An Efficient C-Si/C-H Cross-Coupling Reaction Enabled by a Radical Pathway.

The methods for the cross-coupling of aryl(trialkyl)silanes are long-standing challenges due to the extreme inertness of C-Si(R3) bond, though the reaction is environmentally friendly and highly regioselective to synthesize biaryls. Herein, we report a copper-catalyzed cross-coupling of aryl(trialkyl)silanes and aryl via a radical mechanism. The reaction proceeds efficiently with aryl sulfonium salts as limiting reagents, exhibits broad substrate scope, and provides an important synthetic strategy to acquire biaryls, exemplified by unsymmetrical fluorescence probes and late-stage functionalization of drugs. Of note, the experimental and theoretical mechanistic studies revealed a radical mechanism where the copper catalyst and CsF play critical roles on the radical generation and desilylation process.

Room Temperature Anhydrous Suzuki-Miyaura Polymerization Enabled by C-S Bond Activation.

The Suzuki-Miyaura cross-coupling is one of the most important and powerful methods for constructing C-C bonds. However, the protodeboronation of arylboronic acids hinder the development of Suzuki-Miyaura coupling in the precise synthesis of conjugated polymers (CPs). Here, an anhydrous room temperature Suzuki-Miyaura cross-coupling reaction between (hetero)aryl boronic esters and aryl sulfides was explored, of which universality was exemplified by thirty small molecules and twelve CPs. Meanwhile, the mechanistic studies involving with capturing four coordinated borate intermediate revealed the direct transmetalation of boronic esters in the absence of H2 O suppressing the protodeboronation. Additionally, the room temperature reaction significantly reduced the homocoupling defects and enhanced the optoelectronic properties of the CPs. In all, this work provides a green protocol to synthesize alternating CPs.

Synthetic Routes for Heteroatom-Containing Alkylated/Arylated Polycyclic Aromatic Hydrocarbons.

Synthetic routes for heteroatom-containing polycyclic aromatic hydrocarbons (H-PAHs) with alkyl and aryl substitution are demonstrated. Three H-PAHs, including heteroatom-containing rubicenes (H-rubicenes), angular-benzothiophenes (ABTs), and indenothiophene (IDTs) were successfully synthesized by two key steps, including polysubstituted olefin formation and cyclization. Specifically, ABT and H-rubicenes were comprehensively investigated by single-crystal X-ray diffraction, NMR spectroscopy, UV-vis absorption, cyclic voltammetry, transient absorption, and single-crystal OFET measurements.

Achieving High-Performance Photothermal and Photodynamic Effects upon Combining D-A Structure and Nonplanar Conformation.

Various organic nanoagents have been developed for photothermal therapy (PTT) and photodynamic therapy (PDT) under near-infrared (NIR) irradiation. Among them, small molecule-based nanoagents are very attractive due to their advantages of well-defined chemical structures, high purity, good reproducibility, and easy processability. However, only a few small molecule-based nanoagents have been developed for PDT under NIR irradiation. Moreover, the mechanism of PDT under NIR is still elusive. Herein, a semiconducting small molecule (BTA) with donor-acceptor-donor structure and twisted conformation is developed for PDT/PTT under NIR irradiation. A large π-conjugated electron-deficient unit is used as the core to couple with two electron-donating units, ensuring the strong absorption under 808 nm. Moreover, the donor-acceptor structures and twisted conformation can reduce the energy gap between the singlet and triplet states (∆EST ) to afford effective intersystem crossing, beneficial for reactive oxygen species generation. The mechanism is probed by experimental and theoretical evidence. Moreover, the BTA nanoparticles exhibit excellent biocompatibility and PTT/PDT in vitro performance under NIR irradiation. This provides a strategy for designing highly efficient PDT/PTT molecular materials.

Perylene Diimide-Based Conjugated Polymers for All-Polymer Solar Cells.

In recent decades, non-fullerene acceptors (NFAs) are undergoing rapid development and emerging as a hot area in the field of organic solar cells. Among the high-performance non-fullerene acceptors, aromatic diimide-based electron acceptors remain to be highly promising systems. This review discusses the important progress of perylene diimide (PDI)-based polymers as non-fullerene acceptors in all-polymer solar cells (all-PSCs) since 2014. The relationship between structure and property, matching aspects between donors and acceptors, and device fabrications are unveiled from a synthetic chemist perspective.

Precisely Tuning Photothermal and Photodynamic Effects of Polymeric Nanoparticles by Controlled Copolymerization.

