Ordered and disordered solvates of C60 and CBrCl2H

Carbon, 1991

Chemical Physics, 2007

At room temperature, the unstable-in-air hexagonal C60·2HCClBr2 solvate (a = 10.154(3) Å, c = 10.150(3) Å at 308 K) forms with a negative excess volume, and slowly transforms upon ageing at room temperature into a stable orthorhombic solvate, C60·1.5HCClBr2 (a = 23.009(5) Å, b = 12.649(6) Å, c = 11.659(5) Å).The lattice expansion and the lattice anisotropy of the C60·2YCCl3 (Y = H, CH3, Br, Cl) and C60·2HCBr3 solvates, for which the solvent molecular symmetry is C3V are compared to the new results obtained for C60 solvates formed with HCClBr2 (solvent molecular symmetry C2V). Results indicate that the van der Waals volume of the solvent molecule fully controls both the unit-cell volumes of the C60 intercalated halogenomethane solvates and the lattice expansion along the (0 0 1) hexagonal direction, the solvent molecular symmetry being an irrelevant physical parameter in the temperature range studied.

Carbon, 2005

At room temperature, the hexagonal C 60. 2(CH 3)CCl 3 solvate (a = 10.13(1) Å , c = 10.84(1) Å), made of alternating layers of C 60 and solvent molecules, forms with a negative excess volume, and its desolvation enthalpy is virtually the same as the sublimation enthalpy of the pure solvent. Crystallographic and calorimetric studies vs temperature indicate that hexagonal C 60. 2(CH 3)CCl 3 changes at 211.7 K (1.3 kJ mol À1 of solvate) into an intermediate triclinic phase which transforms at 189.7 K (4.1 kJ mol À1 of solvate) into another triclinic phase. A crystallographic analysis in the series of hexagonal C 60. 2 YCCl 3 solvates (Y = H, Cl, Br, CH 3) reveals that: (i) the change in the unit-cell volume values is due to a change in axis c whose value depends on the size of Y, (ii) the molar volume of the solvates depends linearly on the molar volume of the solvents. Ageing studies at room temperature show that C 60. 2(CH 3)CCl 3 loses its solvent molecules within a few days or a few months, depending on storage conditions.

Russian Chemical Bulletin, 1995

Crystals containing up to 30 wt. % CS2, according to the data of IR and X-ray 9 photoelectron spectroscopy, were isolated from the C60--TSeT--CS 2 (TSeT is tetraselenotetracene) system. The unusually high concentration of carbon disulfide results in the complete sublimation of the crystals at a relatively high temperature (520 ~ The electron energy loss spectra of the crystals obtained were measured and analyzed.

Journal of The Chemical Society-perkin Transactions 2 - J CHEM SOC PERKIN TRANS 2, 1990

The lack of reactivity of buckminsterfullerene, a C , cluster, towards addition reactions is attributed to the high values of the bond localization energies of its bonds.

ACS Omega, 2018

Accurate description of solvation structure of a hydrophobic nanomaterial is of immense importance to understand protein folding, molecular recognition, drug binding, and many related phenomena. Moreover, spontaneous pattern formation through self-organization of solvent molecules around a nanoscopic solute is fascinating and useful in making template-directed nanostructures of desired morphologies. Recently, it has been shown using polarizable atomistic models that the hydration shell of a buckminsterfullerene can have atomically resolved ordered structure, in which C 60 atomic arrangement is imprinted. In analyzing any peculiar behavior of water, traditionally, emphasis has been placed on the long-ranged and orientation-dependent interactions in it. Here, we show through molecular dynamics simulation that the patterned solvation layer with the imprints of the hydrophobic surface atoms of the buckminsterfullerene can be obtained from a completely different mechanism arising from a spherically symmetric, shortranged interaction having two characteristic lengthscales. The nature of the pattern can be modified by adjusting solvent density or pressure. Although solute−solvent dispersion interaction is the key to such pattern formation adjacent to the solute surface, the ordering at longer lengthscale is a consequence of mutual influence of short-range correlations among successive layers. The present study thus demonstrates that the formation of such patterned solvation shells around the buckminsterfullerene is not restricted to water, but encompasses a large class of anomalous fluids represented by two-lengthscale potential.

Journal of the American Chemical Society, 2008

Corannulene (COR) buckybowls were proposed as near ideal hosts for fullerene C60, but direct complexation of C60 and COR has remained a challenge in supramolecular chemistry. We report the formation of surface-supported COR-C60 host-guest complexes by deposition of C60 onto a COR lattice on Cu(110). Variable-temperature scanning tunneling microscopy studies reveal two distinctly different states of C 60 on the COR host lattice, with different binding energies and bowl-ball separations. The transition from a weakly bound precursor state to a strongly bound host-guest complex is found to be thermally activated. Simple model calculations show that this bistability originates from a subtle interplay between homo-and heteromolecular interactions.

