Europium Triple-Decker Complexes Containing Phthalocyanine and Nitrophenyl–Corrole Macrocycles

A series of europium triple-decker complexes containing phthalocyanine and nitrophenyl–corrole macrocycles were synthesized and characterized by spectroscopic and electrochemical methods in nonaqueous media. The examined compounds are represented as Eu₂[Pc­(OC₄H₉)₈]₂­[Cor­(Ph)_<i>n</i>(NO₂Ph)_3–<i>n</i>], where <i>n</i> varies from 0 to 3, Pc­(OC₄H₉)₈ represents the phthalocyanine macrocycle, and Cor indicates the corrole macrocycle having phenyl (Ph) or nitrophenyl (NO₂Ph) meso substituents. Three different methods were used for syntheses of the target complexes, two of which are reported here for the first time. Each examined compound undergoes five reversible one-electron oxidations and 3–5 one-electron reductions depending upon the number of NO₂Ph substituents. The nitrophenyl groups on the meso positions of the corrole are highly electron-withdrawing, and this leads to a substantial positive shift in potential for the five oxidations and first reduction in CH₂Cl₂, PhCN, or pyridine as compared to the parent triple-decker compound with a triphenylcorrole macrocycle. The measured <i>E</i>_1/2 values are linearly related to the number of NO₂Ph groups on the corrole, and the relative magnitude of the shift in potential for each redox reaction was used in conjunction with the results from thin-layer spectro-electrochemistry to assign the initial site of oxidation or reduction on the molecule. The nitrophenyl substituents are also redox-active, and each is reduced to [C₆H₄NO₂]⁻ in a separate one-electron transfer step at potentials between −1.12 and −1.42 V versus saturated calomel electrode

Europium Triple-Decker Complexes Containing Phthalocyanine and Nitrophenyl–Corrole Macrocycles

A series of europium triple-decker complexes containing phthalocyanine and nitrophenyl–corrole macrocycles were synthesized and characterized by spectroscopic and electrochemical methods in nonaqueous media. The examined compounds are represented as Eu₂[Pc­(OC₄H₉)₈]₂­[Cor­(Ph)_<i>n</i>(NO₂Ph)_3–<i>n</i>], where <i>n</i> varies from 0 to 3, Pc­(OC₄H₉)₈ represents the phthalocyanine macrocycle, and Cor indicates the corrole macrocycle having phenyl (Ph) or nitrophenyl (NO₂Ph) meso substituents. Three different methods were used for syntheses of the target complexes, two of which are reported here for the first time. Each examined compound undergoes five reversible one-electron oxidations and 3–5 one-electron reductions depending upon the number of NO₂Ph substituents. The nitrophenyl groups on the meso positions of the corrole are highly electron-withdrawing, and this leads to a substantial positive shift in potential for the five oxidations and first reduction in CH₂Cl₂, PhCN, or pyridine as compared to the parent triple-decker compound with a triphenylcorrole macrocycle. The measured <i>E</i>_1/2 values are linearly related to the number of NO₂Ph groups on the corrole, and the relative magnitude of the shift in potential for each redox reaction was used in conjunction with the results from thin-layer spectro-electrochemistry to assign the initial site of oxidation or reduction on the molecule. The nitrophenyl substituents are also redox-active, and each is reduced to [C₆H₄NO₂]⁻ in a separate one-electron transfer step at potentials between −1.12 and −1.42 V versus saturated calomel electrode

Effect of Dexmedetomidine on Preventing Postoperative Agitation in Children: A Meta-Analysis

