Role of ancillary ligands in -nitrosothiol and NO generation from nitrite-thiol interactions at mononuclear zinc(ii) sites.

Generation of -nitrosothiol (RSNO) and nitric oxide (NO) mediated by zinc(ii) coordination motifs is of prime importance for understanding the role of zinc(ii)-based cofactors in redox-signalling pathways. This study uniquely employs a set of mononuclear [LZn] cores (where L = MePzPz/MePzPy/MePzQu) for introducing subtle alterations of the primary coordination sphere and investigates the role of ligand tuning in the transformation of NO in the presence of thiols. Single crystal X-ray diffraction (SCXRD) analyses on [LZn-X](X) (where X = perchlorate/triflate) illustrate consistent changes in the bond distances, thereby showing variations of the metal-ligand interactions depending on the nature of the heterocyclic donor arms (pyrazole/pyridine/quinoline).

Synergistic Activation of Nitrite and Thiocarbonyl Compounds Affords NO and Sulfane Sulfur via (Per)thionitrite (SNO /SSNO ).

(Per)thionitrite (SNO /SSNO ) intermediates play vital roles in modulating nitric oxide (NO) and hydrogen sulfide (H S) dependent bio-signalling processes. Whilst the previous preparations of such intermediates involved reactive H S/HS or sulfane sulfur (S ) species, the present report reveals that relatively stable thiocarbonyl compounds (such as carbon disulfide (CS ), thiocarbamate, thioacetic acid, and thioacetate) react with nitrite anion to yield SNO /SSNO . For instance, the reaction of CS and nitrite anion (NO ) under ambient condition affords CO and SNO /SSNO .

Nitrite and Nitric Oxide Interconversion at Mononuclear Copper(II): Insight into the Role of the Red Copper Site in Denitrification.

Nitrite (NO ) and nitric oxide (NO) interconversion is crucial for maintaining optimum NO flux in mammalian physiology. Herein we demonstrate that [L Cu (nitrite)] moieties (in 2 a and 2 b; where, L = Me PzPy and Me PzQu) with distorted octahedral geometry undergo facile reduction to provide tetrahedral [L Cu ] (in 3 a and 3 b) and NO in the presence of biologically relevant reductants, such as 4-methoxy-2,6-di-tert-butylphenol (4-MeO-2,6-DTBP, a tyrosine model) and N-benzyl-1,4-dihydronicotinamide (BNAH, a NAD(P)H model). Interestingly, the reaction of excess NO gas with [L Cu (MeCN) ] (in 1 a) provides a putative {CuNO} species, which is effective in mediating the nitrosation of various nucleophiles, such as thiol and amine.

Relative contribution of neutral and deterministic processes in shaping fruit-feeding butterfly assemblages in Afrotropical forests.

The unified neutral theory of biodiversity and biogeography has gained the status of a quantitative null model for explaining patterns in ecological (meta)communities. The theory assumes that individuals of trophically similar species are functionally equivalent. We empirically evaluate the relative contribution of neutral and deterministic processes in shaping fruit-feeding butterfly assemblages in three tropical forests in Africa, using both direct (confronting the neutral model with species abundance data) and indirect approaches (testing the predictions of neutral theory using data other than species abundance distributions).