the shearing just after the precipitation of the oligomers started was quite efficient to enhance the selectivity more. The χ_p of the precipitates prepared with shearing at γ of 489 s^?1 just after the precipitation was only 3.9 mol % even at χ_f of 60 mol %. The shear flow reduced the difference in the reactivity between p‐ABAD and m‐ABA, resulting in the decrease in the selectivity with regard to the formation of p‐oxybenzoyl homo‐oligomer. However, the shear flow enhanced the difference in the miscibility between homo‐oligomers and co‐oligomers. This change in the miscibility by shear flow brought about the more rapid precipitation of homo‐oligomers, leading to the enhancement of the selectivity. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and Solution Conformation of β‐Hairpin Mimetics Utilizing a Template Derived from (2S,3R,4R)‐Diaminoproline

A novel template was synthesized for stabilizing β‐hairpin conformations in cyclic peptide mimetics. The template is a diketopiperazine derived formally from L ‐aspartic acid and (2S,3R,4R)‐diaminoproline, the latter being available by an efficient synthetic route from vitamin C. The template was incorporated by solid‐phase peptide synthesis into a cyclic loop mimetic containing the sequence (‐Ala‐Asn‐Pro‐Asn‐Ala‐Ala‐template‐). This mimetic was shown by NMR to adopt a stable β‐hairpin conformation in (D₆)DMSO solution. The template may prove to be generally useful for creating small‐molecule mimetics of hairpin loops on proteins of diverse function.     

Tetra(p‐tolyl)borate‐Functionalized Solvent Polymeric Membrane: A Facile and Sensitive Sensing Platform for Peroxidase and Peroxidase Mimetics

The determination of peroxidase activities is the basis for enzyme‐labeled bioaffinity assays, peroxidase‐mimicking DNAzymes‐ and nanoparticles‐based assays, and characterization of the catalytic functions of peroxidase mimetics. Here, a facile, sensitive, and cost‐effective solvent polymeric membrane‐based peroxidase detection platform is described that utilizes reaction intermediates with different pK_a values from those of substrates and final products. Several key but long‐debated intermediates in the peroxidative oxidation of o‐phenylenediamine (o‐PD) have been identified and their charge states have been estimated. By using a solvent polymeric membrane functionalized by an appropriate substituted tetraphenylborate as a receptor, those cationic intermediates could be transferred into the membrane from the aqueous phase to induce a large cationic potential response. Thus, the potentiometric indication of the o‐PD oxidation catalyzed by peroxidase or its mimetics can be fulfilled. Horseradish peroxidase has been detected with a detection limit at least two orders of magnitude lower than those obtained by spectrophotometric techniques and traditional membrane‐based methods. As an example of peroxidase mimetics, G‐quadruplex DNAzymes were probed by the intermediate‐sensitive membrane and a label‐free thrombin detection protocol was developed based on the catalytic activity of the thrombin‐binding G‐quadruplex aptamer.     

Electrochemical synthesis of carbonyl- and phosphoryl-containing methano[60]fullerenes

The combined electrochemical reduction of fullerene C₆₀ in the presence of p-bromo-benzoyldibromomethane or bis(diisopropoxyphosphoryl)dibromomethane at a brass electrode in a mixed solvent o-dichlorobenzene-MeCN (3:1 v/v)/0.05 M Bu₄NBF₄ at room temperature affords 61-(p-bromobenzoyl)methano[60]fullerene or 61,61-bis(diisopropoxyphosphoryl)methano[60]fullerene, respectively, in 50% yields.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2681–2685, December, 2004.     

系列双核稀土配合物的合成、晶体结构及光物理性质

本文采用水热法合成了4种双核稀土配合物[Y₂(p-MBA)₆(Phen)₂] (1)、[Y₂(p-ClBA)₆(Phen)₂] (2)、[Pr₂(BA)₆(Phen)₂](3)和[Pr₂(p-ClBA)₆(H₂O)₂(Phen)₂](4)[Phen=邻菲咯啉、p-MBA=对甲基苯甲酸、BA=苯甲酸、p-ClBA=对氯苯甲酸]。测定了4种配合物的单晶结构。4种配合物在结构和配位方式上有很多的相似之处,它们的晶体都属于三斜晶系,P1空间群。在分子中,每个稀土离子与1个邻菲咯啉分子螯合,2个稀土离子均以苯甲酸根或其衍生物为桥。但是,桥连配体的数目以及配体的配位方式不尽相同。配合物4中配位水分子与对氯苯甲酸根之间形成了氢键,氢键将双核配合物4连接成二维层状网络结构。对4种配合物的UV-Vis-NIR、IR和荧光性质进行了测定和对比分析。配合物1和2的荧光指认为LLCT和LMCT,而配合物3和4的荧光表现出LLCT与LMCT混合跃迁及Pr³⁺的特征发射。     

