Pushing fullerene absorption into the near-IR region by conjugately fusing oligothiophenes

Phosphine-Mediated Dimerization of Open-[60]Fullerenes

By a reaction of trimethylphosphine with an open-[60]fullerene, corresponding dimers could be generated via two-fold deoxygenation processes even though the formation of β-oxo-phosphorous ylide is inevitable, a part of which is hydrolyzed to yield an α-methylene carbonyl derivative. Nevertheless, Wittig reaction and aldol condensation did not proceed well, indicating the presence of an unknown dimerization pathway. In the ylide formation, 1-phosphonium-3-carbabetaine was previously proposed as a key intermediate. Upon assuming that the betaine also participates in the dimerization process, we examined a possible reaction pathway computationally. As the results, the betaine formed by a reaction with the first phosphine was suggested to undergo nucleophilic addition to an unreacted molecule of the open-[60]fullerene, yielding an epoxide dimer which is then deoxygenated by the second phosphine to furnish the desired open-[60]fullerene dimer.

Open-[60]fullerene-aniline conjugates with near-infrared absorption

Two open-[60]fullerene-aniline conjugates were synthesized, in which the two-fold addition of diamine gave a thiazolidine-2-thione ring on the [60]fullerene cage in the presence of CS₂. By increasing the number of N,N-dimethylaniline moieties, the absorption edge was considerably shifted up to 1200 nm owing to effective acceptor-donor interactions.

Near-Infrared-Absorbing Chiral Open [60]Fullerenes

Though [60]fullerene is an achiral molecular nanocarbon with I_h symmetry, it could attain an inherent chirality depending upon a functionalization pattern. The conventional chiral induction of C₆₀ relies mainly upon a multiple addition affording a mixture of achiral and chiral isomers while their chiral function would be largely offset by the existence of pseudo-mirror plane(s). These are major obstacles to proceed further study on fullerene chirality and yet leave its understanding elusive. Herein, we showcase a carbene-mediated synthesis of C₁ -symmetric chiral open [60]fullerenes showing an intense far-red to near-infrared absorption. The large dissymmetry factor of |g_abs |=0.12 was achieved at λ=820 nm for circular dichroism in benzonitrile. This is, in general, unachievable by other small chiral organic molecules, demonstrating the potential usage of open [60]fullerenes as novel types of chiral chromophores.

π-Extended Fullerenes with a Reactant Inside

Fullerene-graphene hybrids potentially exhibit unprecedented properties owing to interactive communication between the two units through a linkage. However, most of their discrete molecular structures have been still undisclosed thus far. With the recent rise in the awareness of facile access to molecular nanocarbon hybrids, we showcase novel π-extended fullerenes with a fused pyrazine or imidazole. Owing to the effective planar-curved π-conjugation, their absorption coefficients significantly increased in the visible region. Curiously enough, during the formation of π-extended fullerenes, an in situ generated NH₃ molecule was spontaneously encapsulated inside the fullerene cavity. The NH₃ molecule then underwent a timed orifice-expansion triggered by its sustained release. This is the first demonstration that fullerene captures a reactant inside, suggesting their potential usage for a sustained dosing and/or material delivery toward postfunctionalization of fullerene-graphene hybrids.

Fullerene superlattices containing charge transfer complexes for an improved nonlinear optical performance

To improve the nonlinear optical (NLO) properties of fullerene C₆₀, chemical modifications are normally needed to construct a donor-π-acceptor (D-π-A) system, which requires tedious and time-consuming synthesis procedures. In addition, the conjugated structure of C₆₀ will inevitably be destroyed, which is disadvantageous for other applications. Here, we use solvent-based nanoarchitectonics to obtain highly ordered, three-dimensional (3D) C₆₀ supramolecular structures. For this purpose, a liquid-liquid interfacial precipitation (LLIP) method was employed using quinoline as the good solvent. Hollow polyhedra (HPH) and multilayer flowers (MFs) were obtained when methanol and ethanol were selected as the poor solvents, respectively. While quinoline failed to enter the HPH, it was found to be successfully intercalated with the MFs, which induced a transition of the C₆₀ organization from a pristine face-centered-cubic (fcc) phase to a hexagonal close packed (hcp) lattice. When embedded in a poly(methyl methacrylate) (PMMA) matrix, the HPH and MFs both show reverse saturable absorption (RSA) and optical limiting (OL) properties. The MFs-based film showed a third-order nonlinear absorption coefficient (β) of 1.25 × 10⁵ cm·GW^-1 and an optical limiting threshold (F_ol) of 0.00625 J·cm^-2. Comparatively, the HPH-based film exhibited a lower β value of 9.80 × 10⁴ cm GW^-1 and a higher F_ol value of 0.00834 J cm^-2. The better NLO performance of the MFs was mainly ascribed to the formation of the charge transfer complexes between quinoline and C₆₀, proven by UV-vis and electrochemical measurements. The fine tuning of the NLO properties of C₆₀ without chemical modification provides new opportunities for C₆₀ to be applied in nonlinear optics.

