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1.
Yuanhe Huang Mayumi Okada Kenichi Fukui Kazuyoshi Tanaka Hiroo Aoki Tokio Yamabe 《International journal of quantum chemistry》1997,63(2):361-366
Mixing of triply degenerated lowest unoccupied molecular orbitals (LUMO; t1u) and the next LUMO (NLUMO; t1g) of a neutral C60 molecule was estimated when it becomes dianionic (C602−) and trianionic (C603−) species. The electronic structure of the basic C60 was obtained by a semiempirical (INDO type) Hartree-Fock scheme and the mixing of the t1u and t1g MOs by the conventional configuration interaction (CI) method assuming Ih structural symmetry of a C60 for the sake of simplicity. The most favorable electronic states of C602− and C603− are predicted to be triplet and doublet, respectively. Furthermore, in C602−, the energy difference of this triplet state and the first excited singlet state is very close, which agrees well with the experimental observation. © 1997 John Wiley & Sons, Inc. 相似文献
2.
Dr. Maximiliano L. Agazzi Dr. Javier E. Durantini Dr. Natalia S. Gsponer Dr. Andrés M. Durantini Prof. Sonia G. Bertolotti Prof. Edgardo N. Durantini 《Chemphyschem》2019,20(9):1110-1125
A covalently linked BODIPY−fullerene C60 dyad (BDP−C60) was synthesized as a two-segment structure, which consists of a visible light-harvesting antenna attached to an energy or electron acceptor moiety. This structure was designed to improve the photodynamic action of fullerene C60 to inactivate bacteria. The absorption spectrum of BDP−C60 was found to be a superposition of the spectra of its constitutional moieties, whereas the fluorescence emission of the BODIPY unit was strongly quenched by the fullerene C60. Spectroscopic, calculations, and redox studies indicate a competence between photoinduced energy and electron transfer. Protonating the dimethylaminophenyl substituent through addition of an acidic medium led to a substantial increase in the fluorescence emission, triplet excited state formation, and singlet molecular oxygen production. At physiological pH, photosensitized inactivation of Staphylococcus aureus mediated by 1 μM BDP−C60 exhibited a 4.5 log decrease of cell survival (>99.997 %) after 15 min irradiation. A similar result was obtained with Escherichia coli using 30 min irradiation. Moreover, proton-activated photodynamic action of BDP−C60 turned this dyad into a highly effective photosensitizer to eradicate E. coli. Therefore, BDP−C60 is an interesting photosensitizing structure in which the light-harvesting antenna effect of the BODIPY unit combined with the protonation of dimethylaminophenyl group can be used to improve the photoinactivation of bacteria. 相似文献
3.
R. G. Bulgakov D. I. Galimov Yu. G. Ponomareva E. Yu. Nevyadovskii R. Kh. Gainetdinov 《Russian Chemical Bulletin》2006,55(6):955-960
Quenching of electronically excited states of Ln3+* ions generated upon photoexcitation of toluene solutions of Ln(acac)3·H2O (Ln = Tb, Eu) complexes by C60 fullerene at 293 K was detected and investigated. The dependences of quenching efficiency on C60 concentration obtained from data on the decrease in the photoluminescence intensity and Ln3+* lifetimes obey the Stern-Volmer law. Quenching is due to inductive-resonant energy transfer from Ln3+* to C60 fullerene. The bimolecular rate constants for quenching, the overlap integrals of the Ln3+* photoluminescence spectra with the C60 absorption spectra, and the critical energy transfer distances were determined. No sensitized luminescence of C60 in the system studied was detected.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 921–925, June, 2006. 相似文献
4.
