Preparation of a series of NiL(η2-C60) complexes (L = 1,2-bis(diphenylphosphino)ethane,and 1,1′-bis(diphenylphosphino)ferrocene) by zinc dust reduction

A simple method for preparation of nickel-fullerene coordination complexes has been developed. NiLCl₂(Br₂) and C₆₀ mixtures are reduced by zinc dust upon heating in o-dichlorobenzene. Diffusion of hexane into the reaction mixture results in formation of crystals of NiL(η²-C₆₀)?solvent (L = 1,2-bis(diphenylphosphino)ethane (dppe, 1), 1,3-bis(diphenylphosphino)propane (dppp, 2) and 1,1′-bis(diphenylphosphino)ferrocene (dppf, 3)). Nickel coordinates to the 6–6 bonds of C₆₀ by η²- type and has distorted square-planar geometry. The average Ni–C(C₆₀) bond lengths are 1.936(6)–1.977(3)?Å. We found that increase in the P(L)–Ni–P(L) angle and the dihedral angle between the PNiP and CNiC planes results in elongation of the Ni–C(C₆₀) and Ni–P(L) bonds by 0.04–0.06?Å. Complexes 1–3 contain zero-valent nickel since fullerenes are neutral according to the IR- and visible-NIR spectra. Some of the IR-active bands of C₆₀ are split into three bands in spectra of 1–3 due to C₆₀ symmetry lowering, and the F_1u(4) C₆₀ mode is shifted to lower wave numbers due to the π-back donation. The formation of 1–3 is accompanied by appearance of new bands in the visible range at 435–447 and 661–680 nm.     

单加成环丙烷富勒烯膦酸酯衍生物的合成与电化学性能

在Mn(OAc)₃•2H₂O催化下, C₆₀分别和亚甲基二膦酸四乙酯、氰基亚甲基膦酸二乙酯或乙氧羰基亚甲基膦酸二乙酯在氯苯中回流, 生成3个单加成环丙烷富勒烯膦酸衍生物C₆₀C(R)PO(OEt)₂ [1, R＝PO(OEt)₂; 2, R＝COOEt; 3, R＝CN]. 与以前报道的Bingel反应法相比, 该方法副产物少并且缩短了反应时间. 采用循环伏安法发现1, 2的还原电位相对于C₆₀发生负移, 而3的还原电位相对于C₆₀却正移40 mV, 表明引入象氰基一样具有很强吸电子能力的取代基团, 可以改善富勒烯球的电化学性能, 合成电子接受能力较强的富勒烯衍生物.     

Direct Formation of Cycloadducts Between Fullerenes and Amino Acids Through Electron-Transfer Processes

Abstract

The reactions of [60]fullerene and amino acids in the absence of aldehyde in o-dichlorobenzene (ODCB) at 150 °C have been investigated. Fulleropyrrolidines 1 [C₆₀(CH₂N(CH₃)CHC₆H₂(NO₂)₃)], 2 [C₆₀(CH₂N(CH₃)CH₂)], 3 [C₆₀(CH₂NHCH₂)], and 5a–b [C₆₀(RCHNHCHR), R?CH₃ (5a), R?CH₂Ph (5b)] were obtained in moderate yields from the reactions of C₆₀ and corresponding amino acids. The reaction of C₇₀ and N-methylglycine in the absence of aldehyde was also studied and was found to give the positional isomers of N-methyl[70]fulleropyrrolidines 6 (1,9-isomer) and 7(7,8-isomer). All products were fully characterized by ultraviolet–visible, Fourier transform–infrared (FT-IR), NMR, and mass spectrometry. The reactions were also carried out in the dark to exclude the possible interference of the photoinduced reactions, and almost the same yields of products were obtained.     

