Endohedrally Helium-doped CL-20:A DFT Treatment

In order to investigate whether endohedral He-doping is possible or not in CL-20,a density functional treatment has been carried out at the levels of B3LYP/6-31++G(d,p)and B3PW91/6-31++G(d,p).Some physicochemical and quantum chemical properties of the helium-doped CL-20 (He@CL-20)are compared with the respective values of the parent explosive CL-20.The helium doping caused swelling of CL-20cage but no bond rupture occurred.Doped helium acquired some positive charge.

笼内金属富勒烯的合成与分析

自1985年,Smalley等人首次在飞行时间质谱仪中检测到C60以来[1],富勒烯碳原子族的研究便不断深入,最初发现的激光蒸发含稀土化合物的石墨只能得到微量的金属富勒烯,仅限于质谱检测,直到1990年,Kratschmer等人采用石墨电子弧放电首次得到宏观量的富勒烯[2],才使得富勒烯研究进入了实质性的研究阶段.……

Theoretical Studies on Structures and Properties of Endohedral Fullerenes Complexes: XH_n@C_(32)(X=F, O, N, C; n=1―4)

Theoretical studies on structures and properties of endohedral fullerene complexes formed by encapsulating small molecules of HF, H20, NH3, and CH4 in a C32 fullerene cage, were carried out by ab initio method. Current calculations reveal that these processes to encase them in fullerene are energetically unfavorable because of the small cavity size of C32. The red shift in the F-H stretching frequency indicates the potential existence of hydrogen bonding between the HF molecule and the carbon cage.

Dipole and generalized oscillator strength derived electronic properties of an endohedral hydrogen atom embedded in a Debye-Huckel plasma

We report electronic properties of a hydrogen atom encaged by an endohedral cavity under the influence of a weak plasma interaction. Weimplement a finite-difference approach to solve the Schrodinger equation for a hydrogen atom embedded in an endohedral cavity modeled by theWoods-Saxon potential with well depth V0, inner radius R0, thickness D, and smooth parameter g. The plasma interaction is described by aDebye-Hu¨ckel screening potential that characterizes the plasma in terms of a Debye screening length lD. The electronic properties of theendohedral hydrogen atom are reported for selected endohedral cavity well depths, V0, and screening lengths, lD, that emulate differentconfinement and plasma conditions. We find that for low screening lengths, the endohedral cavity potential dominates over the plasma interaction by confining the electron within the cavity. For large screening lengths, a competition between both interactions is observed. We assessand report the photo-ionization cross section, dipole polarizability, mean excitation energy, and electronic stopping cross section as function of lD and V0. We find a decrease of the Generalized Oscillator Strength (GOS) when the final excitation is to an s state as the plasma screeninglength decreases. For a final excitation into a p state, we find an increase in the GOS as the endohedral cavity well-depth increases. For the caseof the electronic stopping cross section, we find that the plasma screening and endohedral cavity effects are larger in the low-to-intermediateprojectile energies for all potential well depths considered. Our results agree well to available theoretical and experimental data and are afirst step towards the understanding of dipole and generalized oscillator strength dependent properties of an atom in extreme conditions encagedby an endohedral cavity immersed in a plasma medium.

High-Yield Synthesis and Extraction of Endohedral Metallofullerenes Dy@C_(2n)

The successful encapsulation of dysprosium(Dy) into fullerene cages by activating the Dy2O3, containing graphite rods in situ 'back-burning' carbonarc evaporation with a high-yield of pyridine extraction technique is reported.

Water Molecules in the Carbon C60 Confined Space

Experimental scenario of the world being successful in planting water molecule at binary level in fullerene C70 is of utmost importance to pursue the theoretical properties of predictive triple water molecules and poly water molecules in Vander Waals confined space like fullerenes. Here, we present a paper in these lines of exploration of embedding triple water molecules in a Carbon confined space through the studies of behavior of three water molecules in Fullerene C60 by ab-initio methods. This heterogeneous system manifests cyclic hydrogen bonds which may be working with flipping actions. The unusual structural property of water trimers is reported. There exists a dipole moment of 0.9 ± 0.1 Debye which indicates the probable semiconductor properties.

