The Influence of Secondary Interactions on the [N-I-N] Halogen Bond.

[Bis(pyridine)iodine(I)] complexes offer controlled access to halonium ions under mild conditions. The reactivity of such stabilized halonium ions is primarily determined by their three-center, four-electron [N-I-N] halogen bond. We studied the importance of chelation, strain, steric hindrance and electrostatic interaction for the structure and reactivity of halogen bonded halonium ions by acquiring their N NMR coordination shifts and measuring their iodenium release rates, and interpreted the data with the support of DFT computations.

Modulating photoswitch performance with halogen, coordinative and hydrogen bonding: a comparison of relative bond strengths.

The behavior of an enediyne photoswitch is modulated with halogen bonding, coordinative bonding and hydrogen bonding. Through NMR and computational studies we demonstrate that the relative strength of the secondary bonding directly influences the rate of photoisomerization and the photostationary state.

O-I-O halogen bond of halonium ions.

The reactivity of halonium ions is conveniently modulated by three-center, four-electron halogen bonds. Such stabilized halonium complexes are valuable reagents for oxidations and halofunctionalization reactions. We report the first example of the stabilization of a halenium ion in a three-center, four-electron halogen bond with two oxygen ligands.

A Meroisoprenoid, Heptenolides, and -Benzylated Flavonoids from ssp. .

A new meroisoprenoid (), two heptenolides ( and ), two -benzylated flavonoids ( and ), and 11 known compounds (-) were isolated from leaf, stem bark, and root bark extracts of ssp. by chromatographic separation. The structures of the new metabolites - were established by NMR, IR, and UV spectroscopic and mass spectrometric data analysis.

Halogen Bonding Helicates Encompassing Iodonium Cations.

The first halonium-ion-based helices were designed and synthesized using oligo-aryl/pyridylene-ethynylene backbones that fold around reactive iodonium ions. Halogen bonding interactions stabilize the iodonium ions within the helices. Remarkably, the distance between two iodonium ions within a helix is shorter than the sum of their van der Waals radii.

Halogen Bond Asymmetry in Solution.

Halogen bonding is the noncovalent interaction of halogen atoms in which they act as electron acceptors. Whereas three-center hydrogen bond complexes, [D···H···D] where D is an electron donor, exist in solution as rapidly equilibrating asymmetric species, the analogous halogen bonds, [D···X···D], have been observed so far only to adopt static and symmetric geometries. Herein, we investigate whether halogen bond asymmetry, i.

The N-methyl-d-aspartic acid receptor antagonist memantine ameliorates and delays the development of arthritis by enhancing regulatory T cells.

The neuroendocrine impact on rheumatoid arthritis is not yet fully described although numerous neurotransmitters are shown to act as inflammatory modulators. One of these is the excitatory transmitter glutamate (Glu). In this study, the influence of the Glu receptor (GluR)-mediated effects on collagen-induced arthritis (CIA) was investigated.

Smoking and nicotine exposure delay development of collagen-induced arthritis in mice.

Introduction: Recent epidemiologic studies have implicated smoking as an environmental risk factor for the development of rheumatoid arthritis (RA). The aim of the present study is the evaluation of the role of cigarette smoke (CS) in the pathogenesis of collagen-induced arthritis in mice.

Methods: DBA/1 mice exposed to CS for 16 weeks (n = 25) and mice exposed to nicotine in drinking water (n = 10) were immunized with collagen type II (CII).

Ethanol prevents development of destructive arthritis.

Environmental factors are thought to play a major role in the development of rheumatoid arthritis. Because the use of ethanol is widespread, we assessed the role of ethanol intake on the propensity to develop chronic arthritis. Collagen type II-immunized mice were given water or water containing 10% (vol/vol) ethanol or its metabolite acetaldehyde.

Balance between survivin, a key member of the apoptosis inhibitor family, and its specific antibodies determines erosivity in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a highly heterogeneous disease with respect to its joint destructivity. The reasons underlying this heterogeneity are unknown. Deficient apoptosis in rheumatoid synovial tissue has been recently demonstrated.