6-氨基己酸及2-氨基乙磺酸C60加成物的合成及溶解性

水溶性Fullerenes (C₆₀)衍生物的制备对于C₆₀的生物学研究具有十分重要的意义. 氨基酸与C₆₀的胺化反应可得到水溶性的氨基酸C₆₀衍生物. 以C₆₀与过量6-氨基己酸或2-氨基乙磺酸(摩尔比为1∶10)于80 ℃搅拌反应24 h, 分别得到加成度为5和4的氨基酸C₆₀主产物, 产率按加入的C₆₀计算分别为30%, 28%. 氨基酸碳链的长度及加成产物在反应体系中能否及时沉淀析出影响和控制着加成度的大小. C₆₀[NH(CH₂)₅COOH]₅H₅ (3a), C₆₀(NHCH₂CH₂SO₃H)₄H₄ (6a)用柱层析进一步纯化, 其结构组成经元素分析, ¹H NMR, ¹³C NMR, IR所证实. 6a的水溶性受溶液pH的影响较小, 3a在不同pH缓冲溶液中的溶解性用光谱法测定, 分别为: pH＝10.25时为71.81 mg•mL^－1, pH＝7时为23.68 mg•mL^－1, pH＝3.36时为10.12 mg•mL^－1. 在波长273 nm处, 3a的摩尔消光系数为ε＝3.43×10⁴ L•mol^－1•cm^－1.     

Supramolecular dyad derived from a buckybowl series of O2N2-donor naphthodiaza-crowns coordinated to C60: photophysical,NMR and theoretical studies

Supramolecular complexation of C₆₀ with L¹-L⁵ were studied in toluene, chloroform and 1,2-dichlorobenzene solvents using UV–vis, fluorescence, ¹H, ¹³C NMR spectroscopy as well as density functional theory (DFT) calculations. The Job’s plot of continuous variation method established 1:1 stoichiometry for L¹-L⁵/C₆₀. Binding constants (K) calculated for L¹-L⁵/C₆₀ were also determined employing UV–vis and fluorescence spectroscopy. Both steady-state and time-resolved fluorescence spectroscopic surveys showed remarkable fluorescence quenching phenomenon for L¹-L⁵ in the presence of C₆₀ which was primarily attributed to involvement of a static process. The observed fluorescence quenching in L¹–L⁵ was described in terms of both π–π and n–π interactions of the naphthalene moieties and the nitrogen donor groups on the aza-crown macrocyclic ligands with C₆₀, respectively. Moreover, DFT calculations using B₃LYP/6-31G* basis set confirmed on the aforesaid π–π interaction of naphthalene groups on the aza-crowns with C₆₀. The DFT calculations also established significant distributions of charge between C₆₀ and L¹-L⁵ in according to the electronic structure and geometry of L¹-L⁵/C₆₀, very similar to phthalocycnine/C₆₀ systems.     

Supramolecular polymer networks based on calix[5]arene chained poly(p-phenyleneethynylene) and C60 fulleropyrrolidine

Abstract

A poly(p-phenyleneethynylene) polymer (PCF[5]), bearing two π-rich cone-like calix[5]arene cavities (assembling cores) attached to a rigid p-phenyleneethynylene spacer, was synthesised by a Pd-catalysed cross-coupling reaction. UV–vis absorption and fluorescence spectroscopies combined with dynamic light scattering measurements provide evidence for the self-assembly of PCF[5] (homopolytopic host molecule) with a complementary C₆₀ fulleropyrrolidine (C₆₀-Pyr) guest in solution, in the construction of a supramolecular polymer network. Atomic force microscopy analysis of PCF[5]/C₆₀-Pyr highlights the formation of a bicontinuous network consisting of a uniform distribution of prominent structures, within a polymeric background forming a biphasic structure.     

Molecular complexes of C60 with tetrasulfur tetranitride

Compounds C₆₀(S₄N₄)_2−x (C₆H₆) _x (1a-d) withx=0.67 (a), 1.0 (b), 1.1 (c), and 1.2 (d), in which isomorphous replacement of S₄N₄ with benzene takes place, were obtained by the reaction of fullerence C₆₀ with tetrasulfur tetranitride in benzene. Complexes C₆₀·S₄N₄ (2) and C₆₀(S₄N₄)₂ (3) containing no solvent were isolated from toluene. The compositions of the compounds were established by elemental and thermogravimetric analyses. The data of IR and X-ray photoelectron (XP) spectroscopies show that in the complexes studied the transfer of electron density occurs mainly from the nitrogen atoms of S₄N₄. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 37–40. January 1977.     

