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1.
Psychol Rep ; : 332941241242405, 2024 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-38551459

RESUMO

While theoretical connections between social inequity and boredom have been established, empirical evidence is lacking. Inequity aversion is important in this relationship. If individuals believe that the amount of work invested in pursuing an outcome has been unfairly devalued in relation to the investment of others, they may feel that their investment is greater than the outcome's worth. This experimental study explores whether devaluation of one's investment in a task, in relation to another individual's investment required to obtain equal rewards, is experienced as boredom. Undergraduate and graduate students (N = 31) were randomly assigned to one of three conditions and performed a monotonous task in the presence of a confederate, for equal reward. Exposure time to the confederate varied. It was expected that participants who spent more time on the task than the confederate would report more boredom and a negatively distorted time experience. Significant between-group effects were found for Tedium (F(2, 28) = 3.55, p = .04) and Temporal Estimation (F(2, 28) = 5.37, p = .01). Participants who spent more time on the task felt more bored (Mdiff = -1.05, p = .05) and rated time as progressing slower (Mdiff = -1.26, p = .03). There were no significant differences between the other conditions. A parsimonious interpretation is that the perceived inequity in resource investment costs associated with different lengths of social exposure during the boredom-inducing task increased the salience of investment loss, which was experienced as boredom and resulted in a distorted time experience.

2.
Worldviews Evid Based Nurs ; 21(3): 271-278, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38362722

RESUMO

BACKGROUND: Many adverse events are identified as nursing-sensitive indicators (NSIs) and have evidence-based care bundles known to reduce risk of occurrence. Kamishibai cards are a tool from the manufacturing industry used for practice auditing and improvements. Use of Kamishibai cards is believed to be common in the healthcare setting, but true evidence-based guidelines do not yet exist to guide their implementation. AIMS: The aim of this integrative review was to identify best practices around the implementation of Kamishibai cards in the healthcare setting for improvement in NSI-associated outcomes. METHODS: Eleven nurses at three facilities worked through the evidence using the Johns Hopkins Evidence-Based Practice Model. RESULTS: Ten articles were included for this review. Broad themes included direct observation with non-punitive and timely feedback, clearly visualized results, use of evidence-based care bundles, pre-implementation education, and both leadership and frontline-staff involvement. All facilities showed improvement in NSI-associated outcomes after the implementation of K-cards. LINKING ACTION TO ACTION: In health care, K-cards can be implemented and designed with additional focus on the bundles of care they are intended to audit and staff support, but further evidence would better define guidelines around implementation.


Assuntos
Prática Clínica Baseada em Evidências , Humanos , Prática Clínica Baseada em Evidências/métodos
3.
Adv Mater ; 36(25): e2314242, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38346232

RESUMO

Strain-engineering in atomically thin metal dichalcogenides is a useful method for realizing single-photon emitters (SPEs) for quantum technologies. Correlating SPE position with local strain topography is challenging due to localization inaccuracies from the diffraction limit. Currently, SPEs are assumed to be positioned at the highest strained location and are typically identified by randomly screening narrow-linewidth emitters, of which only a few are spectrally pure. In this work, hyperspectral quantum emitter localization microscopy is used to locate 33 SPEs in nanoparticle-strained WSe2 monolayers with sub-diffraction-limit resolution (≈30 nm) and correlate their positions with the underlying strain field via image registration. In this system, spectrally pure emitters are not concentrated at the highest strain location due to spectral contamination; instead, isolable SPEs are distributed away from points of peak strain with an average displacement of 240 nm. These observations point toward a need for a change in the design rules for strain-engineered SPEs and constitute a key step toward realizing next-generation quantum optical architectures.