Broken orbital symmetry and the description of valence hole states in the tetrahedral [CrO4]2− anion
The localization of ligand-based valence holes in the tetrahedral complex ion [CrO4]2? in a crystalline environment is studied by SCF calculations on the hole states, with progressively less restrictions on the spatial symmetry of the molecular orbitals. The final wavefunctions are obtained by constructing, from the symmetry broken SCF solutions, wavefunctions that exhibit again the proper transformation properties under the operations of T d . The crystal environment of the [CrO4]2? anion is represented by a point charge model. In contrast with the situation for core hole states, the projection afterwards into T d symmetry is important. The final ionization energies, which are obtained from projected C 3v adapted SCF solutions, are reduced considerably (?3 eV) with respect to the T d ΔSCF results, but the ordering of the states has not changed essentially. The calculated ionization energies compare favourably with results of XPS experiments on Na2CrO4. The evaluation of the energies of projected symmetry broken SCF solutions requires the calculation of hamiltonian matrix elements between determinantal wavefunctions built from mutually non-orthogonal orbital sets. An efficient method for the calculation of such matrix elements is presented. 相似文献
5.
The molecular and electronic structure of hypothetical complexes of unsubstituted fullerene C60 withI
h
symmetry and its cyclopentadienyl type derivatives were simulated by the MNDO/PM3 method taking the C60(XC[)
n
molecules (n=1, 2, 10, 12; X=Si, Ge, Sn) and η5-C60H5XCp (X=Ge, Sn), respectively, as example. The complexes 12η5-πC60(XCp)12 and η5-πC60XCp withI
h
andC
5v symmetry, respectively, were found to be the most stable compounds. The energies of the X−C60 bonds in these complexes are close to those of X−Cp bonds in bis(cyclopentadienyl) complexes XCp2 and are substantially higher than the energies of similar bonds in complexes of unsubstituted fullerene η1-πC60(XCp)− and η5-πC60(XCp)+. Geometric parameters and spin densities in radicals C60XCp and biradicals C60(XCp)2 and C60H10 were calculated.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2155–2165, November, 1998. 相似文献
6.
The principles and structure of an LCAO -MO ab-initio computer program which recalculates all two-electron integrals needed in each SCF iteration are formulated and discussed. This approach—termed “direct SCF ”—is found to be particularly efficient for calculations on very large systems, and also for calcuations on small and medium-sized molecules with modern minicomputers. The time requirements for a number of sample calculations are listed, and the distribution of two-electron integrals according to magnitude is investigated for model systems. 相似文献
7.
Susumu Narita Takeshi Hamakawa Tetsuo Morikawa Tai-ichi Shibuya 《Monatshefte für Chemie / Chemical Monthly》2002,133(7):987-990
Summary. The generalized Pauling bond order was enumerated in the C60 fullerene cage molecule (truncated icosahedral symmetry). This index measures chemical similarity in fullerene derivatives
such as dihydrofullerene (C60H2), anionized monohydrofullerene (C60H−), N-substituted monohydrofullerene (C59NH), the fullerene dimer ((C60)2), and the dianionic fullerene dimer ((C60)2
2−). It is also useful in judging the chemical stability of isomers.
Received October 9, 2001. Accepted November 9, 2001 相似文献
8.
PaulA. Liddell Gerdenis Kodis Linda delaGarza JeffreyL. Bahr AnaL. Moore ThomasA. Moore Devens Gust 《Helvetica chimica acta》2001,84(9):2765-2783
The two molecular triads 1a and 1b consisting of a porphyrin (P) covalently linked to a fullerene (C60) electron acceptor and tetrathiafulvalene (TTF) electron‐donor moiety were synthesized, and their photochemical properties were determined by transient absorption and emission techniques. Excitation of the free‐base‐porphyrin moiety of the TTF−P2 H−C60 triad 1a in tetrahydro‐2‐methylfuran solution yields the porphyrin first excited singlet state TTF−1P2 H−C60, which undergoes photoinduced electron transfer with a time constant of 25 ps to give TTF−P2 H.+−C60.−. This intermediate charge‐separated state has a lifetime of 230 ps, decaying mainly by a charge‐shift reaction to yield a final state, TTF.+−P2 H−C60.−. The final state has a lifetime of 660 ns, is formed with an overall yield of 92%, and preserves ca. 1.0 eV of the 1.9 eV inherent in the porphyrin excited state. Similar behavior is observed for the zinc analog 1b . The TTF‐PZn.+−C60.− state is formed by ultrafast electron transfer from the porphyrinatozinc excited singlet state with a time constant of 1.5 ps. The final TTF.+−PZn−C60.− state is generated with a yield of 16%, and also has a lifetime of 660 ns. Although charge recombination to yield a triplet has been observed in related donor‐acceptor systems, the TTF.+−P−C60.− states recombine to the ground state, because the molecule lacks low‐energy triplet states. This structural feature leads to a longer lifetime for the final charge‐separated state, during which the stored energy could be harvested for solar‐energy conversion or molecular optoelectronic applications. 相似文献
9.