Preparation of π-extended fullerene derivatives through addition of phenylenediamine to open-cage fullerene derivatives

Open-cage fullerenes with a quinoxaline moiety on the rim of the orifice showed evident π-system extension effect on the NMR and UV-Vis spectra.

Phosphorus ylides of cage-opened sulphide [60]fullerene derivatives

The replacement of a ketone with a sulfide moiety changes the electronic properties of cage-opened fullerene ylides, thus causing a hypsochromic shift in absorption and a cathodic shift of reduction potentials.

Amino-Functionalized Cage-Opened C60 Derivatives

The amino-functionalized cage-opened [60]fullerene derivatives were synthesized by reactions with phenylenediamine. In this reaction, the diamine undergoes direct addition to the α,β-unsaturated carbonyl moiety. Further C-C bond scission is promoted by the intramolecular S_N2 reaction. These amino-functionalized derivatives possess high-lying highest occupied molecular orbital levels as suggested by electrochemical analyses. These compounds showed intense near-infrared absorption bands that tail to 900 nm, reflecting the optical transition with π-π* and charge transfer character.

Thiophene-Based Trimers and Their Bioapplications: An Overview

Certainly, the success of polythiophenes is due in the first place to their outstanding electronic properties and superior processability. Nevertheless, there are additional reasons that contribute to arouse the scientific interest around these materials. Among these, the large variety of chemical modifications that is possible to perform on the thiophene ring is a precious aspect. In particular, a turning point was marked by the diffusion of synthetic strategies for the preparation of terthiophenes: the vast richness of approaches today available for the easy customization of these structures allows the finetuning of their chemical, physical, and optical properties. Therefore, terthiophene derivatives have become an extremely versatile class of compounds both for direct application or for the preparation of electronic functional polymers. Moreover, their biocompatibility and ease of functionalization make them appealing for biology and medical research, as it testifies to the blossoming of studies in these fields in which they are involved. It is thus with the willingness to guide the reader through all the possibilities offered by these structures that this review elucidates the synthetic methods and describes the full chemical variety of terthiophenes and their derivatives. In the final part, an in-depth presentation of their numerous bioapplications intends to provide a complete picture of the state of the art.

Reactions of C60 with Pyridazine and Phthalazine

Cage-opened bisfulleroids are one of suitable building blocks for making a large hole on fullerenes. This work focuses on the Diels-Alder reaction of C₆₀ with azines, among synthetic methods developed thus far, to provide bisfulleroids. Surprisingly, the computational study predicted that the reaction proceeds with normal electron demand in contrast to hitherto considered inverse-electron-demand pathway. The benzoannulation to the pyridazine ring, i. e., phthalazine, resulted in the remarkably shortened reaction time due to the better interaction between the HOMO of phthalazine and the LUMO of C₆₀ as well as stronger 2,3-diaza-1,3-butadiene character in the phthalazine as confirmed crystallographically. Contrary to expectations, the benzobisfulleroid was converted into corresponding orifice-enlarged derivative via the photooxygenation slightly faster than the fulleroid derived from pyridazine.

Carbon-Oxygen-Bridged Ladder-Type Building Blocks for Highly Efficient Nonfullerene Acceptors

Recently, acceptor-donor-acceptor (A-D-A) small molecules have emerged as promising nonfullerene acceptors (NFAs) for organic solar cells and have attracted great attention. The carbon-bridged (C-bridged) ladder-type D unit plays a crucial role in developing high-performance A-D-A NFAs. However, the medium electron-donating capability of C-bridged units is unfavorable for making NFAs with strong light-harvesting capability. In this regard, carbon-oxygen-bridged (CO-bridged) ladder-type units present advantages in developing strong light-absorbing NFAs. Here, recent progress in the newly emerging CO-bridged NFAs is highlighted. The synthetic methods for the polycyclic CO-bridged building blocks are introduced. The photovoltaic performance for CO-bridged NFAs is summarized and discussed. Perspectives on developing high-performance CO-bridged-NFA-based solar cells are made.

A Wide-Band Gap Copolymer Donor for Efficient Fullerene-Free Solar Cells

The performance of a wide-band gap copolymer donor PDTPO-BDTT in nonfullerene solar cells was investigated. These solar cells presented broad photoresponse and high short-circuit current density. PDTPO-BDTT:IT-4F and PDTPO-BDTT:NNFA-4F solar cells with more efficient photoluminescence quenching and better film morphology gave decent power conversion efficiencies of 10.96 and 10.04%, respectively, which are much higher than those of the previously reported PDTPO-BDTT:fullerene solar cells.

