Preparation of dipyrrins from F-BODIPYs by treatment with methanesulfonic acids

An alternative metal-free soft procedure for the preparation of dipyrrins from F-BODIPYs is reported. The new method makes possible to obtain certain dipyrrin derivatives that were unaccessible from F-BODIPYs to date. To demonstrate the ability of the new procedure, dipyrrins having highly reactive groups, such as chloro, cyano or acetoxyl, have been easily obtained from the corresponding F-BODIPY, which shows the synthetic utility of the reported methodology

Circularly Polarized Luminescence from Simple Organic Molecules

This article aims to show the identity of “circularly polarized luminescent active simple organic molecules” as a new concept in organic chemistry due to the potential interest of these molecules, as availed by the exponentially growing number of research articles related to them. In particular, it describes and highlights the interest and difficulty in developing chiral simple (small and non-aggregated) organic molecules able to emit left- or right-circularly polarized light efficiently, the efforts realized up to now to reach this challenging objective, and the most significant milestones achieved to date. General guidelines for the preparation of these interesting molecules are also presented

Exploring N-BODIPYs as Privileged Scaffolds to Build Off/On Fluorescent Sensors by PET

A new N-boron dipyrromethene (N-BODIPY) substituted with a crown ether moiety has been synthesized by reaction of an F-BODIPY with a crown-ether-substituted bis(sulfonamide). The workability of this N-BODIPY as an off/on sensor for cations by modulation of a photoinduced electron transfer (PET) is explored. The new N-BODIPY demonstrates the possibilities of functionalization of these still unexplored but promising dyes

C*-BODIPYs: Exploring a New Strategy to Transfer Chirality towards BODIPY Chiroptics

C*-BODIPYs, that is, boron dipyrromethenes (BODIPYs) which have chiral carbons attached directly to the boron center, are introduced for the first time. These novel chiral BODIPYs mean a new strategy for the chiral perturbation of the inherently achiral BODIPY chromophore that is directed to enable chiroptical properties. Their preparation is very simple and only implies the complexation of a dipyrrin with an enantiopure dialkylborane having boron bonded to chiral carbons

Exploring BODIPY Derivatives as Singlet Oxygen Photosensitizers for PDT

This minireview is devoted to honoring the memory of Dr. Thomas Dougherty, a pioneer of modern photodynamic therapy (PDT). It compiles the most important inputs made by our research group since 2012 in the development of new photosensitizers based on BODIPY chromophore which, thanks to the rich BODIPY chemistry, allows a finely tuned design of the photophysical properties of this family of dyes to serve as efficient photosensitizers for the generation of singlet oxygen. These two factors, photophysical tuning and workable chemistry, have turned BODIPY chromophore as one of the most promising dyes for the development of improved photosensitizers for PDT. In this line, this minireview is mainly related to the establishment of chemical methods and structural designs for enabling efficient singlet oxygen generation in BODIPYs. The approaches include the incorporation of heavy atoms, such as halogens (iodine or bromine) in different number and positions on the BODIPY scaffold, and also transition metal atoms, by their complexation with Ir(III) center, for instance. On the other hand, low‐toxicity approaches, without involving heavy metals, have been developed by preparing several orthogonal BODIPY dimers with different substitution patterns. The advantages and drawbacks of all these diverse molecular designs based on BODIPY structural framework are described

Development of Geometry-Controlled All-Orthogonal BODIPY Trimers for Photodynamic Therapy and Phototheragnosis

We have established an easy synthetic protocol for selectively developing all-orthogonal BODIPY trimers with unprecedented geometries on the basis of selecting methyl oxidation versus electrophilic formylation of key dimeric precursors. Photophysical characterization together with biological assays unraveled the most suitable BODIPY−BODIPY geometrical arrangements within the trimer, forcing them to serve as molecular platforms for the development of new, advanced heavy-atom-free photosensitizers for photodynamic therapy and phototheragnosis

Aprendizaje gamificado en la asignatura de “Repercusiones bucales de las enfermedades sistémicas” en los alumnos de Odontología evidenciado a través de procesos metacognitivos: Comparación de diferentes herramientas interactivas