Enantioselective Synthesis and Application to the Allylic Imidate Rearrangement of Amine‐Coordinated Palladacycle Catalysts of Cobalt Sandwich Complexes

The reaction of (η⁵‐(N,N‐dimethylaminomethyl)cyclopentadien‐yl)(η⁴‐tetraphenylcyclobutadiene)cobalt with sodium tetrachloropalladate and (R)‐N‐acetylphenylalanine gave planar chiral palladacycle di‐μ‐chloridebis[(η⁵‐(S_p)‐2‐(N,N‐dimethylaminomethyl)cyclopentadienyl,1‐C,3′‐N)(η⁴‐tetraphenylcyclobutadiene)cobalt]dipalladium [(S_p)‐Me₂‐CAP‐Cl] in 92 % ee and 64 % yield. Enantiopurity (>98 % ee) was achieved by purification of the monomeric (R)‐proline adducts and conversion back to the chloride dimer. Treatment with AgOAc gave (S_p)‐Me₂‐CAP‐OAc which was applied to asymmetric transcyclopalladation (up to 78 % ee). The (R)‐N‐acetylphenylalanine mediated palladation methodology was applicable also to the corresponding N,N‐diethyl (82 % ee, 39 % yield) and pyrrolidinyl (>98 % ee, 43 % yield) cobalt sandwich complexes. A combination of 5 mol % of the latter [(S_p)‐Pyrr‐CAP‐Cl] and AgNO₃ (3.8 equiv) is a catalyst for the allylic imidate rearrangement of an (E)‐N‐aryltrifluoroacetimidate (up to 83 % ee), and this catalyst system is also applicable to the rearrangement of a range of (E)‐trichloroacetimidates (up to 99 % ee). This asymmetric efficiency combined with the simplicity of catalyst synthesis provides accessible solutions to the generation of non‐racemic allylic amine derivatives.     

Catalytic Diastereoselective Imidation of Diaryl Sulfides Bearing a Chiral Oxazolinyl Moiety with Chloramine T Trihydrate

Up to 99 % de is obtained in the imidation of diaryl sulfides bearing a chiral oxazolinyl moiety at the ortho position. The corresponding N-p-tosylsulfimides are produced upon use of chloramine T trihydrate in the presence of Cu(OTf)₂ as catalyst [Eq. (1)]. OTf=trifluoromethanesulfonate; Ts=toluenesulfonyl.     

Surface activities and thermodynamic properties of novel cationic surfactants with hydroxymethyl group

A new series of cationic surfactants, N–alkyl–N,N–dimethyl–N–(p–(hydroxymethyl) benzyl) ammonium chlorides (p-DHBA-m), were synthesized and the structures were characterized by ¹HNMR, ¹³CNMR, FT–IR and ESI–MS. The surface activities, thermodynamic properties and aggregation behaviors of p-DHBA-m in aqueous solutions were respectively studied by means of surface tension, isothermal titration calorimetry and steady-state fluorescence methods. Thermodynamic parameters show that the micellization is an entropy-driven process. According to the fluorescence quenching method, the micelle aggregation numbers (N_agg) of p-DHBA-m were calculated and found that the increase of temperature or the elongation of alkyl chain length could lead to the reduction of the N_agg, respectively.     

Study on the Reaction of Electron‐deficient Cyclopropane Derivatives with Amines

Reaction of electron deficient cyclopropane derivatives cis‐1‐methoxycarbonyl‐2‐aryl‐6, 6‐dimethyl‐5, 7‐dioxa‐spiro‐[2,5]‐4,8‐octadiones (1a‐d) (X = CH₃, H, Cl, NO₂) with anilines (2a‐e) (Y = p‐CH₃, H, p‐Br, p‐NO₂, o‐CH₃) at room temperature gives N‐aryl‐trans, trans‐α‐carboxyl‐β‐methoxycarbonyl‐γ‐aryl‐γ‐butyrolactams (3a‐p) in high yields with high stereoselectivity. For example, 1a (X= CH₃) reacts with ammonia 4 or benzyl amine 5 at room temperature to give inner ammonium salt 6 or 7 in the yield of 83% or 97% respectively. The reaction mechanisms for formation of the products are proposed.     

p-tert-Butylcalix[5]arene: a New Synthetic Pathway and Crystal Structure of the N,N-Dimethylformamide Complex

The formation of p-tert-butylcalix[5]arene by the opening ofp-tert-butyldihomooxacalix [4]arene and the addition of a monomer has beenstudied. Various facets, including the effects of bases and the nature ofthe monomer added to the p-tert-butyldihomooxacalix[4]arene, have beeninvestigated. p-tert-Butylcalix[5]arene can be prepared in yields up to30%. The structure of its 1 : 2 complex with DMF has been determinedby X-ray crystallography. Crystals are triclinic, space group P¯1, a =1428.2(3) pm, b = 1837.3(3) pm, c = 1276.1(2) pm, = 108.98(1)°, = 105.02(2)°, = 95.21(1)°, Z = 2, D _c = 1.059 kg m^-3,final R value = 0.087. The macrocycle adopts a cone conformation, one guestenclosed inside the cavity, the other one outside.     

Synthesis of hetero‐telechelic polymers by self‐polyaddition of monomers containing both oxetanyl and carboxyl groups

The synthesis and self‐polyaddition of new monomers, o‐, m‐, and p‐[(3‐ethyloxetane‐3‐yl)methoxyethyl]benzoic acid (o‐EOMB, m‐EOMB, and p‐EOMB) containing both oxetanyl groups and carboxyl groups were examined. The reactions of o‐EOMB, m‐EOMB, and p‐EOMB in the presence of tetraphenylphosphonium bromide as a catalyst in o‐dichlorobenzene at 150–170 °C resulted in self‐polyaddition to give the corresponding hetero‐telechelic polymers poly(o‐EOMB), poly(m‐EOMB), and poly(p‐EOMB) with M_ns = 14,500–33,400 in satisfactory yields. The M_n of poly(o‐EOMB) decreased at higher reaction temperatures than 150 °C, unlike those of poly(m‐EOMB) and poly(p‐EOMB), possibly due to inter‐ or intraester exchange side reactions. It was also found that the thermal properties and solubilities of these polymers were supposed with the proposed structures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7835–7842, 2008     

Synthesis of 1-triphenylgermylpropiono-4-substituted semicarbazides,thiosemicarbazides and their heterocyclic derivatives

Twenty-one new organogermanium compounds with the formulae Ph₃GeCHR¹CH₂CONHNHC(X)NHR² (1) (R¹=H, Ph; = Ph, p-CH₃Ph, O -CH₃Ph, p-ClPh, COPh, X = S, O) and (R¹ = H, Ph; R² = Ph, p-CH₃Ph, o-CH₃Ph, p-ClPh; X=S, O) were synthesized and characterized by elemental analysis, ¹H NMR, IR, MS and X-ray diffraction techniques. Compounds l were prepared by the reactions of Ph₃GeCHR¹CH₂CONHNH₂ with R²NCX in chloroform in 77-94% yields, and 2 were obtained by refluxing l with sodium hydroxide (8%) with yields of 55-94%.     

