Controllable Synthesis of Covalent Porphyrinic Cages with Varying Sizes via Template-Directed Imine Condensation Reactions

Covalent porphyrinic cages (CPCs) have been a target of interest for years. In this paper, we report the design and synthesis of two CPCs in which the cofacial porphyrins have a distance of 7.66 and 11.96 Å via template-directed imine condensation reactions and through the selective choice of templating linker and diamine length

Controllable Synthesis of Covalent Porphyrinic Cages with Varying Sizes via Template-Directed Imine Condensation Reactions

Covalent porphyrinic cages (CPCs) have been a target of interest for years. In this paper, we report the design and synthesis of two CPCs in which the cofacial porphyrins have a distance of 7.66 and 11.96 Å via template-directed imine condensation reactions and through the selective choice of templating linker and diamine length

Lu₂@C₈₂ Nanorods with Enhanced Photoluminescence and Photoelectrochemical Properties

One-dimensional (1D) single-crystalline hexagonal nanorods of Lu₂@<i>C</i>_3<i>v</i>(8)–C₈₂ were prepared for the first time using the liquid–liquid interface precipitation (LLIP) method from the interfaces between carbon disulfide (CS₂) and isopropyl alcohol (IPA). The length of the nanorods can be readily controlled by varying the concentration of the Lu₂@C₈₂ solution in addition to the volume ratio of CS₂ to IPA. The latter factor also exhibits a significant influence on the morphology of the crystals. The crystalline structure of the nanorods has been investigated by XRD and selected area electron diffraction (SAED), suggesting a face-centered cubic structure. Photoluminescence of the Lu₂@C₈₂ nanorods shows a remarkable enhancement as compared to that of pristine Lu₂@C₈₂ powder because of the high crystallinity. Furthermore, we have investigated the photoelectrochemical properties of Lu₂@C₈₂ nanorods, proving their potential applications as photodetectors

Isolation and Crystallographic Characterization of La₂C₂@C_s(574)‑C₁₀₂ and La₂C₂@C₂(816)‑C₁₀₄: Evidence for the Top-Down Formation Mechanism of Fullerenes

Tubular higher fullerenes are prototypes of finite-length end-capped carbon nanotubes (CNTs) whose structures can be accurately characterized by single-crystal X-ray diffraction crystallography. We present here the isolation and crystallographic characterization of two unprecedented higher fullerenes stabilized by the encapsulation of a La₂C₂ cluster, namely, La₂C₂@C_s(574)-C₁₀₂, which has a perfect tubular cage corresponding to a short (10, 0) zigzag carbon nanotube, and La₂C₂@C₂(816)-C₁₀₄ which has a defective cage with a pyracylene motif inserting into the cage waist. Both cages provide sufficient spaces for the large La₂C₂ cluster to adopt a stretched and nearly planar configuration, departing from the common butterfly-like configuration which has been frequently observed in midsized carbide metallofullerenes (e.g., Sc₂C₂@C_80–84), to achieve strong metal–cage interactions. More meaningfully, our crystallographic results demonstrate that the defective cage of C₂(816)-C₁₀₄ is a starting point to form the other three tubular cages known so far, i.e., D₅(450)-C₁₀₀, C_s(574)-C₁₀₂, and D_3d(822)-C₁₀₄, presenting evidence for the top-down formation mechanism of fullerenes. The fact that only the large La₂C₂ cluster has been found in giant fullerene cages (C_>100) and the small clusters M₂C₂ (M = Sc, Y, Er, etc.) are present in midsized fullerenes (C₈₀–C₈₆) indicates that geometrical matching between the cluster and the cage, which ensures strong metal–cage interactions, is an important factor controlling the stability of the resultant metallofullerenes, in addition to charge transfer

Anomalous Compression of D₅(450)‑C₁₀₀ by Encapsulating La₂C₂ Cluster instead of La₂

We demonstrate that a finite-length (10,0) carbon nanotube (CNT) with two fullerene caps, namely D₅(450)-C₁₀₀, is an ideal prototype to study the mechanical responses of small CNTs upon endohedral metal doping. Encapsulation of a large La₂C₂ cluster inside D₅(450)-C₁₀₀ induces a 5% axial compression of the cage, as compared with the structure of La₂@D₅(450)-C₁₀₀. Detailed crystallographic analyses reveal quantitively the flexibility of the [10]­cyclacene-sidewall segment and the rigidity of the pentagon-dominating caps for the first time. The internal C₂-unit acts as a molecular spring that attracts the surrounding cage carbon atoms through strong interactions with the two moving lanthanum ions. This is the first crystallographic observation of the axial compression of CNTs caused by the internal stress, which enhances our knowledge about the structural deformation of novel carbon allotropes at the atomic level

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

Stabilization of Giant Fullerenes C₂(41)‑C₉₀, D₃(85)‑C₉₂, C₁(132)‑C₉₄, C₂(157)‑C₉₆, and C₁(175)‑C₉₈ by Encapsulation of a Large La₂C₂ Cluster: The Importance of Cluster–Cage Matching

