Chemical and photochemical properties of chloroharmine derivatives in aqueous solutions

Thermal and photochemical stability (ΦR), room temperature UV-vis absorption and fluorescence spectra, fluorescence quantum yields (ΦF) and lifetimes (τF), quantum yields of hydrogen peroxide (ΦH2O2) and singlet oxygen (ΦΔ) production, and triplet lifetimes (τT) have been obtained for the neutral and protonated forms of 6-chloroharmine, 8-chloroharmine and 6,8-dichloroharmine, in aqueous media. When it was possible, the effect of pH and oxygen concentration was evaluated. The nature of electronic transitions of protonated and neutral species of the three investigated chloroharmines was established using Time-Dependent Density Functional Theory (TD-DFT) calculations. The impact of all the foregoing observations on the biological role of the studied compounds is discussed.Fil: Rasse Suriani, Federico Ariel Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Denofrio, Maria Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Yañuk, Juan Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Gonzalez, Maria Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Wolcan, Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Seifermann, Marco. University of Mainz; AlemaniaFil: Erra Balsells, Rosa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; ArgentinaFil: Cabrerizo, Franco Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); Argentin

First Confirmed Report of Powdery Mildew Caused by Erysiphe aquilegiae on Casuarina cunninghamiana in Argentina

Casuarina cunninghamiana Miq. (Fam. Casuarinaceae) is native to Australia and was introduced to Argentina and used as a windbreak, shade tree and for ornamental purposes. In autumn 2009, the potted seedlings in the nursery of La Plata University were found to be infected with a powdery mildew. Symptoms first appeared as thin white colonies, which subsequently developed into an abundant growth on the leaves and young stems. The damage caused by the powdery mildew infection has been observed every year after this initial infection and was again confirmed in April, 2011. There have been a few reports on the presence of powdery mildew on Casuarina spp. (Mantz et al., 2008; Farr and Rossman, 2011). In all the reports, the pathogen was cited to be Oidium sp. Thus, the aim of this work was to identify the causal agent of the powdery mildew observed on casuarina in Argentina

Enanismo y podredumbre basal de Eustoma grandiflorum y su relación con la densidad de Fusarium solani en el suelo

En cultivos comerciales de lisianthus de La Plata y alrededores (Argentina), se observó que Fusarium solani afecta al 100% de los establecimientos productivos provocando enanismo y podredumbre basal. Se realizó un ensayo para analizar la densidad de F. solani del suelo bajo el efecto de distintos tratamientos y relacionarla con la evolución de ambas patologías. Los análisis del suelo se hicieron en 3 épocas: antes del transplante (octubre), al inicio (enero) y al final (marzo) de la floración. En enero y marzo se evaluó la incidencia de cada enfermedad y se cuantificaron las plantas cosechadas. La población de F. solani no varió en las 3 épocas y se redujo significativamente con los fumigantes y el vapor. Esto determinó una incidencia del enanismo (enero) de 0 a 9,5% con los primeros y de 31,4% con el vapor. Para el testigo y los fungicidas la incidencia varió entre el 87,9 y el 100%, disminuyendo las plantas cosechadas. La podredumbre basal comenzó con el ingreso del patógeno a través de las heridas producidas por la cosecha. Ésta fue significativamente mayor con los fumigantes (90,7 a 99%) y también con el vapor (76,8%), produciéndose la mayor incidencia en marzo (15,7 a 22,2 y 10,1% respectivamente), reduciéndose el período productivo. Se destaca la importancia de disminuir la densidad de F. solani en el momento del transplante. Entre los métodos de control el Metam sodio y Dazomet podrían ser eficaces sustitutos del Bromuro de metilo, seguidos por el vapor.Fusarium solani was recorded in 100% of the commercial crops of lisianthus (Eustoma grandiflorum) located around La Plata (Argentina). The pathogen causes stunt and basal rot. A trial was carried out to analyse the F. solani soil density and its relation to the development of both diseases. Soil samples were analysed at three times: before transplant (October), at the beginning of flowering (January) and at the ending of flowering (March) of flowering. The incidence of each disease was evaluated in January and March, and the plants harvested were quantified. The soil density of F. solani was not altered during the three times for each treatment, and fumigants and steam decrease it significantly. In January the stunt incidence reached 0 to 9.5% with the fumigants and 31.4% with the steam treatment. In the control and fungicide plots, the incidence reached 87.9 to 100%, and a consequent reduction of flower production was observed. Stem rot began after the flowers were harvested as a result of pathogen entry through the wounds. The major values of harvested plants were obtained with fumigants (90.7 to 99%) and steam (76.8%), so the greatest stem rot incidence was 15.7 to 22.2 and 10.1%, respectively, in March, and the productive period was shortened. The need of reducing F. solani soil density before lisianthus transplant is emphasized. Among soil control treatments, Metham sodium and Dazomet could be effective substitutes for Methil bromide followed by steam treatment

