The synthesis of complexes using precursor complexes with ferrocenyl carboxylate units as building blocks

Using ferrocenyl carboxylates as functional ligands, we synthesized a mononuclear complex [Zn(η²-OOCCHCHFc)₂(CH₃OH)₂] (1) and a binuclear complex [Cd(bafca)₂(H₂O)₂]₂ (2) (bafca⁻ = α-benzamido-β-ferrocenylacrylic carboxylate) as precursor complexes. Investigation on the substitution reaction of precursor complexes as building blocks in solution-state, four complexes [Zn(OOCCHCHFc)₂(bbbm)]_n (1a), {[Zn(OOCCHCHFc)(ntb)](CH₃OH)} (1b), [Cd(bafca)₂(2,2′-bpy)]₂ · 9H₂O (2a) and {[Cd(bafca)₂(bbbm)(CH₃OH)₂] · 6CH₃OH}_n (2b) were obtained (bbbm = 1,1-(1,4-Butanediyl)bis-1H-benzimidazole, ntb = N,N-bis(1H-benzimidazol-2-ylmethyl)-1H-Benzimidazole-2-methanamine and 2,2′-bpy = 2,2′-bipyridine). As anticipated, the structural integrity of precursor complexes can be maintained in these four complexes. It indicates that we can synthesize the desired complexes with the destination structures by using precursor complexes as building blocks and choosing appropriate auxiliary ligands. In addition, the electrochemical properties of all complexes were investigated, and it can be seen from the results that half-wave potentials of these complexes are slightly higher than that of the corresponding ligand.     

Identification of reaction compounds in micrometric layers from gothic paintings using combined SR-XRD and SR-FTIR

Synchrotron radiation X-ray diffraction (μ-SR-XRD) and Fourier transform infrared spectroscopy (μ-SR-FTIR) are used in the non-destructive identification of reaction and aging compounds from micrometric ancient painting layers. The combination of the micrometer size and non-destructive nature of the techniques together with the high resolution and brilliance of the synchrotron radiation has proved to be a procedure most advantageous for the study of reaction, aging and degradation processes. Copper, lead and calcium carboxylates and oxalates are determined in the chromatic, preparation and alteration layers from 15th century egg tempera and oil paintings. Their nature and crystallinity have been assessed. Some hypothesis about the mechanisms of development of both carboxylates and oxalates are presented.     

Novel Vesicular Aqueous Two-Phase Systems

Aqueouspolymertwo-phase(APTP)systemsandpartitioningofvariousmaterialsinthemhavebeeninvetigated,whichhavebeenutilizedinanalysisandseparationofchemicalandbiochemicalmaterialsl'2.InthelasttwodecadessurfactantshavebeenfOundveryusefulinanalysisandseparation,basedonitsphasebehavior3.Usuallythecloudpointphenomenonofnonionicsurfactantwasutilized.Phaseseparationalsooccursindiluteaqueoussolutionofmixedcationicandanionicsurfactants,fOrmingco-.-existingtwodiluteaqueoussolutions'-6.Thisphenomenaofphases…     

三丁胺胺化强碱性阴离子交换树脂催化合成羧酸苄酯

用组合化学方法筛选出的对无外加碱条件下的亲核取代催化活性最高的聚合物季铵盐-三丁胺胺化强碱性阴离子交换树脂为相转移催化剂,催化合成了乙酸苄酯、丙酸苄酯、丁酸苄酯、戊酸苄酯等羧酸苄酯。讨论了各种反应条件对合成丙酸苄酯的产率的影响,并对传统合成方法进行了改进。在优化反应条件下,反应产率接近100%。     

Synthesis of α-CF3-substituted γ,δ-didehydro lysine derivatives

An efficient and selective access to novel α-CF₃-substituted γ,δ-didehydro lysine derivatives and their phosphorus analogues has been developed via the Cu-catalyzed Mannich reaction of α-amino α-propargyl α-trifluoromethyl carboxylates or phosphonates with different secondary amines and paraformaldehyde.     