4.
J Man Manip Ther ; 32(2): 198-205, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37694967

RESUMO

BACKGROUND: Ankle sprains are a commonly occurring musculoskeletal injury potentially resulting in persistent pain and/or altered motion. Thrust manipulation may serve as an interventional strategy but limited evidence exists on the mechanism(s) by which a change to symptoms might occur. OBJECTIVE: The study sought to quantify the immediate effect of a thrust manipulation to the ankle to determine a mechanism by which change to symptoms occurred. METHODS: Eleven participants (6 m/5f, 26.09 ± 4.25 yrs) with a history of ankle sprain that occurred greater than three months ago with recurring pain and/or altered motion were recruited. Participants underwent neurophysiological testing to assess any pain alterations and instrumented gait analysis (IGA) for biomechanical assessment pre-post thrust manipulation to the ankle. RESULTS: There were no significant differences in ankle dorsiflexion (DF) (p = 0.62), plantarflexion (PF) (p = 0.23), ground reaction force (GRF), or velocity (p = 0.63) following thrust manipulation compared to baseline; however, pre- and post-data did show differences in pain pressure threshold (p = 0.046). There were no significant differences in dynamic pain measurements. CONCLUSIONS: Ankle sprains that result in persistent pain and/or altered motion can be impacted by a thrust manipulation which appears to act through neurophysiological mechanisms.


Assuntos
Traumatismos do Tornozelo , Tornozelo , Humanos , Amplitude de Movimento Articular/fisiologia , Articulação do Tornozelo , Dor , Traumatismos do Tornozelo/terapia
5.
Dev Psychol ; 2023 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-37870802

RESUMO

Self-regulation (SR) is a central developmental task of early childhood and is considered essential for children's success during elementary school. It has typically been conceptualized as effortful control (EC) or executive function (EF), drawing respectively on research traditions in temperament and cognitive development. These aspects of SR are theorized to emerge from an intertwined developmental process, but the nature of their relation throughout elementary school has not been established. In particular, it is not known whether ratings given by teachers based on behavioral observations align with those directly assessed via novel performance tasks. This article addresses this gap in the knowledge by examining the codevelopment of EC and EF with regard to intraindividual trajectories of change. Drawing on a national sample (N = 8,742) from the Early Childhood Longitudinal Study-Kindergarten Cohort of 2010-2011, two longitudinal modeling approaches (parallel-process latent growth curves with structured residuals, Curran et al., 2014; multidimensional growth mixture models, Wickrama et al., 2021) were applied to examine children's SR between second and fifth grade. Overall, results do not reveal a systematic codevelopmental relation between EC and EF when accounting for intraindividual processes. Findings are discussed with regard to developmental theory and application. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

6.
J Am Chem Soc ; 145(36): 19655-19661, 2023 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-37643086

RESUMO

Most photochemistry occurs in the regime of weak light-matter coupling, in which a molecule absorbs a photon and then performs photochemistry from its excited state. In the strong coupling regime, enhanced light-matter interactions between an optical field and multiple molecules lead to collective hybrid light-matter states called polaritons. This strong coupling leads to fundamental changes in the nature of the excited states including multi-molecule delocalized excitations, modified potential energy surfaces, and dramatically altered energy levels relative to non-coupled molecules. The effect of strong light-matter coupling on covalent photochemistry has not been well explored. Photoswitches undergo reversible intramolecular photoreactions that can be readily monitored spectroscopically. In this work, we study the effect of strong light-matter coupling on the kinetics of photoswitching within optical cavities. Reproducing prior experiments, photoswitching of spiropyran/merocyanine photoswitches is decelerated in a cavity. Fulgide photoswitches, however, show the opposite effect, with strong coupling accelerating photoswitching. While modified merocyanine switching can be explained by changes in radiative decay rates or the amount of light in the cavity, modified fulgide switching kinetics suggest direct changes to excited-state reaction kinetics.

7.
Nat Commun ; 14(1): 4804, 2023 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-37558658

RESUMO

This work proposes a photophysical phenomenon whereby ultraviolet/visible (UV/vis) excitation of a molecule involving a Franck-Condon (FC) active vibration yields infrared (IR) emission by strong coupling to an optical cavity. The resulting UV/vis-to-IR photonic down conversion process is mediated by vibrational polaritons in the electronic excited state potential. It is shown that the formation of excited state vibrational polaritons (ESVP) via UV/vis excitation only involve vibrational modes with both a non-zero FC activity and IR activity in the excited state. Density functional theory calculations are used to identify 1-Pyreneacetic acid as a molecule with this property and the dynamics of ESVP are modeled. Overall, this work introduces an avenue of polariton chemistry where excited state dynamics are influenced by the formation of vibrational polaritons. Along with this, the UV/vis-to-IR photonic down conversion is potentially useful in both sensing excited state vibrations and quantum transduction schemes.