<div><p>Background</p><p>Emergence agitation (EA) is one of the most common postoperative complications in children. The purpose of this meta-analysis is to assess the effect of dexmedetomidine for preventing postoperative agitation in children.</p><p>Methods</p><p>We searched the Cochrane Central Register of Controlled Trails, MEDLINE, and EMBASE. Randomized controlled trials were included. The following outcome measures were evaluated: incidence of EA, number of patients requiring rescue, time to eye-open, time to extubation, time to discharge from the postanesthesia care unit (PACU).</p><p>Results</p><p>We analyzed 19 trials (1608 patients) that met the inclusion criteria. Compared with placebo, intravenous dexmedetomidine significantly reduced the incidence of EA [risk ratio (RR) 0.34, 95% confidence interval (CI) 0.25–0.44, <i>P</i><0.00001). Dexmedetomidine also decreased the incidence of severe pain (RR 0.41, 95% CI 0.27–0.62, <i>P</i><0.0001) and requirement of a rescue drug (RR 0.31, 95% CI 0.18–0.53, <i>P</i><0.0001). However, compared with placebo, dexmedetomidine increased the time to eye-open by 0.98 min (<i>P</i> = 0.01) and the time to PACU discharge by 4.63 min (<i>P</i> = 0.02). Dexmedetomidine was also compared with midazolam, propofol, ketamine, and fentanyl, among others. No significant difference was found in the incidence of EA for most of these comparisons, with the exception of fentanyl and propofol, where dexmedetomidine was more beneficial.</p><p>Conclusions</p><p>Dexmedetomidine was proved effective for preventing EA and for reducing severe pain and the requirement of rescue drugs. It slightly increased the time to eye-open and the time to PACU discharge. Dexmedetomidine was also more beneficial than propofol or fentanyl in preventing EA.</p></div

Incidence of emergence agitation (EA): dexmedetomidine vs. placebo.

<p>Forest plot shows that the overall effect of pooled trials was in favor of dexmedetomidine. D, dexmedetomidine; P, placebo.</p

Incidence of EA: dexmedetomidine vs. fentanyl.

<p>Forest plot shows that the overall effect of pooled trials without the Pestieau 2011 was in favor of dexmedetomidine. The Pestieau 2011 study was excluded because of clinical and statistical heterogeneity. D, dexmedetomidine; F, fentanyl</p

Time to eye-open: dexmedetomidine vs. placebo.

<p>Forest plot shows that the overall effect of pooled trials was in favor of placebo. Patients given dexmedetomidine took more time to recover. Heterogeneity was observed when these studies were pooled and the random effects model was chosen for analysis. D, dexmedetomidine; P, placebo</p

Flow diagram of included/excluded studies.

<p>Flow diagram of included/excluded studies.</p

Incidence of severe postoperative pain: dexmedetomidine vs. placebo.

<p>Forest plot shows that the overall effect of pooled trials was in favor of dexmedetomidine. D, dexmedetomidine; P, placebo</p

Microwave-Mediated Synthesis of Bulky Lanthanide Porphyrin–Phthalocyanine Triple-Deckers: Electrochemical and Magnetic Properties

Five heteroleptic lanthanide porphyrin–bis-phthalocyanine triple-decker complexes with bulky peripheral groups were prepared via microwave-assisted synthesis and characterized in terms of their spectroscopic, electrochemical, and magnetic properties. These compounds, which were easily obtained under our preparative conditions, would normally not be accessible in large quantities using conventional synthetic methods, as a result of the low yield resulting from steric congestion of bulky groups on the periphery of the phthalocyanine and porphyrin ligands. The electrochemically investigated triple-decker derivatives undergo four reversible one-electron oxidations and three reversible one-electron reductions. The sites of oxidation and reduction were assigned on the basis of redox potentials and UV–vis spectral changes during electron-transfer processes monitored by thin-layer spectroelectrochemistry, in conjunction with assignments of electronic absorption bands of the neutral compounds. Magnetic susceptibility measurements on two derivatives containing Tb^III and Dy^III metal ions reveal the presence of ferromagnetic interactions, probably resulting from magnetic dipolar interactions. The Tb^III derivative shows SMM behavior under an applied field of 0.1 T, where the direct and Orbach process can be determined, resulting in an energy barrier of <i>U</i>_eff = 132.0 K. However, Cole–Cole plots reveal the presence of two relaxation processes, the second of which takes place at higher frequencies, with the data conforming to a 1/<i>t</i> ∝ <i>T</i>⁷ relation, thus suggesting that it can be assigned to a Raman process. Attempts were made to form two-dimensional (2D) self-assembled networks on a highly oriented pyrolytic graphite (HOPG) surface but were unsuccessful due to bulky peripheral groups on the two Pc macrocycles