Investigação teórica das propriedades fotoquímicas da silola ao longo das coordenadas de abertura do anel pela ligação C-Si

O uso de moléculas orgânicas semicondutoras para a conversão de energia solar em energia elétrica é estratégico, uma vez que são potencialmente mais leves, podem apresentar transparência e ser facilmente modificadas por via química. Apesar dos semicondutores orgânicos apresentarem baixa eficiência, baixo coeficiente de difusão de éxcitons e perda de energia de excitação via acoplamento vibrônico, o menor custo de produção torna seu uso viável economicamente. A silolas têm sido estudadas experimentalmente como unidades de polímeros semicondutores para o uso em células solares, OFETs e LCDs, pois elas são eficientes aceptores de elétrons. Nestre trabalho busca-se compreender e mapear recortes da superfície de energia potencial da silola ao longo das coordenadas de abertura do anel pelo alongamento da ligação C-Si. Foram estudados dois tipos de abertura: uma seguindo o modo de vibração 2A (fora do plano) e uma seguindo a média dos modos normais 5A e 10A (no plano). O método utilizado para a construção das superfícies de energia potencial foi o equation-of-motion coupled cluster singles and doubles (EOM-CCSD) implementado no pacote MOLPRO. A geometria do estado fundamental (0) e dos dois primeiros estados excitados (1 e 2) foram otimizadas na base 6-31++G**. A partir de cálculos de energia de excitação verticais foi determinado o desvio de Stokes para o processo 1 − 0 (0,99 eV) e 2 − 0 (1,45 eV). Os cortes nas superfícies de energia potencial indicam possíveis cruzamentos entre o bright state 3 e os estados 2 e 4 para o mecanismo de abertura do anel no plano e possíveis cruzamentos entre os estados 1/2, 2/3 e 3/4 para a abertura do anel fora do plano. Nenhum dos dois mecanismos apresentou cruzamentos entre as superfícies dos estados excitados e o estado fundamental, o que indica que a silola apresenta uma certa fotoestabilidade em relação a esse processo. Para uma investigação mais criteriosa destas SEPs, foram feitos estudos preliminares para a escolha do espaço ativo mais adequado para o sistema utilizando o método complete active space self-consistent field (CASSCF). Seguindo critérios de energia,custo computacional e natureza do processo para a escolha, obteve-se que o espaço ativo escolhido considera a inclusão de 6 elétrons e 8 orbitais - CAS(6,8)

Towards developing novel and sustainable molecular light-to-heat converters

Light-to-heat conversion materials generate great interest due to their widespread applications, notable exemplars being solar energy harvesting and photoprotection. Another more recently identified potential application for such materials is in molecular heaters for agriculture, whose function is to protect crops from extreme cold weather and extend both the growing season and the geographic areas capable of supporting growth, all of which could help reduce food security challenges. To address this demand, a new series of phenolic-based barbituric absorbers of ultraviolet (UV) radiation has been designed and synthesised in a sustainable manner. The photophysics of these molecules has been studied in solution using femtosecond transient electronic and vibrational absorption spectroscopies, allied with computational simulations and their potential toxicity assessed by in silico studies. Following photoexcitation to the lowest singlet excited state, these barbituric absorbers repopulate the electronic ground state with high fidelity on an ultrafast time scale (within a few picoseconds). The energy relaxation pathway includes a twisted intramolecular charge-transfer state as the system evolves out of the Franck–Condon region, internal conversion to the ground electronic state, and subsequent vibrational cooling. These barbituric absorbers display promising light-to-heat conversion capabilities, are predicted to be non-toxic, and demand further study within neighbouring application-based fields

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Simulation de la dynamique moléculaire et de la structure électronique de chromophores photoexcités en phase gazeuse et dans des environnements complexes

Le développement d'une nouvelle classe de molécules calorifères, déposées directement sur les plantes, est une nouvelle stratégie pour étendre les lieux propices à l'agriculture à des altitudes plus élevées, en prévenant les dommages causés par le froid. L'idée sous-jacente est que ces molécules calorifères sont capables d'absorber le rayonnement UV-visible et de le convertir en chaleur, dans ce cas, à destination de la surface des feuilles. Inspirés par les stratégies photoprotectrices efficaces trouvées dans la nature, nous étudions des dérivés du malate de sinapoyle (SM). Après absorption de la lumière, ces dérivés présentent une désexcitation non radiative rapide et efficace. D'autre part, les dicétopyrrolopyrroles sont également des candidats. Le dimère possède un état doublement excité de faible énergie qui n'est pas accessible au monomère, permettant à la conversion interne de se produire en premier. Nous caractérisons la fonction d'onde de l'état doublement excité en modifiant de façon systématique les dérivés de façon à ajuster la taille du système π et les caractères de l'accepteur et du donneur. Cette analyse ouvre de nouvelles voies pour contrôler l'équilibre entre la luminescence et la conversion interne dans de tels systèmes. Cependant, une caractérisation correcte des états doublement excités reste un défi : il n'existe aucun schéma de classification rigoureux et transférable entre les méthodes. Nous proposons donc de classer les états doublement excités selon deux cas limites : les états doublement excités à couche ouverte ou fermée. Notre schéma de classification est basé sur des descripteurs extraits des matrices de la densitéDeveloping a new class of molecular heaters to be applied in plants is a new strategy to extend locations suitable for agriculture to higher altitudes, preventing damages caused by the cold. The underlining idea is that molecular heaters can absorb UV-vis radiation and convert it into heat, in this case, to the leaves' surface. Inspired by nature and its efficient photoprotective features, we study the photophysics of derivatives of sinapoyl malate (SM). These derivatives exhibit a fast and efficient nonradiative decay through a twisted charge-transfer state. Another class of potential candidates as molecular heaters are the diketopyrrolopyrroles. The dimer has a low-lying doubly excited state that is not energetically accessible to the monomer, and this delays the fluorescence allowing internal conversion to occur first. We characterize the doubly excited state wavefunction by systematically changing the derivatives to tune the pi-scaffold size and the acceptor and donor characters. This analysis opens new ways to control the balance between luminescence and internal conversion in such systems. However, a proper characterization of doubly excited states is still a challenge, and no rigorous and transferable classification scheme between methods exists. Then, we propose classifying doubly excited states according to two limiting cases: the open- and closed-shell doubly excited states, based on descriptors extracted from density matrice