Phytophthora nicotianae causing root and stem rot on Dieffenbachia picta in Argentina

Dieffenbachia picta is a worldwide appreciated crop due to its ornamental value. In Argentina it is cultivated in warm provinces and in the outskirts of Buenos Aires city, where in spring 2007 a great amount of plants were lost in commercial greenhouses. Symptoms such as wilting and soaked lesions in the basal leaves began in four- to six-month-old plants causing plants to wilt due to basal stem and root rot processes. A Peronosporomycete was consistently isolated from diseased tissues. The pathogen was identified as Phytophthora nicotianae based on cultural characteristics, morphology of vegetative and reproductive structures, and on the analysis of the sequence of the nuclear ribosomal internal transcribed spacer (ITS) region. Pathogenicity tests were carried out and Koch’s postulates were fulfilled. In complementary studies, the dieffenbachia varieties Alex, Compact, Camilla and Marianne were susceptible to the infection caused by P. nicotianae, whereas Tropic snow (D. amonea) was resistant. This is the first report of P. nicotianae causing stem and root rot of D. picta in Argentina and in the Americas.Dieffenbachia picta (“comigo-ninguém-pode”) é uma espécie difundida em todo o mundo devido ao seu valor ornamental. Na Argentina, é cultivada nas províncias de clima mais quente e nos arredores da cidade de Buenos Aires. Na primavera de 2007 um grande número de plantas apresentou sintomas de murcha e presença de lesões encharcadas (anasarca) nas folhas inferiores, principalmente em plantas de 4 a 6 meses de idade. Em seguida, constatou-se murcha da planta devido ao apodrecimento do caule e raiz. Um organismo peronosporomycete foi isolado de tecidos afetados. O patógeno foi identificado como Phytophthora nicotianae com base em características culturais, morfologia das estruturas vegetativas e reprodutivas, e testes moleculares baseados na sequência da região ITS do DNA ribossômico. Os testes de patogenicidade foram conduzidos e os postulados de Koch atendidos. Em estudos complementares, as variedades de D. picta Alex, Compact, Marianne e Camilla foram suscetíveis, enquanto a variedade Tropic snow (D. amoena) foi resistente. Este é o primeiro relato de P. nicotianae causando podridão radicular de Dieffenbachia picta na Argentina e nas Américas

Anion-Dependent Construction of Two Hexanuclear 3D-4F Complexes with a Flexible Schiff Base Ligand

Two hexanuclear 3d-4f Ni-Eu and Cu-Eu complexes [Eu4Ni2L2(OAc)(12)(EtOH)(2)] (1) and [Eu4Cu2L2(OAc)(12)]center dot 2H(2)O (2) are reported which are formed from the salen type Schiff-base ligand H2L (H2L = N,N'-bis(3-methoxysalicylidene)butane-1,4-diamine). In both complexes, four Eu3+ cations are bridged by eight OAc- groups and the chain is terminated at each end by two ML (M = Ni and Cu) units. The structures of 1 and 2 were determined by single crystal X-ray crystallographic studies and the luminescence properties of the free ligand and metal complexes in solution were measured.HHMI Undergraduate Science Education Award 52005907National Science Foundation CHE-0629136, CHE-0741973, CHE-0847763Welch Foundation F-1631, F-816Hong Kong Baptist University FRG/06-07/II-16Hong Kong Research Grants Council HKBU 202407Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)Open Foundation of Jiangsu Province Key Laboratory of Fine Petrochemical Technology KF1005UT-CNM and UT-AustinChemistr

Morphology-dependent photophysical properties of Poly-4-vinylpyridine polymers containing –Re(CO)3 (N^N)+ pendants

We review the morphological and the photophysical properties of several inorganic polymers that can be prepared from poly-4- vinylpyridine (P4VP). These polymers contain –Re(CO)3 (N^ N)+ pendants attached to their backbone with α-diimine ligands (N^ N) such as 2,2´-bipyridine (bpy), 1,10-phenanthroline (phen), 3,4,7,8-tetramethyl-1,10-phenanthroline (tmphen) and 5-nitro-1,10- phenanthroline (NO2 -phen). These Re(I) polymers, show marked differences in their photophysical properties when compared to single [pyRe(CO)3 (N^ N)]+ molecules in diluted solutions. For example, Re→phen charge transfer excited states (MLCT) in the Re(I) polymers undergo a more efficient annihilation and/or secondary photolysis than in [pyRe(CO)3 phen]+ complexes. Depending on solvent and/or cast film conditions, several aggregates of polymer strands with different morphologies were observed by transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques. Morphological changes derived from media-imposed changes (solvent, temperature) or from polymer backbone chemical modifications (protonation or peralkylation in P4VP uncoordinated pyridines) are responsible for the marked differences observed between the photophysical properties of these Re(I) polymers and those of the single pyRe(CO)3 (N^ N)+ molecules. Therefore, these Re(I) polymers can provide a good reaction scenario for other photochemical reactions. Thus, resonance energy transfer between –Re(CO)3 (tmphen)+ and –Re(CO)3 (NO2 -phen)+ pendants was observed in Re(I)-P4VP polymers containing both chromophores attached to their backbone. In addition, in the quenching of the MLCT luminescence of –Re(CO)3 (N^ N)+ pendants by amines, we observed a retardation of the molecular motion due to the restricted media that favored the observation of the Marcus inverted effect in bimolecular reactions due to the fact that low values of the solvent reorganization energies are achieved within aggregates.Fil: Wolcan, Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentin

First report of downy mildew caused by Bremia lactucae on Gerbera jamensonii in Argentina

In autumn 2007, leaves of Gerbera jamensonii with typical symptoms of downy mildew were collected in Buenos Aires province, Argentina. Based on symptoms and the morphology of the fungus, the pathogen was identified as Bremia lactucae. This is the first report of downy mildew on gerbera in Argentina.Facultad de Ciencias Agrarias y Forestale

First report of downy mildew caused by Bremia lactucae on Gerbera jamensonii in Argentina

In autumn 2007, leaves of Gerbera jamensonii with typical symptoms of downy mildew were collected in Buenos Aires province, Argentina. Based on symptoms and the morphology of the fungus, the pathogen was identified as Bremia lactucae. This is the first report of downy mildew on gerbera in Argentina.Facultad de Ciencias Agrarias y Forestale

<i>Podosphaera balsaminae</i> on <i>Impatiens balsamina</i> and <i>Impatiens × hawkeri</i>

Podosphaera balsaminae was recorded for the first time in Argentina and apparently in the Americas, causing powdery mildew on Impatiens balsamina (balsam) and Impatiens × hawkeri (New Guinea impatiens). This is also the first record of P. balsaminae on New Guinea impatiens. In a preliminary test, results of cross inoculations suggest that a pathogenic specialisation of P. balsaminae for these two hosts is present.Centro de Investigaciones en FitopatologíaComisión de Investigaciones Científicas de la provincia de Buenos Aire

El género Phytophthora (Peronosporales) en Argentina

Background and aims: The genus Phytophthora includes plant pathogens that affect a wide host range and cause severe damage and economic losses. The aim of this study was to achieve a more comprehensive knowledge of Phytophthora in Argentina. To this end, a review was carried out from the first reports in the late nineteenth century until March 2019. M&amp;M: Information was taken from printed and on-line primary and secondary sources such as Proceedings of National and International Scientific Meetings, Bulletins from National Institutions and Universities, periodical Journals, books and data bases, and then analyzed and categorized. Results: The revision allowed updating the status of Phytophthora species recorded in the country, considering their geographical distribution, groups of crops affected, host-pathogen relationships, symptoms and nomenclature changes, as well as presenting a quick and comparative access to different subjects related to these pathogens. The results showed that, to date, 20 Phytophthora spp., one species affinis and one taxon affect 223 host-pathogen relationships in Argentina. The diversity of Phytophthora species in the world suggests that a larger number of species, still not cited, could be present in Argentina. Conclusions: Researchers specialized in the genus Phytophthora, molecular techniques and phylogenetic studies, may allow progressing in the accurate identification of the species and knowledge of their genetic variability.Introducción: El género Phytophthora incluye patógenos de plantas que afectan un amplio rango de hospedantes, causando severos daños y pérdidas económicas. Con la finalidad de conocer el estado actual de la información disponible sobre este género en Argentina, se llevó a cabo una revisión desde fines del siglo XIX hasta marzo de 2019. M&amp;M: Se consultaron fuentes primarias y secundarias de información escrita y electrónica: presentaciones en congresos nacionales e internacionales, publicaciones periódicas nacionales e internacionales, boletines de instituciones y universidades, libros y bases de datos. La información obtenida fue analizada y categorizada. Resultados: La presente revisión permitió actualizar las especies presentes en el país, considerando su distribución geográfica y por grupos de cultivos, relaciones hospedante-patógeno, sintomatología y los cambios en su nomenclatura. Se presenta un rápido y comparativo acceso a los diferentes tópicos relacionados con estas patologías. Se encontraron citadas 20 Phytophthora spp., 1 especie affinis y 1 taxon que afectan a 223 relaciones hospedante-patógeno. La diversidad de Phytophthora spp. citadas en el mundo sugiere que en el país podría haber una mayor cantidad de especies aún no registradas. Conclusión: Investigadores especializados en el género Phytophthora, técnicas moleculares y estudios filogenéticos permitirán avanzar en la certera identificación de las especies y el conocimiento de su variabilidad genética