8.
Inorg Chem ; 62(23): 8903-8913, 2023 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-37260199

RESUMO

Magnesium vanadate (MgV2O6) and its alloys with copper vanadate were synthesized via the solution combustion technique. Phase purity and solid solution formation were confirmed by a variety of experimental techniques, supported by electronic structure simulations based on density functional theory (DFT). Powder X-ray diffraction combined with Rietveld refinement, laser Raman spectroscopy, diffuse reflectance spectroscopy, and high-resolution transmission electron microscopy showed single-phase alloy formation despite the MgV2O6 and CuV2O6 end members exhibiting monoclinic and triclinic crystal systems, respectively. DFT-calculated optical band gaps showed close agreement in the computed optical bandgaps with experimentally derived values. Surface photovoltage spectroscopy, ambient-pressure photoemission spectroscopy, and Kelvin probe contact potential difference (work function) measurements confirmed a systematic variation in the optical bandgap modification and band alignment as a function of stoichiometry in the alloy composition. These data indicated n-type semiconductor behavior for all the samples which was confirmed by photoelectrochemical measurements.

9.
Nat Commun ; 14(1): 2193, 2023 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-37069140

RESUMO

Two-dimensional (2D) materials have attracted attention for quantum information science due to their ability to host single-photon emitters (SPEs). Although the properties of atomically thin materials are highly sensitive to surface modification, chemical functionalization remains unexplored in the design and control of 2D material SPEs. Here, we report a chemomechanical approach to modify SPEs in monolayer WSe2 through the synergistic combination of localized mechanical strain and noncovalent surface functionalization with aryl diazonium chemistry. Following the deposition of an aryl oligomer adlayer, the spectrally complex defect-related emission of strained monolayer WSe2 is simplified into spectrally isolated SPEs with high single-photon purity. Density functional theory calculations reveal energetic alignment between WSe2 defect states and adsorbed aryl oligomer energy levels, thus providing insight into the observed chemomechanically modified quantum emission. By revealing conditions under which chemical functionalization tunes SPEs, this work broadens the parameter space for controlling quantum emission in 2D materials.

11.
J Am Chem Soc ; 2023 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-36780431

RESUMO

The synthesis as well as the structural and photophysical characterization of two isoleptic bis-cyclometalated Pt(II) and Pd(II) complexes, namely [PtL] and [PdL], bearing a tailored dianionic tetradentate ligand (L2-) are reported. The isostructural character and intermolecular interactions of [PtL] and [PdL] were assessed by NMR spectroscopy and X-ray diffraction analysis. Both complexes show fully ligand-controlled aggregation, demonstrating that a judicious molecular design can tune the photophysical properties. In fact, by introduction of fluorine atoms on defined positions and methoxy groups on complementary sites, metal-metal interactions can be forced by a head-to-tail stacking. Hence, [PtL] shows luminescence from metal-perturbed ligand-centered or from metal-metal-to-ligand charge-transfer triplet states in diluted solutions, in frozen glasses and in crystals, with high photoluminescence quantum yields and long lifetimes in the microsecond range. At room temperature (RT) in concentrated fluid solutions, the palladium analogue [PdL] surprisingly emits luminescence from aggregated species involving supramolecular interactions. Time-resolved photoluminescence and transient absorption spectroscopies demonstrated that ultrafast intersystem crossing occurs for both metals, which outruns any competitive relaxation pathway from the photoexcited singlet state. Furthermore, we demonstrate that the radiationless deactivation can be suppressed in frozen glassy matrices at 77 K and by intermolecular interactions in fluid solutions at RT. In both cases and as indicated by density functional theory calculations, the lowest emissive state acts as an energy trap from which the thermal population of dissociative states with formal occupation of an antibonding Pd-centered 4dx2-y2 orbital is suppressed. This occurs as the energy gap between the emissive and the dark states surpasses kT.

