Facile Access to Y₂C_2<i>n</i> (2<i>n</i> = 92–130) and Crystallographic Characterization of Y₂C₂@<i>C</i>₁(1660)‑C₁₀₈: A Giant Nanocapsule with a Linear Carbide Cluster

A series of giant metallofullerenes Y₂C_2<i>n</i> (2<i>n</i> = 92–130) have been successfully obtained through the treatment of the fraction enriched by 1,2-dichlorobenzene with SnCl₄. Subsequent chromatographic separation gives a pure sample with a composition of Y₂C₁₁₀. Crystallographic results reveal that this endohedral takes the carbide form, namely Y₂C₂@<i>C</i>₁(1660)-C₁₀₈, representing as the largest metallofullerene that has been characterized by crystallography to date. Despite the disorder of the metal cluster, the major Y₂C₂ adopts a previously predicted linear configuration, indicating that the compression of the internal cluster by the cage is almost negligible in this giant cage. Electrochemical studies suggest that Y₂C₂@<i>C</i>₁(1660)-C₁₀₈ is a good electron donor instead of an electron acceptor

Evidence of Oxygen Activation in the Reaction between an N‑Heterocyclic Carbene and M₃N@<i>I</i>_<i>h</i>(7)–C₈₀: An Unexpected Method of Steric Hindrance Release

We herein demonstrate for the first time the unexpected oxygen-involving reaction between M₃N@<i>I</i>_<i>h</i>(7)–C₈₀ (M = Sc, Lu) and 1,3-bis­(diisopropylphenyl)­imidazol-2-ylene (<b>1</b>). By introducing a tiny amount of oxygen into the reaction, unprecedented products (<b>2a</b> for Sc₃N@C₈₀ and <b>3a</b> for Lu₃N@C₈₀) with the normal carbene center C2 singly bonded to a triple hexagonal junction (THJ) cage carbon together with an oxygen atom bridging the same THJ carbon atom and a neighboring carbon atom forming an epoxy structure are obtained. In situ mechanism study, in combination with theoretical calculations, reveals that the bond-breaking peroxidation facilitates the formation of the unexpected products <b>2a</b> and <b>3a</b>, providing new insight into fullerene chemistry

Evidence of Oxygen Activation in the Reaction between an N‑Heterocyclic Carbene and M₃N@<i>I</i>_<i>h</i>(7)–C₈₀: An Unexpected Method of Steric Hindrance Release

We herein demonstrate for the first time the unexpected oxygen-involving reaction between M₃N@<i>I</i>_<i>h</i>(7)–C₈₀ (M = Sc, Lu) and 1,3-bis­(diisopropylphenyl)­imidazol-2-ylene (<b>1</b>). By introducing a tiny amount of oxygen into the reaction, unprecedented products (<b>2a</b> for Sc₃N@C₈₀ and <b>3a</b> for Lu₃N@C₈₀) with the normal carbene center C2 singly bonded to a triple hexagonal junction (THJ) cage carbon together with an oxygen atom bridging the same THJ carbon atom and a neighboring carbon atom forming an epoxy structure are obtained. In situ mechanism study, in combination with theoretical calculations, reveals that the bond-breaking peroxidation facilitates the formation of the unexpected products <b>2a</b> and <b>3a</b>, providing new insight into fullerene chemistry

Lu₂@C_2<i>n</i> (2<i>n</i> = 82, 84, 86): Crystallographic Evidence of Direct Lu–Lu Bonding between Two Divalent Lutetium Ions Inside Fullerene Cages

Although most of the M₂C_2<i>n</i>-type metallofullerenes (EMFs) tend to form carbide cluster EMFs, we report herein that Lu-containing EMFs Lu₂C_2<i>n</i> (2<i>n</i> = 82, 84, 86) are actually dimetallofullerenes (di-EMFs), namely, Lu₂@<i>C</i>_<i>s</i>(6)-C₈₂, Lu₂@<i>C</i>_3<i>v</i>(8)-C₈₂, Lu₂@<i>D</i>_2<i>d</i>(23)-C₈₄, and Lu₂@<i>C</i>_2<i>v</i>(9)-C₈₆. Unambiguous X-ray results demonstrate the formation of a Lu–Lu single bond between two lutetium ions which transfers four electrons in total to the fullerene cages, thus resulting in a formal divalent state for each Lu ion. Population analysis indicates that each Lu atom formally donates a 5d electron and a 6s electron to the cage with the remaining 6s electron shared with the other Lu atom to form a Lu–Lu single bond so that only four electrons are transferred to the fullerene cages with the formal divalent valence for each lutetium ion. Accordingly, we confirmed both experimentally and theoretically that the dominating formation of di-EMFs is thermodynamically very favorable for Lu₂C_2<i>n</i> isomers

Regioselective Benzyl Radical Addition to an Open-Shell Cluster Metallofullerene. Crystallographic Studies of Cocrystallized Sc₃C₂@<i>I</i>_<i>h</i><i>‑</i>C₈₀ and Its Singly Bonded Derivative

