Multifunctional Amino Acid Derivative Coordination Compounds: Novel Contrast Agent and Luminescence Materials.

In this work a family of multidimensional (2-(1H-tetrazol-5-yl)ethyl) amino acid coordination compounds have been synthesized and thoroughly characterized. For this purpose, glycine, valine, phenylalanine and tyrosine have been selected as starting amino acids and Mn2+, Zn2+ and Cd2+ as metallic nodes. From one side, for Mn2+ based dimer magnetic resonance imaging studies have been conducted, prompted by the number and disposition of the coordinated water molecules and taking into consideration the promising future of manganese-based coordination compounds as bio-compatible substitutes to conventional Gd based contrast agents. From another side, d10 block metal-based complexes allowed exploring photoluminescence properties derived by in situ synthesized ligands. Finally, amino acid preserved structural chirality allowed us to examine chiroptical properties, particularly focusing on circularly polarized luminescence.

Enantiopure [6]-Azairidahelicene by Dynamic Kinetic Resolution of a Configurationally Labile [4]-Helicene.

A pair of enantiopure [6]-azairidahelicenes incorporating chirality at the metal center and on the helicenic ligand were synthesized by dynamic kinetic resolution (dkr) of a configurationally labile [4]-helicenic ligand (4-(2-pyridyl)-benzo[g]phenanthrene, L1H) using bis-cyclometalated chiral-at-metal only iridium(III) precursors as chiral inductors. The origin of the observed dkr is attributed to the different conformation and stability of diastereomeric reaction intermediates formed during the cyclometalation process. The isolated enantiomers exhibited circularly polarized phosphorescence (CPP), with |gphos| values of 1.8×10-3.

Metallo-Supramolecular Helical Fibres from Chiral Phenylacetylene Monomers: Cation Induced Self-Assembly.

Chiral metallo-supramolecular fibres can be easily obtained by mixing a chloroform solution of a phenylacetylene monomer (PA) that bears a chiral sulfoxide group as pendant, with different equivalents of a methanolic solution of AgClO4 . Thus, while the PA is found molecularly dissolved in chloroform, the addition of Ag+ ions induce its aggregation through the formation of an axially chiral metallo-supramolecular aggregate with high thermal stable properties. In this case, the ability of the metal ion to coordinate the PA triple bond, combined with the argentophilicity of the metal ion and the planarity of the phenylacetylene drives to the formation of a helical coordination polymer, whose P or M axial chirality is determined by the chirality of the sulfoxide used as substituent of the PA. Depending on the PA/Ag+ (mol/mol) ratio, it is possible to tune the morphology of the metallo-supramolecular aggregate from chiral fibers to chiral gel.

Exchangeable Self-Assembled Lanthanide Antennas for PLIM Microscopy.

Lanthanides have unique photoluminescence (PL) emission properties, including very long PL lifetimes. This makes them ideal for biological imaging applications, especially using PL lifetime imaging microscopy (PLIM). PLIM is an inherently multidimensional technique with exceptional advantages for quantitative biological imaging. Unfortunately, due to the required prolonged acquisitions times, photobleaching of lanthanide PL emission currently constitutes one of the main drawbacks of PLIM. In this study, we report a small aqueous-soluble, lanthanide antenna, 8-methoxy-2-oxo-1,2,4,5-tetrahydrocyclopenta[de]quinoline-3-phosphonic acid, PAnt, specifically designed to dynamically interact with lanthanide ions, serving as exchangeable dye aimed at mitigating photobleaching in PLIM microscopy in cellulo. Thus, self-assembled lanthanide complexes that may be photobleached during image acquisition are continuously replenished by intact lanthanide antennas from a large reservoir. Remarkably, our self-assembled lanthanide complex clearly demonstrated a significant reduction of PL photobleaching when compared to well-established lanthanide cryptates, used for bioimaging. This concept of exchangeable lanthanide antennas opens new possibilities for quantitative PLIM bioimaging.

Supramolecular Large Nanosheets Assembled at Air/Water Interfaces and in Solution from Amphiphilic Heptagon-Containing Nanographenes.

