Hydro(solvo)thermal synthesis and structural characterization of three lanthanide–carboxylate coordination polymers based on BDC and/or EDTA

Three lanthanide coordination polymers, [Ln₄(BDC)₆(H₂O)₂] _n (Ln = Er, 1; Ln = Tm, 2; BDC = 1,2-benzenedicarboxylate) and {[Nd₂(BDC)(EDTA)(H₂O)₂] · 1.5H₂O} _n , 3, were prepared by hydrothermal synthesis and characterized by elemental analysis, IR spectra, as well as single-crystal X-ray diffraction. The isostructural coordination polymers 1 and 2 exhibit four different coordination modes, which are rarely found in one lanthanide complex. Complex 3 displays a 2-D wave-like network assembled by two polycarboxylate ligands.     

Studies on Dioxygen Adducts of Cobalt(II) Complexes with Salen-Analogs Containing A Pendant Group

Abstract

New cobalt(II) complexes ([Co(sal-P)]) with pentadentate salen-analogs possessing a pendant group capable of axial coordination have been synthesized and discussed with respect to coordination behavior of the pendant groups.     

Double Fluorescence Conversion in Ultraviolet and Visible Region for Some Praseodymium Complexes of Aromatic Carboxyates

Four praseodymium complexes of aromatic carboxylates (benzoate, 4-tert-butylbenzoate, 2-benzoylbe-noate, and benzimidazole-5-carboxylate) have been synthesized and characterized, whose photophysical properties have been studied with ultraviolet spectra, phosphorescence spectra, and fluorescence spectra. The fluorescent emission spectra of all praseodymium complexes show two emission peaks under the excitation band of 245 nm at about 395 and 595 nm respectively, while one peak under 415 nm at about 595 nm, which attributed to be ¹S₀ → ¹I₆ (395 nm) transition and the characteristic emission ¹D₂ → ³H₄ (595 nm) transition of Pr³⁺ ion. The ¹S₀ → ¹I₆ transition can be ascribed as the transition of charge transfer state, and the ¹D₂ → ³H₄ can be further proved that there exists an antenna effect in the fluorescence of praseodymium with aromatic carboxylic acids. In conclusion, the praseodymium complexes systems can realize the double fluorescent conversion in both ultraviolet and visible region and can be further studied the application of this conversion.     

Interaction of methyltin(IV) compounds with carboxylate ligands. Part 1: formation and stability of methyltin(IV)–carboxylate complexes and their relevance in speciation studies of natural waters

Quantitative data on the stability of mono‐, di‐ and trimethyltin(IV)‐carboxylate complexes (acetate, malonate, succinate, malate, oxydiacetate, diethylenetrioxydiacetate, tricarballylate, citrate, butanetetracarboxylate and mellitate) are reported at t = 25 °C and I→ 0 mol l^?1. Several mononuclear, mixed proton, mixed hydroxo and polynuclear species are formed in these systems. As expected, the stability trend is mono‐ > di‐ > trimethyltin(IV) and mono < di < tri < tetra < hexa for the organotin moieties and carboxylate ligands investigated, respectively. Moreover, ligands containing, in addition to carboxylic,? O? and? OH groups show a significantly higher stability with respect to analogous ligands with the same number of carboxylic binding sites. The results obtained from all the systems investigated allowed us to formulate the following empirical predictive equation for correlation between complex stability and some simple structural parameters, (1) where n_carb and n_OH are the number of carboxylic and alcoholic groups in the ligand, respectively, r is the stoichiometric coefficient of H⁺ (positive) or OH^? (negative) and z_cat is the methyltin cation charge (CH₃)_xSn^z+ (z⁺ = 4 ? x). Distribution diagrams for some representative systems are also reported and are discussed in the light of speciation studies in natural waters. A literature data comparison is made with carboxylate complexes of other metal ions with the same charge as the organotin cations investigated here. Copyright © 2005 John Wiley & Sons, Ltd.     

Quantitative determination of melphalan DNA adducts using HPLC - inductively coupled mass spectrometry

For the quantification of Melphalan DNA adducts, an analytical approach based on the detection of phosphorus using liquid chromatography combined with inductively-coupled-plasma mass spectrometry (ICP-MS) was developed. In reaction mixtures of native 2'-deoxynucleotides-5'-monophosphates and Melphalan, which were separated using reversed phase chromatography, phosphate adducts were found as the most abundant modifications. Besides the phosphate adducts, several base alkylated adducts were observed. In calf thymus DNA incubated with Melphalan and enzymatically digested using Nuclease P1, the phosphate adducts as well as monoalkylated dinucleotides were found. The most abundant single Melphalan adduct observed in DNA was a ring-opened adenosine monophosphate. Some dinucleotide adducts and the adenosine adduct were identified using electrospray ionization mass spectrometry (ESI-MS).     

