Search results for "SOLVENT"

Solvent-modulated structures in anilato-based 2D coordination polymers

2017

Abstract This work highlights the key role of the solvents in the structures of the series of 2D compounds [Ln2(C6O4Br2)3·(Solvent)n]·G (G = Guest). This study is based on the affinity and ability of these solvents to coordinate to lanthanides and on their possibility to act as solvation molecules. For this purpose here we focus on the Er(III) ion and on the bromanilato bridging ligand ([C6O4Br2]2− = dianion of 3,6-dibromo-2,5-dihydroxy-1,4-benzoquinone) and we play with three solvents: H2O, DMSO (dimethylsulfoxide) and DMF (dimethylformamide). Here we report the synthesis, crystal structure and magnetic characterization of compounds [Er2(C6O4Br2)3(H2O)6]·12H2O (1), [Er2(C6O4Br2)3(DMSO)4]·2…

Solvent-modulation of the structure and dimensionality in lanthanoid-anilato coordination polymers.

2018

We show the key role that the size and shape of the solvent molecules may play in the dimensionality and structure of a series of lanthanoid–chloranilato coordination polymers. We report the synthesis, structure and magnetic properties of six different coordination polymers prepared with Er(III) and chloranilato (C6O4Cl22− = 3,6-dichloro-2,5-dihydroxy-1,4-benzoquinone) and six different solvents: [Er2(C6O4Cl2)3(H2O)6]·10H2O (1), [Er2(C6O4Cl2)3(FMA)6]·4FMA·2H2O (2) (FMA = formamide = NH2CHO), [Er2(C6O4Cl2)3(DMSO)4]·2DMSO·2H2O (3) (DMSO = dimethy sulfoxide = Me2SO), [Er2(C6O4Cl2)3(DMF)6] (4) (DMF = dimethylformamide = Me2NCHO), [Er2(C6O4Cl2)3(DMA)4] (5) (DMA = dimethylacetamide = Me2NC(Me)O) …

Lanthanide complexation with CMPO and CMPO-calix[4]arenes in solution: spectrophotometric and electrospray mass spectrometric approaches.

2007

The binding of lanthanide(III) cations with organophosphorous ligands like CMPO and related calix[4]arene-based derivatives have been investigated using two experimental methods. The stability constants of the lanthanum, europium and ytterbium complexes were first determined in methanol by UV absorption spectrophotometry in the presence of nitrate or chloride anions. The results showed that the stoichiometry and the stability of the complexes formed depend on the position of the CMPO moieties either on the wide or the narrow rim of the calixarene scaffold, the nature of the medium, the conformational mobility of the ligands. Complexation of lanthanum was also followed by ESI-mass spectromet…

Di- and Tricationic Organic Salts: An Overview of Their Properties and Applications

2014

During recent years growing interest has been devoted to the synthesis and applications of polycationic organic salts. Among them, di- and tricationic organic salts can be considered the natural evolution of monocationic ones. These last have given rise to the large class of ionic liquids. In the cases of di- and tricationic organic salts, the potential to change their structural features simply by varying the properties either of the charged heads or of the spacers separating them provides the opportunity to obtain materials suitable for different applications. This review article highlights recent progress in the study of the properties of di- and tricationic organic salts, as well as in …

Comparison of the polymorphs and solvates of two analogous fungicides—a case study of the applicability of a supramolecular synthon approach in cryst…

2011

The polymorphism and solvate formation of thiophanate-ethyl (TE), a fungicidal active, were investigated by solvent crystallization and compared to a close analogue, thiophanate-methyl (TM). Four polymorphs and seven solvates of TE were found and structurally compared with the previously found two polymorphs and fourteen solvates of TM by analyzing the hydrogen bonding patterns and using fingerprint plots, packing coefficients and lattice energies. TE and TM have the same functional groups that can build identical supramolecular synthons. Despite the strong similarities, the polymorphs and solvates of the two actives show significant differences in hydrogen bonding and packing. The results …

Latvijas Universitātes Filoloģijas un filozofijas fakultātes Vēstures nodaļa studentu lietās (1919-1940)

2015

Darbs veltīts Latvijas Universitātes Filoloģijas un filozofijas fakultātes Vēstures nodaļas izpētei. Tajā tiek aprakstīts studentu sastāvs un studiju organizācija nodaļā, sniedzot ieskatu Vēstures nodaļas darbībā no 1919. gada, kad tā tika dibināta, – līdz Latvijas Universitātes likvidācijai 1940. gadā. Nozīmīgākie darbā izmantotie materiāli ir Vēstures nodaļas absolventu studentu personīgās lietas, kuras iepriekš nav pētītas. No lietām iegūto informāciju papildinot ar skaidrojumiem historiogrāfijā un citiem materiāliem, tiek parādīts Vēstures nodaļas nozīmīgums Latvijas vēsturē.

Latvijas Universitātei - 80

1999

Solvent for removing silicone oil from intraocular lenses: experimental study comparing various biomaterials.

2000

Abstract Purpose To evaluate the effectiveness of a perfluorocarbon—perfluorohexyloctane (PFHO)—in removing silicone oil from different intraocular lenses (IOLs) and determine whether any removal technique enhances the removal of silicone oil. Methods Six IOL materials were analyzed: standard poly(methyl methacrylate) (PMMA), heparin-surface-modified (HSM) PMMA, AcrySof, 2 polyHEMAs with different water contents, and a second-generation SLM-2 silicone. One or 2 μL of a highly viscous silicone oil (5700 cs) was applied to the center of each IOL optic. Perfluorohexyloctane (2 mL) was then used to remove the silicone oil by 1 of 3 techniques: immersion of the IOL in PFHO; irrigation of the sil…

Cationic Cyclopentadienyl Phenylenediamido Titanium Species Generated by Reaction of TiCpR[1,2-C6H4(NCH2t-Bu)2]R (CpR = η5-C5H5, η5-C5Me5; R = CH3, C…

2006

The reaction of TiCpR[1,2-C6H4(NNp)2]R with the Lewis acid B(C6F5)3 in noncoordinating solvent affords the new zwitterionic species TiCpR[1,2-C6H4(NNp)2)][μ-RB(C6F5)3]. When the reaction is performed in dichloromethane, the [μ-RB(C6F5)3]- anion is displaced by solvent molecules, giving ionic products in which the anion is not coordinated. The cyclopentadienyl zwitterionic complexes TiCp[1,2-C6H4(NNp)2)[μ-RB(C6F5)3] decompose via ligand scrambling between boron and titanium to give the neutral titanium complex TiCp[1,2-C6H4(NNp)2](C6F5) along with the byproduct RB(C6F5)2. In contrast, the pentamethylcyclopentadienyl analogues TiCp*[1,2-C6H4(NNp)2][μ-RB(C6F5)3] evolve through C−H activation t…

Ligand entrapment in twofold interpenetrating PtS matrixes by metallo-organic frameworks.

2003

Single-crystal X-ray crystallography was used to determine the structures of four metallo-organic frameworks (MOFs). A dendritic tetradentate ligand (tetrakis(isonicotinoxymethyl)methane, TINM) was used with first-row transition-metal elements copper, nickel, and cobalt to synthesize MOFs with a PtS interpenetration, due to both planar and tetrahedral junctions being present in the framework. Two different polymeric complexes, 1 and 2, were obtained from similar starting materials, TINM and Cu(NO(3))(2).3H(2)O, but different solvents. The use of dichloromethane in addition to methanol and water promoted the coordination of nitrate ions to the copper. With only methanol and water used as sol…