We report the synthesis of a new set of amphiphilic saddle-shaped heptagon-containing polycyclic aromatic hydrocarbons (PAHs) functionalized with tetraethylene glycol chains and their self-assembly into large two-dimensional (2D) polymers. An in-depth analysis of the self-assembly mechanism at the air/water interface has been carried out, and the proposed arrangement models are in good agreement with the molecular dynamics simulations. Quite remarkably, the number and disposition of the tetraethylene glycol chains significantly influence the disposition of the PAHs at the interface and conditionate their packing under pressure. For the three compounds studied, we observed three different behaviors in which the aromatic core is parallel, perpendicular, and tilted with respect to the water surface. We also show that these curved PAHs are able to self-assemble in solution into remarkably large sheets of up to 150 µm2. These results show the relationship, within a family of curved nanographenes, between the monomer configuration and their self-assembly capacity in air/water interfaces and organic-water mixtures.

Can Magnetic Dipole Transition Moment Be Engineered?

The development of chiral compounds with enhanced chiroptical properties is an important challenge to improve device applications. To that end, an optimization of the electric and magnetic dipole transition moments of the molecule is necessary. Nevertheless, the relationship between chemical structure and such quantum mechanical properties is not always clear. That is the case of magnetic dipole transition moment (m) for which no general trends for its optimization have been suggested. In this work we propose a general rationalization for improving the magnitude of m in different families of chiral compounds. Performing a clustering analysis of hundreds of transitions, we have been able to identify a single group in which |m| value is maximized along the helix axis. More interestingly, we have found an accurate linear relationship (up to R2 =0.994) between the maximum value of this parameter and the area of the inner cavity of the helix, thus resembling classical behavior of solenoids. This research provides a tool for the rationalized synthesis of compounds with improved chiroptical responses.

Short-Peptide Supramolecular Hydrogels for In Situ Growth of Metal-Organic Framework-Peptide Biocomposites.

The development of bio-MOFs or MOF biocomposites through the combination of MOFs with biopolymers offers the possibility of expanding the potential applications of MOFs, making use of more environmentally benign processes and reagents and giving rise to a new generation of greener and more bio-oriented composite materials. Now, with the increasing use of MOFs for biotechnological applications, the development of new protocols and materials to obtain novel bio-MOFs compatible with biomedical or biotechnological uses is needed. Herein, and as a proof of concept, we have explored the possibility of using short-peptide supramolecular hydrogels as media to promote the growth of MOF particles, giving rise to a new family of bio-MOFs. Short-peptide supramolecular hydrogels are very versatile materials that have shown excellent in vitro and in vivo biomedical applications such as tissue engineering and drug delivery vehicles, among others. These peptides self-assemble by noncovalent interactions, and, as such, these hydrogels are easily reversible, being more biocompatible and biodegradable. These peptides can self-assemble by a multitude of stimuli, such as changes in pH, temperature, solvent, adding salts, enzymatic activity, and so forth. In this work, we have taken advantage of this ability to promote peptide self-assembly with some of the components required to form MOF particles, giving rise to more homogeneous and well-integrated composite materials. Hydrogel formation has been triggered using Zn2+ salts, required to form ZIF-8, and formic acid, required to form MOF-808. Two different protocols for the in situ MOF growth have been developed. Finally, the MOF-808 composite hydrogel has been tested for the decontamination of water polluted with phosphate ions as well as for the catalytic degradation of toxic organophosphate methyl paraoxon in an unbuffered solution.

Chiral Single-Molecule Potentiometers Based on Stapled ortho- Oligo(phenylene)ethynylenes.

We report on the chemical design of chiral molecular junctions with stress-dependent conductance, whose helicity is maintained during the stretching of a single molecule junction due to the stapling of both ends of the inner helix. In the reported compounds, different conductive pathways are observed, with clearly different conductance values and plateau-length distributions, attributed to different conformations of the helical structures. The large chiro-optical responses and the potential use of these molecules as unimolecular spin filters have been theoretically proved using state-of-the-art Density Functional Theory (DFT) calculations, including a fully ab-initio estimation of the CISS-originating spin polarization which is done, for the first time, for a realistic molecular system.

