Y.F.Wang

Formation of a tetrameric heteropolyoxometalate ring of bismuth-containing lacunary phosphomolybdate clusters.

Abstract

A new hetero-bimetallic polyoxometalate (POM) nano-ring was synthesized in a one-pot procedure. The structure consists of tetrameric units containing four bismuth-substituted monolacunary Keggin anions including distorted [BiO₈] cubes. The nano-ring is formed via self-assembly from metal precursors in aqueous acidic medium. The compound (NH₄)₁₆[(BiPMo₁₁O₃₉)₄] ⋅ 22 H₂O; (P₄Bi₄Mo₄₄) was characterized by single-crystal X-ray diffraction, extended X-ray absorption fine structure spectroscopy (EXAFS), Raman spectroscopy, matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF), and thermogravimetry/differential scanning calorimetry mass spectrometry (TG-DSC-MS). The formation of the nano-ring in solution was studied by time-resolved in situ small- and wide-angle X-ray scattering (SAXS/WAXS) and in situ EXAFS measurements at the Mo−K and the Bi−L₃ edge indicating a two-step process consisting of condensation of Mo-anions and formation of Bi−Mo-units followed by a rapid self-assembly to yield the final tetrameric ring structure.

The role of the organic building units of MOFs towards selective detection of a targeted metal cation (Fe³⁺) has been demonstrated by systematic screening by varying the number of Lewis basic (pyridyl-N atoms) sites in a series of isostructural metal–organic frameworks (MOFs). All three fluorescent MOFs are seen to present a quenching response towards Fe³⁺ ions in water; however, only UiO-67@N exhibits highly selective and sensitive response, whereas the emission of both UiO-67 and UiO-67@NN is quenched by several metal ions. More information can be found in the Research Article by S. K. Ghosh et al. (DOI: 10.1002/chem.202104175).

Thin-film saturable absorbers (SAs) are extensively used in mode-locked fiber laser due to the robust and simple application methods that arise because SAs are alignment-free and self-standing. Single-walled c...

Photosensitizer: The first BOPHY–fullerene C₆₀ dyad (BP-C₆₀ ) has been synthesized and obtained as two atropisomers. The presence of the BOPHY light-harvesting antenna in the dyad increases the absorption of the fullerene moiety in the visible region and improves its photodynamic action. Photoinduced energy/electron transfer processes (EnT/PeT) take place from BOPHY to fullerene C₆₀. The dyad exhibits an efficient production of reactive oxygen species. BP-C₆₀ is a promising heavy-atom-free photosensitizer with potential application in photodynamic treatments..

Abstract

A novel BOPHY–fullerene C₆₀ dyad (BP-C₆₀ ) was designed as a heavy-atom-free photosensitizer (PS) with potential uses in photodynamic treatment and reactive oxygen species (ROS)-mediated applications. BP-C₆₀ consists of a BOPHY fluorophore covalently attached to a C₆₀ moiety through a pyrrolidine ring. The BOPHY core works as a visible-light-harvesting antenna, while the fullerene C₆₀ subunit elicits the photodynamic action. This fluorophore–fullerene cycloadduct, obtained by a straightforward synthetic route, was fully characterized and compared with its individual counterparts. The restricted rotation around the single bond connecting the BOPHY and pyrrolidine moieties led to the formation of two atropisomers. Spectroscopic, electrochemical, and computational studies disclose an efficient photoinduced energy/electron transfer process from BOPHY to fullerene C₆₀. Photodynamic studies indicate that BP-C₆₀ produces ROS by both photomechanisms (type I and type II). Moreover, the dyad exhibits higher ROS production efficiency than its individual constitutional components. Preliminary screening of photodynamic inactivation on bacteria models (Staphylococcus aureus and Escherichia coli) demonstrated the ability of this dyad to be used as a heavy-atom-free PS. To the best of our knowledge, this is the first time that not only a BOPHY–fullerene C₆₀ dyad is reported, but also that a BOPHY derivative is applied to photoinactivate microorganisms. This study lays the foundations for the development of new BOPHY-based PSs with plausible applications in the medical field.

In this work, plasmonic copper nanoparticles (Cu NPs) were loaded onto carbon nanotubes (CNTs) from various sources including commercial CNTs and those directly derived from plastic wastes. Under visible-light irradiation, the synergetic effect between Cu NPs and CNTs could efficiently promote Ullmann coupling of phenols and aryl halides, achieving high yields of diaryl ethers.

