We describe the detailed syntheses and characterization of two new electron-donor molecules based on an acceptor–donor–acceptor (A–D–A) structure with carbazole as the electron-rich building block, benzothiadiazole (BT) as the electron-acceptor building block and octylrhodanine as the end group. We also examined the effects of a thiophene group as a spacer between the BT and the carbazole units on the optoelectronic, morphological and photovoltaic properties. The presence of the thiophenes has pronounced effects on both the optical and electrical properties. ECTBT, which contains thiophenes units, showed a red-shifted absorption and a lower HOMO level compared to ECBT, which has no thiophene spacers. Optimized photovoltaic device fabrication based on ECTBT and [6,6]-phenyl-C₇₀-butyric acid methyl ester (PC₇₁BM) in a 1:1.5 ratio (w/w) exhibited the best power conversion efficiency (PCE), at 3.26 %.

Three new dyes (1–3) with a triarylamine electron donor, a cyanoacrylic acid moiety as both electron acceptor and anchoring group, and a fluorene-9-ylidene moiety as an antenna were synthesized, and their electrochemical, photophysical, and photovoltaic properties were evaluated. Despite minor differences in absorption properties, as the starburst shape of the dyes increases and highly hindered hydrophobic groups are introduced, the measured open-cell voltage (V_oc) increased noticeably from 0.79 to 0.83 V, and the power-conversion efficiency (PCE) value increased from 3.98 to 4.73 %.

The development of high-surface-area carbon electrodes with a defined pore size distribution and the incorporation of pseudo-active materials to optimize the overall capacitance and conductivity without destroying the stability are at present important research areas. Composite electrodes of carbon nano-onions (CNOs) and polypyrrole (Ppy) were fabricated to improve the specific capacitance of a supercapacitor. The carbon nanostructures were uniformly coated with Ppy by chemical polymerization or by electrochemical potentiostatic deposition to form homogenous composites or bilayers. The materials were characterized by transmission- and scanning electron microscopy, differential thermogravimetric analyses, FTIR spectroscopy, piezoelectric microgravimetry, and cyclic voltammetry. The composites show higher mechanical and electrochemical stabilities, with high specific capacitances of up to about 800 F g⁻¹ for the CNOs/SDS/Ppy composites (chemical synthesis) and about 1300 F g⁻¹ for the CNOs/Ppy bilayer (electrochemical deposition).

Four easily isolable regio- and stereoselective bis-adducts of C₆₀ and C₇₀, as well as a new C₇₀-dumbbell derivative, have been synthesized by using two different bismalonate tethered moieties. The derivatives that possess relatively long-tethered moieties show highly symmetric addition patterns, as evidenced by spectroscopic measurements, whereas the derivatives possessing the shorter-tethered moiety exhibit interesting addition patterns on C₆₀ and C₇₀.

Thermal annealing of nanodiamonds with diameters of a few nanometers (in an inert atmosphere and at temperatures in the range: 1500–1800 °C) leads to the formation of carbon nano-onions (CNOs) with diameters between 5 and 6 nm, which correspond to nanostructures with six to eight graphitic layers. The resulting spherical CNO structures were thermally modified under different atmospheres and characterized by SEM, TEM, thermogravimetric analysis and spectroscopic (Raman and diffuse reflectance infrared Fourier transform/FTIR) spectroscopy. The electrochemical properties of the CNOs prepared under different conditions were determined and compared. The results reveal that the CNOs show different structures with predominant spherical “small” carbon nano-onions. The aim of this article is to investigate the impact of the CNO′s synthesis conditions on the resulting structures and study the effect of further thermal modifications on the sizes, shapes and homogeneity of these carbon nanostructures.

Cage-cluster complementarity is of crucial importance in determining the sizes and structures, as well as the properties of endohedral fullerenes. The encapsulated atoms or clusters, which are typically in a positively charged state, are irreversibly, mechanically, and electrostatically trapped inside the typically negatively charged cages. These rather exotic compounds exhibit exquisitely complementary properties between their components. Here, we present a short overview to show that size and shape are crucial in determining the specific structures that are formed, and the presence of electrostatic interactions result in structural motifs that are never observed for pristine fullerene cages. Copyright © 2014 John Wiley & Sons, Ltd.

A new donor–acceptor system, in which the electron donor triphenylamine (TPA) and the electron acceptor C₆₀ are bridged through a cis- or trans-platinum(II) acetylide spacer have been prepared. Ground-state studies were conducted using electrochemistry and UV/Vis spectroscopy. Fluorescence studies suggested that charge transfer is the deactivation mechanism for the singlet excited state, and this was verified by transient absorption spectroscopy. Selective photoexcitation of 1 and 2 at 387 nm leads to a fast charge transfer between the TPA and C₆₀, which gives rise to a radical ion-pair state (TPA^.+–Pt–C₆₀^.−). Our results suggest that charge transfer is favored for the cis configuration while the presence of the trans configuration in the Pt^II diacetylide results in a longer-lived charge separated states.

