Luminescent complexes of heavy metals such as iridium, platinum, and ruthenium play an important role in photocatalysis and energy conversion applications as well as organic light-emitting diodes (OLEDs). Achieving comparable performance from more–earth-abundant copper requires overcoming the weak spin-orbit coupling of the light metal as well as limiting the high reorganization energies typical in copper(I) [Cu(I)] complexes. Here we report that two-coordinate Cu(I) complexes with redox active ligands in coplanar conformation manifest suppressed nonradiative decay, reduced structural reorganization, and sufficient orbital overlap for efficient charge transfer. We achieve photoluminescence efficiencies >99% and microsecond lifetimes, which lead to an efficient blue-emitting OLED. Photophysical analysis and simulations reveal a temperature-dependent interplay between emissive singlet and triplet charge-transfer states and amide-localized triplet states.

In response to the coronavirus disease 2019 (COVID-19) pandemic, state and local governments implemented mitigation strategies, including lockdowns, thereby averting the typical fall/winter 2020 bronchiolitis season and reducing the incidence of respiratory viruses, such as respiratory syncytial virus (RSV). Florida implemented a strict lockdown from April 1, 2020, to April 30, 2020. The removal of lockdown precautions on September 25, 2020, was followed by an atypical out-of-season surge of bronchiolitis in April 2021. Anecdotally, this surge appeared to be associated with both increased poly-viral coinfections and disease severity. ObjectiveTo determine if the bronchiolitis out-of-season surge differed from historical seasonal case patterns. MethodsA single-center retrospective cohort study of admissions to the pediatric intensive care unit (PICU) with International Classification of Diseases, Tenth Revision (ICD-10) codes of bronchiolitis, from December 9, 2019, to February 29, 2020 (12 weeks, pre-lockdown group or PreLD), was compared to March 29, 2021, to June 19, 2021 (12 weeks, post-lockdown group or PostLD). Variables used for comparison were gender, ethnicity, age, viral coinfections, viruses detected, PICU length of stay, hospital length of stay, mortality, maximum respiratory support needed, mechanical ventilation days, extracorporeal life support (ECLS) days, and severity of disease measured by Pediatric Logistic Organ Dysfunction-2 (PELOD-2) and Pediatric Sequential Organ Failure Assessment (pSOFA). Categorical data were analyzed using Fisher's exact test, and a t-test was used for continuous variables. A two-sided p < 0.05 was considered significant. ResultsA total of 135 subjects were analyzed from the two cohorts. More patients were admitted during the PostLD phase (87 vs. 48). The PostLD group had a higher age at admission (11.2 ± 12.3 vs. 6.6 ± 7.5, p = 0.0075), but there were no differences in gender or race/ethnicity. The PostLD group also exhibited a higher proportion of RSV infections (73 vs. 16, p < 0.0001) and poly-viral infections (p < 0.0001). Higher coronavirus OC43 (9 vs. 0, p = 0.0263) and parainfluenza types 1-4 (human parainfluenza virus (HPIV)) (19 vs. 1, p = 0.0017) detections, yet fewer human metapneumovirus (HMPV) detections (0 vs. 4, p = 0.0147), were observed PostLD. No differences were found in hospital length of stay, PICU length of stay, mortality, mechanical ventilation days, ECLS days, or severity of illness scores based on PELOD-2 or pSOFA scores. ConclusionIn the bronchiolitis out-of-season surge, there were an increased number of admissions to the PICU. Those patients were older, and more likely to have RSV, as well as a coinfection with coronavirus OC43 or HPIV, yet less likely to have HMPV. No difference in length of stay or disease severity was demonstrated.

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