Tribenzotriquinacene Receptors for C60 Fullerene Rotors: Towards C3 Symmetrical Chiral Stators for Unidirectionally Operating Nanoratchets
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Dr. Björn Bredenkötter Dr. Maciej Grzywa Dr. Mohammad Alaghemandi Dr. Rochus Schmid Prof. Dr. Wouter Herrebout Prof. Dr. Patrick Bultinck Prof. Dr. Dirk Volkmer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(29):9100-9110
The synthesis of a stereochemically pure concave tribenzotriquinacene receptor ( 7 ) for C60 fullerene, possessing C3 point group symmetry, by threefold condensation of C2‐symmetric 1,2‐diketone synthons ( 5 ) and a hexaaminotribenzotriquinacene core ( 6 ) is described. The chiral diketone was synthesized in a five‐step reaction sequence starting from C2h‐symmetric 2,6‐di‐tert‐butylanthracene. The highly diastereo‐discriminating Diels–Alder reaction of 2,6‐di‐tert‐butylanthracene with fumaric acid di(?)menthyl ester, catalyzed by aluminium chloride, is the relevant stereochemistry introducing step. The structure of the fullerene receptor was verified by 1H and 13C NMR spectroscopy, mass spectrometry and single crystal X‐ray diffraction. VCD and ECD spectra were recorded, which were corroborated by ab initio DFT calculations, establishing the chiral nature of 7 with about 99.7 % ee, based on the ee (99.9 %) of the chiral synthon ( 1 ). The absolute configuration of 7 could thus be established as all‐S [(2S,7S,16S,21S,30S,35S)‐( 7 )]. Spectroscopic titration experiments reveal that the host forms 1:1 complexes with either pure fullerene (C60) or fullerene derivatives, such as rotor 1′‐(4‐nitrophenyl)‐3′‐(4‐N,N‐dimethylaminophenyl)‐pyrazolino[4′,5′:1,2][60]fullerene ( R ). The complex stability constants of the complexes dissolved in CHCl3/CS2 (1:1 vol. %) are K([ C60 ? 7 ])=319(±156) M ?1 and K([ R ? 7 ])=110(±50) M ?1. With molecular dynamics simulations using a first‐principles parameterized force field the asymmetry of the rotational potential for [ R ? 7 ] was shown, demonstrating the potential suitability of receptor 7 to act as a stator in a unidirectionally operating nanoratchet. 相似文献
10.
《Solid State Sciences》2001,3(5):531-537
EPR and MMMA methods revealed two K3C60 phases, the unstable one with Tc=21.0 K containing C1−60 centers and a stable one with Tc=18.0 K constituting of C60 molecules in the form of C3−60 ions. The metastable phase appears only in the first stage of potassium intercalation of fullerene at the C60/K3C60 phase boundary. This phase is being transformed to a stable one on further doping to K3C60. The appearance of a metastable phase is related to the instability of the fullerene C60 fcc structure during the process of octahedral sites being filled by potassium ions. The critical temperature Tc shift upwards from 18.5 to 21.0 K is ascribed to the possible process of potassium transient back charge transfer valency, i.e. K31+C603−↔K21+K1−C601− [3K1++C3−60⇔2K1++K1−+C601−], which could enlarge the unit cell necessary to shift a superconducting critical temerature according to Tc on volume dependence. 相似文献
11.