Abstract

Utilizing light and plastic wastes as resources to turn the wasted phenols and hazardous aryl halides into value added chemicals seems to be an attractive idea for alleviating the energy crisis and environmental problems. In this work, plasmonic copper nanoparticles (Cu NPs) were loaded onto carbon nanotubes (CNTs) from various sources including commercial CNTs and those derived from plastic wastes. Under visible-light irradiation, the catalyst could efficiently convert phenols and aryl halides to diaryl ethers. Similar with commercial CNTs, excellent activity is also achieved when utilizing CNTs derived from different kinds of plastic wastes as support for the system. Further investigation shows that the visible-light irradiation and light-excited plasmonic Cu NPs are necessary to inhibit the phenol degradation on CNTs and in turn promote the cross-coupling of phenol and aryl halides. Compared with metal oxides and other carbon materials, the excellent capability of CNTs to absorb light, to convert light to heat, and to adsorb both two reactants simultaneously are critical to enhance the activity of Cu NPs, achieving high yields of diaryl ethers. This study could provide a novel strategy for catalyst design and generate a more economically sustainable process.

A heavy-atom-free BOPHY-based photosensitizer (PS) has been obtained as a mixture of two atropisomers. The BOPHY core works as a visible light-harvesting center and donor antenna, while a fullerene C₆₀ acceptor acts as an effective spin converter and triggers photodynamic action. The dyad is capable of producing reactive oxygen species (ROS) by both photodynamic mechanisms. In-vitro studies indicate that the dyad photokills microorganisms after visible light irradiation. More information can be found in the Research Article by D. A. Heredia et al. (DOI: 10.1002/chem.202103884).

All they′re cracked up to be: C₆₀ microstructures featuring surface cracks were synthesized for the first time from a phenetole/propan-1-ol (NPA) solvents system, in which phenetole and NPA molecules participate in the formation of the fcc ends and hcp sidewalls of the C₆₀ microstructures, respectively. The introduction of surface cracks into C₆₀ crystals benefits the photoluminescence enhancement and the development of microscopic recognition of C₆₀ crystals, demonstrating their potential applications from optoelectronics to biology.

Abstract

Surface cracks could improve the optical and photoelectronic properties of crystalline materials as they increase specific surface area, but the controlled self-assembly of fullerene (C₆₀) molecules into micro-/nanostructures with surface cracks is still challenging. Herein, we report the morphology engineering of novel C₆₀ microstructures bearing surface cracks for the first time, selecting phenetole and propan-1-ol (NPA) as good and poor solvents, respectively. Our systematic investigations reveal that phenetole molecules initially participate in the formation of the ends of the C₆₀ microstructures, and then NPA molecules are involved in the gradual growth of the sidewalls of the microstructures. Therefore, the surface cracks of C₆₀ microstructures can be finely regulated by adjusting the addition of NPA and the crystallization time. Interestingly, the cracked C₆₀ microstructures show superior photoluminescence properties relative to the smooth microstructures due to the increased specific surface area. In addition, C₆₀ microstructures with wide cracks show preferential recognition of silica particles over C₆₀ particles owing to electrostatic interactions between the negatively charged C₆₀ microstructures and the positively charged silica microparticles. These C₆₀ crystals with surface cracks have potential applications from optoelectronics to biology.

Hollow carbon sphere–implanted graphitic carbon nitride nanosheet photocatalysts were prepared by a bottom-up method. The photocatalysts promote photoelectron transfer and suppress charge recombination through special interface coupling and hollow carbon spheres as an electron acceptor, leading to remarkably improved photocatalytic efficiency. This work thus provides an efficient pathway for the design of efficient and low-cost cocatalysts for photocatalysis. More information can be found in the Full Paper by D. Jing, J. Tang et al. (DOI: 10.1002/chem.202102330).

Metallic/semimetallic transition metal dichalcogenides (m-TMDs) have grabbed widespread attention in recent years due to their exotic physical properties and potential applications in various fields. The state-of-the-art progress in m-TMDs is reviewed, including electronic and crystal structures, synthetic methods, physical properties, and practical applications. Moreover, views on development, challenges, and future prospects of m-TMDs are put forward.

Abstract

2D materials and the associated heterostructures define an ideal material platform for investigating physical and chemical properties, and exhibiting new functional applications in (opto)electronic devices, electrocatalysis, and energy storage. 2D transition metal dichalcogenides (2D TMDs), as a member of the 2D materials family including 2D semiconducting TMDs (s-TMDs) and 2D metallic/semimetallic TMDs (m-TMDs) have attracted considerable attention in the scientific community. Over the past decade, the 2D s-TMDs have been extensively researched and reviewed elsewhere. Because of their distinctive physical properties including intrinsic magnetism, charge-density-wave order and superconductivity, and potential applications, such as high-performance electronic devices, catalysis, and as metal electrode contacts, 2D m-TMDs have grabbed widespread attention in recent years. However, reviews demonstrating the m-TMDs systematically and comprehensively have been rarely reported. Here, the recent advances in 2D m-TMDs in the aspects of their unique structures, synthetic approaches, distinctive physical properties, and functional applications are highlighted. Finally, the current challenges and perspectives are discussed.

