Search results for " Ligands"
showing 6 items of 196 documents
Bulky Surface Ligands Promote Surface Reactivities of [Ag141X12(S-Adm)40]3+ (X=Cl, Br, I) Nanoclusters: Models for Multiple-Twinned Nanoparticles
2017
Surface ligands play important roles in controlling the size and shape of metal nanoparticles and their surface properties. In this work, we demonstrate that the use of bulky thiolate ligands, along with halides, as the surface capping agent promotes the formation of plasmonic multiple-twinned Ag nanoparticles with high surface reactivities. The title nanocluster [Ag141X12(S-Adm)40]3+ (where X = Cl, Br, I; S-Adm = 1-adamantanethiolate) has a multiple-shell structure with an Ag71 core protected by a shell of Ag70X12(S-Adm)40. The Ag71 core can be considered as 20 frequency-two Ag10 tetrahedra fused together with a dislocation that resembles multiple-twinning in nanoparticles. The nanocluster…
Synthesis and Structure-Affinity Relationships of Spirocyclic Benzopyrans with Exocyclic Amino Moiety
2019
σ1 and/or σ2 receptors play a crucial role in pathological conditions such as pain, neurodegenerative disorders, and cancer. A set of spirocyclic cyclohexanes with diverse O-heterocycles and amino moieties (general structure III) was prepared and pharmacologically evaluated. In structure-activity relationships studies, the σ1 receptor affinity and σ1:σ2 selectivity were correlated with the stereochemistry, the kind and substitution pattern of the O-heterocycle, and the substituents at the exocyclic amino moiety. cis-configured 2-benzopyran cis-11b bearing a methoxy group and a tertiary cyclohexylmethylamino moiety showed the highest σ1 affinity ( Ki = 1.9 nM) of this series of compounds. In…
A Unified AMBER-Compatible Molecular Mechanics Force Field for Thiolate-Protected Gold Nanoclusters.
2016
We present transferable AMBER-compatible force field parameters for thiolate-protected gold nanoclusters. Five different sized clusters containing both organo-soluble and water-soluble thiolate ligands served as test systems in MD simulations, and parameters were validated against DFT and experimental results. The cluster geometries remain intact during the MD simulations in various solvents, and structural fluctuations and energetics showed agreement with DFT calculations. Experimental diffusion coefficients and crystal structures were also reproduced with sufficient accuracy. The presented parameter set contains the minimum number of cluster-specific parameters enabling the use of these p…
Weak Interactions between Trivalent Pnictogen Centers: Computational Analysis of Bonding in Dimers X3E···EX3 (E = Pnictogen, X = Halogen)
2009
The nature of weak interactions in dimers X3E···EX3 (E = N−Bi, X = F−I) was investigated by wave function and density functional theory (DFT)-based methods. Out of the 20 systems studied, 10 are found to be bound at the CP-MP2 and LMP2 levels of theory. Detailed partition of the interaction energy into different components revealed that dispersion is the primary force holding the dimers together but there also exists an important ionic component whose contribution increases with increasing halogen size. As expected, standard density functionals fail to describe bonding in the studied systems. However, the performance of DFT methods can be easily improved via empirical dispersion correction …
New Tetraphosphane Ligands {(X2P)2NC6H4N(PX2)2} (X = Cl, F, OMe, OC6H4OMe-o): Synthesis, Derivatization, Group 10 and 11 Metal Complexes and Catalyti…
2008
The reaction of p-phenylenediamine with excess PCl3 in the presence of pyridine affords p-C6H4[N(PCl2)2]2 (1) in good yield. Fluorination of 1 with SbF3 produces p-C6H4[N(PF2)2]2 (2). The aminotetra(phosphonites) p-C6H4[N{P(OC6H4OMe-o)2}2]2 (3) and p-C6H4[N{P(OMe)2}2]2 (4) have been prepared by reacting 1 with appropriate amount of 2-(methoxy)phenol or methanol, respectively, in the presence of triethylamine. The reactions of 3 and 4 with H2O2, elemental sulfur, or selenium afforded the tetrachalcogenides, p-C6H4[N{P(O)(OC6H4OMe-o)2}2]2 (5), p-C6H4[N{P(S)(OMe)2}2]2 (6), and p-C6H4[N{P(Se)(OMe)2}2]2 (7) in good yield. Reactions of 3 with [M(COD)Cl2] (M = Pd or Pt) (COD = cycloocta-1,5-diene)…
Dioxomolybdenum(VI) and -Tungsten(VI) Amino Bisphenolates as Epoxidation Catalysts
2016
Low-cost metallate salts Na2MO4·2H2O (M = molybdenum, tungsten) react with a tridentate amine bisphenol bis(2-hydroxy-3-tert-butyl-5-methylbenzyl)methylamine (H2ONOtBu) under ambient conditions in acidic methanol solutions. The reactions lead to the formation of isostructural dioxo complexes [MO2(ONOtBu)(MeOH)]·MeOH in convenient yields. Spectral data as well as X-ray analyses reveal these complexes to be isostructural. Both compounds were tested as catalysts for epoxidation of olefins using cis-cyclooctene, cyclohexene, norbornene and styrene as substrates and tert-butyl hydroperoxide and hydrogen peroxide as oxidants. The molybdenum complex catalyses selectively the oxidation of cis-cyclo…