Dr. Junning Kou Dr. Qi Wu Dr. Dongxu Cui Dr. Yun Geng Dr. Kunhao Zhang Prof. Dr. Min Zhang Prof. Dr. Hongying Zang Prof. Dr. Xinlong Wang Prof. Dr. Zhongmin Su Prof. Dr. Chunyi Sun 《Angewandte Chemie (International ed. in English)》2023,62(47):e202312733
Chiral induction has been an important topic in chemistry, not only for its relevance in understanding the mysterious phenomenon of spontaneous symmetry breaking in nature but also due to its critical implications in medicine and the chiral industry. The induced chirality of fullerenes by host–guest interactions has been rarely reported, mainly attributed to their chiral resistance from high symmetry and challenges in their accessibility. Herein, we report two new pairs of chiral porous aromatic cages (PAC), R- PAC-2 , S- PAC-2 (with Br substituents) and R- PAC-3 , S- PAC-3 (with CH3 substituents) enantiomers. PAC-2 , rather than PAC-3 , achieves fullerene encapsulation and selective binding of C70 over C60 in fullerene carbon soot. More significantly, the occurrence of chiral induction between R- PAC-2 , S- PAC-2 and fullerenes is confirmed by single-crystal X-ray diffraction and the intense CD signal within the absorption region of fullerenes. DFT calculations reveal the contribution of electrostatic effects originating from face-to-face arene-fullerene interactions dominate C70 selectivity and elucidate the substituent effect on fullerene encapsulation. The disturbance from the differential interactions between fullerene and surrounding chiral cages on the intrinsic highly symmetric electronic structure of fullerene could be the primary reason accounting for the induced chirality of fullerene. 相似文献
12.
Neretin I. S. Lyssenko K. A. Antipin M. Yu. Slovokhotov Yu. L. 《Russian Chemical Bulletin》2002,51(5):754-763
Two solvates of fluorinated derivatives of C60 fullerene were studied by single-crystal X-ray diffraction analysis. The crystals of fluorinated fullerene solvate C60F18·C6H5Me belong to the monoclinic system with the unit cell parameters a = 11.532(2) , b = 21.501(3) , c = 16.261(2) , = 101.798(5)°. The fluorinated fullerene molecule with the approximate symmetry C
3v occupies a general position. The crystals of fluorinated fullerene solvate C60F48·2C6H3Me3 belong to the cubic system (a = 23.138(2) ). The C60F48 molecule occupies the special position with the S
6 symmetry. The experimental molecular geometry agrees with the results of quantum-chemical calculations. 相似文献
13.
Dandan Chen Dr. Dariusz W. Szczepanik Prof. Dr. Jun Zhu Dr. Alvaro Muñoz-Castro Prof. Dr. Miquel Solà 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(2):802-808
The isolated-pentagon rule (IPR) is a determining structural feature that accounts for hollow fullerene stabilization and properties related to Cn (n≥60) cages. The recent characterization of an unprecedented non-IPR hydrofullerene, C2v C66H4, bearing two heptagons with adjacent fused-pentagon motifs, largely dismisses this feature. Herein, employing DFT calculations, the 13C NMR spectroscopy and aromatic behavior of C2v C66H4 are explored. The results show the presence of three π-aromatic circuits at the bottom boat section of C66H4, indicating the unique features of this hydrofullerene in comparison to those of pristine C60. In addition, under specific orientations of the external field, certain π-aromatic circuits are enabled, resulting in a more aromatic fullerene than that of C60, but lower than that of the spherical aromatic C606− fulleride. Notably, under a field aligned with the saturated carbon atoms, nonaromatic characteristics are exposed. This reveals that spherical-like cages can involve a complex magnetic response that heavily depends on the orientation of the applied field. 相似文献
14.