On-surface synthesis of non-benzenoid conjugated polymers by selective atomic rearrangement of ethynylarenes.

Here, we report a new on-surface synthetic strategy to precisely introduce five-membered units into conjugated polymers from specifically designed precursor molecules that give rise to low-bandgap fulvalene-bridged bisanthene polymers. The selective formation of non-benzenoid units is finely controlled by the annealing parameters, which govern the initiation of atomic rearrangements that efficiently transform previously formed diethynyl bridges into fulvalene moieties. The atomically precise structures and electronic properties have been unmistakably characterized by STM, nc-AFM, and STS and the results are supported by DFT theoretical calculations. Interestingly, the fulvalene-bridged bisanthene polymers exhibit experimental narrow frontier electronic gaps of 1.2 eV on Au(111) with fully conjugated units. This on-surface synthetic strategy can potentially be extended to other conjugated polymers to tune their optoelectronic properties by integrating five-membered rings at precise sites.

Influence of Tartrate Ligand Coordination over Luminescence Properties of Chiral Lanthanide-Based Metal-Organic Frameworks.

The present work reports on a detailed discussion about the synthesis, characterization, and luminescence properties of three pairs of enantiopure 3D metal-organic frameworks (MOFs) with general formula {[Ln2(L/D-tart)3(H2O)2]·3H2O}n (3D_Ln-L/D, where Ln = Sm(III), Eu(III) or Gd(III), and L/D-tart = L- or D-tartrate), and ten pairs of enantiopure 2D coordination polymers (CPs) with general formula [Ln(L/D-Htart)2(OH)(H2O)2]n (2D_Ln-L/D, where Ln = Y(III), Sm(III), Eu(III), Gd(III), Tb(III), Dy(III), Ho(III), Er(III), Tm(III) or Yb(III), and L/D-Htart = hydrogen L- or D-tartrate) based on single-crystal X-ray structures. Enantiopure nature of the samples has been further corroborated by Root Mean Square Deviation (RMSD) as well as by circular dichroism (CD) spectra. Solid-state emission spectra of Eu(III), Tb(III), and Dy(III)-based compounds confirm the occurrence of ligand-to-metal charge transfers in view of the characteristic emissions for these lanthanide ions, and emission decay curves were also recorded to estimate the emission lifetimes for the reported compounds. A complete theoretical study was accomplished to better understand the energy transfers occurring in the Eu-based counterparts, which allows for explaining the different performances of 3D-MOFs and 2D-layered compounds. As inferred from the colorimetric diagrams, emission characteristics of Eu-based 2D CPs depend on the temperature, so their luminescent thermometry has been determined on the basis of a ratiometric analysis between the ligand-centered and Eu-centered emission. Finally, a detailed study of the polarized luminescence intensity emitted by the samples is also accomplished to support the occurrence of chiro-optical activity.

Highly contorted superhelicene hits near-infrared circularly polarized luminescence.

Herein we describe a novel superhelicene structure consisting of three hexa-peri-hexabenzocoronene (HBC) units arranged in a helical geometry and creating two carbo[5]helicenes and a carbo[7]helicene. The central HBC bears a tropone moiety, which induces a saddle-helix hybrid geometry into the 3D structure of the prepared nanographene. The introduction of multiple helicenes and the position of the tropone unit trigger near-infrared circularly polarized luminescence (NIR-CPL, up to 850 nm, |g lum| = 3.0 × 10-3) combined with good photoluminescence quantum yields (ϕ F = 0.43) and upconverted emission based on two-photon absorption (TPA). Compared to previously reported superhelicenes of similar size, higher quantum yields, CPL brightness, and red-shifted absorption and emission spectra are achieved. Besides, chiroptical properties of enantiopure thin films were evaluated. These findings place this novel superhelicene as the first NIR-CPL superhelicene ever reported and make it a promising candidate for use as a chiral luminescent material in optoelectronic devices.

Tooth color in dental students from Buenos Aires University, Dental School, Argentina.

