Electrochemically Generated Luminescence of Luminol and Luciferin in Ionic Liquids

Electrochemiluminescence (ECL) is the generation of light triggered by an electrochemical reaction. ECL has been extensively studied in solvent-based electrolytes, but there is a lack of data on using electrode reactions to populate an excited-state light emitter in room temperature ionic liquids (RTILs). This work explores the current response, light intensity (photon counting), and spectral signatures of the cathodic ECL of luminol and firefly's luciferin in imidazolium-based RTILs. We have demonstrated that the cathodic (superoxide-triggered) ECL of both luminol and adenylate-ester of firefly's luciferin is viable in RTILs, explored the effect of water contaminations, and importantly, shown that the ECL signal persists for up to about 700 s after the removal of the external cathodic pulse, which is probably due to the stabilization of superoxide by double-layer cation-rich structures. Long-lived RTIL double-layer structures and their endogenous fields are detected as stable and discrete open-circuit potential plateaus

Diabetic foot infections: a team-oriented review of medical and surgical management

As the domestic and international incidence of diabetes and metabolic syndrome continues to rise, health care providers need to continue improving management of the long-term complications of the disease. Emergency department visits and hospital admissions for diabetic foot infections are increasingly commonplace, and a like-minded multidisciplinary team approach is needed to optimize patient care. Early recognition of severe infections, medical stabilization, appropriate antibiotic selection, early surgical intervention, and strategic plans for delayed reconstruction are crucial components of managing diabetic foot infections. The authors review initial medical and surgical management and staged surgical reconstruction of diabetic foot infections in the inpatient setting

Synthesis, physicochemical and vibrational spectral properties of 2–pyridone and 2–aminopyridine derivatives: An experimental and theoretical study

A convenient and efficient one–pot three–component reaction of acetyl acetone, malononitrile and ammonium acetate was investigated for the synthesis of 3–cyano–4,6–dimethyl–2–pyridone (PI) and 2–amino–3–cyano–4,6–dimethylpyridine (PII). The products were achieved with high purity, high yields and short reaction time. The yields of the two products depend on the concentration of ammonium acetate, reaction time and the solvent used. The structures of the isolated products were confirmed by elemental analysis and spectral data, supported by quantum chemical (MP2) calculations, both in gas phase and solvents (water and ethanol), that were also employed to track the reaction mechanisms and model vibrational spectral properties for final characterization and interpretation of spectral data. A remarkable matching between theoretical predictions and experiments was attained both for the geometrical parameters, as compared to X-Ray data available in the literature, and for vibrational frequencies, leading to a correlation coefficient (R2) of 0.99. Molecular docking was further studied to predict the docking binding energy of the synthesized compounds with the target proteins

Intramelcular Photoinduced Charge Transfert in Visual Retinal Chromophore Mimics: Electron Density Based Indices at the DFT and post-HF Levels

International audienc

Photoelectrochromism in the Retinal Protonated Schiff Base Chromophore: Photoisomerization Speed and Selectivity under a Homogeneous Electric Field at Different Operational Regimes

The spectral tunability, photoisomerization efficiency and selectivity, of the native all-trans retinal protonated Shiff base (PSB) chromophore driven by a homogeneous electric field is systematically investigated. By analyzing the absorption wavelength dependence, charge distribution, and PES profiles along selected torsional angles, as well as the electronic structure, energetics, and topography of the CI seam in the presence of strong positive and negative electric fields, we recognize the existence of qualitatively/fundamentally different photophysics and photochemistry with respect to the unperturbed (i.e., absence of an electric field) chromophore. We rationalize the findings within the scope of molecular orbital theory and deliver a unified picture of the photophysics of the retinal PSB chromophore over a wide, even beyond the usually observed, spectral regime, ranging from the near-infrared to the ultraviolet absorption energies. This work has a 3-fold impact: a) it accounts for, and extends, previous theoretical studies on the subject; b) it delivers a rationale for the ES lifetimes observed in retinal proteins, both archeal and visual rhodopsins, as well as in solvent; and c) the transferability of the discovered trends on PSB mimics is demonstrated