The cover picture shows octapalladium metal strings catching a soccer ball of C₆₀ or C₇₀ fullerene in the central Pd–Pd junction to give metal-chain-wired bucky balls. The enantiopure chiral Pd₈ strings also afforded the chiral bucky balls through dimensionally and chirality controlled self-assembly. These findings could provide a new platform for developing functional metal-carbon nanocomposite materials, including nano-electronics with unusual properties derived from the combination of redox active fullerenes and metal chains. More information can be found in the Communication by T. Tanase et al. (DOI: 10.1002/chem.202102020).

A series of C₇₀ microcrystals with high uniformity from perfect cubes, defective hoppers to novel cruciform-pillars were obtained by reprecipitation method. Among them, novel pillar-shaped microcrystals are obtained for the first time by further decreasing the amount of mesitylene. The hopper-shaped microcrystals exhibit excellent photoluminescence properties relative to those of cubes and cruciform-pillars owing to the enhanced light absorption, proving their potential applications in optoelectronic devices.

Abstract

Controlled crystallization of fullerene molecules into ordered molecular assemblies is important for their applications. However, the morphology engineering of fullerene[C₇₀] assemblies is challenging, and complicated architectures have rarely been reported due to the low molecular symmetry of C₇₀ molecules, which makes their crystallization difficult to control and the low production yield as well. Herein, with the assistance of solvent intercalation, a general reprecipitation approach is reported to prepare morphologically controllable C₇₀ microcrystals with mesitylene as a good solvent and n-propanol as a poor solvent in one solvent system without replacing specific solvents. A series of C₇₀ microcrystals with high uniformity from perfect cubes and defective hoppers to novel cruciform-pillars are obtained by intentionally tuning C₇₀ concentration and the volume ratio of mesitylene to n-propanol. Among them, novel cruciform-pillar-shaped microcrystals are obtained for the first time by further decreasing the amount of mesitylene in the solvent-intercalated microcrystals. Notably, the C₇₀ concentration is a key parameter for the selective growth of C₇₀ hopper, rather than the volume ratio of mesitylene to n-propanol. Interestingly, the hopper-shaped microcrystals exhibit excellent photoluminescence properties relative to those of cubes and cruciform-pillars owing to the enhanced light absorption, proving their potential applications in optoelectronic devices. This study offers new insights into the morphology-controlled synthesis of other micro/nanostructured organic microcrystals and the fine tuning of photoluminescence properties of organic crystals.

The chemical transformation of a 1,2‐dicarbonyl moiety embedded in a cage‐opened fullerene C₆₀ derivative was examined to produce β‐oxo‐phosphorus ylide, α‐methylene carbonyl, and acid anhydride compounds. The former two showed a significantly supressed encapsulation/escape dynamics of a water molecule as well as electrochemical properties largely different from the last one.

Abstract

A 1,2‐dicarbonyl moiety on a cage‐opened fullerene skeleton is one of suitable building blocks for the further derivatization. Herein, we discuss the chemical transformation of a 1,2‐dicarbonyl compound into β‐oxo‐phosphorus ylide, acid anhydride, and α‐methylene carbonyl derivatives. Despite possessing a sterically small methylene unit in the last one, the release of an encapsulated water molecule was significantly supressed whereas the β‐oxo‐phosphorus ylide bearing three bulky p‐tolyl groups on the P‐atom enabled the faster insertion/release dynamics, implying the flexibility of the phosphonium substituent. The replacement of the carbonyl group with phosphorus ylide and methylene units largely varied electrochemical properties of the fullerene skeleton, likely arising from the anionic charge delocalized over the entire molecule and removal of an electron‐withdrawable carbonyl group, respectively.

Rolling up: Larger acenes are potential carriers of diffuse interstellar bands, and should undergo dehydrogenation reactions upon absorption of interstellar UV photons. This could result in 2,3‐didehydroacenes that have a reactive aryne functionality at one of the short ends of the long molecule. The intramolecular Diels‐Alder reaction to dihydroethenocyclacenes with the other end of the acene and the subsequent cycloreversion of acetylene were studied computationally and were shown to have energy requirements that are compatible with cyclacene formation under the extreme conditions of interstellar space. More information can be found in the Full Paper by H. F. Bettinger et al. on page 4605.

The nucleophilic addition of phosphites to a cage‐opened fullerene C₆₀ derivative gave α‐hydrophosphates and enol phosphates as kinetic and thermodynamic products, respectively. Different from classical Abramov reactions, which give phosphonates bearing a P−C bond, these products possess a P−O bond. Theoretical calculations suggested that the charge delocalization of zwitterionic intermediates along with the π‐framework facilitate the phospha‐Brook rearrangement, thus forming nonclassical Abramov products. More information can be found in the Communication by Y. Murata et al. on page 4864.