Synthesis and characterisation of dialkyltin 2,3-bis(diphenylphosphino)maleic acid adducts

The novel dialkyltin 2,3-bis(diphenylphosphino)maleic acid adducts (R₂Sn)(O,O′-dpmaa) [1a, R = Me; 1b, R = Bu; dpmaa = bis(diphenylphosphino)maleic acid] were synthesised from dpmaa and R₂SnCl₂ or Bu₂SnO. They were fully characterised by elemental analysis, IR- and multinuclear NMR-spectroscopies as well as X-ray crystallography [in the case of 1a as its Ph₂P(O)(CH₂)₂P(O)Ph₂ adduct]. Both were found to be cyclic trimers in the solid state that dissolve in the case of 1b into an equilibrium mixture of oligomers.     

Chiral self-assembly of methyltin(IV)-naproxenates: Combining dative Sn-O bonds, secondary Sn?O interactions and C-H?O hydrogen bonding to make an inter-helical meander-shaped network and a cross-linked Z-shaped ribbon

Three new chiral organotin(IV) carboxylates, Me₂Sn(nap)₂ (1), {[Me₂Sn(nap)]₂O}₂ (2) and Me₃Sn(nap) (3) (nap = (S)-(+)-6-methoxy-α-methyl-2-naphthaleneaceto anion) have been synthesized. All of them have been characterized by elemental analysis, multinuclear (¹H, ¹³C and ¹¹⁹Sn) NMR and IR spectroscopy. The crystal structures of 1 and 2 have been determined by X-ray diffraction analysis. The bicapped tetrahedral molecules of 1 are linked by C-H?O hydrogen bonds into homochiral helices, which are also interconnected by C-H?O interactions to form an inter-helical meander-shaped network. The molecule of 2 is a parallel double helix incorporating four chiral tin centers in a Sn₄O₁₀C₄ ladder type molecular skeleton. The C-H?O interactions translate the molecular chirality of 2 throughout the crystal via formation of infinite ribbons. These ribbons in their turn are further cross-linked by C-H?O hydrogen bonds. The structural characterization of the complexes 1-3 in solution has been performed by routine multinuclear ¹H, ¹³C and ¹¹⁹Sn NMR as well as specialized multidimensional (¹H-¹¹⁹Sn-gHMQC and ¹H-DOSY) experiments. The relevant ²J_{¹H-¹¹⁹Sn} and ¹J_{¹³C-¹¹⁹Sn} coupling constants have been extracted and related to molecular geometries on the basis of the literature data. The measurement of the translational diffusion constants using diffusion ordered spectroscopy allowed the estimation of the spherical hydrodynamic radii of the newly prepared structures.     

HPTLC and magnetochromatography of new complexes of carboxylates with transition metals or rare earth elements and their ligands – study of lipophilicity

Nineteen new complexes of carboxylates with transition and rare elements as central ions and their ligands were characterized by chromatographic analyses. The parameter of relative lipophilicity (R _M0) of the tested compounds was determined experimentally by the reversed‐phase high‐performance thin layer chromatography method with mixtures of various organic modifiers (acetonitrile, acetone, dioxane) and water as a mobile phase. The extrapolated R _M0 values were compared with the logP values calculated from the molecular structures of tested solutes. Similarities between the lipophilicity indices were analysed by principal component analysis and linear regression. Thin‐layer chromatography combined with a magnetic field has been proposed as a complementary method for determination of lipophilicity of the investigated compounds. The chromatograms in the field and outside it were developed simultaneously in two identical chromatographic chambers. One of them was placed in the external magnetic field of 0.4 T inductivity. We proved that chelation causes a drastic change in compound lipophilicity, but all complexes did not exhibit enhanced activity as compared with the parent ligand. Also in the magnetic field the retention of some complexes changed, which means that the presence of the field influences the physicochemical properties of the compounds and their interactions with the stationary phase.