Type and density of dislocations in a plastically deformed long-period stacking ordered magnesium alloy

The density and type of dislocations were studied in a plastically deformed long-period stacking ordered (LPSO) phase of a MgYZn (at.%) alloy. The volume fraction of the LPSO phase was as high as ∼85%. The plastic deformation was carried out by uniaxial compression up to the strain of ∼25% in both as-cast and extruded states. The order of magnitude of the dislocation density was ∼10 m after compression to the strain of ∼25% for both as-cast and extruded materials. It was also found that most of the dislocations formed in the LPSO phase during extrusion and compression were of -type. The as-cast sample did not exhibit a strong crystallographic texture, but extrusion caused a texture in which the normal vector of the basal plane was perpendicular to the extrusion axis. The texture developed during extrusion yielded an anisotropic evolution of the dislocation density during subsequent compression. Namely, the density of dislocations developed during compression was lower when the deformation was carried out parallel to the extrusion axis.The authors thank Prof. M. Leoni (University of Trento) for his help and providing the PM2K software. This work was financed partly by the Ministry of Human Capacities of Hungary within the ELTE University Excellence program (1783-3/2018/FEKUTSRAT). Authors would like to acknowledge financial support the Czech Grant Agency under grant Nr. 16-12075S.Peer Reviewe

Relationship between Excited State Lifetime and Isomerization Quantum Yield in Animal Rhodopsins: Beyond the One-Dimensional Landau-Zener Model

We show that the speed of the chromophore photoisomerization of animal rhodopsins is not a relevant control knob for their light sensitivity. This result is at odds with the momentum-driven tunnelling rationale (i.e., assuming a one-dimensional Landau-Zener model for the decay: Zener, C. Non-Adiabatic Crossing of Energy Levels. Proc. R. Soc. London, Ser. A 1932, 137 (833), 696-702) holding that a faster nuclear motion through the conical intersection translates into a higher quantum yield and, thus, light sensitivity. Instead, a model based on the phase-matching of specific excited state vibrational modes should be considered. Using extensive semiclassical hybrid quantum mechanics/molecular mechanics trajectory computations to simulate the photoisomerization of three animal rhodopsin models (visual rhodopsin, squid rhodopsin and human melanopsin), we also demonstrate that phase-matching between three different modes (the reactive carbon and hydrogen twisting coordinates and the bond length alternation mode) is required to achieve high quantum yields. In fact, such "phase-matching" mechanism explains the computational results and provides a tool for the prediction of the photoisomerization outcome in retinal proteins

Photoelectrochromism in the Retinal Protonated Schiff Base Chromophore: Photoisomerization Speed and Selectivity under a Homogeneous Electric Field at Different Operational Regimes

The spectral tunability, photoisomerization efficiency and selectivity, of the native all-trans retinal protonated Shiff base (PSB) chromophore driven by a homogeneous electric field is systematically investigated. By analyzing the absorption wavelength dependence, charge distribution, and PES profiles along selected torsional angles, as well as the electronic structure, energetics, and topography of the CI seam in the presence of strong positive and negative electric fields, we recognize the existence of qualitatively/fundamentally different photophysics and photochemistry with respect to the unperturbed (i.e., absence of an electric field) chromophore. We rationalize the findings within the scope of molecular orbital theory and deliver a unified picture of the photophysics of the retinal PSB chromophore over a wide, even beyond the usually observed, spectral regime, ranging from the near-infrared to the ultraviolet absorption energies. This work has a 3-fold impact: a) it accounts for, and extends, previous theoretical studies on the subject; b) it delivers a rationale for the ES lifetimes observed in retinal proteins, both archeal and visual rhodopsins, as well as in solvent; and c) the transferability of the discovered trends on PSB mimics is demonstrated