Solvent‐Free Reactions of Fullerenes with Diethyl Bromomalonate in the Presence of Inorganic Bases Under High‐Speed Vibration Milling Conditions

Abstract

Solvent‐free reactions of C₆₀ and C₇₀ with diethyl bromomalonate in the presence of various inorganic bases were investigated under the high‐speed vibration milling (HSVM) conditions, and are shown to give methanofullerenes 1 and 2 in good to excellent yields based on consumed fullerenes. Several weak inorganic bases were found to be quite effective in promoting the solvent‐free mechanochemical Bingel reactions of C₆₀ and C₇₀ under the HSVM conditions. Among the studied bases, sodium acetate gave the highest yield of monoadducts, while potassium carbonate afforded a considerable amount of bisadducts for both C₆₀ and C₇₀.     

Synthesis and Spectroscopic Properties of a Covalently Linked Porphyrin–Fullerene C60 Dyad

A covalently linked porphyrin–fullerene C₆₀ dyad 6 was conveniently synthesized by 1,3‐dipolar cycloaddition using 5‐(4‐carbonylphenyl)‐10,15,20‐tris(4‐methoxylphenyl)porphyrin 5, N‐methylglycine and fullerene C₆₀. Spectroscopic studies show that dyad 6 is a promising architecture with potential application as photoactive organic material.     

Photophysical Investigations on Determination of Ionicity and Electronic Structures for the Non-covalent Complexes of Calix[4]resorcinarene with Fullerenes C<Subscript>60</Subscript> and C<Subscript>70</Subscript> in the Solution State

Ground state non-covalent interactions between a macrocyclic receptor, C-methylcalix[4]resorcinarene (1) and fullerenes (C₆₀ and C₇₀) have been studied in benzonitrile by an absorption spectrophotometric method. Absorption bands are located in the visible region due to the charge transfer (CT) transition between 1 and various electron acceptors (including fullerenes), namely, 2,3-dichloro-5,6-dicyano-p-benzoquinone, tetracyanoquinodimethane and p-chloranil. Utilizing the CT absorption bands, various important physicochemical parameters, including oscillator strength, resonance energy, transition dipole strength of all the acceptor-1 complexes and vertical ionization potential of 1 are determined. Job’s method of continuous variation reveals 1:1 stoichiometry between fullerenes and 1. The most fascinating feature of the present study is that 1 binds selectively to C₇₀ compared to C₆₀ as obtained from binding constant (K) data of C₆₀-1 (K_C60-1K_{\mathrm{C}60\mbox{-}\mathbf{1}}) and C₇₀-1 (K_C70-1K_{\mathrm{C}70\mbox{-}\mathbf{1}}) complexes, i.e., K_C60-1=190K_{\mathrm{C}60\mbox{-}\mathbf{1}}=190 dm³⋅mol⁻¹ and K_C70-1=5,800K_{\mathrm{C}70\mbox{-}\mathbf{1}}=5{,}800 dm³⋅mol⁻¹ and selectivity (K_C70-1 /K_C60-1 ) ∼30. Quantum chemical calculations based on hybrid density functional theory estimate the enthalpies of formation of the fullerene-1 complexes in vacuo and provide very good support for selectivity in the K values of the C₇₀ and C₆₀ complexes of 1. The exchange and correlation energies have been calculated using a hybrid DFT functional method. We have opted to use the hybrid DFT functional over the Hartree-Fock method, as it can account for correlation effects also. Molecular electrostatic potential map calculations give a clear picture on the electronic structures of the fullerene-1 complexes.     