12.
Adv Mater ; 35(5): e2208066, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36373540

RESUMO

Solid-state single photon emitters (SPEs) within atomically thin transition metal dichalcogenides (TMDs) have recently attracted interest as scalable quantum light sources for quantum photonic technologies. Among TMDs, WSe2 monolayers (MLs) are promising for the deterministic fabrication and engineering of SPEs using local strain fields. The ability to reliably produce isolatable SPEs in WSe2 is currently impeded by the presence of numerous spectrally overlapping states that occur at strained locations. Here nanoparticle (NP) arrays with precisely defined positions and sizes are employed to deterministically create strain fields in WSe2 MLs, thus enabling the systematic investigation and control of SPE formation. Using this platform, electron beam irradiation at NP-strained locations transforms spectrally overlapped sub-bandgap emission states into isolatable, anti-bunched quantum emitters. The dependence of the emission spectra of WSe2 MLs as a function of strain magnitude and exposure time to electron beam irradiation is quantified and provides insight into the mechanism for SPE production. Excitons selectively funnel through strongly coupled sub-bandgap states introduced by electron beam irradiation, which suppresses spectrally overlapping emission pathways and leads to measurable anti-bunched behavior. The findings provide a strategy to generate isolatable SPEs in 2D materials with a well-defined energy range.

13.
Perspect Psychol Sci ; 18(2): 513-526, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36173751

RESUMO

The extent of the deleterious effects of the COVID-19 pandemic on mental health is recognized ubiquitously. However, these effects are subject to many modulatory factors from a plethora of domains of examination. It is important to understand the intersection of societal and individual levels for global stressors compared with local phenomena and physical-health outcomes. Here, we consider three perspectives: international/cultural, social, and individual. Both the enduring threat of COVID-19 infection and the protective measures to contain contagion have important consequences on individual mental health. These consequences, together with possible remedial interventions, are the focus of this article. We hope this work will stimulate more research and will suggest factors that need to be considered in the coordination of responses to a global threat, allowing for better preparation in the future.


Assuntos
COVID-19 , Saúde Mental , Pandemias , Humanos , COVID-19/epidemiologia , COVID-19/prevenção & controle , COVID-19/psicologia , Saúde Mental/estatística & dados numéricos , Pandemias/prevenção & controle , Saúde Global/estatística & dados numéricos , Masculino , Feminino , Distanciamento Físico , Fatores Socioeconômicos , Determinantes Sociais da Saúde
14.
Behav Sci (Basel) ; 12(8)2022 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-36004869

RESUMO

Throughout the COVID-19 pandemic, studies have demonstrated increases in boredom and its negative impact on mental health. This cross-sectional study examines state and trait boredom at four different points of the pandemic using an online sample of participants from the United States (n = 783). The results showed significant increases in boredom proneness, state boredom, substance use, loneliness, and distress. Boredom was associated with increases in each of these variables and a greater likelihood of testing positive for COVID-19. Moreover, the increases in distress, loneliness, and substance use became non-significant when controlling for boredom. Boredom proneness remained associated with all adverse outcomes when accounting for state boredom. In contrast, the relationships between state boredom and most adverse outcomes lost significance when controlling for boredom proneness, and state boredom was positively associated with increased hope for the future. Overall, the results suggest that high boredom proneness is an important vulnerability factor for poor psychological health and risky behaviors during the pandemic. However, high levels of recent state boredom, independent of boredom proneness, do not predict similarly negative outcomes. State boredom may indicate the extent to which one remains hopeful that circumstances will improve without resorting to risky, potentially maladaptive coping strategies.

15.
Artigo em Inglês | MEDLINE | ID: mdl-36011757

RESUMO

Dysphagia refers to swallowing difficulty, which impacts patients' quality of life. Dysphagia influences clinical outcomes, including mortality rates and length of hospital stay of older hospitalized patients. Dysphagia may affect the current and future quality of life of these patients. However, its exact impact remains unclear. We aimed to clarify the impact of dysphagia on discharge to home in older patients in a rural rehabilitation unit. We conducted a secondary analysis using data from a retrospective cohort study including patients aged over 65 years who had been discharged from a community hospital rehabilitation unit in rural Japan. Data from the participants had been previously collected from April 2016 to March 2020. The primary outcome was home discharge. The average participant age was 82.1 (standard deviation, 10.8) years; 34.5% were men. Among medical conditions, brain stroke (44.3%) was the most frequent reason for admission; the most frequent orthopedic condition was femoral fracture (42.9%). The presence of dysphagia (odds ratio [OR] = 0.38, 95% confidence interval [CI]: 0.20-0.73), polypharmacy (OR = 0.5, 95% CI: 0.32-0.90), and admission for internal medicine diseases (OR = 0.44, 95% CI: 0.26-0.77) were negatively associated with home discharge. High motor domain scores of the Functional Independence Measure were positively associated with home discharge (OR = 1.07, 95% CI: 1.05-1.08). Dysphagia was negatively associated with home discharge as were polypharmacy and admission for internal medicine diseases and conditions. By clarifying effective interventions through interventional studies, including approaches to managing multimorbidity and polypharmacy through interprofessional collaboration, the health conditions of older patients in rural areas may be improved.