El alumno tras una reflexión guiada de lo aprendido, preparará en equipo Sesiones Clínicas, con los conceptos que crea importantes para la formación de sus compañeros. Se utilizarán herramientas interactivas, un ranking y un ganador individual/equipo. Se trabajan los contenidos a través de procesos de metacognición y del empleo de la gamificación. Se comparan las herramientas interactivas utilizadas en el proceso.Depto. de Salud Pública y Materno - InfantilDepto. de Especialidades Clínicas OdontológicasFac. de MedicinaFac. de OdontologíaFALSEsubmitte

The Mechanism of Hydrolysis of Aryldiazonium Ions Revisited: Marcus Theory vs. Canonical Variational Transition State Theory

Several models, theoretical levels and computational methods, all based on the canonical variational transition state approximation, have been used to predict both the experimental activation energies (ΔEexp≠) and the experimental activation free energies (ΔGexp≠) for the hydrolysis of aryldiazonium ions. It is demonstrated that the computation of activation energies (ΔE≠), instead of activation free energies (ΔG≠), agrees better with the corresponding experimental data, showing that the employed computational methods do not afford reliable entropic contributions to the free energy barriers in the case of the studied reaction. However, the most fitted computations of ΔE≠ were not able to clearly differentiate between the mechanisms proposed for this interesting reaction (SN1, SN2 and water cluster). In contrast, the use of the Marcus theory (hyperbolic-cosine equation) instead of the canonical variational transition state theory leads to excellent agreement between the in-water-computed activation energies (ΔEwM≠) and the corresponding ΔEexp≠ values for the SN2 mechanism, but far beyond the limit of error for the SN1 process. The validity of the Marcus theory for the studied SN1 and SN2 reactions is ensured by the fact that both reactions can be described as SET processes. On the other hand, apparently compelling evidence against the SN2 mechanism, such as 13C KIEs and experimental observation of N2 scrambling, are also discussed and alternative explanations are proposed

Electron ionization-induced fragmentation of bridgehead-substituted norbornan-2-ones derived from fenchone

Camphor- and fenchone-based bridgehead-substituted norbornan-2-ones constitute an interesting class of chiral synthons with applications in stereoselective synthesis, due to the wide variety of stereo-controlled transformations which they can undergo. Despite their synthetic value, few mass spectral studies have been realized for these compounds due to the lack of general procedures for their preparation. In this paper we have carried out an electron ionization (EI) mass spectral study of a series of heteroatomically bridgehead-substituted 7,7-dimethylnorbornan-2-ones. Their cleavage mechanisms have been rationalized on the basis of the substituent shifts, as well as on the identification of relevant peaks through accurate mass measurements and collision-induced dissociation (CID) tandem mass-spectrometric experiments. The driving force for the main fragmentation pathways of C(1)-O- and C(1)-N-substituted 7,7-dimethylnorbornan-2-ones is the alpha-cleavage of the C(1) C(2) bond directed by the bridgehead substituent. Further rearrangements and fragmentations of the distonic ions initially formed lead to the major ions in the spectra of all the compounds. A comparison with the known behaviour of their isomeric 3,3-dimethylnorbornan-2-ones reveals that the key bridgehead heteroatom effect controlling the fragmentation pathways can be modulated by the position of the gem-dimethyl group. As a consequence, the corresponding fragmentation patterns of both isomeric series are very different. In contrast, the fragmentation patterns of 7,7-dimethyl-2-oxo-norbornanesulphonamides, whose main fragmentation pathway involves homolytic S N bond cleavage, are almost identical to those displayed by their 3,3-dimethylated isomer

Speeding up heterogeneous catalysis with an improved highly reusable catalyst for the preparation of enantioenriched secondary alcohols

A new catalytic heterogeneous system, very efficient and highly reusable, for the preparation of enantioenriched secondary alcohols through the addition of diethylzinc to benzaldehyde has been developed. This system is based on a chiral bis(hydroxyamide) ligand supported on crosslinked polystyrene. The catalyst has been shown to be very efficient, leading to the corresponding secondary alcohol with an enantiomeric excess of 93% in a time as short as 2 h and using just 4% of the heterogeneous catalyst and just 1.5 equivalents of the organozinc reagent. We have demonstrated that the new catalyst is very stable and can be efficiently recycled with no decrease in yield or enantioselectivity. The presented system has an unquestionable interest for the potential transfer of the reaction to the industry by using catalytic fluidized-bed reactors