5,11-Diisopropyl-2,8-dimethyl-1H,7H-diimidazo[c,h][1,6]diazecine dihydrate

Crystals of the title compound, C18H30N6·2H2O, are composed of units of diimidazo[c,h][1,6]diazecine and two water mol­ecules. The asymmetric unit contains one half-molecule of diazecine and one uncoordinated water molecule in a general position. The complete ten-membered heterocycle is generated by an inversion center.The organic residue and water mol­ecules form a two-dimensional hydrogen-bonded network. The 1,6-diazecine ring shows a chair conformation, with angles and distances in normal ranges

Epistemología histórica e historiografía

Ensayos cuyo tema gira sobre la historicidad de la razón científica que ahora es cuestionada desde la misma ciencia. Desde ella se puede seguir una línea desde Gaston Bachelard a Michel Foucault del lado de la reflexión francesa, y, del lado anglosajón, desde el giro lingüístico al programa fuerte de la Escuela de Edimburgo. Por todo esto no es azaroso que la epistemología histórica y la historiografía surjan simultáneamente a partir de la década de 1960. Obras tan significativas como la de Kuhn en el ámbito de la ciencia, o como las de Foucault, se inscriben en este momento. Comparten pues, esta misma preocupación: repensar las condiciones de posibilidad del conocimiento y las de la historiografía. El libro está dividido en dos partes. La primera contiene las reflexiones que incumben directamente a la epistemología histórica, y la segunda parte, las de historiografía. Ambas tienen en común la centralidad de la historicidad.Norma Durán R. A., coordinador

Revisión sobre el uso de residuos de mármol, para elaborar materiales para la construcción.

In this study, an analysis for residues of marble and research conducted around the world, on its possible application in building materials is presented. Particularly at the end of article a portrait of the project that is being conducted in the Laguna Region (located in northern Mexico), on the implementation of waste in the development of structural bricks are made. The project aims to find a feasible using the marble waste, and help reverse the negative effects caused to the environment and the population of the area of influence of these wastes. Applications made in research in general have been basically to use the marble waste as a substitute for any material (cement, sand) to develop, concrete, mortars, pavements, blocks and bricks. Also, it can be appreciated that the measurements made are mainly compression resistance.En este estudio, se presenta un análisis respecto a los residuos de mármol y de las investigaciones realizadas alrededor del mundo, sobre su posible aplicación en materiales para la construcción. Particularmente al final de artículo se hace una semblanza del proyecto que se está realizando en la Comarca Lagunera (Ubicada en el norte de México), sobre la aplicación de residuos en la elaboración de ladrillos estructurales. El proyecto, tiene como objetivo, encontrar un uso factible a los residuos de mármol, y contribuir a revertir los efectos negativos que causa al medio ambiente y a la población del área de influencia de estos residuos. Las aplicaciones realizadas en las investigaciones, en general han sido básicamente para utilizar el residuo de mármol como sustituto de algún material (cemento, arena) para elaborar, concretos, morteros, pavimentos, bloques y ladrillos. Asimismo, se puede apreciar que las mediciones realizadas son principalmente de resistencia a la compresión

Concentration depending fluorescence of 8-(di-(2-picolyl)) aminoBODIPY in solution

[EN] An 8-dipicolylBODIPY derivative has been prepared and its photophysical properties evaluated under different conditions. Two different structures, hemicyanine and cyanine, are observed (depending on the solvent or the solution concentration). The hemicyanine form is not emissive whereas the cyanine form is fluorescent. This behavior is related with the planarity degree of the BODIPY core. The X-ray structure of the compound is reported and it shows that in solid state the hemicyanine form is present. The hemicyanine form seems to be stabilized by aggregation and is the main compound in concentrated solutions whereas the cyanine form is present in diluted solutions that are photochemically transformed into a new compound 3. Both species cyanine and hemicyanine, are able to complex Zn2+ being the complex with the cyanine form of higher stability. The presence of the cation precludes any ulterior transformation from the cyanine form. (C) 2014 Elsevier Ltd. All rights reserved.We thank the Spanish Government and the European FEDER Funds (project MAT2012-38429-C04-02 and 01). SCSIE and ICMOL (Universidad de Valencia) and Laboratorio de Analisis Instrumental "Q. Fernando de Jesus Amezquita Lopez" (Universidad de Guanjuato) are gratefully acknowledged for all the equipment employed. M.L.B.M. wish to thank to CONACyT for scholarships. CONACyT Grant 129572 is also gratefully acknowledged.Betancourt-Mendiola, M.; Peña-Cabrera, E.; Gil Grau, S.; Chulvi, K.; Ochando Gómez, LE.; Costero Nieto, AM. (2014). Concentration depending fluorescence of 8-(di-(2-picolyl)) aminoBODIPY in solution. Tetrahedron. 70(23):3735-3739. https://doi.org/10.1016/j.tet.2014.03.095S37353739702

Nanoclays: Promising Materials for Vaccinology

Clay materials and nanoclays have gained recent popularity in the vaccinology field, with biocompatibility, simple functionalization, low toxicity, and low-cost as their main attributes. As elements of nanovaccines, halloysite nanotubes (natural), layered double hydroxides and hectorite (synthetic) are the nanoclays that have advanced into the vaccinology field. Until now, only physisorption has been used to modify the surface of nanoclays with antigens, adjuvants, and/or ligands to create nanovaccines. Protocols to covalently attach these molecules have not been developed with nanoclays, only procedures to develop adsorbents based on nanoclays that could be extended to develop nanovaccine conjugates. In this review, we describe the approaches evaluated on different nanovaccine candidates reported in articles, the immunological results obtained with them and the most advanced approaches in the preclinical field, while describing the nanomaterial itself. In addition, complex systems that use nanoclays were included and described. The safety of nanoclays as carriers is an important key fact to determine their true potential as nanovaccine candidates in humans. Here, we present the evaluations reported in this field. Finally, we point out the perspectives in the development of vaccine prototypes using nanoclays as antigen carriers