The aim of this study was to evaluate tooth color in dental students at the University of Buenos Aires, Argentina. The participants were 184 students (157 women and 27 men) aged 21 to 33 years, mean age 24.45 (SD 2.79) years, who were in the fourth year of their dental degree. They agreed to participate through an informed consent. Exclusion criteria were: having undergone a bleaching treatment within the previous six months, presence of total or partial peripheral restoration, pigmentations, fracture, carious and non-carious lesions or absence of the right upper central incisor (1.1). A dental prophylaxis procedure was performed on the buccal surface of each 1.1 tooth with a prophylaxis brush (TDV) mounted on a low-speed rotary instrument Kavo 2068 CHC (Germany) micromotor and a Kavo LUX K201(Germany) contra-angle. Shade was measured in the middle third of each 1.1 tooth, by the same observer, using a VITA Easyshade V spectrophotometer (Zahnfabrikn Bad Säckingen, Germany), which was calibrated before each determination according to manufacturer's instructions, in the same dental unit (Sino S2316), with natural illumination, in the same time slot, without using the dental unit lamp. The results were recorded in an ad-hoc form and rates and confidence interval were obtained. Shade prevalence percentages (95% CI) were: A1: 46.2 (38.83 - 53.68); followed by A2 and B2, both with 17.39 (12.21 - 23.66); A3: 6.52 (3.41-11.11); B1: 4.35 (1.9-8.39); D2: 2.72 (0.89 - 6.23); B3: 2.17 (0.60-5.47) and C2: 1.09 (0.13-3.87); D3, C3, A3.5 and A4: 0.54 (0.01-2.99). Shades D1 and C1 were not determined in any subject. Within the conditions of this study, A1 was the most prevalent shade in central incisors, followed by A2 and B2.

El objetivo de este estudio fue evaluar la prevalencia de color dental en estudiantes de odontología de la Universidad de Buenos Aires (UBA). Los participantes fueron 184 estudiantes de cuarto año de la carrera de Odontología (157 mujeres y 27 hombres) de entre veintiuno y treinta tres años, con un promedio de edad de 24,45 (DE 2,79) años que aceptaron participar mediante consentimiento informado. Criterios de exclusión: quienes hayan recibido blanqueamiento en los últimos seis meses, tenían una restauración periférica total o parcial, pigmentaciones, fractura, lesiones cariosas y/o no cariosas en el incisivo central superior derecho (1.1) o éste estaba ausente. Se realizó profilaxis dental en la superficie bucal de cada 1.1 con un cepillo ad-hoc (TDV) montado en un micromotor de baja velocidad Kavo 2068 CHC (Alemania) y un contra-ángulo Kavo LUX K201 (Alemania). La medición del color se llevó a cabo en el tercio medio de cada 1.1, por el mismo observador, en la misma clínica dental, con iluminación natural en la misma franja horaria y sin utilizar la lámpara del equipo dental. Se utilizó un espectrofotómetro VITA Easyshade V (Zahnfabrikn Bad Säckingen, Alemania) que se calibró antes de cada determinación de acuerdo con las instrucciones del fabricante. Los resultados se registraron en una planilla ad-hoc y se obtuvieron tasas e intervalos de confianza. Prevalencia de colores % (IC 95%): A1: 46,2 (38,83 - 53,68), seguido de A2 y B2 ambos con 17,39 (12,21 - 23,66), A3: 6,52 (3,41-11,11), B1: 4,35 ( 1,9- 8,39), D2: 2,72 (0,89 - 6,23), B3: 2,17 (0,60-5,47) y C2: 1,09 (0,13- 3,87); D3, C3, A3.5 y A4: 0.54 (0.01-2.99) D1 y C1 no se determinaron en ningún sujeto. Dentro de las condiciones de este estudio A1 fue el color más prevalente en los incisivos centrales de estudiantes de odontología, seguido de A2 y B2.