Novel Intermolecular C-H…π Interactions from a One-dimensional Chain:Synthesis and Crystal Structure of a Ladder Dibenzyl Tin Carboxylate

The title ladder organotin carboxylate,{[(C6H5CH2)2Sn]4(p-NH2C6H4-COO)2O2(OCH3)2}·0.5H2O 1,has been synthesized and structurally characterized by elemental analyses,IR and single-crystal X-ray diffraction analysis.Complex 1 is located across on an inversion center and displays a Sn4O4 ladder-like structure with a one-dimensional supramolecular chain through C-H…π interactions.In the asymmetric unit two Sn(Ⅳ) atoms assume similar trigonal bipyramidal coordination geometry.Two aminobenzoate groups coordinate to the terminal Sn(Ⅳ) atoms.The deprotonated methanol molecule bridges two independent Sn(Ⅳ) atoms.A half of lattice water molecule is disorderly filled in the cavity formed by Sn(Ⅳ) complexes.     

In situ Fe XAFS of reversible lithium insertion in a flexible metal organic framework material

X-ray absorption fine structure (XAFS) analysis of the Fe K-edge during lithium insertion and extraction into the metal organic framework material MIL-53 (Fe^III(OH, F)bdc; bdc = benzene-1,4-dicarboxylate) reveals changes in local atomic environment about iron during the process. The average oxidation state of iron is reduced upon lithium insertion, as evidenced by the edge shift of the XANES spectra, and this is accompanied by a lengthening of Fe–O bonds, seen in the EXAFS. In contrast, the EXAFS analysis shows that the closest Fe–Fe distance remains approximately constant during the insertion and extraction of lithium, consistent with a distortion of the structure due to its flexible nature. The process is reversible upon lithium extraction, proving the redox-active flexibility of the framework.     

Analysis of glutathione adducts of patulin by means of liquid chromatography (HPLC) with biochemical detection (BCD) and electrospray ionization tandem mass spectrometry (ESI-MS/MS)

Abstract  A novel method for the identification of glutathione/electrophile adducts that are inhibiting glutathione-S-transferase (GST) activity was developed and applied for the analysis of the mycotoxin patulin. The method is based on high-performance liquid chromatography (HPLC) coupled to a continuous-flow enzyme reactor serving as biochemical detector (BCD) in parallel to electrospray mass spectrometric detection (ESI-MS). This HPLC-BCD technique combines a separation step and the detection of the inhibition and is therefore ideally suited for the analysis of the activity of single patulin/glutathione adducts within a complex mixture of adducts. Two out of at least 15 detected patulin–glutathione adducts showed strong GST inhibition. In ESI-MS, the inhibitory active adducts were characterized by [M + H]⁺ ions with m/z 462.1138 and m/z 741.2011, respectively. They could be identified as a dihydropyranone adduct containing one molecule glutathione and a ketohexanoic acid bearing two glutathione molecules. Graphical Abstract  OnlineAbstractFigure Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Polymer Composites Based on Reactive Carboxylate-Alumoxanes

Summary: The possibility of applying basic aluminum carboxylates as the cross-linking monomers in radical polymerization processes as well as the initiators for ATRP of styrene and coordination ROP of heterocyclic monomers was examined. It was established, that aluminum carboxylates containing in their structure the acrylic and lauric acids derivatives show high activity in the copolymerization with vinyl monomers which results in the hybrid polymer networks formation. In the typical ATRP conditions, polymers grafted with styrene are obtained while basic aluminum 2-bromopropionate is used as the initiator. Hybrid composites i.e. core-shell nanospheres can be obtained in this way at low degree of polymerization. Nanoparticles of basic aluminum caroboxylates when reacted with triethylaluminum show high activity as initiators in the polymerization processes of ε-caprolactone, trimethylene carbonate as well as propylene and ethylene oxides. Cross-linked products in the form of a gel were formed as the result of ROP in such systems. However, linear polymers characterized by M_n above 10⁴ and PDI ≥ 1.9 were obtained after aluminum residuals removal.