Search results for "ligand"

Synthesis of isomorphous cobalt and nickel thiocyanate coordination compounds: Effect of metals on compound properties

2019

The reaction of 2-methylpiperazine with the thiocyanate ligand and two transition metals leads to the production of two new isomorphous [ML2SCN4] where L is the 2-methylpiperazine and [M =Co (1), and Ni (2)], presenting an octahedral configuration. These compounds were characterized by single crystal X-ray crystallography, TG-DTA analysis, as well as infrared and UV-Vis spectroscopy and TG-DTA. The magnetic and antibacterial properties were also determined. Through the link with N-H···S hydrogen bonds, a global 3D network was established. The studied compounds show the metal center’s impact leading to different properties. Indeed, the first compound shows high spin orbit coupling, whereas t…

Rare‐earth cyclobutadienyl sandwich complexes: Synthesis, structure and dynamic magnetic properties

2018

The potassium cyclobutadienyl [K2{η4‐C4(SiMe3)4}] (1) reacts with MCl3(THF)3.5 (M=Y, Dy) to give the first rare‐earth cyclobutadienyl complexes, that is, the complex anions [M{η4‐C4(SiMe3)4}{η4‐C4(SiMe3)3‐κ‐(CH2SiMe2}]2−, (2M), as their dipotassium salts. The tuck‐in alkyl ligand in 2M is thought to form through deprotonation of the “squarocene” complexes [M{η4‐C4(SiMe3)4}2]− by 1. Complex 2Dy is a single‐molecule magnet, but with prominent quantum tunneling. An anisotropy barrier of 323(22) cm−1 was determined for 2Dy in an applied field of 1 kOe, and magnetic hysteresis loops were observed up to 7 K. nonPeerReviewed

The Instability of Ni{N(SiMe3)2}2: A Fifty Year Old Transition Metal Silylamide Mystery

2015

The characterization of the unstable NiII bis(silylamide) Ni{N(SiMe3)2}2 (1), its THF complex Ni{N(SiMe3)2}2(THF) (2), and the stable bis(pyridine) derivative trans-Ni{N(SiMe3)2}2(py)2 (3), is described. Both 1 and 2 decompose at ca. 25 °C to a tetrameric NiI species, [Ni{N(SiMe3)2}]4 (4), also obtainable from LiN(SiMe3)2 and NiCl2(DME). Experimental and computational data indicate that the instability of 1 is likely due to ease of reduction of NiII to NiI and the stabilization of 4 through dispersion forces. peerReviewed

Modeling the atomic and electronic structure of nanoparticle-ligand interfaces

2013

Modulation of melanoma-associated antigens by monoclonal antibodies as visualized by radioimmunoelectron microscopy and radioantibody binding assay

1987

There is a wealth of information about monoclonal antibody (MAb) specificity and function on fixed tissues, yet little is known about formation and release of antigen-antibody complexes and their functional behavior in vivo. We analyzed the pathway of radiolabeled MAbs directed against melanoma-associated antigens by radioimmunoelectron microscopy (RIEM) on metabolically active cells of the melanoma cell lines SK-MEL-28, MeWo and Colo 38 at different time intervals. In parallel, binding and release of MAbs were investigated by the radioantibody binding assay (RBA). Both procedures gave essentially concordant results. Preferentially stable binding of immune complexes (ICs) to the cell surfac…

Screening for inhibitors of HIV gp120-CD4 binding using an enzyme-linked immunoabsorbent assay.

1993

Binding of the HIV-1 major viral surface glycoprotein, gp120, to the major cell receptor, CD4, is essential for HIV infection of the target cell and syncytium formation. An enzyme-linked immunoassay using solid phase CD4 was used to quantitate the binding of HIV-1 gp120 to CD4, and to assess the activity and mechanism of action of putative inhibitors of that reaction. Monoclonal antibodies to the gp120 binding site on CD4 (e.g., Leu3a) blocked gp120 binding, while monoclonal antibodies to other portions of CD4 (e.g. OKT4) did not. Both aurintricarboxylic acid and sulfonated polysaccharides (e.g., dextran sulfate) blocked CD4-gp120 interactions by binding to the CD4 component. Human polyclon…

16α-Iodo-3,17β-estradiol: A stable ligand for estrogen receptor determinations in tissues with high 17β-hydroxysteroid dehydrogenase activity

1983

Recently, the successful synthesis of radioiodinated 16 alpha-iodo-3,17 beta-estradiol-[125I] [125I]E2 was reported [1]. This new ligand has similar binding characteristics to the estrogen receptor (ER) [2-5] as the currently used tritium labeled estradiol [3H]E2. However, it offers several advantageous features: (a) high specific activity (theoretically 2,000 Ci/mmol) [1]; (b) minor problems with radioactive waste due to its short half life and (c) the possibility of simultaneous determination of ER and progesterone receptors (PgR) by double labeling with [125I]E2 and [3H]R5020 [6, 7]. As we are presently trying to determine ER and PgR in human placental cytosols we were interested in the …

Centenarians overexpress BCL-xL, which confers them a protection against apoptosis, oxidative stress and immunosenescence

2015

Centenarians not only have an extraordinary longevity, but also show a compression of morbidity. They preserve the capacity of maintaining homeostasis, and this is the reason for them to reach such a long life. We studied their mRNA expression profile and identified 1721 mRNAs differentially expressed by centenarians when compared with septuagenarians and young people. A sub-network analysis showed six common genes: interferon, T-cell receptor, tumor necrosis factor, SP1 transcription factor, transforming growth factor and IL-32.These six centenarian-specific genes are related to Bcl-xL, Fas, and Fas ligand all of them involved in the control of apoptosis. RT-PCR analysis confirmed that cen…

Aging and systemic hormonal status affects the circulating miR-21, miR-146a and FasL levels

2015

MicroRNAs are small molecules, found in all cell types and body fluids, which most commonly affect negatively to gene expressions by translational repression. Their role in various physiological conditions and diseases has been emphasized during the last twenty years. In our recent studies with postmenopausal monozygotic twin sisters (n=11), we have investigated how different systemic hormonal status affects the levels of specific circulating microRNAs and other molecules related to inflammation and apoptosis, both processes associated with aging. Our results have shown that the systemic levels of miR-21, miR-146a and Fas ligand are lower within the postmenopausal women who are using estrog…

Getting the Fat out of Met and Fas

2008

Lack of Fas antagonism by Met in human fatty liver disease. Zou C, Ma J, Wang X, Guo L, Zhu Z, Stoops J, Eaker AE, Johnson CJ, Strom S, Michalopoulos GK, DeFrances MC, Zarnegar R. Hepatocytes in fatty livers are hypersensitive to apoptosis and undergo escalated apoptotic activity via death receptor-mediated pathways, particularly that of Fas–FasL, causing hepatic injury that can eventually proceed to cirrhosis and end-stage liver disease. Here we report that the hepatocyte growth factor receptor, Met, plays an important part in preventing Fas-mediated apoptosis of hepatocytes by sequestering Fas. We also show that Fas antagonism by Met is abrogated in human fatty liver disease (FLD). Throug…