Tooth color in dental students from Buenos Aires University, Dental School, Argentina / Color dentario en estudiantes de la Facultad de Odontología de la Universidad de Buenos Aires, Argentina

ABSTRACT The aim of this study was to evaluate tooth color in dental students at the University of Buenos Aires, Argentina. The participants were 184 students (157 women and 27 men) aged 21 to 33 years, mean age 24.45 (SD 2.79) years, who were in the fourth year of their dental degree. They agreed to participate through an informed consent. Exclusion criteria were: having undergone a bleaching treatment within the previous six months, presence of total or partial peripheral restoration, pigmentations, fracture, carious and non-carious lesions or absence of the right upper central incisor (1.1). A dental prophylaxis procedure was performed on the buccal surface of each 1.1 tooth with a prophylaxis brush (TDV) mounted on a low-speed rotary instrument Kavo 2068 CHC (Germany) micromotor and a Kavo LUX K201(Germany) contra-angle. Shade was measured in the middle third of each 1.1 tooth, by the same observer, using a VITA Easyshade V spectrophotometer (Zahnfabrikn Bad Säckingen, Germany), which was calibrated before each determination according to manufacturer's instructions, in the same dental unit (Sino S2316), with natural illumination, in the same time slot, without using the dental unit lamp. The results were recorded in an ad-hoc form and rates and confidence interval were obtained. Shade prevalence percentages (95% CI) were: A1: 46.2 (38.83 - 53.68); followed by A2 and B2, both with 17.39 (12.21 - 23.66); A3: 6.52 (3.41-11.11); B1: 4.35 (1.9-8.39); D2: 2.72 (0.89 - 6.23); B3: 2.17 (0.60-5.47) and C2: 1.09 (0.13-3.87); D3, C3, A3.5 and A4: 0.54 (0.01-2.99). Shades D1 and C1 were not determined in any subject. Within the conditions of this study, A1 was the most prevalent shade in central incisors, followed by A2 and B2.

RESUMEN El objetivo de este estudio fue evaluar la prevalencia de color dental en estudiantes de odontología de la Universidad de Buenos Aires (UBA). Los participantes fueron 184 estudiantes de cuarto año de la carrera de Odontología (157 mujeres y 27 hombres) de entre veintiuno y treinta tres años, con un promedio de edad de 24,45 (DE 2,79) años que aceptaron participar mediante consentimiento informado. Criterios de exclusión: quienes hayan recibido blanqueamiento en los últimos seis meses, tenían una restauración periférica total o parcial, pigmentaciones, fractura, lesiones cariosas y/o no cariosas en el incisivo central superior derecho (1.1) o éste estaba ausente. Se realizó profilaxis dental en la superficie bucal de cada 1.1 con un cepillo ad-hoc (TDV) montado en un micromotor de baja velocidad Kavo 2068 CHC (Alemania) y un contra-ángulo Kavo LUX K201 (Alemania). La medición del color se llevó a cabo en el tercio medio de cada 1.1, por el mismo observador, en la misma clínica dental, con iluminación natural en la misma franja horaria y sin utilizar la lámpara del equipo dental. Se utilizó un espectrofotómetro VITA Easyshade V (Zahnfabrikn Bad Säckingen, Alemania) que se calibró antes de cada determinación de acuerdo con las instrucciones del fabricante. Los resultados se registraron en una planilla ad-hoc y se obtuvieron tasas e intervalos de confianza. Prevalencia de colores % (IC 95%): A1: 46,2 (38,83 - 53,68), seguido de A2 y B2 ambos con 17,39 (12,21 - 23,66), A3: 6,52 (3,41-11,11), B1: 4,35 ( 1,9- 8,39), D2: 2,72 (0,89 - 6,23), B3: 2,17 (0,60-5,47) y C2: 1,09 (0,13- 3,87); D3, C3, A3.5 y A4: 0.54 (0.01-2.99) D1 y C1 no se determinaron en ningún sujeto. Dentro de las condiciones de este estudio A1 fue el color más prevalente en los incisivos centrales de estudiantes de odontología, seguido de A2 y B2.

Photostability and Dynamic Helical Behavior in Chiral Poly(phenylacetylene)s with a Preferred Screw-Sense.

