(PBP)Ir(CO)2 possesses
a Lewis acidic boryl center and
a basic monovalent Ir center. Heterolytic cleavage of O–H,
N–H, and F–H bonds by this molecule was examined. (PBP)Ir(CO)2 reacted with water, methanol, ethanol, cyclohexanol, phenols,
benzoic acid, and triethylamine trihydrofluoride to add the O–H
and F–H units across the B–Ir bond with preservation
of both carbonyl ligands. For the benzoate adduct, one of the CO ligands
is lost upon thermolysis with the benzoate bridging B and Ir. Thermolysis
of (PBP)Ir(CO)2 with nBuNH2 ultimately
resulted in a monocarbonyl product of the N–H cleavage with
the resultant amido group bridging B and Ir. Dicarbonyl intermediates
were observed in this reaction. Structures of the X–H cleavage
products and the possible mechanistic pathways are discussed. Mechanistic
experiments indicate that the reaction with ROH substrates proceeds
by initial protonation of Ir, consistent with slower reactions with
less acidic ROH substrates (and no reaction with
t
BuOH). For amines, the reaction appears to require coordination
of the basic nitrogen to boron and to be limited by the basicity of
the N and the steric encumbrance, as evidenced by lack of reaction
of (PBP)Ir(CO)2 with tert-butylamine,
diethylamine, aniline, p-anisidine, and pyrrole.
Novel coronavirus pneumonia has had a significant impact on people's lives and psychological health. We developed a stage model to analyse the spatial and temporal distribution of public panic during the two waves of the coronavirus disease 2019 (COVID-19) pandemic. We used tweets with geographic location data from the popular hashtag ‘Lockdown Diary’ recorded from 23 January to April 8, 2020, and ‘Nanjing Outbreak’ recorded from 21 July to 1 September 2021 on Weibo. Combining the lexicon-based sentiment analysis and the grounded theory approach, this panic model could explain people's panic and behavioural responses in different areas at different stages of the pandemic. Next, we used the latent Dirichlet allocation topic model to reconfirm the panic model. The results showed that public sentiments fluctuated strongly in the early stages; in this case, panic and prayers were the dominant sentiments. In terms of spatial distribution, public panic showed hierarchical and neighbourhood diffusion, with highly assertive expressions of sentiment at the outbreak sites, economically developed areas, and areas surrounding the outbreak. Most importantly, we considered that public panic was affected by the 17 specific topics extracted based on the perceived and actual distance of the pandemic, thus stimulating the process of panic from minimal, acute, and mild panic to perceived rationality. Consequently, the public's behavioural responses shifted from delayed, negative, and positive, to rational behavioural responses. This study presents a novel approach to explore public panic from both a time and space perspective and provides some suggestions in response to future pandemics.
Pyridine and quinoline undergo selective C-H activation in the 2-position with Rh and Ir complexes of a boryl/bis(phosphine) PBP pincer ligand, resulting in a 2-pyridyl bridging the transition metal and...
While protective measures in response to infectious diseases may reduce the freedom of tourists (regarding their behaviors), few studies have documented the effects of destination protective measures on the self-protective behaviors of tourists. By applying the protection motivation theory, this study examines the effects of perceived destination protective supports on the social distancing intentions of tourists during the COVID-19 pandemic. The results reveal significant relationships among perceived destination support, coping appraisal, threat appraisal, and the social distancing intentions of tourists. Moreover, two cognitive appraisals—toward the pandemic—partially mediate the relationship between perceived destination support and social distancing intention, and this mediational process is ‘intervened’ with by social norms. This has implications on whether tourist destinations apply more rigorous social distancing polices during the COVID-19 pandemic, to enhance the coping confidence behaviors of tourists, without causing anxiety and fear, and to achieve the goal of enhancing tourists’ intentions to protect themselves.
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