Magnetism of Co₁₃-Filled Carbon Nanotubes of Diverse Chiral Symmetry

The attempt to study magnetism in (n,m) chiral space of single-walled carbon nanotubes (SWNTs) with embedded metal cluster is presented. Co13 metallic cluster inside zigzag and chiral single-walled nanotubes was investigated using density functional theory (DFT). Magnetic properties of the endohedral nanotubes with the various chiral index (n,m) were characterized by calculation of the total spin magnetic moment (S). The dependence of S on the chiral symmetry of nanotubes, as well as the orientation of Co13 cluster within nanotubes was found. Longitudinal orientation of icosahedral Co13 cluster was preferable for magnetization in general. However, it was shown that the magnetic landscape M = f(n,m) of endohedral nanotubes is very complex and sharp.

Path integral Monte Carlo study of(H_2)_n@C_(70)(n = 1, 2, 3)

The path integral Monte Carlo(PIMC) method is employed to study the thermal properties of C70 with one, two,and three H2 molecules confined in the cage, respectively. The interaction energies and vibrationally averaged spatial distributions under different temperatures are calculated to evaluate the stabilities of(H2)n@C70(n = 1, 2, 3). The results show that(H2)2@C70is more stable than H2@C70. The interaction energy slowly changes in a large temperature range,so temperature has little effect on the stability of the system. For H2@C70and(H2)2@C70, the interaction energies keep negative; however, when three H2 molecules are in the cage, the interaction energy rapidly increases to a positive value.This implies that at most two H2 molecules can be trapped by C70. With an increase of temperature, the peak of the spatial distribution gradually shifts away from the center of the cage, but the maximum distance from the center of H2 molecule to the cage center is much smaller than the average radius of C70.

Water Molecules in Carbon 70, (H₂O)₃@C₇₀

Endohedral fullerene studies are the fascinating one, particularly with Carbon 60 and Carbon 70. Water molecules inside fullerenes alter their cage structure, reorientations make them to play a lot in charge distribution. In this line we are presenting our work on Carbon 70 with three water molecules inside. Ab initio SCF calculations are carried out for the fullerene Carbon 70 and Carbon 70 with three water molecules. Carbon 70 is a rugby ball structure, when three water molecules are added inside it, dissociation of charges takes place. Unusual flip flop circular hydrogen bond formation takes place inside Carbon 70. The dipole moment of endohedral C70 with three water molecules has been found to be 0.53 Debye, 0.49 Debye and 0.71 Debye respectively for STO-3G, 3-21G and 6-31G basis sets. Total energies for this molecule are reported in addition to the Hydrogen bond length and bond angles of the three water molecules trapped inside C70.

ScY@C_(3v)(8)-C_(82):Metal-Metalσ^(2)Bond in Mixed Rare-Earth Di-metallofullerenes

Comprehensive Summary The experimental investigation of rare-earth metal-metal bonds remains a challenge in the study of chemical bonds.Herein,we report the synthesis and characterization of a novel heteronuclear di-metallofullerene,ScY@C_(3v)(8)-C_(82),which contains a mixed rare-earth metal-metal bond.ScY@C_(3v)(8)-C_(82)was successfully synthesized by arc-discharging method and characterized by mass spectrometry,UV-vis-NIR spectroscopy and single-crystal X-ray diffraction crystallography,which unambiguously determined its molecular structure.Theoretical calculations were also performed to study the optimized positions of Sc-Y metallic dimer and the electronic configuration.The combined experimental and theoretical results confirmed that both Sc and Y atoms transfer two electrons to the C_(3v)(8)-C_(82)cage,i.e.,(ScY)4+@(C_(3v)(8)-C_(82))4-.In particular,a covalent Sc-Yσ2 bond,which has never been reported before,is proven to be formed inside C_(3v)(8)-C_(82)fullerene cage.This work presents a novel di-metallofullerene containing mixed rare-earth metal-metal bond and expands the understanding of metal-metal bonding of rare earth elements.