New complexes of fullerences C60 and C70 with CoII and MnII tetraphenylporphyrinates and their ESR study

Complexes of fullerenes C₆₀ and C₇₀ with cobalt(II) and manganese(II) tetraphenylporphyrinates of compositions Mn(TPP)·(C₆₀)₂(CS₂)_1.5 (1), Mn(TPP)·C₇₀(CS₂) _x , wherex<=1.25 (2), Co(TPP)·C₆₀(CS₂)_0.5 (3), and Co(TPP)·C₇₀(CS₂) _x , wherex<0.25 (4), were synthesized and studied by ESR spectroscopy. At 77 K, complexes1 and2 have singlet ESR spectra characteristic of the low-spin (S=1/2) state of Mn^II, withg=2.002 and linewidths of 250 G and 300 G, respectively, and differing significantly from that of the initial Mn^II(TPP) (g ₁=5.9 andg=2.0,S=5/2). The spectra of complexes1 and2 exposed to oxygen exhibit hyperfine structure due to interaction with⁵⁵Mn and¹⁴N nuclei. The ESR spectra of complexes3 and4 are asymmetric (<g>=2.4, ΔH _pp=(500–600) G), which is due to the overlap of parallel and perpendicular spectral components. The absence of ESR signals from C₆₀ ^.− and C₇₀ ^.− radical anions makes it possible to conclude that the formation of complexes1–4 is not accompanied by electron transfer from Co(TPP) and Mn(TPP) to fullerences C₆₀ and C₇₀. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 722–725, April, 1999.     

Coordination interactions in the crystalline lattice of alkaline ions with the polyoxometalate [V12B18O60H6]10− ligand

In the present work, the synthesis and structural characterization of two new polyoxovanadoborate (BVO) frameworks, based on the [V₁₂B₁₈O₆₀H₆]^10? polyanion, are reported, K(H₃O)(enH₂)₄[V₁₂B₁₈O₆₀H₆]·9.60H₂O (1) and Li₈(NH₄)₂[V₁₂B₁₈O₆₀H₆]·8.02H₂O (2). Both compounds are obtained in a mixed valence ratio of 10V^IV/2V^V. Framework 1 is characterized by potassium ions coordinated by the BVO cluster and ethylenediammonium and hydronium ions as charge-compensating agents. In framework 2, the BVO clusters are coordinating lithium ions and the charge is compensated by ammonium ions. Using the SHAPE 2.1 program, it was possible to calculate the best geometry for the existing lithium and potassium ions. For 2, the lithium ions are five-coordinate, best described by a square pyramid (SPY-5), while the coordination sphere around the potassium ions in 1 are six-coordinate. For 1, the coordination sphere of the existing potassium ions in the framework can be described as trigonal prism (TPR-6). Calculations were also done for a previously reported cluster [Na₁₀[(H₂O)V₁₂B₁₈O₆₀H₆]·18H₂O] (3), in which the sodium ions are six-coordinate but in two different geometries, these being octahedral and TPR-6. The influence of the interactions of the alkali ions with the [V₁₂B₁₈O₆₀H₆]^10? polyanion, on the vanadate and borate absorption bands observed in the infrared spectra, is discussed.     

Molecular complex of C60 fullerene with an organic π-donor,bis(methylenedithiotetrathiafulvalene): synthesis,crystal structures,and properties

A new molecular complex based on [60]fullerene, namely, (BMDT-TTF)·C₆₀·2CS₂ (1) (where BMDT-TTF is bis(methylenedithiotetrathiafulvalene)) was synthesized. The molecular and crystal structures of 1 were established by X-ray diffraction analysis. Complex 1 has a layered structure, layers of C₆₀ molecules alternating with those formed by BMDT-TTF molecules and CS₂ molecules located between them. In complex 1, there are short contacts between C₆₀ and the donor molecules, which results in a changed BMDT-TTF geometry. The donor molecules in 1 form in addition short S...S contacts. The data of IR spectroscopy indicate that the charge transfer to the fullerene molecule is insignificant if at all present. The conductivity of a single crystal of 1 measured at 20 °C using a four-contact method is 2·10^–5 ( cm)^–1.     