Cancer possesses normoxic and hypoxia microenvironments with different levels of oxygen, needing different efficacies of photothermal and photodynamic therapies. It is important to precisely tune the photothermal and photodynamic effects of phototherapy nano-agents for efficient cancer treatment. Now, a series of copolymeric nanoparticles (PPy-Te NPs) were synthesized in situ by controlled oxidative copolymerization with different ratios of pyrrole to tellurophene by FeCl3 . The photothermal and photodynamic effects of semiconducting nano-agents under the first near-infrared (NIR) irradiation were precisely and systematically tuned upon simply varying the molar ratio of the pyrrole to tellurophene. The PPy-Te NPs were used for cancer treatment in mice, exhibiting excellent biocompatibility and therapeutic effect. This work presents a simple method to tune photothermal and photodynamic therapies effect in semiconducting nano-agents for cancer treatment.

The Synthesis and Optoelectronic Applications for Tellurophene-Based Small Molecules and Polymers.

Tellurophene-based small molecules and polymers have received great attentions owing to their applications in thin-film transistors, solar cells, and sensors. This article reviews the current progress of the synthesis and applications of tellurophene-based small molecules and polymers. The physicochemical properties and optoelectronic applications of tellurophene-based materials are summarized and discussed. In the end, the challenges and outlook of tellurophene-based materials are presented.

A Turn-On Fluorescent Probe for Detection of Sub-ppm Levels of a Sulfur Mustard Simulant with High Selectivity.

A new type of fluorescent probe capable of detecting a sulfur mustard (SM) simultant at a concentration of 1.2 µM in solution and 0.5 ppm in the gas phase has been developed. Owing to its molecular structure with a thiocarbonyl component and two piperidyl moieties integrated into the xanthene molecular skeleton, this probe underwent a highly selective nucleophilic reaction with the SM simultant and generated a thiopyronin derivative emitting intensive pink fluorescence. The distinct difference in electronic structure between the probe and thiopyronin derivative generated a marked shift of the absorption band from 445 to 567 nm, which enabled an optimal wavelength propitious for exciting the thiopyronin derivative but adverse to the probe. Such efficient separation of the excitation wavelength and tremendous increase in fluorescence quantum yield, from less than 0.002 to 0.53, upon conversion from the probe to the thiopyronin derivative, jointly led to a distinct contrast in the beaconing fluorescence signal (up to 850-fold) and therefore the unprecedented sensitivity for detecting SM species.

Triplet Tellurophene-Based Acceptors for Organic Solar Cells.

Triplet materials have been employed to achieve high-performing organic solar cells (OSCs) by extending the exciton lifetime and diffusion distances, while the triplet non-fullerene acceptor materials have never been reported for bulk heterojunction OSCs. Herein, for the first time, three triplet molecular acceptors based on tellurophene with different degrees of ring fusing were designed and synthesized for OSCs. Significantly, these molecules have long exciton lifetime and diffusion lengths, leading to efficient power conversion efficiency (7.52 %), which is the highest value for tellurophene-based OSCs. The influence of the extent of ring fusing on molecular geometry and OSCs performance was investigated to show the power conversion efficiencies (PCEs) continuously increased along with increasing the extent of ring fusing.

A Colorimetric Fluorescent Probe for SO2 Derivatives-Bisulfite and Sulfite at Nanomolar Level.

A colorimetric fluorescent probe with fluorescence emission feature sensitive to SO2 derivatives, i.e. bisulfite (HSO3-) and sulfite (SO32-), was developed based on the HSO3-/SO32--mediated nucleophilic addition reaction of the probe that. This probe exhibited SO32- sensing ability with detection limit down to 46 nM and desired selectivity over other reference anions and redox species. The preliminary fluorescence bioimaging experiments have validated the practicability of the as-prepared probe for SO2 derivatives sensing in living cells.

Photoassisted magnetization of fullerene C60 with magnetic-field trapped Raman scattering.

We report a photoassisted method to magnetize microcrystal fullerene C(60) at room temperature by exciting it to triplet states via a proper laser radiation and then trapping the spin-polarized states under a strong magnetic field. Novel changes on Raman scattering of the C(60) microcrystals were observed in the presence and absence of the magnetic field. In particular, the Raman spectra were found to exhibit a "hysteresis" phenomenon when the external magnetic field was removed. In light of this, we propose magnetic-field-trapped Raman spectroscopy (MFTRS) and employ first-principle calculations to reproduce the Raman activities of C(60) at different states. Further, MFTRS of the fullerene is demonstrated to originate from its photoassisted magnetization (PAM). The PAM strategy enables the magnetization of materials which consist of only light elements; meanwhile, the MFTRS investigation may open a new research field in Raman spectroscopy.

Achieving Efficient NIR-II Type-I Photosensitizers for Photodynamic/Photothermal Therapy upon Regulating Chalcogen Elements.