Calculations of lattice constants, energies of cohesion, and compressibilities of G@C_(60) (G= He, Ne, Ar ) molecular crystals

SINCE the discovery and subsequent macroscopic synthesis of fullerenes,due to their unusualstructure and widely potential applications,many theoretical and experimental scientists havedone a lot of work on fullerenes.Fullerenes are the hollow cage molecules,the large,closedspheroidal shapes suggest that they could hold a variety of small guest atoms and/or

Interaction between the alkali atoms and the C_(60) cage in the endohedral complexes (Alkali@C_(60))

At present, research interest in C60 is mainly focused on its complexes and its chemical modification and doping. Putting an atom （or a radical） or a molecule into another molecule to form a stable compound is a completely new novel field in chemistry. The quite large cavity in football-like C60 cage has put forward the possibility of trapping inside it an atom or a radical to form the endohedral complexes (X@C60). The alkali-containing complex (Alkali@C60) formed from C60 cage and alkali atoms is one kind of this endohedral complex. On these entirely new endohedral complexes, much valuable

Molecular mechanics on bonding and non-bonding interactions in (atom@C_(60))

The interactions between the embedded atom X (X=Li,Na,K,Rb,Cs; F,Cl,Br,I) and C60cage in the endohedral-form complexes (X@C60) are calculated and discussed according to molecular mechanics from the point of view of the bonding and non-bonding.It is found from the computational results that for atoms with radii larger than Li’s,their locations with the minimum interaction in (X@C60) are at the cage center,while atom Li has an off-center location with the minimum interaction deviation of-0.05 nm,and the cage-environment in C60 can be regarded as sphero-symmetry in the region with radius r of ~0.2 nm.It is shown that the interaction between X and C60 cage is of non-bonding characteristic,and this non-bonding interaction is not purely electrostatic.The repulsion and dispersion in non-bonding interactions should not be neglected,which make important contribution to the location with minimum interaction of X,at center or off center.Some rules about the variations of interactions with atomic radii have been

Geometric and Electronic Properties of Metallofullerene Fe@C60

The generalized gradient approximation （GGA） based on density functional theory （DFT） was used to analyze the structural and electronic properties of Fe@C60 and C59Fe for comparison. Among the six possible optimized geometries of Fe@C60, the most favorable endohedral site of Fe atom is under the center of a hexagon ring, i.e., Fe@C60-6. The Energy gap （Eg） of Fe@C60-6 is smaller than those of C59Fe and C60, indicating the higher chemical reactivity. The magnetic moment of Fe atom in Fe@C60-6 is preserved to some extent though there is the hybridization between the ge atom and C atoms of the cage, in contrast to the completely quenched magnetic moment of the Fe atom in C59Fe.

PRODUCTION, ISOLATION AND SPECTROSCOPIC STUDIES OF THE ENDOHEDRAL FULLERENE Sc_2@C_(80)(I-III)

The isolation of multiple-isomers of Sc2@C80 (I, II, III) endohedral metallofullerenes is reported for the first time. The new C80-based Sc-metallofullerenes are characterized by UV-Vis-NIR absorption spectroscopy and detailed chromatographic retention time data. A close relationship between the isomer structure and the corresponding HPLC retention time of the metallofullerenes is presented.

Encapsulation Chalcogen Anions in Perfluorinated Silicon Fullerene： X^2-@Si20F20 （X=O, S, Se）

The structures and stabilities of cage Si20F2o and its endohedral complexes X^2-@Si20F20 （X=O, S, Se） were determined at the B3LYP/6-31G（d） levels of density functional theory （DFT）. It is found that the adiabatic electron affinity （EAad） of host cage Si20F20 （1h） is higher than that of isolated O atom （4.24 vs. 1.46 eV）. This suggests the Si20F20 cage can selectively trap and stabilize the capsulated spherical anions. The calculations predict that X=S and Se are nearly located at the center of the cage, and O dramatically deviates from the center in C3v symmetry. Moreover, the corresponding X^2- @Si20F20 complexes have more negative inclusion energies （AEinc） and thermodynamic parameters （AZ） than X2 @C20F20. The amount of charge that is being transferred from the encapsulated anions to the cage increases with the atomic radius, i.e., from O^2- （ca. 45%）, S^2- （ca. 51%） to Se^2- （ca. 59%）, and such a novel model of cage may have practical uses as potential and electrical building units of nanoscale materials.

Structure and Stability of Endohedral Complexes X@（HBNH）12

Using quantum chemistry methods B3LYP/6-31＋＋G（d,p） to optimize endohedral complexes X@（HBNH）12 （X=Li^0/＋, Na^0/＋, K^0/＋, Be^0/2＋, Mg^0/2＋, Ca^0/2＋, H and He）, the geometries with the lowest energy were achieved. Inclusion energy, standard equilibrium constant, natural charge, spin density, ionization potentials, and HOMO-LUMO energy gap were also discussed. The calculation predicted that X=Na^0/＋, K^0/＋, Mg^0/2＋, Ca^0/2＋, H and He are nearly located at the center of （HBNH）12 cluster. Li^＋ lies in less than 0.021 nm departure from the center. Li and Be^0/2＋ dramatically deviate from the center. （HBNH）12 prefers to enclose Li^＋, Be^2＋, Mg^2＋, and Ca^2＋ in it than others. Moreover, M@（HBNH）12 （M=Li, Na, K） species are ＂superalkalis＂ in that they possess lower first ionization potentials than the Cs atom （3.9 eV）.

通过Y_(3)N@C_(80)内嵌金属富勒烯修饰调节钙钛矿太阳能电池的界面性质

富勒烯衍生物在钙钛矿太阳能电池(PSC)中具有广泛的应用,例如作为电子传输层(ETL)、界面改性剂或添加剂.然而,很少有研究报道利用内嵌金属富勒烯(EMF)来改善PSC的性能.在此,本文报道了一种新颖的Y_(3)N@C_(80) EMFs的合成,并将其用作SnO_(2) ETL基PSCs的界面改性剂.结果表明,在SnO_(2) ETL器件中观察到的能级不匹配和载流子复合严重等问题,在Y_(3)N@C_(80)分子的修饰下得以改善.与SnO_(2) ETL相比,由于SnO_(2)-Y_(3)N@C_(80)/钙钛矿界面之间更合适的能级排列和更快的电子提取,器件开路电压(VOC)从1.10 V(SnO_(2))显著提高到1.14 V(SnO_(2)-Y_(3)N@C_(80)),能量转换效率由20.59%提高到21.66%,并大大降低了电池的滞后效应.此外,Y_(3)N@C_(80)的疏水性和晶界减少导致缺陷态密度降低,使得目标器件的稳定性也有所提高.

Atomically Precise Insights into Metal–Metal Bonds Using Comparable Endo-Units of Sc_(2) and Sc_(2)C_(2)

The precise identification of metal-metal bonds is critical to fully understanding the nature of metal-metal bonding but remains a fundamental challenge.Herein,we show the essence of Sc-Sc bonds with a metal-metal distance of 3.36 Å in a C_(3v)(8)-C_(82) fullerene cage using crystallography.

Energy relationship and the polarization of C_(60) cage in the endohedral complexes (X@C_(60))

In this paper, we carry out the calculation on the system (X@C60)(X=Li, Na, K, Kb, Cs; F, Cl, Br, I), where the position of X changes along 5 typical symmetry directions. For the calculation of quantum chemistry we use EHMO/ASED method, for the calculation of molecular mechanics we use Buckingham potential (exp-6-1) function, and for the calculation of thermo-chemical cycle we use individually isolating the processes such as the structure variation, charge transfer and charge distribution, and their interactions etc. The calculation results show that (1) In the region of radius r≈0.2 nm of the Ceo cage, the potential field is nearly spherical; (2) Except for Li and Na, the systems are the most stable with minimum energies at the center of C60 cage. For Li and Na, the systems are the most stable with minimum energies at r≈0.16 nm and r≈0.13 nm, respectively. In view of the interactive region of chemical bonds, the interactions between X and the C60 cage do not belong to the classical chemical bonds; (3) The non-bonding interaction between the X and C60 cage are not purely electro-static, in which the electro-static interactions only occupy -90% at most on an average. The repulsion owing to the overlap of the electron cloud and the attraction owing to the dispersion can not be neglected. These two interactions determine the variations of size and trend of the system energies with r; (4) The polarization due to the position of X deviating from the center of C60 cage plays an important role at the most stable positions of Li and Na.