Helical polymers such as poly(phenylacetylene)s (PPAs) are interesting materials due to the possibility of tuning their helical scaffold (sense and elongation) once they have been prepared and by the presence of external stimuli. The main limitation in the application of PPAs is their poor photostability. These polymers degrade under visible light exposure through a photochemical electrocyclization process. In this work, it was demonstrated, through a selected example, how the photochemical degradation in PPAs is directly related to their dynamic helical behavior. Thus, while PPAs with dynamic helical structures show poor photostability under UV/Vis light exposure, poly-(R)-1, bearing an enantiopure sulfoxide group as pendant group and designed to have a quasi-static helical behavior, shows a large photostability due to the restricted conformational composition at the polyene backbone, needed to orient the conjugated double bonds prior to the photochemical electrocyclization process and the subsequent degradation of the material.

Helically Chiral Hybrid Cyclodextrin Metal-Organic Framework Exhibiting Circularly Polarized Luminescence.

Three achiral polycyclic aromatic fluorophores─namely, 1-pyrenecarboxylic acid, 9-anthracenecarboxylic acid, and perylene-3,9-dicarboxylic acid─were chosen based on their desired properties before being incorporated into the construction of a K+-carrying gamma-cyclodextrin (γ-CD)-based metal-organic framework (CD-MOF-1) and γ-CD-containing hybrid frameworks (CD-HFs). Among these fluorophores, only the pyrene-carrying one shows significant noncovalent bonding interactions with γ-CD in solution. This fluorophore is encapsulated in a CD-HF with a trigonal superstructure instead of the common cubic CD-MOF-1 found in the case of the other two fluorophores. Single-crystal X-ray diffraction analysis of the trigonal CD-HF reveals a π-stacked chiral positioning of the pyrene-carrying fluorophore inside the (γ-CD)2 tunnels and held uniformly around an enantiomorphous 32 screw axis along the c direction in the solid-state structure. This helix-like structure demonstrates an additional level of chirality over and above the point-chiral stereogenic centers of γ-CD and the axial chirality associated with the self-assembled π-stacked fluorophores. These arrangements result in specifically generated photophysical and chiroptical properties, such as the controlled emergence of circularly polarized luminescence (CPL) emission. In this manner, a complete understanding of the mechanism of chirality transfer from a chiral host (CD-HF) to an encapsulated achiral fluorophore has been achieved, an attribute which is often missing in the development of materials with CPL.

On-Surface Thermal Stability of a Graphenic Structure Incorporating a Tropone Moiety.

On-surface synthesis, complementary to wet chemistry, has been demonstrated to be a valid approach for the synthesis of tailored graphenic nanostructures with atomic precision. Among the different existing strategies used to tune the optoelectronic and magnetic properties of these nanostructures, the introduction of non-hexagonal rings inducing out-of-plane distortions is a promising pathway that has been scarcely explored on surfaces. Here, we demonstrate that non-hexagonal rings, in the form of tropone (cycloheptatrienone) moieties, are thermally transformed into phenyl or cyclopentadienone moieties upon an unprecedented surface-mediated retro-Buchner-type reaction involving a decarbonylation or an intramolecular rearrangement of the CO unit, respectively.

Central incisors shape and proportions prevalence in Argentinian university students: by visual assessment and a new standardized method.

The aim of this study was to analyze the dimensions of the clinical crown of upper central incisors and the prevalence of tooth shapes by two different protocols. Assessment was performed on each of the 111 dental stone type V maxillae models of students of dentistry from Buenos Aires University [93 females and 18 males, mean age 23.70 (± 2.26) years] The mesial and distal-vestibular angles were defined on each right upper incisor, and the following segments were defined: AB (zenith - incisal edge), CD, EF, GH (apical, middle, and incisal thirds - vestibule - mesial and vestibule-distal angles) and their lengths were determined with a precision caliper. Then, the CD/AB, EF/AB and mean CD-EF/AB ratios were calculated. Shapes were assessed by four independent observers, three of whom evaluated digital images of the models, while the fourth had no access to the images, and determined the shapes using an algorithm developed from the dimensions of the studied segments. Rates and confidence intervals were determined, and Fleiss' Kappa was calculated to assess the agreement among the evaluators who worked with the images and among all of them. Average incisor length was 10 mm, and widths at CD and EF were 7.35 mm (0.65) and 8.27 mm (0.58), respectively. Regarding shapes, 51.58% (47.90-55.20) of the incisors were identified as square, 18.02% (14.50-21.90) as ovoid and 30.41% (30.00-30.90) as triangular. Fleiss' Kappa agreement was 0.71 (0.62-0.80). The application of the proposed algorithm provided a considerable level of agreement among the observers. Regarding tooth size, both the average segment length and the proportions were similar to those reported by various authors.