Research data underlying the manuscript "Classification of Doubly Excited Molecular Electronic States" by M. T. do Casal, J. M. Toldo, M. Barbatti and F. Plasser.

Research data underlying the manuscript "Classification of Doubly Excited Molecular Electronic States" by M. T. do Casal, J. M. Toldo, M. Barbatti and F. Plasser.  Content: Single point calculations were performed on the systems below. Each molecule folder contains subfolders with inputs and outputs at the electronic structure level indicated below.  1. Formaldehyde Dimer   a. ADC(3) 2. Polyenes   a. DFT/MRCI   b. ADC(3)   c. MRCISD   d. TDDFT 3. Cycloaddtion of Ethylene   a. MRCISD 4. DPP Dimer   a. DFT/MRCI 5. Tetracene Dimer   a. DFT/MRCI 6. Tetrazine    a. DFT/MRCI 7. bis-Thiophene   a. DFT/MRCIa singlets DFT/MRCI folders contain the following files:   control: TURBOMOLE's input file  coord: Input geometry for TURBOMOLE and DFT/MRCI   mrci.inp: Input file for DFT/MRCI  run_dftci.inp: Input file for the driver interfacing TURBOMOLE and DFT/MRCI  mrci.sum: Summary of DFT/MRCI calculations ADC(3) folders contain the following files:   qchem-monomer.in: Q-Chem input file  qchem.out: Q-Chem output file  libwfa_summ.txt: Output file summarising excited state properties  MRCISD folders contain:  INPUT directory: All necessary input files for COLUMBUS  LISTINGS: All output files generated by COLUMBUS TDDFT folders contain:  coord.qchem: Input geometry for Q-Chem  qchem.in: Q-Chem input file  qchem.out: Q-Chem output file  libwfa_summ.txt: Output file summarising excited state properties  Output files for TheoDORE summarising excited state properties are also provided:  tden_summ.txt: Output file from TheoDORE for the transition density matrix analysis sden_summ.txt.: Output file from TheoDORE for the state density matrix analysis.  All results used for plotting are compiled in two datasets: cycloaddition.csv and polyenes.csv.</p

Surface hopping modeling of charge and energy transfer in complex environments

A complex environment is any atomic or molecular system changing a chromophore\u27s nonadiabatic dynamics compared to the isolated molecule. The action of the environment on the chromophore occurs by changing the potential energy landscape and triggering new energy and charge flows unavailable in the vacuum. Surface hopping is a mixed quantum-classical approach whose extreme flexibility has made it the primary platform for implementing novel methodologies to investigate the nonadiabatic dynamics of a chromophore in complex environments. This Perspective paper surveys the latest developments in the field, focusing on charge and energy transfer processes

Classification of doubly excited molecular electronic states

Electronic states with partial or complete doubly excited character play a crucial role in many areas, such as singlet fission and non-linear optical spectroscopy. Although doubly excited states have been studied in polyenes and related systems for many years, the assignment as singly vs. doubly excited, even in the simplest case of butadiene, has sparked controversies. So far, no well-defined framework for classifying doubly excited states has been developed, and even more, there is not even a well-accepted definition of doubly excited character as such. Here, we present a solution: a physically motivated definition of doubly excited character based on operator expectation values and density matrices, which works independently of the underlying orbital representation, avoiding ambiguities that have plagued earlier studies. Furthermore, we propose a classification scheme to differentiate three cases: (i) two single excitations occurring within two independent pairs of orbitals leaving four open shells (DOS), (ii) the promotion of both electrons to the same orbital, producing a closed-shell determinant (DCS), and (iii) a mixture of singly and doubly excited configurations not aligning with either one of the previous cases (Dmix). We highlight their differences in underlying energy terms and explain their signatures in practical computations. The three cases are illustrated through various high-level computational methods using dimers for DOS, polyenes for Dmix, and cyclobutane and tetrazine for DCS. The conversion between DOS and DCS is investigated using a well-known photochemical reaction, the photodimerization of ethylene. This work provides a deeper understanding of doubly excited states and may guide more rigorous discussions toward improving their computational description while also giving insight into their fundamental photophysics. </p