Ab initio MO LCAO SCF simulation of molecular and electronic structure of η5-π-C60H5XCp (X=Fe, Si) complexes

The problem of existence of η⁵-π-complexes of unsubstituted fullereneI _h -C₆₀ and its cyclopentadienyl type derivative C₆₀H₅ ^. is discussed.Ab initio MO LCAO SCF calculations of hypothetical sandwich systems η⁵-π-C₆₀H₅XCp (X=Fe (1a), Si (1b)), the cationic complex C₆₀FeCp⁺ of unsubstituted C₆₀, and the C₆₀H₅ ^. radical were performed in the STO-3G and 3-21G basis sets. In the1a, 1b, and C₆₀H₅ ^. systems, hydrogen atoms are attached to carbon atoms of fullerenei _h -C₆₀ at α-positions relative to the same pentagonal face (pent ^*). In η⁵-complexes, XCp species are also coordinated to this face. According to calculations in the 3-21G basis set, the Fe-pent ^* bond energy in complex1a is much higher than those of similar bonds in1b and in the η⁵-π-C₆₀FECp⁺ cation (117 kcal mol⁻¹ vs. 37 and 64 kcal mol⁻¹, respectively) and is 7 kcal mol⁻¹ higher than the Fe−Cp bond energy in the classical sandwich system FeCp₂. The Fe…C _pent* and Fe…C_Cp distances in complex1a are slightly shorter than the Fe…C distance in the ferrocene molecule. The spin populations in the C₆₀H₅ ^. radical are almost completely localized on the atoms of thepent ^* face, which must favor the formation of η⁵-π-complexes of this radical. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1657–1662, September, 1999.     

Absorption Spectrophotometric,NMR and Quantum Chemical Investigations of Ground State Non-Covalent Interactions between Fullerenes and a Designed Trihomocalix[6]arene in Solution

Ground state non-covalent interactions between a newly designed macrocyclic 1,3,5-trihomo calix[6]arene receptor, designated as 1, and the C₆₀ and C₇₀ fullerenes have been studied in toluene solutions. It was observed that the absorbances of both C₆₀ and C₇₀ solutions increased upon the addition of increasing concentrations of compound 1. Job’s method of continuous variation established 1:1 stoichiometry for these fullerene-1 complexes. The binding constant (K) data reveal that compound 1 binds to C₇₀ more strongly compared to C₆₀, i.e., K_C60-1 = 230 dm³·mol^-1K_{C60\mbox{-}\boldsymbol{1}} = 230~\mathrm{dm}^{3}{\cdot}\mathrm{mol}^{-1} and K_C70-1 = 517 dm³·mol^-1K_{C70\mbox{-}\boldsymbol{1}}= 517~\mathrm{dm}^{3}{\cdot}\mathrm{mol}^{-1}. Proton NMR analysis provides very good support for strong binding between C₇₀ and 1. Estimations of the solvent reorganization energy (R _S ) suggest that the C₇₀-1 complex is stabilized more than the corresponding C₆₀-1 complex, with R_S(C60-1) = -1.970 eVR_{S(C60\mbox{-}\boldsymbol{1})} = -1.970~\mathrm{eV} and R_S(C70-1) = -2.300 eVR_{S(C70\mbox{-}\boldsymbol{1})}= -2.300~\mathrm{eV}. Molecular mechanics force field method calculations established that the binding pattern of C₇₀ towards 1 occurs in the side-on rather than end-on orientation, and that the C₇₀-1 complex gains 5.23 kJ⋅mol⁻¹ of extra stabilization energy with this side-on geometrical arrangement.     

The reaction of diaryl derivatives of bis(triphenylphosphine)platinum(II) with [60]fullerene as a route to the platinum complex η2-C60Pt(PPh3)2

The reaction ofcis-Ar₂Pt(PPh₃)₂ (Ar=p-MeC₆H₄ (1a) and Ar=Ph (1b)) with [60]fullerene in toluene afforded the metal-fullerene complex η²-C₆₀Pt(PPh₃)₂ (2), which was isolated in the crystalline state. The reductive elimination between C₆₀ and1a or1b also resulted in the formation of biaryls (p-MeC₆H₄)₂ and Ph−Ph. The composition and structure of the compounds were established by¹H and³¹P NMR spectroscopy, electronic absorption spectroscopy, and elemental analysis. The homolytic phosphorylation of2 was additionally studied by the ESR method.     

