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Single-walled carbon nanotubes (SWNTs) prepared by pulsed laser vaporization, dispersed, and surfactant-stabilized in near-infrared transparent D2O show weak photoluminescence (PL) from ~1300 up to >1750 nm corresponding to the lowest electronic interband transitions of semiconducting tubes. The characteristic features of this PL, such as a multiple peak emission and a strong excitation wavelength dependence (investigated for λexc from 457 up to 1064 nm), are similar to those reported recently for SWNTs with smaller diameters of around 1 nm (O'Connell et al. Science 2002, 297, 593). The luminescence is significantly polarized with an anisotropy value r of up to 0.32, depending on the excitation and emission wavelengths. The PL data can be used for the structural assignment of emitting tubes; however, in agreement with the results of O'Connell et al., these data are only qualitatively consistent with the tight-binding model widely applied for SWNTs. The luminescence is sensitive to chemical treatment/interactions of SWNTs; much weaker and broader PL was observed above 1300 nm for dispersions of acid-treated tubes in D2O, whereas raw SWNTs in N,N-dimethylformamide show practically no PL. The Raman spectra of dispersed SWNTs differ from those of the solid samples.

The photoluminescence (PL) properties of several recently synthesized ligand-stabilized polynuclear gold(I) selenide complexes were investigated. [Au18Se8(dppe)6]Br2 {dppe = bis(diphenylphosphanyl) ethane} (I) is distinguished by the bright-red long-lived PL (phosphorescence) in the solid state, photosensitization of singlet oxygen, ¹O2, in solution, and high photostability. The quantum yield of PL, ϕPL, is (7.5 ± 0.5) × 10^-2 for the polycrystalline I at 293 K (determined using an integrating sphere) and increases up to ~0.8 at 77 K. The quantum yield of ¹O2 is 0.17 ± 0.02 in O2-saturated dichloromethane solutions. [Au10Se4(dpppe)4]Br2 {dpppe = bis(diphenylphosphanyl)pentane} (II) shows a broad near-infrared PL at 880 nm in dichloromethane [ϕPL = (4 ± 1) × 10^-3], which is shifted up to ~1020 nm in the solid II at 77 K (ϕPL ~ 3 × 10^-3). Although the quantum efficiency of II as a luminophor is quite moderate, it is comparable to that of organic infrared laser dyes such as Styryl-20 and IR26. A particular configuration of the Au10Se4 core appears to be crucial for the near-infrared PL:  the “isomeric” complexes [Au10Se4(dppm)4]Br2 {dppm = bis(diphenylphosphanyl) methane} (III) and [Au10Se4(depe)4]Cl2 {depe = bis(diethylphosphanyl) ethane} (IV) show no significant PL.

A [2+2] cycloaddition cap-to-cap C70 dimer with C2h molecular symmetry was synthesized in high yield by pressure treatment of polycrystalline C70 at 1 GPa and 200 °C. It was separated from unreacted monomers by chromatography and characterized by ¹³C NMR, Raman, and infrared spectroscopy, and other methods. Remarkably, only one isomer was produced out of the five possible [2+2] cycloaddition products which have equally low formation energies according to semiempirical modeling calculations. The dimer obtained is the one favored when C70 molecules adopt an ordered packing with parallel D5 axes. The intercage bonding in C140, its thermal stability, and intercage vibrational modes are similar to those found for the C60 dimer, C120. Both dimers photodissociate to the monomers in solution, probably via excited triplet states. The UV absorption and fluorescence properties of C140 are not very different from those of C70, suggesting only weak electronic interactions between the two cages of C140. In comparison, the pressure-induced dimerization of C60, under the conditions used for C70, results mainly in C60 oligomers and polymeric chains, but the dimer C120 could be isolated at low yield when short reaction times (≤5 min) were used.

ESR spectra of M@C82 (M=La, Y) metallofullerene solutions show the monotonic decrease of the metal ion hyperfine coupling constant between -70 and +260°C and changes in the lineshape of Y@C82 signals above 80°C, which were attributed to anharmonic metal-to-cage vibrations and to the motion of Y between different chemisorption sites in a C82 cage, respectively.

Two products, A and B, with the formula C120O2 have been characterized by HPLC, MALDI-TOF MS, FT-Raman, and ¹³C NMR spectroscopy. C120O2(A) was found as a byproduct accompanying C120O in the solid-phase reaction at 200 °C of mixtures containing approximately a 4:1 ratio of C60 to C60O and traces of C60O2. Raman spectra indicated that A has a furanoid bridge (analogous to C120O) linking a C60 fullerene cage with a C60O cage containing an epoxy group. ¹³C NMR confirmed this and showed that the isolated product A consists of two closely related isomers with C1 symmetry in a 4:1 ratio. C120O2(A) can be formed by the [3 + 2] cycloaddition of C60O to a second C60O or possibly by the addition of C60O2 to C60. The 16 possible regioisomers of A were modeled by semiempirical methods, and isomers with the epoxy group located in the cis-1, e, or trans positions relative to the furanoid bridge have lower energies compared with those of cis-2 or -3 forms. The NMR and modeling data provide strong evidence that the two isomers of A represent the two possible cis-1 configurations. The other isomers (but not cis-1 forms) can react further with C60 to form trimeric C180O2 compounds, which were also observed. Thermolysis of solid C120O at temperatures above 300 °C yielded C120O2(B) and other products but no A. C120O2(B) consists of a single isomer with C2v symmetry in which the C60 cages are linked by two neighboring furanoid bridges in a cis-1 configuration. Modeling calculations indicate that this isomer has an energy that is significantly lower than that of other possible double-bridged isomers and ca. 50 kcal/mol below the energy of the A isomers.

Endohedral metallofullerene Ce@C82dissolved in dimethylformamide or pyridine is reduced to the radical anion. Analysis of hyperfine coupling with the topologically different 13C nuclei indicates the electronic structure with bivalent cerium and the paramagnetic carbon framework Ce2+@C82·3–. The ESR spectra of the radical anions of the functionalized Ce@C82derivatives are detected.