Assuntos
Transtornos de Deglutição , Reabilitação do Acidente Vascular Cerebral , Idoso , Criança , Transtornos de Deglutição/epidemiologia , Feminino , Hospitais , Humanos , Japão/epidemiologia , Masculino , Alta do Paciente , Qualidade de Vida , Estudos Retrospectivos
16.
Nat Chem ; 14(9): 1007-1012, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35681045

RESUMO

The production of polymers from ethylene requires the ethylene feed to be sufficiently purified of acetylene contaminant. Accomplishing this task by thermally hydrogenating acetylene requires a high temperature, an external feed of H2 gas and noble-metal catalysts. It is not only expensive and energy-intensive, but also prone to overhydrogenating to ethane. Here we report a photocatalytic system that reduces acetylene to ethylene with ≥99% selectivity under both non-competitive (no ethylene co-feed) and competitive (ethylene co-feed) conditions, and near 100% conversion under the latter industrially relevant conditions. Our system uses a molecular catalyst based on earth-abundant cobalt operating under ambient conditions and sensitized by either [Ru(bpy)3]2+ or an inexpensive organic semiconductor (metal-free mesoporous graphitic carbon nitride) under visible light. These features and the use of water as a proton source offer advantages over current hydrogenation technologies with respect to selectivity and sustainability.


Assuntos
Cobalto , Água , Acetileno , Luz , Prótons
17.
J Am Chem Soc ; 144(14): 6390-6409, 2022 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-35378979

RESUMO

The nature of the organic cation in two-dimensional (2D) hybrid lead iodide perovskites tailors the structural and technological features of the resultant material. Herein, we present three new homologous series of (100) lead iodide perovskites with the organic cations allylammonium (AA) containing an unsaturated C═C group and iodopropylammonium (IdPA) containing iodine on the organic chain: (AA)2MAn-1PbnI3n+1 (n = 3-4), [(AA)x(IdPA)1-x]2MAn-1PbnI3n+1 (n = 1-4), and (IdPA)2MAn-1PbnI3n+1 (n = 1-4), as well as their perovskite-related substructures. We report the in situ transformation of AA organic layers into IdPA and the incorporation of these cations simultaneously into the 2D perovskite structure. Single-crystal X-ray diffraction shows that (AA)2MA2Pb3I10 crystallizes in the space group P21/c with a unique inorganic layer offset (0, <1/2), comprising the first example of n = 3 halide perovskite with a monoammonium cation that deviates from the Ruddlesden-Popper (RP) halide structure type. (IdPA)2MA2Pb3I10 and the alloyed [(AA)x(IdPA)1-x]2MA2Pb3I10 crystallize in the RP structure, both in space group P21/c. The adjacent I···I interlayer distance in (AA)2MA2Pb3I10 is ∼5.6 Å, drawing the [Pb3I10]4- layers closer together among all reported n = 3 RP lead iodides. (AA)2MA2Pb3I10 presents band-edge absorption and photoluminescence (PL) emission at around 2.0 eV that is slightly red-shifted in comparison to (IdPA)2MA2Pb3I10. The band structure calculations suggest that both (AA)2MA2Pb3I10 and (IdPA)2MA2Pb3I10 have in-plane effective masses around 0.04m0 and 0.08m0, respectively. IdPA cations have a greater dielectric contribution than AA. The excited-state dynamics investigated by transient absorption (TA) spectroscopy reveal a long-lived (∼100 ps) trap state ensemble with broad-band emission; our evidence suggests that these states appear due to lattice distortions induced by the incorporation of IdPA cations.

