Electronic Excited States of Tungsten(0) Arylisocyanides

W(CNAryl)_6 complexes containing 2,6-diisopropylphenyl isocyanide (CNdipp) are powerful photoreductants with strongly emissive long-lived excited states. These properties are enhanced upon appending another aryl ring, e.g., W(CNdippPh^(OMe)_2)_6; CNdippPh^(OMe)_2 = 4-(3,5-dimethoxyphenyl)-2,6-diisopropylphenylisocyanide (Sattler et al. J. Am. Chem. Soc. 2015, 137, 1198−1205). Electronic transitions and low-lying excited states of these complexes were investigated by time-dependent density functional theory (TDDFT); the lowest triplet state was characterized by time-resolved infrared spectroscopy (TRIR) supported by density functional theory (DFT). The intense absorption band of W(CNdipp)_6 at 460 nm and that of W(CNdippPh^(OMe)_2)_6 at 500 nm originate from transitions of mixed ππ*(C≡N–C)/MLCT(W → Aryl) character, whereby W is depopulated by ca. 0.4 e– and the electron-density changes are predominantly localized along two equatorial molecular axes. The red shift and intensity rise on going from W(CNdipp)_6 to W(CNdippPh^(OMe)_2)_6 are attributable to more extensive delocalization of the MLCT component. The complexes also exhibit absorptions in the 300–320 nm region, owing to W → C≡N MLCT transitions. Electronic absorptions in the spectrum of W(CNXy)_6 (Xy = 2,6-dimethylphenyl), a complex with orthogonal aryl orientation, have similar characteristics, although shifted to higher energies. The relaxed lowest W(CNAryl)_6 triplet state combines ππ* excitation of a trans pair of C≡N–C moieties with MLCT (0.21 e–) and ligand-to-ligand charge transfer (LLCT, 0.24–0.27 e–) from the other four CNAryl ligands to the axial aryl and, less, to C≡N groups; the spin density is localized along a single Aryl–N≡C–W–C≡N–Aryl axis. Delocalization of excited electron density on outer aryl rings in W(CNdippPh^(OMe)_2)_6 likely promotes photoinduced electron-transfer reactions to acceptor molecules. TRIR spectra show an intense broad bleach due to ν(C≡N), a prominent transient upshifted by 60–65 cm^(–1), and a weak down-shifted feature due to antisymmetric C≡N stretch along the axis of high spin density. The TRIR spectral pattern remains unchanged on the femtosecond-nanosecond time scale, indicating that intersystem crossing and electron-density localization are ultrafast (<100 fs)

Geographical and temporal distribution of SARS-CoV-2 clades in the WHO European Region, January to June 2020

We show the distribution of SARS-CoV-2 genetic clades over time and between countries and outline potential genomic surveillance objectives. We applied three available genomic nomenclature systems for SARS-CoV-2 to all sequence data from the WHO European Region available during the COVID-19 pandemic until 10 July 2020. We highlight the importance of real-time sequencing and data dissemination in a pandemic situation. We provide a comparison of the nomenclatures and lay a foundation for future European genomic surveillance of SARS-CoV-2.Peer reviewe

Peripheral circadian clocks are diversely affected by adrenalectomy

<p>Glucocorticoids are considered to synchronize the rhythmicity of clock genes in peripheral tissues; however, the role of circadian variations of endogenous glucocorticoids is not well defined. In the present study, we examined whether peripheral circadian clocks were impaired by adrenalectomy. To achieve this, we tested the circadian rhythmicity of core clock genes (<i>Bmal1, Per1-3, Cry1, RevErbα, Rora</i>), clock-output genes (<i>Dbp, E4bp4</i>) and a glucocorticoid- and clock-controlled gene (<i>Gilz</i>) in liver, jejunum, kidney cortex, splenocytes and visceral adipose tissue (VAT). Adrenalectomy did not affect the phase of clock gene rhythms but distinctly modulated clock gene mRNA levels, and this effect was partially tissue-dependent. Adrenalectomy had a significant inhibitory effect on the level of <i>Per1</i> mRNA in VAT, liver and jejunum, but not in kidney and splenocytes. Similarly, adrenalectomy down-regulated mRNA levels of <i>Per2</i> in splenocytes and VAT, <i>Per3</i> in jejunum, <i>RevErbα</i> in VAT and <i>Dbp</i> in VAT, kidney and splenocytes, whereas the mRNA amounts of <i>Per1</i> and <i>Per2</i> in kidney and <i>Per3</i> in VAT and splenocytes were up-regulated. On the other hand, adrenalectomy had minimal effects on <i>Rora</i> and <i>E4bp4</i> mRNAs. Adrenalectomy also resulted in decreased level of <i>Gilz</i> mRNA but did not alter the phase of its diurnal rhythm. Collectively, these findings suggest that adrenalectomy alters the mRNA levels of core clock genes and clock-output genes in peripheral organs and may cause tissue-specific modulations of their circadian profiles, which are reflected in changes of the amplitudes but not phases. Thus, the circulating corticosteroids are necessary for maintaining the high-amplitude rhythmicity of the peripheral clocks in a tissue-specific manner.</p