El objetivo de este trabajo fue analizar las dimensiones de las coronas clínicas de incisivos centrales superiores, y la prevalencia de cada una de las formas dentarias según diferentes formas de determinación. Se utilizaron modelos de yeso tipo V de 111 estudiantes (93 mujeres y 18 varones) con una media de edad de 23,70 (± 2,26) años. Se definieron los ángulos vestíbulo - mesial y distal para los incisivos centrales superiores derechos (1.1), se definieron los siguientes segmentos: AB (cenit - borde incisal), CD, EF, GH (tercios apical, medio e incisal - ángulos vestíbulo - mesial y vestíbulo- distal) y se determinaron sus longitudes con un calibre de precisión. Se calcularon las proporciones CD/AB, EF/AB y media CDEF/ AB. Las formas de las piezas dentarias fueron identificadas por cuatro observadores independientes, tres lo hicieron mediante la evaluación de imágenes digitales de los modelos confeccionados. El cuarto observador, sin acceso a las imágenes, asignó a cada pieza una de las formas determinadas mediante la aplicación de un algoritmo elaborado ad-hoc. Se obtuvieron tasas e intervalos de confianza y se calculó Kappa de Fleiss para valorar la concordancia entre evaluadores. La longitud promedio fue de 10 mm y el ancho en los segmentos CD y EF fueron de 7.35 mm (0.65) y 8.27 mm (0.58) respectivamente. En cuanto a formas el 51,58% (47.90-55.20) de los incisivos estudiados fueron identificados como cuadrados, el 18.02% (14.50-21.90) como ovoides y el 30,41% (30.00-30.90) triangulares. La concordancia de Kappa de Fleiss fue de 0.71 (0.62-0.80). La aplicación del algoritmo propuesto alcanzó un nivel de concordancia considerable entre los evaluadores. En cuanto al tamaño dentario, tanto la longitud promedio de los segmentos estudiados como las proporciones halladas son similares a las reportadas por diversos autores.

Studying the reactivity of alkyl substituted BODIPYs: first enantioselective addition of BODIPY to MBH carbonates.

The first enantioselective addition of alkyl BODIPYs to Morita-Baylis-Hillman (MBH) carbonates is reported. This is the first reported enantioselective methodology using the methylene position of BODIPYs as a nucleophile. The reaction is efficiently catalyzed by cinchona alkaloids, achieving high enantioselectivities and total diastereoselectivity. The use of cinchona alkaloid pseudo enantiomers (chinine/cinchonine) allows us to obtain both pairs of enantiomers in similar yields and enantioselectivities, a common issue in this type of reaction. The photophysical study of these dyes (absorption and fluorescence) has been performed in order to determine their parameters and explore future possible application in bioimaging. In addition, electronic circular dichroism (ECD) studies supported by time-dependent density functional theory (TD-DFT) calculations were also performed.

Central incisors shape and proportions prevalence in Argentinian university students / Prevalencia de forma y tamaño de los incisivos centrales en estudiantes universitarios argentinos