Synthesis and liquid crystalline properties of substituted 2,5‐diaryl 1,3,4‐oxadiazole derivatives without flexible chains

A series of new compounds based on aromatically 2,5‐disubstituted 1,3,4‐oxadiazoles without flexible chains, formulated as p‐R–C₆H₄–(OC₂N₂)–(p‐C₆H₄)₂–R′ with (i) R = CH₃O, R′ = CH₃O, CH₃S, F, H (Ia–Id), (ii) R = CH₃S, R′ = CH₃O, CH₃S, F, H (IIa–IId) and (iii) R = F, R′ = CH₃O, CH₃S, F, H (IIIa–IIId) (p‐C₆H₄ and OC₂N₂ represent a p‐phenylene spacer and a 1,3,4‐oxadiazole ring, respectively), were synthesised and characterised by ¹H and ¹³C NMR, MS and HRMS techniques. Mesomorphic properties were investigated using differential scanning calorimetry and polarizing optical microscopy. All of the target compounds (except Id, IId, IIIc and IIId) exhibited an enantiotropic nematic mesophase with high melting temperatures. The liquid crystalline properties of these compounds were influenced greatly by polarity, steric factors and positions of the terminal groups. The effect of the terminal groups on the liquid crystal properties is discussed.     

Syntheses and molecular structures of organo-tellurium(IV) halides trans-[(Ph2Te)(μ-Cl)2]n,cis-[(Ph2Te)(μ-Cl)2]n, [(p-MeC6H4)2TeBr2], and [{(p-MeC6H4)2TeBr}2(μ-O)]

Abstract

Treatment of Ph₂Te with aqueous hydrogen chloride under air in refluxing THF gave trans-[(Ph₂Te)(μ-Cl)₂]_n (1), whereas interaction of Ph₂Te with ammonium chloride under similar condition afforded cis-[(Ph₂Te)(μ-Cl)₂]_n (2). Reaction of (p-MeC₆H₄)₂Te and bromine in refluxing THF resulted in formation of a discrete complex [(p-MeC₆H₄)₂TeBr₂] (3) with a step-like tetrameric structure, which further reacted with sodium hydroxide in refluxing THF to give a dinuclear tellurium oxide [{(p-Me-C₆H₄)₂TeBr}₂(μ-O)] (4) with a bridging oxygen atom. Complexes 1–4 have been spectroscopically characterized and their crystal structures have been established by X-ray crystallography.     

Nitro‐substituted iron(II) tridentate bis(imino)pyridine complexes as high‐temperature catalysts for the production of α‐olefins

A new series of nitro‐substituted bis(imino)pyridine ligands {2,6‐bis[1‐(2‐methyl‐4‐nitrophenylimino)ethyl]pyridine, 2,6‐bis[1‐(4‐nitrophenylimino)ethyl]pyridine, (1‐{6‐[1‐(4‐nitro‐phenylimino)‐ethyl]‐pyridin‐2‐yl}‐ethylidene)‐(2,4,6‐trimethyl‐phenyl)‐amine, and 2,6‐bis[1‐(2‐methyl‐3‐nitrophenylimino)ethyl]pyridine} and their corresponding Fe(II) complexes [{p‐NO₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐ Me? p‐NO₂}FeCl₂ ( 10 ), L₂FeCl₂ ( 11 ), {m‐NO₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me? m‐NO₂}FeCl₂ ( 12 ), and {p‐NO₂? Ph? N?C(Me)? Py? C(Me)?N? Mes}FeCl₂ ( 14 )] were synthesized. According to X‐ray analysis, there were shortenings of the axial Fe? N bond lengths (up to 0.014 Å) in para‐nitro‐substituted complex 10 and (up to 0.015 Å) in meta‐nitro‐substituted complex 12 versus the Fe(II) complex without nitro groups [{o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me}FeCl₂ ( 1 )]. Complexes 10 , 12 , and 14 afforded very active catalysts for the production of α‐olefins and were more temperature‐stable and had longer lifetimes than parent non‐nitro‐substituted Fe(II) complex 1 . The reaction between FeCl₂ and a sterically less hindered ligand [p‐NO₂? Ph? N?C(Me)? Py? C(Me)?N? Ph? p‐NO₂] resulted in the formation of octahedral complex 11 . A para‐dialkylamino‐substituted bis(imino)pyridine ligand [p‐NEt₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me? p‐NEt₂] and the corresponding Fe(II) complex [{p‐NEt₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me? p‐NEt₂}FeCl₂ ( 16 )] were synthesized to evaluate the effect of enhanced electron donation of the ligand on the catalytic performance. According to X‐ray analysis, there was a shortening (up to 0.043 Å) of the axial Fe? N bond lengths in para‐diethylamino‐substituted complex 16 in comparison with parent Fe(II) complex 1 . © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2615–2635, 2006