Makiko Seno Hironori Fukunaga Tsuneyuki Sato 《Journal of polymer science. Part A, Polymer chemistry》1998,36(16):2905-2912
The effect of fullerene (C60) on the radical polymerization of methyl methacrylate (MMA) in benzene was studied kinetically and by means of ESR, where dimethyl 2,2′-azobis(isobutyrate) (MAIB) was used as initiator. The polymerization rate (Rp) and the molecular weight of resulting poly(MMA) decreased with increasing C60 concentration ((0–2.11) × 10−4 mol/L). The molecular weight of polymer tended to increase with time at higher C60 concentrations. Rp at 50°C in the presence of C60 (7.0 × 10−5 mol/L) was expressed by Rp = k[MAIB]0.5[MMA]1.25. The overall activation energy of polymerization at 7.0 × 10−5 mol/L of C60 concentration was calculated to be 23.2 kcal/mol. Persistent fullerene radicals were observed by ESR in the polymerization system. The concentration of fullerene radicals was found to increase linearly with time and then be saturated. The rate of fullerene radical formation increased with MAIB concentration. Thermal polymerization of styrene (St) in the presence of resulting poly(MMA) seemed to yield a starlike copolymer carrying poly(MMA) and poly(St) arms. The results (r1 = 0.53, r2 = 0.56) of copolymerization of MMA and St with MAIB at 60°C in the presence of C60 (7.15 × 10−5 mol/L) were similar to those (r1 = 0.46, r2 = 0.52) in the absence of C60. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2905–2912, 1998 相似文献
15.
R.B. King 《Journal of mathematical chemistry》1998,23(1-2):197-227
Elemental carbon has recently been shown to form molecular polyhedral allotropes known as fullerenes in addition to the familiar
graphite and diamond known since antiquity. Such fullerenes contain polyhedral carbon cages in which all vertices have degree
3 and all faces are either pentagons or hexagons. All known fullerenes are found to satisfy the isolated pentagon rule (IPR)
in which all pentagonal faces are completely surrounded by hexagons so that no two pentagonal faces share an edge. The smallest
fullerene structures satisfying the IPR are the known truncated icosahedral C60 of I
h
symmetry and ellipsoidal C70 of D
5h
symmetry. The multiple IPR isomers of families of larger fullerenes such as C76, C78, C82 and C84 can be classified into families related by the so-called pyracylene transformation based on the motion of two carbon atoms
in a pyracylene unit containing two linked pentagons separated by two hexagons. Larger fullerenes with 3ν vertices can be
generated from smaller fullerenes with ν vertices through a so‐called leapfrog transformation consisting of omnicapping followed
by dualization. The energy levels of the bonding molecular orbitals of fullerenes having icosahedral symmetry and 60n
2 carbon atoms can be approximated by spherical harmonics. If fullerenes are regarded as constructed from carbon networks of
positive curvature, the corresponding carbon allotropes constructed from carbon networks of negative curvature are the polymeric
schwarzites. The negative curvature in schwarzites is introduced through heptagons or octagons of carbon atoms and the schwarzites
are constructed by placing such carbon networks on minimal surfaces with negative Gaussian curvature, particularly the so-called
P and D surfaces with local cubic symmetry. The smallest unit cell of a viable schwarzite structure having only hexagons and
heptagons contains 168 carbon atoms and is constructed by applying a leapfrog transformation to a genus 3 figure containing
24 heptagons and 56 vertices described by the German mathematician Klein in the 19th century analogous to the construction
of the C60 fullerene truncated icosahedron by applying a leapfrog transformation to the regular dodecahedron. Although this C168 schwarzite unit cell has local O
h
point group symmetry based on the cubic lattice of the D or P surface, its larger permutational symmetry group is the PSL(2,7)
group of order 168 analogous to the icosahedral pure rotation group, I, of order 60 of the C60 fullerene considered as the isomorphous PSL(2,5) group. The schwarzites, which are still unknown experimentally, are predicted
to be unusually low density forms of elemental carbon because of the pores generated by the infinite periodicity in three
dimensions of the underlying minimal surfaces.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