18.
Org Biomol Chem ; 20(31): 6201-6210, 2022 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-35419576

RESUMO

Host-guest 2 : 1 complexation of photoreactive alkene guests improves the selectivity of [2 + 2] photodimerizations by templating alkene orientation prior to irradiation. Host-guest chemistry can also provide 1 : 1 : 1 complexes through the inclusion of electronically complementary donor and acceptor guests, but the photoreactivity of such complexes has not been investigated. We imagined that such complexes could enable selective cross-[2 + 2] photocycloadditions between donor and acceptor stilbenes. In pursuit of this strategy, we investigated a series of stilbenes and found 1 : 1 : 1 complexes with cucurbit[8]uril that exhibited charge-transfer (CT) absorption bands in the visible and near-IR regions. Irradiation of the CT band of an azastilbene, 4,4'-stilbenedicarboxylate, and cucurbit[8]uril ternary complex led to a selective cross-[2 + 2] photocycloaddition, while other substrate pairs exhibited no productive chemistry upon CT excitation. Using transient absorption spectroscopy, we were able to understand the variable photoreactivity of different stilbene donor-acceptor complexes. We found that back electron transfer following CT excitation of the photoreactive complex is positioned deep in the Marcus inverted region due to electrostatic stabilization of the ground state, allowing [2 + 2] to effectively compete with this relaxation pathway. Control reactions revealed that the cucurbit[8]uril host not only serves to template the reaction from the ground state, but also protects the long-lived radical ions formed by CT from side reactions. This protective role of the host suggests that donor-acceptor host-guest ternary complexes could be used to improve existing CT-initiated photochemistry or access new reactivity.


Assuntos
Estilbenos , Alcenos , Transporte de Elétrons , Elétrons , Análise Espectral
19.
J Am Chem Soc ; 144(10): 4300-4304, 2022 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-35254065

RESUMO

Ligands that enable the delocalization of excitons beyond the physical boundary of the inorganic core of semiconductor quantum dots (QDs), called "exciton-delocalizing ligands (EDLs)", offer the opportunity to design QD-based environmental sensors with dynamically responsive optical spectra, because the degree of exciton delocalization depends on the electronic structure of the EDL. This paper demonstrates dynamic, reversible tuning of the optical bandgap of a dispersion of CdSe QDs through the redox states of their 1,3-dimesitylnaphthoquinimidazolylidene N-heterocyclic carbene (nqNHC) ligands. Upon binding of the nqNHC ligands to the QD, the optical bandgap bathochromically shifts by up to 102 meV. Electrochemical reduction of the QD-bound nqNHC ligands shifts the bandgap further by up to 25 meV, a shift that is reversible upon reoxidation.

20.
J Am Chem Soc ; 144(9): 3782-3786, 2022 03 09.
Artigo em Inglês | MEDLINE | ID: mdl-35230100

RESUMO

Triplet excited state-initiated photochemistry is a mild and selective route to cycloadditions, radical rearrangements, couplings, fragmentations, and isomerizations. Colloidal quantum dots are proven visible-light photosensitizers and structural scaffolds for triplet-initiated reactions of molecules that are functionalized (with carboxylates) to anchor on the QD surface. Here, with the aid of polyaromatic energy shuttles that act as noncovalent adsorption sites for substrates on the QD surface, the scope of QD-photocatalyzed intermolecular [2 + 2] cycloadditions is extended to freely diffusing substrates (no anchoring groups). QD-shuttle complexes photocatalyze homo- and heterointermolecular [2 + 2] photocycloadditions of benzalacetone, chalcone and its derivatives with up to 94% yield; the yields for all reactions are comparable to those achieved by Ir(ppy)3 but with the advantages of a factor of 2.5 lower catalyst loading, superior stability, and the ability to recover the catalyst by simple centrifugation and reuse it for multiple reaction cycles. Experiments imply a two-step triplet-triplet energy transfer mechanism, one energy transfer from the QD to the energy shuttle followed by a second energy transfer from the shuttle to the transiently adsorbed substrate.


Assuntos
Pontos Quânticos , Alcenos , Reação de Cicloadição , Luz , Fármacos Fotossensibilizantes/química
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