Raman spectroscopy meets organic biradicals. Study of a new diindeno [B,I] anthracene derivative

Comunicación oral a congresoIn recent years, there has been a renewed interest in the study of open-shell polycyclic aromatic hydrocarbons (PAHs). Among them, biradicals exhibit attractive electronic, magnetic and optical properties which make them promising candidates for a wide range of applications in organic electronics, such as nonlinear optics, molecular spintronics, energy storage and organic photovoltaic devices sensitized by singlet fission. Despite all the promising properties of open-shell PAHs, a common drawback still needs to be overcome: the high reactivity of radicals, which implies that most open-shell species tend to be too short-lived for practical aplications and even for characterization [1]. In this regard, Raman spectroscopy has shown to be a suitable tool for studying this kind of molecular systems, being able to provide valuable information. This work reports the study of a new biradical, diindeno[b,i]anthracene (DIAn)[2], [3] , highlighting the crucial role played by Raman Spectroscopy in the characterization of the ground electronic state as well as in the rationalization of the ambipolar behavior shown in OFETs. To this end, neutral and charged species has been studied by Raman spectroscopy as a function of excitation wavelength, temperatura and pressure.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Raman Activities of Cyano-Ester Quinoidal Oligothiophenes Reveal Their Diradical Character and the Proximity of the Low-Lying Double Exciton State

Quinoidal oligothiophenes have received considerable attention as interesting platforms with remarkable amphoteric redox behavior associated with their diradical character increasing with the conjugation lengths. In this work, we considered a family of quinoidal oligothiophenes bearing cyano-ester terminal groups and characterized them by UV-Vis-NIR absorption and Raman spectroscopy measurements at different excitation wavelengths. The experimental investigation is complemented by quantum-chemical studies to assess the quality of computed density functional theory (DFT) ground state structures and their influence on predicted Raman intensities. In addition, resonance conditions with the optically active HOMO→LUMO transition as well as with the more elusive state dominated by the doubly excited HOMO,HOMO→LUMO,LUMO configuration, are determined with DFT-MRCI calculations and their contributions to Raman activity enhancement are discussed in terms of computed vibrational Huang–Rhys (HR) factorsWe thank MINECO/FEDER of the Spanish Government (project reference PGC2018-098533-B-100) and the Junta de Andalucía, Spain (UMA18FEDERJA057). Partial funding for open access charge: Universidad de Málag

Bases espectroscópicas de la relación estructura-carácter birradical-propiedad en sistemas proaromáticos pi-conjugados derivados de p-QDM

En esta comunicación se estudia, mediante diversos tipos de espectroscopias y haciendo hincapié en la espectroscopia Raman, el efecto que modificaciones estructurales como el aumento de la longitud de la cadena o la planarización del esqueleto pi-conjugado, tienen sobre la expresión del carácter birradical en el estado fundamental de nuevos derivados de p-QDM.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Reversible Dimerization/Polymerization of a Janus Diradical Producing Labile CC Bonds and Giant Chromism

En esta comunicación se presenta el estudio espectroscópico y téorico de la dimerización/oligomerización reversible de un birradical derivado de naftoditiofeno el cual en su forma monomérica presenta una intenso color azul mientras que al agregar se muestra incoloro, siendo éstas formas intercambiables gracias a la aplicación de estímulos débiles como presión o temperatura.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Pooled analysis of WHO Surgical Safety Checklist use and mortality after emergency laparotomy

Background The World Health Organization (WHO) Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. The aim of this study was to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients who had emergency laparotomy. Methods In two multinational cohort studies, adults undergoing emergency laparotomy were compared with those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results Of 12 296 patients included from 76 countries, 4843 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use before emergency laparotomy was more common in countries with a high Human Development Index (HDI) (2455 of 2741, 89.6 per cent) compared with that in countries with a middle (753 of 1242, 60.6 per cent; odds ratio (OR) 0.17, 95 per cent c.i. 0.14 to 0.21, P <0001) or low (363 of 860, 422 per cent; OR 008, 007 to 010, P <0.001) HDI. Checklist use was less common in elective surgery than for emergency laparotomy in high-HDI countries (risk difference -94 (95 per cent c.i. -11.9 to -6.9) per cent; P <0001), but the relationship was reversed in low-HDI countries (+121 (+7.0 to +173) per cent; P <0001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0.60, 0.50 to 073; P <0.001). The greatest absolute benefit was seen for emergency surgery in low- and middle-HDI countries. Conclusion Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low-HDI countries was half that in high-HDI countries.Peer reviewe

Birradicales kekulé: espectroscopia Raman en la transición singlete-triplete

En esta Tesis Doctoral se lleva a cabo la caracterización del estado fundamental y primer estado excitado triplete de una serie de hidrocarburos policíclicos aromáticos (PAHs) con carácter pro-aromático o quinoide basados en la unidad para-quinodimetano (p-QDM). Se estudian cuatro familias de compuestos divididas en: derivados de perileno bis(dicianometileno)sustituidos, derivados cetrénicos, derivados tetrabenzo-chichibabin y derivados de naftoditiofeno con sustituyentes bis(ciano-acil metileno) y bis(diciano-metileno). Mediante la espectroscopia vibracional Raman, fundamentalmente, se determina el carácter de capa cerrada o capa abierta de los mismos. Una vez caracterizado cada sistema en estos términos, en los sistemas de capa abierta, se trata de elucidar la multiplicidad de espín del estado fundamental, así como el carácter birradical de cada sistema, resultados que se interpretan en términos del mecanismo de Doble Polarización de Espín. Se obtienen así, relaciones estructura-propiedad que permiten entender la conexión entre pro-aromaticidad y estabilización de especies de capa abierta, así como la influencia que las distintas modificaciones introducidas en cada familia de compuestos tienen sobre la expresión del carácter birradical y la multiplicidad de espín del estado fundamental

Diradical-mediated weak intermolecular sigma bond formation. Influence of the quinoidal-to-aromatic interplay on the giant and reversible chromism of a novel thienoquinoidal derivative

En esta comunicación se presenta el estudio espectroscópico y teórico de un nuevo derivado de naftoditiofeno que presenta una gran variación del color al aplicarle diversos estímulos muy débiles (Temeperatura, presión, concentración, etc.)debido a la influencia del carácter birradical en la formación reversible de entidades supramoleculares de diversa naturaleza.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech