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81.
Dr. Chi‐Shian Chen Yu‐Fang Lin Dr. Wen‐Yann Yeh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(4):936-940
Reactions of the open‐cage fullerene C63NO2(Py)(Ph)2 ( 1 ) with [Ru3(CO)12] produce [Ru3(CO)8(μ,η5‐C63NO2(Py)(Ph)2)] ( 2 ), [Ru2H(CO)3(μ,η7‐C63N(Py)(Ph)(C6H4))] ( 3 ), and [Ru(CO)(Py)2(η3‐C63NO2(Py)(Ph)2)] ( 4 ), in which the orifice sizes are modified from 12 to 8, 11, and 15‐membered ring, through ruthenium‐mediated C?O and C?C bond activation and formation. 相似文献
82.
Phenothiazine–BODIPY–Fullerene Triads as Photosynthetic Reaction Center Models: Substitution and Solvent Polarity Effects on Photoinduced Charge Separation and Recombination
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Chandra B. KC Gary N. Lim Dr. Vladimir N. Nesterov Prof. Dr. Paul A. Karr Prof. Dr. Francis D'Souza 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(51):17100-17112
Novel photosynthetic reaction center model compounds of the type donor2–donor1–acceptor, composed of phenothiazine, BF2‐chelated dipyrromethene (BODIPY), and fullerene, respectively, have been newly synthesized using multistep synthetic methods. X‐ray structures of three of the phenothiazine‐BODIPY intermediate compounds have been solved to visualize the substitution effect caused by the phenothiazine on the BODIPY macrocycle. Optical absorption and emission, computational, and differential pulse voltammetry studies were systematically performed to establish the molecular integrity of the triads. The N‐substituted phenothiazine was found to be easier to oxidize by 60 mV compared to the C‐substituted analogue. The geometry and electronic structures were obtained by B3LYP/6‐31G(dp) calculations (for H, B, N, and O) and B3LYP/6‐31G(df) calculations (for S) in vacuum, followed by a single‐point calculation in benzonitrile utilizing the polarizable continuum model (PCM). The HOMO?1, HOMO, and LUMO were, respectively, on the BODIPY, phenothiazine and fullerene entities, which agreed well with the site of electron transfer determined from electrochemical studies. The energy‐level diagram deduced from these data helped in elucidating the mechanistic details of the photochemical events. Excitation of BODIPY resulted in ultrafast electron transfer to produce PTZ–BODIPY.+–C60.?; subsequent hole shift resulted in PTZ.+–BODIPY–C60.? charge‐separated species. The return of the charge‐separated species was found to be solvent dependent. In nonpolar solvents the PTZ.+–BODIPY–C60.? species populated the 3C60* prior to returning to the ground state, while in polar solvent no such process was observed due to relative positioning of the energy levels. The 1BODIPY* generated radical ion‐pair in these triads persisted for few nanoseconds due to electron transfer/hole‐shift mechanism. 相似文献
83.
Jun Zhang Prof. Dr. Michael Dolg 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(43):13909-13912
By state‐of‐the‐art quantum chemical methods, we show that for bulky functional groups like cyclohexane, [20]fullerene, dodecahedrane, and C60, the attractive dispersion interaction can have a greater impact on stereochemistry than the repulsive steric effect, making the compact isomer the more stable one. In particular, for the double C60 adduct of pentacene 1 , the syn isomer should be the main product instead of the anti one inferred in the original synthesis experiment (Y. Murata et al., J. Org. Chem. 1999 , 64, 3483). With and without dispersion interactions taken into account, the Gibbs energy difference ΔG(syn?anti) is ?6.36 and +1.15 kcal mol?1, respectively. This study reminds us that dispersion interactions as well as electrostatic or hyperconjugation effects, etc. can lead to some unusual stereochemical phenomena. 相似文献
84.
Cong‐Li Gao Xiang Li Dr. Yuan‐Zhi Tan Xin‐Zhou Wu Dr. Qianyan Zhang Prof.Dr. Su‐Yuan Xie Prof. Rong‐Bin Huang 《Angewandte Chemie (International ed. in English)》2014,53(30):7853-7855
Previously reported fused‐pentagon fullerenes stabilized by exohedral derivatization do not share the same cage with those stabilized by endohedral encapsulation. Herein we report the crystallographic identification of #4348C66Cl10, which has the same cage as that of previously reported Sc2@C66. According to the geometrical data of #4348C66Cl10, both strain relief (at the fused pentagons) and local aromaticity (on the remaining sp2‐hybrided carbon framework) contribute to the exohedral stabilization of this long‐sought 66 carbon atom cage. 相似文献
85.
Dr. Helena Isla Dr. Emilio M. Pérez Prof. Dr. Nazario Martín 《Angewandte Chemie (International ed. in English)》2014,53(22):5629-5633
Supramolecular polymers based on dispersion forces typically show lower molecular weights (MW) than those based on hydrogen bonding or metal–ligand coordination. We present the synthesis and self‐assembling properties of a monomer featuring two complementary units, a C60 derivative and an exTTF‐based macrocycle, that interact mainly through π–π, charge‐transfer, and van der Waals interactions. Thanks to the preorganization in the host part, a remarkable log Ka=5.1±0.5 in CHCl3 at room temperature is determined for the host–guest couple. In accordance with the large binding constant, the monomer self‐assembles in the gas phase, in solution, and in the solid state to form linear supramolecular polymers with a very high degree of polymerization. A MW above 150 kDa has been found experimentally in solution, while in the solid state the monomer forms extraordinarily long, straight, and uniform fibers with lengths reaching several microns. 相似文献
86.
Chong Zhao Dan Lei Prof. Li‐Hua Gan Dr. Zhu‐Xia Zhang Prof. Chun‐Ru Wang 《Chemphyschem》2014,15(13):2780-2784
Sc2S@C84 has recently been detected but not structurally characterized. 1 Density functional theory calculations on C84 and Sc2S@C84 show that the favored isomer of Sc2S@C84 shares the same parent cage as Sc2C2@C84, whereas Sc2S@C84:51383, which violates the isolated‐pentagon rule, is the second lowest energy isomer with the widest HOMO–LUMO gap and shows high kinetic stability. The analysis shows that Sc2S@C84:51575 is favored when the temperature exceeds 2 800 K and it can transform into the most favorable isomer Sc2S@C84:51591. Molecular orbital analysis indicates that both Sc2S and Sc2C2 formally transfer four electrons to the cage, and quantum theory of atoms in molecules analysis demonstrates that there is a covalent interaction between Sc2S and C84:51591. The IR spectra of Sc2S@C84 are provided to aid future structural identification. 相似文献
87.
High‐Potential Perfluorinated Phthalocyanine–Fullerene Dyads for Generation of High‐Energy Charge‐Separated States: Formation and Photoinduced Electron‐Transfer Studies
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Dr. Sushanta K. Das Andrew Mahler Prof. Angela K. Wilson Prof. Dr. Francis D'Souza 《Chemphyschem》2014,15(12):2462-2472
High oxidation potential perfluorinated zinc phthalocyanines (ZnFnPcs) are synthesised and their spectroscopic, redox, and light‐induced electron‐transfer properties investigated systematically by forming donor–acceptor dyads through metal–ligand axial coordination of fullerene (C60) derivatives. Absorption and fluorescence spectral studies reveal efficient binding of the pyridine‐ (Py) and phenylimidazole‐functionalised fullerene (C60Im) derivatives to the zinc centre of the FnPcs. The determined binding constants, K, in o‐dichlorobenzene for the 1:1 complexes are in the order of 104 to 105 M ?1; nearly an order of magnitude higher than that observed for the dyad formed from zinc phthalocyanine (ZnPc) lacking fluorine substituents. The geometry and electronic structure of the dyads are determined by using the B3LYP/6‐31G* method. The HOMO and LUMO levels are located on the Pc and C60 entities, respectively; this suggests the formation of ZnFnPc.+–C60Im.? and ZnFnPc.+–C60Py.? (n=0, 8 or 16) intra‐supramolecular charge‐separated states during electron transfer. Electrochemical studies on the ZnPc–C60 dyads enable accurate determination of their oxidation and reduction potentials and the energy of the charge‐separated states. The energy of the charge‐separated state for dyads composed of ZnFnPc is higher than that of normal ZnPc–C60 dyads and reveals their significance in harvesting higher amounts of light energy. Evidence for charge separation in the dyads is secured from femtosecond transient absorption studies in nonpolar toluene. Kinetic evaluation of the cation and anion radical ion peaks reveals ultrafast charge separation and charge recombination in dyads composed of perfluorinated phthalocyanine and fullerene; this implies their significance in solar‐energy harvesting and optoelectronic device building applications. 相似文献
88.
Lukas Spree Christin Schlesier Dr. Aram Kostanyan Dr. Rasmus Westerström Prof. Dr. Thomas Greber Prof. Dr. Bernd Büchner Dr. Stanislav M. Avdoshenko Dr. Alexey A. Popov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(11):2436-2449
The substitution of scandium in fullerene single-molecule magnets (SMMs) DySc2N@C80 and Dy2ScN@C80 by lutetium has been studied to explore the influence of the diamagnetic metal on the SMM performance of dysprosium nitride clusterfullerenes. The use of lutetium led to an improved SMM performance of DyLu2N@C80, which shows a higher blocking temperature of magnetization (TB=9.5 K), longer relaxation times, and broader hysteresis than DySc2N@C80 (TB=6.9 K). At the same time, Dy2LuN@C80 was found to have a similar blocking temperature of magnetization to Dy2ScN@C80 (TB=8 K), but substantially different interactions between the magnetic moments of the dysprosium ions in the Dy2MN clusters. Surprisingly, although the intramolecular dipolar interactions in Dy2LuN@C80 and Dy2ScN@C80 are of similar strength, the exchange interactions in Dy2LuN@C80 are close to zero. Analysis of the low-frequency molecular and lattice vibrations showed strong mixing of the lattice modes and endohedral cluster librations in k-space. This mixing simplifies the spin–lattice relaxation by conserving the momentum during the spin flip and helping to distribute the moment and energy further into the lattice. 相似文献
89.
Since 1996, a growing number of strained macrocycles, comprising only sp2‐ or sp‐hybridized carbon atoms within the ring, have become synthetically accessible, with the [n]cycloparaphenyleneacetylenes ( CPPAs ) and the [n]cycloparaphenylenes ( CPPs ) being the most prominent examples. Now that robust and relatively general synthetic routes toward a diverse range of nanohoop structures have become available, the research focus is beginning to shift towards the exploration of their properties and applications. From a supramolecular chemistry perspective, these macrocycles offer unique opportunities as a result of their near‐perfect circular shape, the unusually high degree of shape‐persistence, and the presence of both convex and concave π‐faces. In this Minireview, we give an overview on the use of strained carbon‐rich nanohoops in host–guest chemistry, the preparation of mechanically interlocked architectures, and crystal engineering. 相似文献
90.
C~6~0, C~7~0的烷基化 总被引:1,自引:0,他引:1
本文利用低价稀土化物(S~mI~2或YbI~2)与C~6~0、C~7~0及卤代烃(烯丙基溴、氯苄)的混合溶液反应,制得烯丙基化、苄基化的富勒烯。发现与C~6~0相接的苄基数可以从1到14,验证了Krusic等人的结果。此外,还发现C~6~0可以进行烯丙基化,得到(CH~2=CHCH~2)~nC~6~0(n=1-10),C~7~0可以进行苄基化,C~7~0上至少可以接13个苄基,实验证明这类反应是对富勒烯进行烷基化的一种简便、有效的方法。 相似文献