Prof. Keiichi Katoh Dr. Nobuhiro Yasuda Dr. Marko Damjanović Prof. Wolfgang Wernsdorfer Prof. Brian K. Breedlove Prof. Masahiro Yamashita 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(21):4805-4815
A supramolecular complex ( 1⋅ C60) was prepared by assembling (C60-Ih)[5,6]fullerene (C60) with the dinuclear Tb3+ triple-decker complex [(TPP)Tb(Pc)Tb(TPP)] ( 1 : Tb3+=trivalent terbium ion, Pc2−=phthalocyaninato, TPP2−=tetraphenylporphyrinato) with quasi-D4h symmetry to investigate the relationship between the coordination symmetry and single-molecule magnet (SMM) properties. Tb3+-Pc triple-decker complexes (Tb2Pc3) have an important advantage over Tb3+-Pc double-decker complexes (TbPc2) since the magnetic relaxation processes correspond to the Zeeman splitting when there are two 4f spin systems. The two Tb3+ sites of 1 are equivalent, and the twist angle (φ) was determined to be 3.62°. On the other hand, the two Tb3+ sites of 1⋅ C60 are not equivalent. The φ values for sites Tb1 and Tb2 were determined to be 3.67° and 33.8°, respectively, due to a change in the coordination symmetry of 1 upon association with C60. At 1.8 K, 1 and 1⋅ C60 undergo different magnetic relaxations, and the changes in the ground state affect the spin dynamics. Although 1 and 1⋅ C60 relax via QTM in a zero applied magnetic field (H), H dependencies of the magnetic relaxation times (τ) for H>1500 Oe are similar. On the other hand, for H<1500 Oe, the τ values have different behaviors since the off-diagonal terms ( ) affect the magnetic relaxation mechanism. From temperature (T) and H dependences of τ, spin-phonon interactions along with direct and Raman mechanisms explain the spin dynamics. We believe that a supramolecular method can be used to control the magnetic anisotropy along the C4 rotation axis and the spin dynamic properties in dinuclear Ln3+-Pc multiple-decker complexes. 相似文献
17.
18.
A. S. Lobach A. A. Perov A. I. Rebrov O. S. Roshchupkina V. A. Tkacheva A. N. Stepanov 《Russian Chemical Bulletin》1997,46(4):641-648
Fullerene hydrides were prepared by hydrogenation of fullerences C60 and C70 using proton transfer from 9,10-dihydroanthracene to fullerene and were studied by mass spectrometry (electron impact, field
desorption), IR, UV, and1H and13C NMR spectroscopy. The main product of the hydrogenation of C60 is C60H36, which is sufficiently stable. Hydrogenation of fullerene C70 gives a series of polyhydrides C70H
n
(n=36–46), and the main product is C70H36. The dehydrogenation of C60H36 by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone is not quantitative and results in the formation of fullerene derivatives along
with C60. The comparison of the IR and1H and13C NMR spectral data for solid C60H36 with the theoretical calculations suggests that the fullerene hydride has aT-symmetric structure and contains four isolated benzenoid rings located at tetrahedral positions on the surface of the closed
skeleton of the molecule.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 4, pp. 671–678, April, 1997. 相似文献
19.
A method is described for reducing a large part of the arithmetic of exact ab-initio SCF molecularorbital calculations based on Slater-type-orbitals without noticeable loss of numerical accuracy. The procedure involves the transformation to Löwdin orthogonalized orbitals and then invoking the NDDO approximation. The three- and four-centre two-electron integrals required are estimated by a truncated Ruedenberg expansion. All one-electron integrals are evaluated exactly. No empirical parameters are employed. Numerical tests on CO, OF2, O3 and ONF show that the NDDO approximation is very accurate for Löwdin functions and that the Ruedenberg expansion is arithmetically satisfactory for the SCF MO calculations. 相似文献
20.
V. N. Drozd V. N. Knyazev F. M. Stoyanovich F. M. Dolgushin A. I. Yanovsky 《Russian Chemical Bulletin》1997,46(1):113-121
The interaction of stable 2-RSO2-benzonitrile oxides1a−c (R=Ph, But, or PhMeN) with C60 fullerene proceeds at the double (6,6)-bond of fullerene as the [3+2] cycloaddition to form the corresponding isoxazolines2a−c. The molecular structure of compound2b was established by X-ray structural analysis. The interaction of C60 fullerene with 2-(5-methyl-4-nitrothiophene)carbonitrile sulfide, which was obtained by thermolysis of 5-(5′-methyl-4′-nitro-2′-thienyl)1,3,4-oxathiazol-2-one,
affords only unstable products.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 118–126, January, 1997. 相似文献