Search results for "Measurements"
showing 10 items of 720 documents
Synthesis of Soluble Donor-Acceptor Double-Cable polymers based on polythiophene and tetracyanoanthraquinodimethane (TCAQ).
2003
[structure: see text] Novel suitably functionalized tetracyanoanthraquinodimethane (TCAQ) derivatives covalently linked to thiophene moieties have been synthesized. The thiophene-based monomers have been chemically polymerized and copolymerized to yield new and soluble donor-acceptor double-cable polymers. The absorption and emission data reveal that the optical properties can be finely tuned by modifying the ratio of monomers in the copolymerization process.
Acylated triterpene saponins from Silene jenisseensis
1995
Abstract From the roots of Silene jenisseensis a new trans-p-methoxycinnamoyl triterpene saponin has been isolated along with its cis-p-methoxycinnamoyl isomer as an inseparable mixture. Their structures were established by chemical means and spectroscopic methods including 1D- and 2D-homonuclear and heteronuclear correlation NMR spectroscopy as 3-O-[β- d -galactopyranosyl -(1 → 2)-β- d -glucuronopyranosyl ]-28-O-[β- d -glucopyranosyl -(1 → 2)-α- l - rhamnopyranosyl -(1 → 2)-β- d -4-O-trans-p- methoxycinnamoyl-fucopyranosyl ] quillaic acid and its cis-isomer, respectively. They did not show any activity in the in vitro chemoluminescence granulocytes assay, but exhibited only a weak inhibito…
Triplet-triplet energy transfer controlled by the donor-acceptor distance in rigidly held palladium-containing cofacial bisporphyrins.
2005
Eleven new complexes, including mono-, heterobi-, and homobimetallic cofacial bisporphyrins, (Pd)H 2 DPS, (M)H 2 DPX, (M)H 2 DPB, (PdZn)DPS, (PdZn)DPX, (Pt) 2 DPX, (M) 2 DPB (M=Pd, Pt), and (Pt)P (DPS 4 - = 4,6-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]dibenzothiophene tetraanion, DPX 4 - = 4,5-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]-9,9-dimethylxanthene tetraanion, DPB 4 - =1,8-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]biphenylene tetraanion, P 2 - = 5-phenyl-2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrin dianion) have been synthesized and characterized. The photophysical properties of the donor (M)P (M=Pd or Pt, P= porphy…
Two polymorphs Ni(II) complexes containing the dicyanamide ligand: syntheses, structures and magnetic properties of {[Ni(meso-CTH)(μ1,5-dca)]ClO4}n a…
2004
Abstract Two polymorphs Ni(II) complexes {[Ni(meso-CTH)(μ1,5-dca)]ClO4}n (1) and [Ni(meso-CTH)][Ni(meso-CTH)(dca)2](ClO4)2 (2) have been obtained in the same synthesis from dicyanamide (dca) and [Ni(meso-CTH)](ClO4)2 and have been characterized by X-ray crystallography and magnetic measurements. Complex 1 is a 1D cationic polymeric zig-zag chain with single end-to-end dca bridges connecting Ni(II) ions in trans positions, whereas in compound 2 coexist two different types of Ni(II) mononuclear units, cationic square-planar and neutral octahedral. Variable-temperature magnetic measurements reveal weak ferromagnetic interactions across the single end-to-end dca bridges in 1, while for 2 the ma…
Adducts of organolead(IV) and organothallium(III) chlorides with N,N′-ethylenebis(salicylideneiminato)nickel(II) and bis(β-mercaptoethylamine)nickel(…
1974
Abstract Novel 1/1 adducts of organolead(IV) and organothallium(III) chlorides with the complexes N,N′-ethylenebis(salicylideneiminato)nickel(II) and bis(β-mercaptoethylamine)nickel(II) have been synthesized. Their configurations have been investigated in the solid state by IR and electronic spectroscopy and by magnetic measurements.
Complexes of organometallic compounds
1974
Abstract Novel 1/1 adducts have been obtained from the complex N , N ′-ethylenebis(salicylideneiminato)nickel(II) (NiSalen) with di- and mono-organotin(IV) chlorides, and their solid state configuration investigated by Mossbauer , IR and electronic spectroscopy and magnetic measurements. In coordinated NiSalen the square planar structure is maintained around Ni II , and the coordination to tin involves three-coordinate phenolic oxygens. The environment of Sn IV is judged to be octahedral in both types of compounds. A trans -R 2 , cis -Cl 2 configuration is advanced for R 2 SnCl 2 NiSalen.
Synthesis, crystal structure and magnetic properties of a novel heterobimetallic rhenium(IV)-dysprosium(III) chain.
2015
The use of the mononuclear rhenium(IV) precursor [ReBr5 (H2 pydc)](-) (H2 pydc=3,5-pyridinedicarboxylic acid) as a metalloligand towards dysprosium(III) afforded the first heterobimetallic Re(IV) -Dy(III) complex. Crystal structures and static and dynamic magnetic properties of both rhenium-containing species are reported herein. The 5d-4f compound shows an extended 1D structure and the AC magnetic measurements reveal frequency dependence at low temperature suggesting slow relaxation of the magnetization.
Magneto-structural correlations in dirhenium(iv) complexes possessing magnetic pathways with even or odd numbers of atoms
2017
The employment of pyrazine (pyz), pyrimidine (pym) and s-triazine (triz) ligands in ReIV chemistry leads to the isolation of a family of complexes of general formula (NBu4)2[(ReX5)2(μ-L)] (L = pyz, X = Cl (1) or Br (2); L = pym, X = Br (3); L = triz, X = Br (4)). 1-4 are dinuclear compounds where two pentahalorhenium(iv) fragments are connected by bidentate pyz, pym and triz ligands. Variable-temperature magnetic measurements, in combination with detailed theoretical studies, uncover the underlying magneto-structural correlation whereby the nature of the exchange between the metal ions is dictated by the number of intervening atoms. That is, the spin-polarization mechanism present dictates …
Pressure and Thermally Induced Spin Crossover in a 2D Iron(II) Coordination Polymer {Fe[bipy(ttr)2]}n
2021
Using magnetic measurements and UV -visible spectroscopy we have studied the pressure influence on the spin crossover (SCO) properties of the 2D Fe (II) coordination polymer formulated {Fe[bipy(ttr) 2 ]} n . At variable temperature and fixed pressure, we have measured the magnetic property of this compound. Under different pressures and at room temperature, the visible spectroscopy has been observed. The magnetic experiment displays a two-step spin crossover behavior under pressure. The visible spectroscopic measurements at room temperature show a spin crossover with an asymmetric hysteresis at 0.4GPa.
Studying the reduction of graphene oxide with magnetic measurements
2019
Abstract The reduction of graphene oxide is one of the most facile methods to fabricate a large amount of graphene. The reduction rate is generally examined by various spectroscopic techniques, but each technique is applied for different purposes. Herein, we demonstrate the correlation between spectroscopic results and magnetic data, which plays an important role in determining the quality of reduced graphene oxides. The magnetic signals are related with the carbon-oxygen functional groups analyzed by spectroscopic tools. Especially, highly reduced sample exhibits the diamagnetic property similar to graphene-like materials. This report can provide an insight to determine the reduction rate …