Synthesis, characterization and corrosion inhibition efficiency of 2-(6-methylpyridin-2-yl)-1H-imidazo[4,5-f][1,10] phenanthroline on mild steel in sulphuric acid

AbstractPhenanthroline derivative, 2-(6-methylpyridin-2-yl)-1H-imidazo[4,5-f][1,10] phenanthroline (MIP) was synthesized and characterized by elemental analysis, FT-IR, 1H NMR, 13C NMR, and single crystal X-ray diffraction study. MIP was evaluated as corrosion inhibitor for mild steel in 0.5M H2SO4 solution using gravimetric and UV–Visible spectrophotometric methods at 303–333K. Results obtained show that MIP acts as inhibitor for mild steel in H2SO4 solution. The inhibition efficiency was found to increase with increase in MIP concentration but decreased with temperature. Activation parameters and Gibbs free energy for the adsorption process using statistical physics were calculated and discussed. The UV–Visible absorption spectra of the solution containing the inhibitor after the immersion of mild steel specimen indicate the formation of a MIP-Fe complex

Influence of structural and thermal factors on phenoxazinone synthase activities catalysed by coordinatively saturated cobalt(III) octahedral complexes bearing diazene–disulfonamide N⌃N⌃N chelators

There are increasing efforts towards the development of new synthetic models that can mimic phenoxazinone synthase activity due to the important applications of several biomolecules bearing the phenoxazinone chromophore. However, deliberate studies of systematically varied coordination species for the knowledge of underlying molecular determinants of catalytic outcomes using fully characterized mimicking models are scarce. In this report, two new dianionic and synthetically obtained diazene–disulfonamide N⌃N⌃N chelators of the form RSO2–NH–Ph–N=N–Ph–NHSO2R (R $_2$ methyl for 1 and tolyl for 2) are coordinatively self-assembled around cobalt(III) centres in the presence or absence of co-ligands (acetate, bipyridine, 4-dimethylaminopyridine and/or water) to obtain four new and structurally analysed complexes [Co12][Et3NH], Co1$_2$OAc$=$bpy, Co1$_{\mathbf{2}}$OAc${\cdot }$bpy and Co2${\cdot }$dmap${\cdot }$w, which are all found to be octahedral cobalt(III) polyhedra, distorted to varying extents, by using Continuous Shape Measurement calculations. Based on structural and thermal factors, it is observed that the trends of the phenoxazinone synthase mimicking activities by these complexes correlate with their inherent abilities to generate vacant coordination space for substrate–metal ion interactions. Finally, it is also observed that coordinative steric strains control catalytic trends among the complexes at low temperatures while susceptibility to thermal dissociations is the determinant at higher temperatures

Influence of structural and thermal factors on phenoxazinone synthase activities catalysed by coordinatively saturated cobalt(III) octahedral complexes bearing diazene–disulfonamide N⌃N⌃N chelators

There are increasing efforts towards the development of new synthetic models that can mimic phenoxazinone synthase activity due to the important applications of several biomolecules bearing the phenoxazinone chromophore. However, deliberate studies of systematically varied coordination species for the knowledge of underlying molecular determinants of catalytic outcomes using fully characterized mimicking models are scarce. In this report, two new dianionic and synthetically obtained diazene–disulfonamide N⌃N⌃N chelators of the form RSO2–NH–Ph–N=N–Ph–NHSO2R (R $_2$ methyl for 1 and tolyl for 2) are coordinatively self-assembled around cobalt(III) centres in the presence or absence of co-ligands (acetate, bipyridine, 4-dimethylaminopyridine and/or water) to obtain four new and structurally analysed complexes [Co12][Et3NH], Co1$_2$OAc$=$bpy, Co1$_{\mathbf{2}}$OAc${\cdot }$bpy and Co2${\cdot }$dmap${\cdot }$w, which are all found to be octahedral cobalt(III) polyhedra, distorted to varying extents, by using Continuous Shape Measurement calculations. Based on structural and thermal factors, it is observed that the trends of the phenoxazinone synthase mimicking activities by these complexes correlate with their inherent abilities to generate vacant coordination space for substrate–metal ion interactions. Finally, it is also observed that coordinative steric strains control catalytic trends among the complexes at low temperatures while susceptibility to thermal dissociations is the determinant at higher temperatures

The phosphorylation landscape of infection-related development by the rice blast fungus

Many of the world’s most devastating crop diseases are caused by fungal pathogens that elaborate specialized infection structures to invade plant tissue. Here, we present a quantitative mass-spectrometry-based phosphoproteomic analysis of infection-related development by the rice blast fungus Magnaporthe oryzae, which threatens global food security. We mapped 8,005 phosphosites on 2,062 fungal proteins following germination on a hydrophobic surface, revealing major re-wiring of phosphorylation-based signaling cascades during appressorium development. Comparing phosphosite conservation across 41 fungal species reveals phosphorylation signatures specifically associated with biotrophic and hemibiotrophic fungal infection. We then used parallel reaction monitoring (PRM) to identify phosphoproteins regulated by the fungal Pmk1 MAPK that controls plant infection by M. oryzae. We define 32 substrates of Pmk1 and show that Pmk1-dependent phosphorylation of regulator Vts1 is required for rice blast disease. Defining the phosphorylation landscape of infection therefore identifies potential therapeutic interventions for the control of plant diseases

Spatial control of organelle dynamics during appressorium-mediated plant infection by Magnaporthe oryzae

Magnaporthe oryzae, the pathogen responsible for the rice blast disease, produces a specialised infection structure called an appressorium that uses massive turgor to break the tough outer cuticle of the rice leaf. Appressorium development is a tightly regulated process that requires surface recognition of a hard hydrophobic surface, successful traversal of cell cycle checkpoints, and autophagic conidial cell death. It is however unknown how organelle trafficking is regulated and spatially controlled in parallel with autophagy and cell cycle progression. I developed molecular markers and a quantitative technique to monitor the trafficking of specific organelles in M. oryzae wild-type strain Guy11 and an ∆atg8 autophagic mutant. Live-cell imaging and quantitative analysis enabled us to characterise the regulated trafficking of 10 organelles within the three-celled conidium during appressorium development. High-resolution live-cell imaging using a photoactivatable green fluorescent protein indicates that germination establishes a separate developmental programme for each conidium cell, permitting organelle trafficking from a single conidium cell into the appressorium while targeting the remaining two cells for autophagy. We discovered that organelle trafficking occurs independently of cell cycle checkpoints for transport into the appressorium. I have quantified the temporal sequence of organelle movement and de novo organelle biogenesis in the incipient appressorium using photoconvertible fluorescent localisation microscopy. Our study shed light on the spatial control of organelle dynamics associated with fungal infection-related morphogenesis