ABSTRACT The aim of this study was to analyze the dimensions of the clinical crown of upper central incisors and the prevalence of tooth shapes by two different protocols. Assessment was performed on each of the 111 dental stone type V maxillae models of students of dentistry from Buenos Aires University [93 females and 18 males, mean age 23.70 (± 2.26) years] The mesial and distal-vestibular angles were defined on each right upper incisor, and the following segments were defined: AB (zenith - incisal edge), CD, EF, GH (apical, middle, and incisal thirds - vestibule - mesial and vestibule-distal angles) and their lengths were determined with a precision caliper. Then, the CD/AB, EF/AB and mean CD-EF/AB ratios were calculated. Shapes were assessed by four independent observers, three of whom evaluated digital images of the models, while the fourth had no access to the images, and determined the shapes using an algorithm developed from the dimensions of the studied segments. Rates and confidence intervals were determined, and Fleiss' Kappa was calculated to assess the agreement among the evaluators who worked with the images and among all of them. Average incisor length was 10 mm, and widths at CD and EF were 7.35 mm (0.65) and 8.27 mm (0.58), respectively. Regarding shapes, 51.58% (47.90-55.20) of the incisors were identified as square, 18.02% (14.50-21.90) as ovoid and 30.41% (30.00-30.90) as triangular. Fleiss' Kappa agreement was 0.71 (0.62-0.80). The application of the proposed algorithm provided a considerable level of agreement among the observers. Regarding tooth size, both the average segment length and the proportions were similar to those reported by various authors.

RESUMEN El objetivo de este trabajo fue analizar las dimensiones de las coronas clínicas de incisivos centrales superiores, y la prevalencia de cada una de las formas dentarias según diferentes formas de determinación. Se utilizaron modelos de yeso tipo V de 111 estudiantes (93 mujeres y 18 varones) con una media de edad de 23,70 (± 2,26) años. Se definieron los ángulos vestíbulo - mesial y distal para los incisivos centrales superiores derechos (1.1), se definieron los siguientes segmentos: AB (cenit - borde incisal), CD, EF, GH (tercios apical, medio e incisal - ángulos vestíbulo - mesial y vestíbulo- distal) y se determinaron sus longitudes con un calibre de precisión. Se calcularon las proporciones CD/AB, EF/AB y media CDEF/ AB. Las formas de las piezas dentarias fueron identificadas por cuatro observadores independientes, tres lo hicieron mediante la evaluación de imágenes digitales de los modelos confeccionados. El cuarto observador, sin acceso a las imágenes, asignó a cada pieza una de las formas determinadas mediante la aplicación de un algoritmo elaborado ad-hoc. Se obtuvieron tasas e intervalos de confianza y se calculó Kappa de Fleiss para valorar la concordancia entre evaluadores. La longitud promedio fue de 10 mm y el ancho en los segmentos CD y EF fueron de 7.35 mm (0.65) y 8.27 mm (0.58) respectivamente. En cuanto a formas el 51,58% (47.90-55.20) de los incisivos estudiados fueron identificados como cuadrados, el 18.02% (14.50-21.90) como ovoides y el 30,41% (30.00-30.90) triangulares. La concordancia de Kappa de Fleiss fue de 0.71 (0.62-0.80). La aplicación del algoritmo propuesto alcanzó un nivel de concordancia considerable entre los evaluadores. En cuanto al tamaño dentario, tanto la longitud promedio de los segmentos estudiados como las proporciones halladas son similares a las reportadas por diversos autores.

Bright Long-Lived Circularly Polarized Luminescence in Chiral Chromium(III) Complexes.

A series of highly emissive inert and chiral CrIII complexes displaying dual circularly polarized luminescence (CPL) within the NIR region have been prepared and characterized. The helical [Cr(dqpR)2 ]3+ (dqp=2,6-di(quinolin-8-yl)pyridine; R=OCH3 , Br or C≡CH) complexes were synthesized as racemic mixtures and resolved into their respective PP and MM enantiomers by chiral stationary phase HPLC. The corresponding enantiomers show large glum ≈0.2 and high quantum yield of up to 17 %, which afford important CPL brightness of up to 170 m-1 cm-1 , a key point for applications as chiral luminescent probes. Moreover, the long-lived CP-NIR emission provided by these chromophores (ms range) in aqueous solution opens the way toward the quantification of chiral targets in biological systems with time-gated detection. Thus, such chiral chromophores based on earth abundant and inert 3d metals open new perspectives in the field of CPL and represent an alternative to precious 4d, 5d and to labile 4f metal-based complexes.