Physical Review B, 1993

Detailed analysis of the room-temperature x-ray powder-difT'raction data of pure, as-prepared, solid 0 C70 is reported. C70 adopts a hcp structure (space group P63/rnmc) with a = 10.53(1) A and c = 17.24(1) 0 A. Quantitative agreement between the observed and calculated diffraction patterns require (a) orienta- tional disorder among the molecules, (b) the presence of -5% of stacking faults, and (c) a fraction of the sample to be either microcrystalline or amorphous. Most the studies on solid fullerenes have, so far, fo- cused on the properties of pristine and intercalated C6Q. ' Due to their lesser abundance and the consequent difhculty in the preparation of high-purity samples, much less is known about the next higher fullerene C7Q. An electron-diffraction study of pure C7Q seems to suggest an hcp structure (space group P63/mmc) with a =10.1 0 0 A and c =16.8 A. Atomic force microscopy studies on clean surfaces of C6Q/C7Q mixtures show hexagonal sym- metry for those regions rich in C7Q According to this in- vestigation, C7Q has an hcp structure with a =12.1+1.5 0 A. These observed hcp structures are substantially different from the hcp structure, with four molecules per unit cell, proposed by Guo et al. (the parameters of the proposed structure are . a =9.92 A, b =20.09 A, c = 18.52 A, a=90.01', Ii=90', and y = 119.61'). Sub- limed samples of C6Q/C7Q mixtures are observed to crys- tallize in an fcc structure (space-group Fm 3) with the lat- 0 tice parameter a -14.73 A from which the possibility of C7Q crystallizing in an fcc lattice has been inferred. Preparation through the usual solution route, in general, yields "solvates" which adopt solvent specific low- symmetric structures belonging to either the orthorhom- bic or monoclinic crystal classes. ' Recently, Vaughan et al. ' have carried out a detailed study on the structure of solid C7Q which indicates that the solvent-free sublimed 0 C7Q adopts an fcc structure with a =14.96 A, whereas that grown by evaporation from a toluene solution adopts an hcp structure with a = 10.63 A and c = 17.39 A. In this paper, we report results which confirm that pure solid C7Q prepared by the solution route and the sub- limed samples form, respectively, in the hcp and fcc structures. The lattice parameters are a =10.53(1) A and c =17.24(1) A for the hcp phase and a = 14.89(1) A ' do not contain any trapped solvents.

1994

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The Journal of Physical Chemistry A, 2012

Since the recent achievement of Kurotobi and Murata to capture a water molecule in a C 60 fullerene (Science 2011, 333, 613), there has been a debate about the properties of this H 2 O@C 60 complex. In particular, the polarity of the complex, which is thought to be underlying the easy separation of H 2 O@C 60 from the empty fullerene by HPLC, was calculated and found to be almost equal to that of an isolated water molecule. Here we present our detailed analysis of the charge distribution of the water-encapsulated C 60 complex, which shows that the polarity of the complex is, with 0.5 ± 0.1 D, indeed substantial, but significantly smaller than that of H 2 O. This may have important implications for the aim to design water-soluble and biocompatible fullerenes.

Journal of Organometallic Chemistry, 1994

The highly delocalized distribution of the MOs in C, has been analyzed with the aid of extended Hiickel calculations and their graphic representations. Symmetry and perturbation theory arguments rationalize the MO correlations in terms of the implosion of 12 C, rings distributed at the vertices of an expanded icosahedron. In particular, two distinguishable (r and T C, subsets are each split into 30 filled and 30 empty MOs belonging to the same species under I,, symmetry. As a major difference, whereas 30 new C-C (T bonds add to the 60 pre-existing C, endocyclic bonds, some partial rr bonding at the 6 : 6 edges of C, occurs at the expense of rr bonding at the 5:6 edges. This point has been clarified by referring to the electronic structure of the simpler molecule [5]-radialene which typifies the MO response to the idea of T resonance. An overview at the C-C bonding/ antibonding roles in all of the rr MOs simplifies understanding their possible interactions with the frontier MOs of typical transition metal fragments. The model complexes considered involve the $-coordination of the CzU fragment (PH,),Pt to C, in 6 : 1, 2 : 1 and 1: 1 ratios. The MO analysis highlights the electronic causes of the deformation from sphericity of C, when a metal is attached to one or more 6: 6 edge. Attempts to explore alternative, but as yet unsynthesized coordination modes have also been made.

The Journal of Physical Chemistry B, 1998

Differential scanning calorimetry, solution calorimetry, and room-temperature single-crystal X-ray diffraction were used to study the thermodynamic and structural properties of a solvated crystal C 60 ‚2C 6 H 5 Br. In the monoclinic solvate, two orientations of C 60 were observed with fractional populations of 0.71 and 0.29. The enthalpy of solution of pure C 60 in bromobenzene was determined to be ∆ sol H[C 60 (s)])-11.5 (2.0 kJ/mol. The enthalpy of solution of the solvated crystal was ∆ sol H[C 60 ‚2C 6 H 5 Br(s)]) +28 (1 kJ/mol. The phase diagram of the system C 60-C 6 H 5 Br for T < 423 K was constructed. It predicts the existence of a maximum in the temperature-solubility relationship for C 60 in bromobenzene at 350 K. The activity of bromobenzene vapor over the solvated crystal is predicted to be reduced from its value over the pure liquid by a factor of 3.5.

Chemistry of Materials, 1998

Journal of Chemical Education, 2006

… University Journal of …, 2011

Molecular spectroscopy is an area of active interest and has played an important role to understand and analyse a physical system in both experimental and theoretical approaches. One of the most interesting areas of current research in molecular physics is the study of vibrational ...