Successful isolation and unambiguous crystallographic assignment of a series of higher carbide cluster metallofullerenes present new insights into the molecular structures and cluster-cage interactions of endohedral metallofullerenes. These new species are identified as La₂C₂@C₂(41)-C₉₀, La₂C₂@D₃(85)-C₉₂, La₂C₂@C₁(132)-C₉₄, La₂C₂@C₂(157)-C₉₆, and La₂C₂@C₁(175)-C₉₈. This is the first report for these new cage structures except for D₃(85)-C₉₂. Our experimental and theoretical results demonstrate that La₂C_92–106 are more inclined to exist stably in the carbide form La₂C₂@C_90–104 rather than as the dimetallofullerenes La₂@C_92–106, which are rationalized by considering a synergistic effect of inserting a C₂ unit into the cage, which ensures strong metal–cage interactions by partially neutralizing the charges from the metal ions and by fulfilling the coordination requirement of the La³⁺ ions as much as possible

Kommunikationsstrategier i svensk-danska samtalsrum - några inledande iakttagelser

Öresundsregionen erbjuder många miljöer och situationer där grannspråkskommunikation och strategier för ömsesidig förståelse är viktiga för danskar och svenskar. I artikeln diskuterar Lundin Åkesson och Zola Christensen hur de ackommodations strategier som deras informanter använder kan delas in i tre olika nivåer och hur dessa på ett avgörande sätt påverkar samtalsdeltagarnas olika roller, samarbetet mellan samtalsdeltagarna och inte minst för ståelsen av innehållet i det som sägs.In this article (“Communicative strategies in Swedish-Danish conversation areas – some pre liminary tendencies”), we aim at investigating the different strategies used by Swedes and Danes when discussing different topics with each other. The choice of studying com mu ni ca tion by Swedes and Danes is based on the relatively similar intercomprehension of the neighbour language in the two countries, and on the fact that the Øresund region, more than any other area in Scandinavia, proposes environments where intercomprehension and useful communicative strategies are necessary. The results presented in this article are based on two different investigations, each in turn consisting of classroom observations and interviews. We wish to stress that the studies are to be considered pre-investigations for a major, planned investigation, for which the tentative results reached so far constitute the ground. In the first investigation we refer to, Swedish and Danish students, around the age of 25, discuss a book they have read in advance. The second in vestigation was carried out as a follow-up of the tentative results of the fi rst one; hence we aimed at varying the level of comprehension of the neighbour language of the group members. In the second investigation, the participants, between 25 and 35 years of age and with at least 4 years of university studies, were given different topics as the starting point for an argumenta tion. The strategies of accommodation appearing in our material can be divided tentatively into three different levels, N1, N2, and N3 (‘N’ for Sw. ‘nivå’, Eng. ‘level’). What we here refer to as N2-accommodation is characterized by the participants’choice of words and partly also syntactic patterns, in order to make it easier for the rest of the group to understand. Further more, they also adjust their speech in another and more conscious way than N1-accommodators. N2-accommodation requires relatively fl uent skills in the neighbour language. The accommodation strategies categorised as N3 display a different pattern. In order for N3-accommodation to appear, some participants must, to some extent, know both languages involved, and the result of N3-accommodation points in two different directions. On the one hand, the degree of accommodation of those knowing both languages is so high that the others stop accommodating. As a result, the majority of the group members understand less than the participants involved in N2- or even N1-accommodation. On the other hand, we can also detect the opposite pattern: accommodation becomes superfl uous, and all participants stop accommodating

Molecular Structure and Chemical Property of a Divalent Metallofullerene Yb@<i>C</i>₂(13)‑C₈₄

Endohedral metallofullerenes (EMFs) encapsulating divalent metal ions have received limited attention because of their low production yields. Here, we report the results of structural determination and chemical functionalization of a typical divalent metallofullerene, Yb@C₈₄(II). Single-crystal X-ray crystallographic studies of Yb@C₈₄/Ni^II(OEP) cocrystals (OEP is the dianion of octaethylporphyrin) unambiguously established the chiral <i>C</i>₂(13)-C₈₄ cage structure and revealed multiple sites for Yb²⁺, indicating a moving metal ion inside the cage. The chemical property of Yb@<i>C</i>₂(13)-C₈₄ was probed with the electrophillic adamantylidene carbene (<b>1</b>). Three monoadduct isomers were isolated and characterized. Crystallographic results of the major isomer (<b>2b</b>) revealed that, although the cycloaddition breaks a [5,6]-bond on the cage, Yb²⁺ is localized under a hexagonal ring distant from the sites of addition. Thus, it is proved that the dynamic motion of the divalent metal ion in Yb@C₈₄ has been effectively halted by exohedral functionalization. Spectroscopic results show that the electronic property of Yb@<i>C</i>₂(13)-C₈₄ is pertained in the derivatives, although the addend exerts a mild reduction effect on the electrochemical behavior of the EMF. Computational works demonstrated that addition of <b>1</b> to Yb@<i>C</i>₂(13)-C₈₄ is mainly driven by releasing the local strains of cage carbons rather than charge recombination, which is always prominent to the affinity of typical trivalent EMFs such as M@<i>C</i>_2<i>v</i>(9)-C₈₂ (M = Sc, Y, La, Ce, Gd) toward <b>1</b>. Accordingly, it is speculated that the chemical behaviors of divalent EMFs more likely resemble those of empty fullerenes because both are closed-shell compounds, but they differ from those of trivalent EMFs, which have open-shell electronic configurations instead

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