Analysis and insights into recombination signals in lumpy skin disease virus recovered in the field.

Wide spread incidences of vaccine-like strains of lumpy skin disease virus (LSDV) have recently been reported in a Russian region with a neighboring country that actively vaccinate with a live attenuated LSD vaccine. The use of live-attenuated viruses (LAVs) as vaccines during an active outbreak, creates potential ground for coinfection of hosts and emergence of a strain combining genetic fragments of both parental vaccine and field strains. In this study, we analyse the vaccine-like strain LSDV RUSSIA/Saratov/2017 detected in Saratovskaya oblast, a region sharing border with Kazakhstan. To gain insight into possible recombination signals, a full-genome next-generation sequencing of the viral genome was performed using the Illumina platform. The genome contains the backbone of a live-attenuated vaccine with a patchwork of wild-type field virus DNA fragments located throughout. A total of 27 recombination events were identified. The average distance between the recombination sites was 3400 base pairs (bp). The impact of the recombination events on the virulence and transmission capacity of the identified virus remains to be clarified. These findings provide evidence for the first time of genetic exchanges between closely related strains of capripoxviruses in the field and a vaccine strain, and prompt a revisiting of the vaccination issue for a safe and efficacious prevention and control strategy of LSD

Porphyrins Fused with Unactivated Polycyclic Aromatic Hydrocarbons

A systematic study of the preparation of porphyrins with extended conjugation by <i>meso</i>,β-fusion with polycyclic aromatic hydrocarbons (PAHs) is reported. The <i>meso</i>-positions of 5,15-unsubstituted porphyrins were readily functionalized with PAHs. Ring fusion using standard Scholl reaction conditions (FeCl₃, dichloromethane) occurs for perylene-substituted porphyrins to give a porphyrin β,<i>meso</i> annulated with perylene rings (0.7:1 ratio of <i>syn</i> and <i>anti</i> isomers). The naphthalene, pyrene, and coronene derivatives do not react under Scholl conditions but are fused using thermal cyclodehydrogenation at high temperatures, giving mixtures of <i>syn</i> and <i>anti</i> isomers of the <i>meso</i>,β-fused porphyrins. For pyrenyl-substituted porphyrins, a thermal method gives synthetically acceptable yields (>30%). Absorption spectra of the fused porphyrins undergo a progressive bathochromic shift in a series of naphthyl (λ_max = 730 nm), coronenyl (λ_max = 780 nm), pyrenyl (λ_max = 815 nm), and perylenyl (λ_max = 900 nm) annulated porphyrins. Despite being conjugated with unsubstituted fused PAHs, the β,<i>meso</i>-fused porphyrins are more soluble and processable than the parent nonfused precursors. Pyrenyl-fused porphyrins exhibit strong fluorescence in the near-infrared (NIR) spectral region, with a progressive improvement in luminescent efficiency (up to 13% with λ_max = 829 nm) with increasing degree of fusion. Fused pyrenyl-porphyrins have been used as broadband absorption donor materials in photovoltaic cells, leading to devices that show comparatively high photovoltaic efficiencies

Fused Porphyrin–Single-Walled Carbon Nanotube Hybrids: Efficient Formation and Photophysical Characterization

A systematic study of the interaction between π-extended porphyrins and single-walled carbon nanotubes (SWNTs) is reported here. Zinc porphyrins with 1-pyrenyl groups in the 5,15-<i>meso</i> positions, <b>1</b>, as well as compounds where one or both of the pyrene groups have been fused at the <i>meso</i> and β positions of the porphyrin core, <b>2</b> and <b>3</b>, respectively, have been examined. The strongest binding to SWNTs is observed for porphyrin <b>3</b>, leading to debundling of the nanotubes and formation of stable suspensions of <b>3</b>–SWNT hybrids in a range of common organic solvents. Absorption spectra of <b>3</b>–SWNT suspensions are broad and continuous (λ = 400–1400 nm), and the Q-band of <b>3</b> displays a significant bathochromic shift of 33 nm. The surface coverage of the SWNTs in the nanohybrids was estimated by spectroscopic and analytical methods and found to reach 64% for (7,6) nanotubes. The size and shape of π-conjugated porphyrins were found to be important factors in determining the strength of the π–π interactions, as the linear <i>anti</i>-<b>3</b> isomer displays more than 90% binding selectivity compared to the bent <i>syn</i>-<b>3</b> isomer. Steady-state photoluminescence measurements show quenching of porphyrin emission from the nanohybrids. Femtosecond transient absorption spectroscopy reveals that this quenching results from ultrafast electron transfer from the photoexcited porphyrin to the SWNT (1/<i>k</i>_CT = 260 fs) followed by rapid charge recombination on a picosecond time scale. Overall, our data demonstrate that direct π–π interaction between fused porphyrins and SWNTs leads to electronically coupled stable nanohybrids

N,N-Di<i>aryl</i>anilinosquaraines and Their Application to Organic Photovoltaics

We report new derivatives of symmetric squaraine dyes with N,N-di<i>aryl</i>anilino substituents that have high solubility and high absorptivity (ε = 0.71–4.1 × 10⁵ M^–1cm^–1) in the red solar spectral region (λ_max = 645–694 nm) making them promising candidates for application in organic photovoltaics (OPVs). Unsymmetrical N,N-diisobutylanilino- and N,N-diphenylanilino(diphenylamino)squaraines have also been prepared that give blue-shifted absorption spectra (λ_max = 529–535 nm) relative to their symmetric counterparts. Compared to bis(N,N-diisobutylanilino)squaraine, both symmetrical and unsymmetrical N,N-di<i>aryl</i>anilino squaraines show markedly broader absorption bands in solution than their N,N-di<i>alkyl</i>anilino squaraine counterparts: the full width at half-maximum (fwhm) for N,N-di<i>aryl</i>anilino squaraines range from 1280–1980 cm^–1, while the fwhm value for the N,N-diisobutylanilino squarine is only 630 cm^–1. The absorption bands for thin films of N,N-di<i>aryl</i>anilino squaraines broaden further to 2500–3300 cm^–1. N,N-Di<i>aryl</i>anilino squaraines are fluorescent, albeit with lower quantum yields than bis(N,N-diisobutylanilino)squaraine (ϕ_PL = 0.02–0.66 and 0.80, respectively). OPVs were prepared with solution processed squaraine layers using the following structure: ITO/squaraine (66–85 Å)/C₆₀ (400 Å)/BCP (100 Å)/Al (1000 Å), BCP = bathocuproine. Devices using thin films of the bis(N,N-di<i>aryl</i>anilino)squaraines as donor layers show improved performance relative to OPVs prepared with bis(N,N-di<i>alkyl</i>anilino)squaraines, i.e. bis(N,N-diisobutylanilino)squaraine: open-circuit voltage <i>V</i>_<i>oc</i> = 0.59 ± 0.05 V, short-circuit current <i>J</i>_<i>sc</i> = 5.58 ± 0.16 mA/cm², fill factor <i>FF</i> = 0.56 ± 0.03, and power conversion efficiency η = 1.8 ± 0.2% under 1 sun, AM1.5G simulated illumination, compared with bis(N,N-diphenylanilino)squaraine: <i>V</i>_<i>oc</i> = 0.82 ± 0.02 V, <i>J</i>_<i>sc</i> = 6.71 ± 0.10 mA/cm², <i>FF</i> = 0.59 ± 0.01, and η = 3.2 ± 0.1%. Morphological studies of thin films suggest that the solubility of bis(N,N-di<i>aryl</i>anilino)squaraines plays an important role in controlling the optoelectronic properties of the OPVs