Youzhi

Chiral fullerene–metal hybrids with complete control over the four stereogenic centers, including the absolute configuration of the metal atom, have been synthesized for the first time. The stereochemistry of the four chiral centers formed during [60]fullerene functionalization is the result of both the chiral catalysts employed and the diastereoselective addition of the metal complexes used (iridium, rhodium, or ruthenium). DFT calculations underpin the observed configurational stability at the metal center, which does not undergo an epimerization process.

Chirality at the metal: Fullerene hybrids with iridium-, rhodium-, or ruthenium-centered chirality were prepared by precise control of four newly formed stereogenic centers. The resulting complexes are configurationally stable and do not undergo an epimerization process.

Herein we report the organoplatinum-mediated bottom-up synthesis, characterization, and properties of a novel large π-extended carbon nanoring based on a nanographene hexa-peri-hexabenzocoronene (HBC) building unit. This tubular structure can be considered as an example of the longitudinal extension of the cycloparaphenylene scaffold to form a large π-extended carbon nanotube (CNT) segment. The cyclic tetramer of a tetramesityl HBC ([4]CHBC) was synthesized by the reaction of a 2,11-diborylated hexa-peri-hexabenzocoronene with a platinum complex, followed by reductive elimination. The structure of this tubular molecule was further confirmed by physical characterization. Theoretical calculations indicate that the strain energy of this nanoring is as high as 49.18 kcal mol⁻¹. The selective supramolecular host–guest interaction between [4]CHBC and C₇₀ was also investigated.

A decent slice of a carbon nanotube was synthesized in the form of a large π-extended carbon nanoring based only on hexa-peri-hexabenzocoronene units (see picture). The photophysical properties of the nanoring were investigated by both steady-state and time-resolved fluorescence spectroscopy, and a selective supramolecular host–guest interaction with C₇₀ was identified.

Hybrid covalent/supramolecular porphyrin–fullerene structures were synthesized as highly efficient molecular wires with a remarkably low attenuation factor (β=0.07±0.01 Å⁻¹). Hydrogen-bonding interactions and p-phenylene oligomers of different lengths are responsible for efficient electron transfer in the molecular wires.

Whizzing along the wire: A series of electron-donor–acceptor hybrids of a zinc porphyrin and C₆₀ connected through molecular wires based on a combination of covalent and noncovalent interactions (see picture) exhibited efficient charge transport. Hydrogen-bonding interactions and p-phenylene oligomers of different lengths were responsible for electron transfer in these molecular wires.

Presented herein is a mild, operationally simple, mix-and-go procedure for the synthesis of acyclic trisubstituted Z-enediynes, from readily available terminal alkynes, in good yields. This method stems from a serendipitous discovery, and makes use of cooperative palladium/copper bimetallic catalysis and air as an oxidant to effect an intriguing alkyne trimerization to yield the valuable Z-enediyne moiety.

Mix and go: Presented herein is a mild, operationally simple, mix-and-go procedure for the synthesis of acyclic trisubstituted Z-enediynes from readily available terminal alkynes in good yields. This method stems from a serendipitous discovery, and makes use of cooperative palladium/copper bimetallic catalysis and air as an oxidant to effect an intriguing alkyne trimerization to yield the valuable Z-enediyne moiety.

Hexachlorodisilane reacts with diarylmethanones (aryl=C₆H₅, 4-MeC₆H₄, 4-tBuC₆H₄, 4-ClC₆H₄, 4-BrC₆H₄) to furnish the corresponding tetraarylethylenes in good yields. The reductive conversion requires temperatures of about 160 °C and reaction times of 60–72 h. In the initial step, the Lewis-basic carbonyl groups likely generate low-valent [SiCl₂] as an analogue of [TiCl₂] in the classical McMurry reaction. The coupling sequence further proceeds via benzopinacolones, which have been isolated as key intermediates.

Successful with silanes: Diarylmethanones Ar₂C=O react with Si₂Cl₆ at 160 °C to give tetraarylethylenes in good yields (see scheme). This novel reductive coupling reaction likely proceeds via intermediary [SiCl₂] generation and is thus related to the [TiCl₂]-mediated McMurry reaction.

The synthesis of a donor–acceptor silicon phthalocyanine (SiPc)-azafullerene (C₅₉N) dyad 1 and of the first acceptor–donor–acceptor C₅₉N-SiPc-C₅₉N dumbbell triad 2 was accomplished. The two C₅₉N-based materials were comprehensively characterized with the aid of NMR spectroscopy, MALDI-MS as well as DFT calculations and their redox and photophysical properties were evaluated with CV and steady-state and time-resolved absorption and photoluminescence spectroscopy measurements. Notably, femtosecond transient absorption spectroscopy assays revealed that both dyad 1 and triad 2 undergo, after selective photoexcitation of the SiPc moiety, photoinduced electron transfer from the singlet excited state of the SiPc moiety to the azafullerene counterpart to produce the charge-separated state, with lifetimes of 660 ps, in the case of dyad 1, and 810 ps, in the case of triad 2. The current results are expected to have significant implications en route to the design of advanced C₅₉N-based donor–acceptor systems targeting energy conversion applications.

Union is strength: The synthesis and photophysical properties of SiPc-C₅₉N dyad 1 and the first azafullerene-based acceptor–donor–acceptor C₅₉N-SiPc-C₅₉N dumbbell triad 2 (see figure) are reported. Femtosecond laser-induced transient absorption spectral measurements reveal that both of these undergo photoinduced electron transfer from the singlet excited state of the SiPc moiety to the azafullerene counterpart to produce the charge-separated state.

Supramolecular Chemistry. The use of noncovalent interactions between untethered residues to amplify the regio-, stereo-, and atropselective formation of a C₆₀ fullerene bisadduct racemate is described by G. Bottari, D. M. Guldi, T. Torres et al. in their Communication on page 11020 ff.