Recent Advances in Carbon Nanomaterials for Cancer Phototherapy

Carbon nanomaterials have received great attention from the scientific community over the past few decades because of their unique physical and chemical properties. In this minireview, we will summarize the recent progress of the use of various carbon nanomaterials in the field of cancer phototherapy. The structural characteristics of each category and the surface functionalization strategies of these nanomaterials will be briefly introduced before focusing on their therapeutic applications. Recent advances on their use in photothermal therapy, photodynamic therapy, and combined phototherapies are presented. Moreover, a few challenges and perspectives on the development of carbon nanomaterials for future theranostics are also discussed.

Solvent-promoted catalyst-free regioselective N-incorporation multicomponent domino reaction: rapid assembly of π-functionalized [60]fullerene-fused dihydrocarbolines

An unprecedented solvent-promoted N-incorporation multicomponent domino chemistry was developed for the direct construction of π-functionalized [60]fullerene-fused dihydrocarbolines from simple hydrocarbons.

A D–A copolymer donor containing an alkylthio-substituted thieno[3,2-b]thiophene unit

A D–A copolymer (PSTTF2T) based on alkylthio-substituted thieno[3,2-b]thiophene was prepared. PSTTF2T is compatible with fullerene and non-fullerene acceptors in solar cells.

Regioselective Diels–Alder reaction to open-cage ketolactam derivatives of C60

Open-cage ketolactam fullerenes reacted with dienes on the rim of the orifice both regio- and endo-selectively, which were confirmed by 2D INADEQUATE ¹³C NMR of ¹³C enriched material/HMBC spectra as well as the theoretical calculations.

A facilely synthesized lactam acceptor unit for high-performance polymer donors

A lactam acceptor unit BDTP_i was developed. PThBDTP_i:PC₇₁BM solar cells gave a PCE of 8.11%, indicating that BDTP_i is a promising building block for D–A copolymers.

Modulate Organic-Metal Oxide Heterojunction via [1,6] Azafulleroid for Highly Efficient Organic Solar Cells

By creating an effective π-orbital hybridization between the fullerene cage and the aromatic anchor (addend), the azafulleroid interfacial modifiers exhibit enhanced electronic coupling to the underneath metal oxides. High power conversion efficiency of 10.3% can be achieved in organic solar cells using open-cage phenyl C61 butyric acid methyl ester (PCBM)-modified zinc oxide layer.

Open-cage fullerene with a stopper acts as a molecular vial for a single water molecule

An open-cage fullerene derivative with three carbonyl groups on the rim of the orifice reacts with o-diaminobenzene reversibly to form a tetrahydrofuran moiety above the orifice.

One-step preparation of a water-soluble carbon nanohorn/phthalocyanine hybrid for dual-modality photothermal and photodynamic therapy

The biomedical applications of carbon nanomaterials, especially integrating noninvasive photothermal therapy (PTT) and photodynamic therapy (PDT), into a single system have enormous potential in cancer therapy. Herein, we present a novel and facile one-step method for the preparation of water-soluble single-walled carbon nanohorns (SWNHs) and metal phthalocyanines (MPc) hybrid for PTT and PDT. The hydrophilic MPc, tetrasulfonic acid tetrasodium salt copper phthalocyanine (TSCuPc), is coated on the surface of SWNHs via noncovalent π-π interaction using the sonication method. In this PTT/PDT nanosystem, SWNHs acts as a photosensitizer carrier and PTT agent, while TSCuPc acts as a hydrophilic and PDT agent. The EPR results demonstrated that the generated reactive oxygen species (ROS) not only from the photoinduced electron transfer process from TSCuPc to SWNHs but also from SWNHs without exciting TSCuPc to its excited state. The test of photothermal conversion proved that not only do SWNHs contribute to the photothermal therapy (PTT) effect, TSCuPc probably also contributes to that when it coats on the surface of SWNHs upon exposure to a 650-nm laser. More importantly, the results of in vitro cell viability revealed a significantly enhanced anticancer efficacy of combined noninvasive PTT/PDT, indicating that the SWNHs-TSCuPc nanohybrid is a hopeful candidate material for developing an efficient and biocompatible nanoplatform for biomedical application.

In vitro and in vivo photothermally enhanced chemotherapy by single-walled carbon nanohorns as a drug delivery system

Single-walled carbon nanohorns (SWNHs) have exhibited many special advantages in biomedical applications.