[60]Fullerene-based electron acceptors

Facilitating Electron Transfer by Resizing Cyclocarbon Acceptor from C18 to C16

Recent advances in synthetic methods, combined with tip-induced on-surface chemistry, have enabled the formation of numerous cyclocarbon molecules. Here, we investigate computationally the experimentally studied C16 and C18 molecules as well as their van der Waals (vdW) complexes with several typical donor and acceptor molecules. Our results demonstrate a remarkable electron-withdrawing ability of cyclocarbon molecules. The vdW complexes of C16 and C18 exhibit a thermodynamically favorable photoinduced electron transfer (ET) from the donor partner to the cyclocarbons that occurs on a picosecond time scale. The lower reorganization energy of C16 compared to C18 leads to a significant acceleration of the ET reactions.

Fullerene Covalent Passivation of Black Phosphorus Nanosheets toward Enhanced Near-Infrared-II Photothermal Therapy

Photothermal therapy (PTT) triggered by near-infrared-II (NIR-II, 1000-1700 nm) light is developed as a potential tumor therapy technique with deeper tissue penetration capacity and higher allowable laser power density of the skin than NIR-I (750-1000 nm) biowindow. Black phosphorus (BP) with excellent biocompatibility and favorable biodegradability demonstrates promising applications in PTT but suffers from low ambient stability and limited photothermal conversion efficiency (PCE), and utilization of BP in NIR-II PTT is scarcely reported. Herein, we develop novel fullerene covalently modified few-layer BP nanosheets (BPNSs) with ∼9-layer thickness through an easy one-step esterification process (abbreviated BP-ester-C₆₀), bringing about the dramatically enhanced ambient stability of BPNSs due to bonding of the hydrophobic C₆₀ with high stability and the lone electron pair on the phosphorus atom. BP-ester-C₆₀ is then applied as a photosensitizer in NIR-II PTT, delivering a much higher PCE than the pristine BPNSs. Under 1064 nm NIR-II laser irradiation, in vitro and in vivo antitumor studies reveal that BP-ester-C₆₀ exhibits dramatically enhanced PTT efficacy with considerable biosafety relative to the pristine BPNSs. This is interpreted by the boost of NIR light absorption on account of the modulation of the band energy level resulting from intramolecular electron transfer from BPNSs to C₆₀.

The hunter falls prey: photoinduced oxidation of C60 in inclusion complex with perfluorocycloparaphenylene

Perfluorocycloparaphenylenes (PFCPPs) are cycloparaphenylenes (CPPs) in which all hydrogen atoms have been replaced by fluorine atoms. Like CPPs, PFCPPs are highly strained, hoop‐shaped π‐conjugated molecules. In this article, we report a computational modeling of photoinduced electron transfer processes in the inclusion complex of PF[10]CPP with C₆₀ fullerene. Its unique feature is the favorable electron transfer from C₆₀ to the host molecule. The photooxidation of C₆₀ is predicted to occur on a sub‐nanosecond timescale. The PF[10]CPP⊃C₆₀ dyad is the first nanoring‐fullerene complex in which C₆₀ acts as an electron donor in the photoinduced charge separation.

Structural and electronic properties of a CN fullerene with N = 20, 60, 80, 180, and 240

In this paper, the structural and electronic properties of a C_N fullerene with N = 20, 60, 80, 180, and 240 have been investigated using a sp³ tight-binding model. The analytical expressions for the calculation of the total number of carbon atoms, hexagons, pentagons, and bonds found within the geometrical structure of a C_N fullerene have been developed and verified using the simulation, therefore proving the validation of both the simulation and analytical results. The simulation results show that the total number of carbon atoms within fullerene is equal to the value of N and the total number of hexagons, pentagons, and bonds within the structure of a fullerene increases with the increase in the value of N. Further, the electronic properties of these fullerenes have been identified with the help of their energy level diagrams obtained using the simulation. It has been observed that the C₂₀ and C₈₀ fullerenes are metallic because of their zero band gaps while the C₆₀ fullerene is an insulator with a very wide band gap of 5 eV whereas the C₁₈₀ and C₂₄₀ fullerenes are semiconducting with band gaps of 1.43 eV and 1.05 eV, respectively. Finally, it has been observed from these studies that the metallic fullerenes are best suited for interconnects and the semiconducting fullerenes are bested suited as a channel material for designing high-performance nanoelectronic devices.

Comparative density functional theory-density functional tight binding study of fullerene derivatives: effects due to fullerene size, addends, and crystallinity on band structure, charge transport and optical properties

We present a systematic comparative density functional theory-density functional tight binding study of multiple derivatives of C60 and C70 with different addends, in molecular as well as solid state. In particular, effects due to fullerene size, type and number of addends, and of crystallinity on band structure, charge transport, and optical properties are investigated. These are important, in particular, for rational selection of fullerene derivatives as acceptor and electron transport layers in organic as well as planar inverted perovskite solar cells. We find that by the choice of type and number of addends, one can modulate the LUMO within 0.4 eV. Changes in the HOMO can reach 0.7 eV. Substituting C70 for C60 results in destabilization of the HOMO by about 0.1 eV for indene and quinodimethane addends and by a less significant amount for PCBM addends. The effect of C70-C60 substitution on the LUMO is of similar magnitude. A more significant change in HOMO-LUMO energy is seen for the aryl addends. On the other hand, all C70 based molecules have strong visible absorption. For most addends, the crystal packing leads to a stabilization of both the LUMO and HOMO by about ∼0.2 and ∼0.1 eV, respectively, vs. single molecules. When using bis-addends, it is also possible to enhance the visible absorption. Electron and hole transport rates are computed to vary vastly depending on the addends chosen; specifically, we compute that indene and quimodimethane addends can enhance charge transport rates while the aryl addend is predicted to result in substantially smaller mobilities of electrons and holes, vs. PC₆₀BM. Furthermore, the -CH₂ and bisaddend addition can significantly enhance the charge transfer rates for the PCBM addend.

Fulleropyrrolidines derived from dioxa- and trioxaalkyl-tethered diglycines

The synthesis, characterization, morphological, electrochemical and antioxidant properties of fulleropyrrolidines bridged by polyoxaalkyl chains are described.

Phthalocyanine blends improve bulk heterojunction solar cells

A core phthalocyanine platform allows engineering of the solubility properties the band gap, shifting the maximum absorption toward the red. A simple method for increasing the efficiency of heterojunction solar cells uses a self-organized blend of phthalocyanine chromophores fabricated by solution processing.

Highly Efficient Retro-cycloaddition Reaction of Isoxazolino[4,5:1,2][60]- and -[70]fullerenes

Isoxazolino[4,5:1,2][60]- and -[70]fullerenes undergo an efficient retro-cycloaddition reaction to pristine fullerene by thermal treatment in the presence of an excess of a dienophile and Cu(II) catalysis, which can be selectively used in the presence of malonate or pyrrolidine cycloadducts. Trapping experiments using N-phenylmaleimide as dipolarophile have shown that the reaction mechanism occurs by thermal removal of the nitrile oxide 1,3-dipole, in a process which is favored by the presence of Cu(II) as the catalyst. The ESI-MS study supports the observed retro-cycloaddition process for both C60 and C70 derivatives. In contrast to previous electrochemical retro-cycloaddition processes observed in fulleropyrrolidines, isoxazolinofullerenes were stable under oxidative conditions.