Structural Control of Kinetics for Macrocycle Threading by Fluorescent Squaraine Dye in Water

While the general concept of steric speed bumps has been demonstrated in rotaxane shuttles and macrocycle threading systems, the sensitivity of speed bump effects has not been evaluated as a function of structural geometry. Values of <i>K</i>_a and <i>k</i>_on for macrocycle threading in water are reported for a series of homologous squaraine dyes with different substituents (speed bumps) on the flanking chains and two macrocycles with different cavity sizes. Sensitivity to a steric speed bump effect was found to depend on (a) structural location, being lowest when the speed bump was near the end of a flanking chain, and (b) macrocycle cavity size, which was enhanced when the cavity was constricted. This new insight is broadly applicable to many types of molecular threading systems

A versatile synthetic approach to design tailor-made push-pull chromophores with intriguing and tunable photophysical signatures

Novel modified Biellmann BODIPYs were prepared using a C-H arylation reaction with in-situ formed aryldiazonium salts. The post-functionalization of the methylthio group of these derivatives was demonstrated in SNAr and the Liebeskind-Srogl cross-coupling reactions. The series of compounds herein designed with specific and selective functionalization featuring electron donor and acceptor groups provides valuable information about the impact of the molecular structure and stereoelectronic properties of the substituent on the photophysical signatures of BODIYs. In fact, push-pull dyes showing unexpected high fluorescence response towards the red edge of the visible spectrum can be designed, or, alternatively, chromophores ongoing the expected intramolecular charge transfer states (dark or fluorescent depending on the substituent, the attachment position and the surrounding media) can be also attained owing to the characteristic high charge separation of this king of dyes. We envisage that the reactivity of the selected scaffold as well as the guidelines derived from the computationally-aided spectroscopy study of these luminophores pave the way to the development of tailor made BODIPYs with specific and finely modulable spectroscopic and optical properties.We thank CONACYT (grants 253623, 123732), Gobierno Vasco (IT912-16) and Spanish MICINN (MAT2014-51937-C3-3-P) for financial support. J. L. B.-V. and L. B.-M. thank CONACyT for graduate scholarship. R.S.-L. thanks UPV-EHU for a postdoctoral fellowship. Donation of Biellman BODIPYs by Cuantico de Mexico (www.cuantico.mx) is appreciated

Table1_Synthesis and evaluation of gold nanoparticles conjugated with five antigenic peptides derived from the spike protein of SARS-CoV-2 for vaccine development.pdf

Introduction: The development of innovative anti-COVID-19 vaccines is a need to ensure the population’s immunity worldwide, with broad protection against variants of concern and low cost as the main goals. Gold nanocarriers are potential entities that could aid in the development of innovative vaccines having thermal stability, high immunogenicity, and safety as the main attributes. Moreover, this approach could lead to adjuvant-free formulations, which will reduce the costs of vaccines.Methods: In this study, five peptides (P1, P2, P3, P4, and P5) corresponding to linear epitopes of the SARS-CoV-2 spike (S) protein were chemisorbed on gold nanoparticles (AuNP) of 20 nm, prefunctionalized with heterobifunctional polyethylene glycol, by using glutaraldehyde as crosslinker to generate nanovaccine prototypes.Results and discussion: The surface modification was confirmed by DLS with an increase of 31.7 ± 1.8 nm in the hydrodynamic diameter and an average ζ potential of −8.3 ± 2.2 mV in PBS (as excipient). The coupling concentration achieved was 23.7 ± 7.1 μg of peptide per mg AuNP. These AuNP-based conjugates showed no inherent toxicity in assays performed with HEK293T cells, in which a 100–1,000 μg/mL concentration range only led to a temporary decrease of up to 30% in cell viability after 48 h of treatment with restoration by 72 h. The immunogenicity of the conjugates produced was assessed in test mice subjected to three subcutaneous doses at 2-week intervals. Significant levels of IgM against each target peptide were observed at an early stage of the immunization scheme in all groups, reaching maximum levels after the second dose, whereas the IgG response increased after the third dose. The AuNP-P2, AuNP-P3, and AuNP-P5 conjugates induced the highest levels of IgG antibodies, lasting for at least 2 months after the last boost, with a predominance of the IgG1 subclass. Although the magnitude of the response induced by the gold conjugates was comparable to that with alum as adjuvant, these nanoconjugates induced a longer response. Our data support the use of AuNP as carriers in innovative vaccines against SARS-CoV-2.</p

Blue-to-orange color-tunable laser emission from tailored boron-dipyrromethene dyes

A series of meso-substituted boron-bipyrromethene (BODIPY) dyes are synthesized and their laser and photophysical properties systematically studied. Laser emission covering a wide visible spectral region (from blue to orange) is obtained by just changing the electron donor character of the heteroatom at position 8. The additional presence of methyl groups at positions 3 and 5 results in dyes with a photostability similar to that of the unsubstituted dye but with much improved efficiency. Correlation of the lasing properties of the different dyes to their photophysical properties provides inklings to define synthetic strategies of new BODIPY dyes with enhanced efficiency and modulated wavelength emission over the visible spectral region. Brighter blue-green dyes: The attachment of heteroatoms at the meso position of boron-bipyrromethene (BODIPY) dyes modulates the emission region from orange to blue. Further methylation at positions 3 and 5 improves the laser efficiency, thereby maintaining a high photostability. The combination of both effects leads to BODIPYs with improved laser and fluorescence performance in the blue part of the spectrum. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Peer Reviewe