The endohedral fullerene once erroneously identified as Sc₃@C₈₂ was recently shown to be Sc₃C₂@<i>I</i>_<i>h</i>-C₈₀, the first example of an open-shell cluster metallofullerene. We herein report that benzyl bromide (<b>1</b>) reacts with Sc₃C₂@ <i>I</i>_<i>h</i>-C₈₀ via a regioselective radical addition that affords only one isomer of the adduct Sc₃C₂@<i>I</i>_<i>h</i>-C₈₀(CH₂C₆H₅) (<b>2</b>) in high yield. An X-ray crystallographic study of <b>2</b> demonstrated that the benzyl moiety is singly bonded to the fullerene cage, which eliminates the paramagnetism of the endohedral in agreement with the ESR results. Interestingly, X-ray results further reveal that the 3-fold disordered Sc₃C₂ cluster adopts two different configurations inside the cage. These configurations represent the so-called “planar” form and the computationally predicted, but not crystallographically characterized, “trifoliate” form. It is noteworthy that this is the first crystallographic observation of the “trifoliate” form for the Sc₃C₂ cluster. In contrast, crystallographic investigation of a Sc₃C₂@<i>I</i>_<i>h</i>-C₈₀/Ni­(OEP) cocrystal, in which the endohedral persists in an open-shell structure with paramagnetism, indicates that only the former form occurs in pristine Sc₃C₂@ <i>I</i>_<i>h</i>-C₈₀. These results demonstrate that the cluster configuration in EMFs is highly sensitive to the electronic structure, which is tunable by exohedral modification. In addition, the electrochemical behavior of Sc₃C₂@<i>I</i>_<i>h</i>-C₈₀ has been markedly changed by the radical addition, but the absorption spectra of the pristine and the derivative are both featureless. These results suggest that the unpaired electron of Sc₃C₂@<i>I</i>_<i>h</i>-C₈₀ is buried in the Sc₃C₂ cluster and does not affect the electronic configuration of the cage

Regioselective Benzyl Radical Addition to an Open-Shell Cluster Metallofullerene. Crystallographic Studies of Cocrystallized Sc₃C₂@<i>I</i>_<i>h</i><i>‑</i>C₈₀ and Its Singly Bonded Derivative

The endohedral fullerene once erroneously identified as Sc₃@C₈₂ was recently shown to be Sc₃C₂@<i>I</i>_<i>h</i>-C₈₀, the first example of an open-shell cluster metallofullerene. We herein report that benzyl bromide (<b>1</b>) reacts with Sc₃C₂@ <i>I</i>_<i>h</i>-C₈₀ via a regioselective radical addition that affords only one isomer of the adduct Sc₃C₂@<i>I</i>_<i>h</i>-C₈₀(CH₂C₆H₅) (<b>2</b>) in high yield. An X-ray crystallographic study of <b>2</b> demonstrated that the benzyl moiety is singly bonded to the fullerene cage, which eliminates the paramagnetism of the endohedral in agreement with the ESR results. Interestingly, X-ray results further reveal that the 3-fold disordered Sc₃C₂ cluster adopts two different configurations inside the cage. These configurations represent the so-called “planar” form and the computationally predicted, but not crystallographically characterized, “trifoliate” form. It is noteworthy that this is the first crystallographic observation of the “trifoliate” form for the Sc₃C₂ cluster. In contrast, crystallographic investigation of a Sc₃C₂@<i>I</i>_<i>h</i>-C₈₀/Ni­(OEP) cocrystal, in which the endohedral persists in an open-shell structure with paramagnetism, indicates that only the former form occurs in pristine Sc₃C₂@ <i>I</i>_<i>h</i>-C₈₀. These results demonstrate that the cluster configuration in EMFs is highly sensitive to the electronic structure, which is tunable by exohedral modification. In addition, the electrochemical behavior of Sc₃C₂@<i>I</i>_<i>h</i>-C₈₀ has been markedly changed by the radical addition, but the absorption spectra of the pristine and the derivative are both featureless. These results suggest that the unpaired electron of Sc₃C₂@<i>I</i>_<i>h</i>-C₈₀ is buried in the Sc₃C₂ cluster and does not affect the electronic configuration of the cage

Cost-effectiveness ratio (CER) by city in the nutrition & PA combined intervention group.

<p>^a For BMI, BAZ and overweight & obesity prevalence, the ‘effect’ means BMI, BAZ and overweight & obesity prevalence reduction (post intervention vs before intervention) in intervention group compared with that of in the control group, respectively. ^b ALL CER was presented in US dollars. ^c O & B means overweight & obesity. ^d Total’ means the average effect of four intervention centers (Jinan, Guangzhou, Harbin, Shanghai), Chongqing was excluded here because the intervention in this city was not effective (p>0.05). </p

Anthropometric characteristics and obesity prevalence at baseline, after intervention and changes in different groups<b>^</b>.

<p>^{^} Continuous variables were expressed as mean±standard error.</p><p>^{a, b}: Means shared the different letter means significant difference at baseline among groups in Beijing, p<0.05. </p><p>^{c, d} : Means shared the different letter means significant difference of changes (post-intervention vs. baseline) among groups in Beijing, p<0.05.</p><p>^* Comparison the mean between post-intervention and baseline in each group, p< 0.05.</p><p>^# Comparison means between combined intervention group and control group at baseline as well as for changes (post-intervention vs. baseline), ^# p<0.05; ^## p<0.01.</p><p>^† OR and 95% CI for overweight & obesity prevalence using generalized linear mixed model, no significantly difference of OR between nutrition or PA individual intervention group with their control group, but a borderline difference between combined intervention group with its’ control group (p=0.06). </p

Characteristics of the subjects at baseline by group.

<p>^a^b: Percentage shared the different letter means significant difference at baseline among groups in Beijing, p<0.05. ^* Significant difference (p<0.05) between control and Nutrition & PA intervention group. ^c statistical analysis and compare between intervention group with it’s control group. No superscript means no significant difference among groups.</p

The costs of development and evaluation of the program (RMB (US dollars)^<b>*</b>).

*<p>US dollars was calculated by Jan, 2010 exchange rate (6.8).</p