Synthesis and properties of some RU(11) complexes containing triazole ligands

Photophysical and photochemical properties of a series of Ru(II) complexes containing substituted 1,2,4-triazole ligands have been investigated. Photostability has been observed for a number of complexes containing triazoles. The photoreactivity for these complexes can be induced or inhibited by protonation or deprotonation of the triazole ring; Photoinduced linkage isomerism has been observed for the two isomers of [Ru(bpy)2(Hptr)]2+ (bpy = 2,21-bipyridine; Hptr = 3-(pyridin-2-yl)-1,2,4-triazole). For Ru(bpy)2 complexes containing pyrazyltriazole ligands, it is found that the nature of the emitting 3m l CT state can be controlled by pH: when the triazole ring is changed from the protonated form to the deprotonated form, the LUMO is switched from bpy to pyrazyltriazoles. The emission lifetime for the two isomers of [Ru(phen)2(ptr)]+ (phen = 1 ,1 0 -phenanthroline) is found to be much longer than their bpy- or dmb-based (dmb = 4,41-dimethyl-2 ,2 1-bipyridine) analogues and comparable to [Ru(bpy)3]2+. These phen-based two isomers are photostable. Significant oxygen quenching behaviour has been observed for these two isomers. Ru(II) complexes containing a pyridyltriazole ligand linked to a hydroquinone group have been synthesised and separated using semi-preparative HPLC. The compounds have been characterised using ^H-NMR, UV-vis absorption, emission and electrochemistry. Preliminary photophysical studies show that for one of the coordination isomers, reductive quenching of the 3mlCT state by the hydroquinone group is at best inefficient. For another isomer’, where the hydroquinone group is coordinated, protonation results in an increase in emission lifetime, of which the value is much higher compared to the first isomer, where the hydroquinone is uncoordinated, and also longer compared to the corresponding dinuclear complex. Electrochemically induced proton transfer process has been observed for two Ru(II) complexes containing triazole ligands, where no external proton source is needed and the process can be most likely viewed as intramolecular

H-Theorem and Generalized Entropies Within the Framework of Non Linear Kinetics

In the present effort we consider the most general non linear particle kinetics within the framework of the Fokker-Planck picture. We show that the kinetics imposes the form of the generalized entropy and subsequently we demonstrate the H-theorem. The particle statistical distribution is obtained, both as stationary solution of the non linear evolution equation and as the state which maximizes the generalized entropy. The present approach allows to treat the statistical distributions already known in the literature in a unifying scheme. As a working example we consider the kinetics, constructed by using the $\kappa$-exponential $\exp_{_{\{\kappa\}}}(x)= (\sqrt{1+\kappa^2x^2}+\kappa x)^{1/\kappa}$ recently proposed which reduces to the standard exponential as the deformation parameter $\kappa$ approaches to zero and presents the relevant power law asymptotic behaviour $\exp_{_{\{\kappa\}}}(x){\atop\stackrel\sim x\to \pm \infty}|2\kappa x|^{\pm 1/|\kappa|}$. The $\kappa$-kinetics obeys the H-theorem and in the case of Brownian particles, admits as stationary state the distribution $f=Z^{-1}\exp_{_{\{\kappa\}}}[-(\beta mv^2/2-\mu)]$ which can be obtained also by maximizing the entropy $S_{\kappa}=\int d^n v [ c(\kappa)f^{1+\kappa}+c(-\kappa)f^{1-\kappa}]$ with $c(\kappa)=-Z^{\kappa}/ [2\kappa(1+\kappa)]$ after properly constrained.Comment: To appear in Phys. Lett.

Asian pollution climatically modulates mid-latitude cyclones following hierarchical modelling and observational analysis

Increasing levels of anthropogenic aerosols in Asia have raised considerable concern regarding its potential impact on the global atmosphere, but the magnitude of the associated climate forcing remains to be quantified. Here, using a novel hierarchical modelling approach and observational analysis, we demonstrate modulated mid-latitude cyclones by Asian pollution over the past three decades. Regional and seasonal simulations using a cloud-resolving model show that Asian pollution invigorates winter cyclones over the northwest Pacific, increasing precipitation by 7% and net cloud radiative forcing by 1.0 W m(-2) at the top of the atmosphere and by 1.7 W m(-2) at the Earth's surface. A global climate model incorporating the diabatic heating anomalies from Asian pollution produces a 9% enhanced transient eddy meridional heat flux and reconciles a decadal variation of mid-latitude cyclones derived from the Reanalysis data. Our results unambiguously reveal a large impact of the Asian pollutant outflows on the global general circulation and climate.Multidisciplinary SciencesSCI(E)[email protected]; [email protected]

Radiative absorption enhancement of dust mixed with anthropogenic pollution over East Asia

The particle mixing state plays a significant yet poorly quantified role in aerosol radiative forcing, especially for the mixing of dust (mineral absorbing) and anthropogenic pollution (black carbon absorbing) over East Asia. We have investigated the absorption enhancement of mixed-type aerosols over East Asia by using the Aerosol Robotic Network observations and radiative transfer model calculations. The mixed-type aerosols exhibit significantly enhanced absorbing ability than the corresponding unmixed dust and anthropogenic aerosols, as revealed in the spectral behavior of absorbing aerosol optical depth, single scattering albedo, and imaginary refractive index. The aerosol radiative efficiencies for the dust, mixed-type, and anthropogenic aerosols are −101.0, −112.9, and −98.3 Wm⁻²τ⁻¹ at the bottom of the atmosphere (BOA); −42.3, −22.5, and −39.8 Wm⁻²τ⁻¹ at the top of the atmosphere (TOA); and 58.7, 90.3, and 58.5 Wm⁻²τ⁻¹ in the atmosphere (ATM), respectively. The BOA cooling and ATM heating efficiencies of the mixed-type aerosols are significantly higher than those of the unmixed aerosol types over the East Asia region, resulting in atmospheric stabilization. In addition, the mixed-type aerosols correspond to a lower TOA cooling efficiency, indicating that the cooling effect by the corresponding individual aerosol components is partially counteracted. We conclude that the interaction between dust and anthropogenic pollution not only represents a viable aerosol formation pathway but also results in unfavorable dispersion conditions, both exacerbating the regional air pollution in East Asia. Our results highlight the necessity to accurately account for the mixing state of aerosols in atmospheric models over East Asia in order to better understand the formation mechanism for regional air pollution and to assess its impacts on human health, weather, and climate

Determinant Role of Aerosols From Industrial Sources in Hurricane Harvey's Catastrophe

The destructive power of tropical cyclones is driven by latent heat released from water condensation and is inevitably linked to the abundance of aerosols as cloud condensation nuclei. However, the aerosol effects are unaccounted for in most operational hurricane forecast models. We combined multisource measurements and cloud‐resolving model simulations to show fundamentally altered cloud microphysical and thermodynamic processes by anthropogenic aerosols during Hurricane Harvey. Our observational analyses reveal intense lightning and precipitation in the proximity of Houston industrial areas, and these hot spots exhibit a striking geographic similarity to a climatological maximum of lightning flash density in the south‐central United States. Our ensemble cloud‐resolving simulations of Hurricane Harvey indicate that aerosols increase precipitation and lightning by a factor of 2 in the Houston urban area, unraveling the key anthropogenic factor in regulating flooding during this weather extreme