Anion radicals of [60]fullerenes. An EPR study

Photochemically induced electron transfer in homogeneous systems (using triethylamine donor) and heterogeneous systems (using photoexcited TiO₂ suspension) was applied in in situ reduction of [60]fullerene. The anion radicals generated were characterized by means of EPR and VIS/near-IR spectroscopy. Narrow EPR lines were found. Radical A with g_A=2.0000 and peak-to-peak width, pp_A=0.09mT was observed as the primary product; followed by its consecutive product B with g_B=2.0006, pp_B=0.04mT, and in some cases product C with g_C=2.0009 and pp_c<0.1 mT. Radical A was assigned to [60]fullerene mono-anion, also characterized by a near-IR band at 1077 nm. B is presumably di-anion or a dimeric form of mono-anion. Identical results were also obtained using cathodic in situ reduction. Applying these generation techniques to [60]fullerene derivatives produced narrow EPR lines analogous to those described for pristine [60]fullerene. This was the case not only in organic solvents, but also in aqueous solutions. The results obtained present a contrast with the original ex situ EPR investigations describing [60]fullerene mono-anion with wide lines. According to the results presented here, the narrow and wide EPR lines do not represent contradictory phenomena, but are an integral part of the relatively complicated manifestations of various fullerene states and both will have to be seriously considered in the future.     

A Rational Approach Towards Determination of Optical Ionicity and Non-covalent Interactions in Fullerene-Calix[4]arene Host-Guest Complexes

The present article reports the host-guest complexation of a calix[4]arene derivative, namely 4-iso-propyl-calix[4]arene (1), with fullerenes (both C₆₀ and C₇₀) in toluene and benzonitrile solutions. It is observed that the charge-transfer (CT) absorption bands are located in the ground state for the C₆₀ and C₇₀ complexes of 1. By utilizing the CT absorption bands, various important physicochemical parameters like the oscillator strength, resonance energy, transition dipole moment, electronic coupling element and solvent reorganization energies have been estimated for the C₆₀-1 and C₇₀-1 complexes. The CT transition energy is very helpful for determining the vertical ionization potential of 1 in solution. Jobs method of continuous variation was used to establish 1:1 stoichiometry for the fullerene complexes of 1. The most fascinating feature of the present study is that 1 binds C₇₀ preferentially compared to C₆₀ as obtained from binding constant (K) data. The effect of solvent on the complexation of fullerenes (C₆₀ and C₇₀) with 1 is clearly observed from the trend in the K values: in toluene and whereas in benzonitrile, and . Molecular mechanics force field (MMMF) calculations reveal fascinating features regarding the binding pattern of fullerenes towards 1 in vacuo in terms of enthalpy of formation. MMMF calculations establish that during C₇₀-1 complexation, C₇₀ is directed in an end-on manner rather than the traditional side-on pattern.     

Synthesis, crystal structure, and spectral studies of the molecular complex of [60]fullerene with chloro(triphenylphosphine)gold(I), C60·2[(Ph3P)AuCl]

The molecular complex C₆₀·2[(Ph₃P)AuCl] (1) was synthesized. The crystal and molecular structure of1 was established by X-ray diffraction analysis. At room temperature, the [60]fullerene molecules in complex1 are ordered due to π—π interactions between C₆₀ and the phenyl rings of the chloro(triphenylphosphine)gold(1) molecules. The satellite structure, which accompanies the Cls photoelectron peak of complex1, is indicative of a partial suppression of a channel of losses due to π→π transition in the phenyl ring. The 1R spectral data indicate that either a charge is absent or the charge transfer to the fullerene molecule is negligible. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 365–369, February, 2000.     

The ESR study of the influence of fluorinated alcohols on spin-adducts of phosphoryl radicals with C60 and C70: a change of magnetic resonance parameters and exclusive formation of monoadducts

Complex formation of^.C₆₀P(O)(OPrⁱ)₂ or three isomers of^.C₇₀P(O)(OPrⁱ)₂ with fluorinated alcohols CF₃CH₂OH (1), (CF₃)₃COH (2), and (CF₃)₂CHOH (3) results in an increase in the hyperfine splitting constants with the³¹P nucleus by approximately 3–4 G. Only monoadducts are formed when alcohols1–3 are added to toluene saturated solutions of Hg[P(O)(OPrⁱ)₂]₂ and C₆₀ under photochemical conditions of multi-addition of phosphoryl radicals to C₆₀. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1869–1871, September, 1998.