Given the unique structural and electronic properties of C₆₀, metal–organic frameworks (MOFs) containing C₆₀ linkers are expected to exhibit interesting characteristics. A new hexakisfullerene derivative possessing two pairs of phenyl pyridine groups attached to two methano-carbon atoms located at the trans-1 positions was designed and synthesized. The four pyridyl nitrogen atoms define a perfectly planar rectangle. This new C₆₀ derivative was used to assemble the first fullerene-linked two-dimensional MOF by coordination with Cd²⁺.

Given the unique structural and electronic properties of C₆₀, metal–organic frameworks (MOFs) containing C₆₀ linkers are expected to exhibit interesting characteristics. A new hexakisfullerene derivative possessing two pairs of phenyl pyridine groups attached to two methano-carbon atoms located at the trans-1 positions was designed and synthesized. The four pyridyl nitrogen atoms define a perfectly planar rectangle. This new C₆₀ derivative was used to assemble the first fullerene-linked two-dimensional MOF by coordination with Cd²⁺.

Since the experimental observation of the encapsulation of different species inside fullerene (endohedral fullerenes) cages, several research groups have focused their research in the elaboration of new and novel compounds. Exohedral functionalization of the carbon cages has helped in the discovery of new species and has expanded their potential applications in material science and medicine. Our research group has contributed to the discovery, functionalization, and characterization of new and interesting compounds that have been explored in different applications, but mainly in the field of organic photovoltaics. Here, we report the contribution and progress of our research group in the field of buckyball “maracas.” Copyright © 2012 John Wiley & Sons, Ltd.

Based on the different oxidation potentials of endohedral fullerenes Sc₃N@C₈₀ I_h and D_5h and Sc₃N@C₇₈, an efficient and useful method that avoids HPLC has been developed for their separation. Selective chemical oxidation of the Sc₃N@D_5h-C₈₀ isomer and Sc₃N@C₇₈ by using an acetylferrocenium salt [Fe(COCH₃C₅H₄)Cp]⁺ followed by column chromatographic separation and reduction with CH₃SNa resulted in the isolation of pure Sc₃N@I_h-C₈₀, Sc₃N@C₇₈, and a mixture of Sc₃N@D_5h-C₈₀ and Sc₃N@C₆₈.

Interactions between the π bonds in the aromatic rings of polyaniline (PANI) with carbon nanostructures (CNs) facilitate charge transfer between the two components. Different types of phenyleneamine-terminated CNs, including carbon nano-onions (CNOs) and single-walled and multi-walled carbon nanotubes (SWNTs and MWNTs, respectively), were prepared as templates, and the CN/PANI nanocomposites were easily prepared with uniform core–shell structures. By varying the ratio of the aniline monomers relative to the CNs in the in situ chemical polymerization process, the thickness of the PANI layers was effectively controlled. The morphological and electrical properties of the nanocomposite were determined and compared. The thickness and structure of the PANI films on the CNs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and infrared spectroscopy. TEM and SEM revealed that the composite films consisted of nanoporous networks of CNs coated with polymeric aniline. The electrochemical properties of the composites were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. These studies showed that the CN/PANI composite films had lower resistance than pure polymeric films of PANI, and the presence of CNs much improved the mechanical stability. The specific electrochemical capacitance of the CNO/PANI composite films was significantly larger than for pure PANI.

Composites of unmodified or oxidized carbon nano-onions (CNOs/ox-CNOs) with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) are prepared with different compositions. By varying the ratio of PEDOT:PSS relative to CNOs, CNO/PEDOT:PSS composites with various PEDOT:PSS loadings are obtained and the corresponding film properties are studied as a function of the polymer. X-ray photoelectron spectroscopy characterization is performed for pristine and ox-CNO samples. The composites are characterized by scanning and transmission electron microscopy and differential scanning calorimetry studies. The electrochemical properties of the nanocomposites are determined and compared. Doping the composites with carbon nanostructures significantly increases their mechanical and electrochemical stabilities. A comparison of the results shows that CNOs dispersed in the polymer matrices increase the capacitance of the CNO/PEDOT:PSS and ox-CNO/PEDOT:PSS composites.

Small multilayer fullerenes, also known as carbon nano-onions (CNOs; 5–6 nm in diameter, 6–8 shells), show higher reactivity than other larger carbon nanostructures. Here we report the first example of an in situ polymerization of aniline on phenyleneamine-terminated CNO surfaces. The green, protonated, conducting emeraldine polyaniline (PANI) was directly synthesized on the surface of the CNO. The functionalized and soluble CNO/PANI composites were characterized by TEM, SEM, DSC, Raman, and infrared spectroscopy. The electrochemical properties of the conducting CNO/PANI films were also investigated. In comparison with pristine CNOs, functionalized carbon nanostructures show dramatically improved solubility in protic solvents, thus enabling their easy processing for coatings, nanocomposites, and biomedical applications.

The electrochemical reactions of carboxylic and lactone groups on carbon nano-onions (CNOs) in aqueous solutions result in non-Kolbe products: alcohols, ketones, ethers and epoxides. The anodic/cathodic conversion of ox-CNOs was assessed by Boehm titrations and by Raman and DRIFTS-FTIR (diffuse reflectance infrared Fourier transform spectroscopy). The electrochemical properties of oxidized carbon nano-onions were investigated by cyclic voltammetry in aqueous solutions. The ox-CNOs are electrochemically active as a result of the reduction of the oxygen-containing groups.