Second near-infrared (NIR-II) window type-I photosensitizers have intrinsic advantages in photodynamic/photothermal therapy (PDT/PTT) of some malignant tumors with deep infiltration, large size, complicated location, and low possibility of surgery/radiotherapy. Herein, three chalcogen-element-based donor-acceptor-type semiconducting polymers (poly[2,2″-((E)-4,4″-bis(2-octyldodecyl)-[6,6″-bithieno[3,2-b]pyrrolylidene]-5,5″(4H,4″H)-dione)-alt-2,5-(thiophene)] (PTS), poly[2,2″-((E)-4,4″-bis(2-octyldodecyl)-[6,6″-bithieno[3,2-b]pyrrolylidene]-5,5″(4H,4″H)-dione)-alt-2,5-(selenophene)] (PTSe), and poly[2,2″-((E)-4,4″-bis(2-octyldodecyl)-[6,6″-bithieno[3,2-b]pyrrolylidene]-5,5″(4H,4'H)-dione)-alt-2,5-(tellurophene)] (PTTe)) are synthesized and fully characterized, demonstrating strong absorption in the NIR-II region. Upon adjusting the chalcogen elements, the intramolecular charge-transfer characteristics and the heavy-atom effect are tuned to enhance the intersystem crossing rate, improving the photodynamic effect. Moreover, the energy levels and Gibbs free energies are tuned to facilitate the type-I photodynamic process. As a result, PTTe nanoparticles (NPs) produce superoxide anion radicals (O2 •- ) more efficiently and demonstrate higher photothermal conversion efficiency than PTS and PTSe NPs upon NIR-II (1064 nm) laser irradiation, exhibiting unprecedented NIR-II type-I PDT/PTT performance in vitro and in vivo. This work provides ideas for achieving high-performance NIR-II type-I PDT/PTT semiconducting polymers for hypoxic oncotherapy.

Self-assembled hollow nanospheres strongly enhance photoluminescence.

We report that two molecular building blocks differ only by two protons, yet they form totally different nanostructures. The protonated one self-organized into hollow nanospheres (~200 nm), whereas the one without the protons self-assembled into rectangular plates. Consequently, the geometrically defined nanoassemblies exhibit radically different properties. As self-assembly directing units, protons impart ion-pairing and hydrogen-bonding probabilities. The plate-forming nanosystem fluoresces weakly, probably due to energy transfer among chromophores (Φ < 0.2), but the nanospheres emit strong yellow fluorescence (Φ ≈ 0.58-0.85).

Construction and optoelectronic properties of organic one-dimensional nanostructures.

In the last 10 years, nanomaterials based on small organic molecules have attracted increasing attention. Such materials have unique optical and electronic properties, which could lead to new applications in nanoscale devices. Zero-dimensional (0D) organic nanoparticles with amorphous structures have been widely studied; however, the systematic investigation of crystalline one-dimensional (1D) organic nanostructures has only emerged in recent years. Researchers have used inorganic 1D nanomaterials, such as wires, tubes, and belts, as building blocks in optoelectronic nanodevices. We expect that their organic counterparts will also play an important role in this field. Because organic nanomaterials are composed of molecular units with weaker intermolecular interactions, they allow for higher structural tunability, reactivity, and processability. In addition, organic materials usually possess higher luminescence efficiency and can be grown on almost any solid substrate. In this Account, we describe recent progress in our group toward the construction of organic 1D nanomaterials and studies of their unique optical and electronic properties. First, we introduce the techniques for synthesizing 1D organic nanostructures. Because this strategy is both facile and reliable, liquid phase synthesis is most commonly used. More importantly, this method allows researchers to produce composite materials, including core/sheath and uniformly doped structures, which allow to investigate the interactions between different components in the nanomaterials, including fluorescent resonance energy transfer and photoinduced electron transfer. Physical vapor deposition allows for the synthesis of organic 1D nanomaterials with high crystallinity. Nanomaterials produced with this method offer improved charge transport properties and better optoelectronic performance in areas including multicolor emission, tunable emission, optical waveguide, and lasing. Although inorganic nanomaterials have developed rapidly, our findings highlight the importance of organic compounds as components of novel 1D nanomaterials.

Ultra-stable tellurium-doped carbon quantum dots for cell protection and near-infrared photodynamic application.

It is important to regulate the concentration of reactive oxygen species (ROS) in cells since they play important roles in metabolism. Thus, developing nanoreagents to control the ROS is critical. Herein, tellurium-doped carbon quantum dots (Te-CDs) were developed by a simple and efficient hydrothermal method, which can scavenge H2O2 to protect cells under ambient condition, but generate ·OH under 808 nm irradiation as photodynamic application. This contribution presented a kind of novel CDs with dual-functions, which can potentially regulate ROS under different conditions.

The fabrication of TiO(2) nanorods from TiO(2) nanoparticles by organic protection assisted template method.

We report here the fabrication of TiO(2) nanorods from TiO(2) nanoparticles by using the organic protection assisted template method. After the deposition of perylene nanotubes in the pores of the porous alumina membranes, implantation of TiO(2) nanoparticles resulted in the formation of TiO(2)/perylene composite nanorods. The diameters and lengths of the nanorods correspond well to the diameter of the pores of the membrane and the thickness of the template used. After removing the perylene protection layer by calcination, the TiO(2) nanorods obtained have an anatase structure, the same as that of the original TiO(2) nanoparticles. It is supposed that the organic layers protected the TiO(2) rods from damage during removal of the template by alkaline etching. Such an organic layer protection method presents a new approach to fabricating one-dimensional nanostructures from the corresponding nanoparticles by an AAO template.

Net-like assembly of Au nanoparticles as a highly active substrate for surface-enhanced Raman and infrared spectroscopy.

Anodic aluminum oxide (AAO) templates were employed to filtrate and assemble Au nanoparticles by the pressure difference method. It was found that the colloidal Au nanoparticles can be uniformly arranged as nanonet assembly on the AAO surface. The net-assembled Au nanoparticles are clean and closely packed with nanochains. Taking fullerene C60/C70 as probe molecules, high-quality surface-enhanced Raman scattering (SERS) spectra were observed. The net-assembled Au nanoparticles even synchronously support the observation of surface-enhanced infrared absorption (SEIRA) spectra of the fullerene C60/C70. These results indicate that the AAO template filtrated with net-assembled Au nanoparticles is a highly active substrate for surface-enhanced spectroscopy.

Core-shell nanopillars of fullerene C60/C70 loading with colloidal Au nanoparticles: a Raman scattering investigation.

High-density ordered core-sheath nanopillars of fullerene C60/C70 loading with colloidal Au nanoparticles were fabricated with a template method. The anodic aluminum oxide (AAO) template was first imbedded with the fullerene C60/C70 molecules and then followed by a pressure-difference approach for Au colloid. High-quality surface-enhanced Raman scattering (SERS) spectra of fullerene C60/C70 were obtained. The spectra show intense SERS signals with a fluorescence-free background, even with a 514 nm excitation at which the normal Raman of fullerene C60/C70 present poor signal-to-noise. The assembly of the fullerene C60/C70 on the inner walls of the AAO pores along the Au nanopillars lead to fluorescence quenching; meanwhile, the high-density and ordered arrays of Au nanopillars contribute to surface plasmon resonance for the SERS effect.

Architectural Design of Self-Assembled Hollow Superstructures.

Colloidal nanoparticle assemblies are widely designed and fabricated via various building blocks to enhance their intrinsic properties and potential applications. Self-assembled hollow superstructures have been a focal point in nanotechnology for several decades and are likely to remain so for the foreseeable future. The novel properties of self-assembled hollow superstructures stem from their effective spatial utilization. As such, a comprehensive appreciation of the interactive forces at play among individual building blocks is a prerequisite for designing and managing the self-assembly process, toward the fabrication of optimal hollow nanoproducts. Herein, the emerging approaches to the fabrication of self-assembled hollow superstructures, including hard-templated, soft-templated, self-templated, and template-free methods, are classified and discussed. The corresponding reinforcement mechanisms, such as strong ligand interaction strategies and extra-capping strategies, are discussed in detail. Finally, possible future directions for the construction of multifunctional hollow superstructures with highly efficient catalytic reaction systems and an integration platform for bioapplications are discussed.

A single-chromophore-based agent enables rapid sensing of intracellular hypochlorous acid and in-situ photodynamic therapy to cancer cells.

A single-chromophore-based photoactive agent (MB-DOPA) capable of rapid sensing of nanomolar hypochlorous acid (HOCl) and in-situ generating photocytotoxicity to cancer cells was developed using dopamine moiety as the recognition unit and methylene blue (MB) moiety as the fluorescence signaling unit. Specifically, HOCl triggered conversion of the nonfluorescent MB-DOPA to MB enabling far-red fluorescence emission (λmax ∼ 683 nm) and additional ability to photogenerate 1O2 species. Owing to the catechol nature of dopamine characterized with strong electron-donating property, MB-DOPA underwent HOCl-mediated conversion with response time of ∼20 s and a strong fluorescence OFF-to-ON contrast by a factor of more than 3000. The preliminary bioimaging results confirmed the intracellular HOCl sensing ability of MB-DOPA and the in-situ photodynamic therapy (PDT) effectiveness for inducing massive apoptosis of cancer cells. The figure of merits of MB-DOPA, including ability for sensing of nanomolar HOCl with high specificity, rapid response, practicality for intracellular fluorescence imaging, and the in-situ generation of 1O2 for killing tumor cells, is expected to enable diagnosis of early-stage oncogenesis based on the highly specific detection of abnormal HOCl levels in the transformed cells and the simultaneous treatment in biomedical applications.