Power of four: A supramolecular tetrad featuring benzothiazole, BODIPY, zinc porphyrin and fullerene has been newly assembled and occurrence of multi‐step energy and electron transfer is demonstrated.

Abstract

A panchromatic triad, consisting of benzothiazole (BTZ) and BF₂‐chelated boron‐dipyrromethene (BODIPY) moieties covalently linked to a zinc porphyrin (ZnP) core, has been synthesized and systematically characterized by using ¹H NMR spectroscopy, ESI‐MS, UV‐visible, steady‐state fluorescence, electrochemical, and femtosecond transient absorption techniques. The absorption band of the triad, BTZ‐BODIPY‐ZnP, and dyads, BTZ‐BODIPY and BODIPY‐ZnP, along with the reference compounds BTZ‐OMe, BODIPY‐OMe, and ZnP‐OMe exhibited characteristic bands corresponding to individual chromophores. Electrochemical measurements on BTZ‐BODIPY‐ZnP exhibited redox behavior similar to that of the reference compounds. Upon selective excitation of BTZ (≈290 nm) in the BTZ‐BODIPY‐ZnP triad, the fluorescence of the BTZ moiety is quenched, due to photoinduced energy transfer (PEnT) from ¹BTZ^* to the BODIPY moiety, followed by quenching of the BODIPY emission due to sequential PEnT from the ¹BODIPY* moiety to ZnP, resulting in the appearance of the ZnP emission, indicating the occurrence of a two‐step singlet–singlet energy transfer. Further, a supramolecular tetrad, BTZ‐BODIPY‐ZnP:ImC₆₀, was formed by axially coordinating the triad with imidazole‐appended fulleropyrrolidine (ImC₆₀), and parallel steady‐state measurements displayed the diminished emission of ZnP, which clearly indicated the occurrence of photoinduced electron transfer (PET) from ¹ZnP* to ImC₆₀. Finally, femtosecond transient absorption spectral studies provided evidence for the sequential occurrence of PEnT and PET events, namely, ¹BTZ^*‐BODIPY‐ZnP:ImC₆₀→BTZ‐¹BODIPY^*‐ZnP:ImC₆₀→BTZ‐BODIPY‐¹ZnP^*:ImC₆₀→BTZ‐BODIPY‐ZnP^.+:ImC₆₀ ^.− in the supramolecular tetrad. The evaluated rate of energy transfer, k _EnT, was found to be 3–5×10¹⁰ s⁻¹, which was slightly faster than that observed in the case of BODIPY‐ZnP and BTZ‐BODIPY‐ZnP, lacking the coordinated ImC₆₀. The rate constants for charge separation and recombination, k _CS and k _CR, respectively, calculated by monitoring the rise and decay of C₆₀ ^.− were found to be 5.5×10¹⁰ and 4.4×10⁸ s⁻¹, respectively, for the BODIPY‐ZnP:ImC₆₀ triad, and 3.1×10¹⁰ and 4.9×10⁸ s⁻¹, respectively, for the BTZ‐BODIPY‐ZnP:ImC₆₀ tetrad. Initial excitation of the tetrad, promoting two‐step energy transfer and a final electron‐transfer event, has been successfully demonstrated in the present study.

Two compounds, two natures: Electronic structure and nonadiabatic dynamics methods were used to explore the excited‐state properties of two zinc phthalocyanine (ZnPc)‐fullerene dyads. In one bonding configuration, excitation energy transfer from ZnPc to C₆₀ is inhibited; in the other, this process is thermodynamically favorable, with locally excited and charge‐transfer excitons being shown to participate in the energy‐transfer process.

Abstract

Whether chemical bonding can regulate the excited‐state and optoelectronic properties of donor–acceptor dyads has been largely elusive. In this work, we used electronic structure and nonadiabatic dynamics methods to explore the excited‐state properties of covalently bonded zinc phthalocyanine (ZnPc)‐fullerene (C₆₀) dyads with a 6–6 (or 5–6) bonding configuration in which ZnPc is bonded to two carbon atoms shared by the two hexagonal rings (or a pentagonal and a hexagonal ring) in C₆₀. In both cases, the locally excited (LE) states on ZnPc are spectroscopically bright. However, their different chemical bonding differentiates the electronic interactions between ZnPc and C₆₀. In the 5–6 bonding configuration, the LE states on ZnPc are much higher in energy than the LE states on C₆₀. Thus, the excitation energy transfer from ZnPc to C₆₀ is thermodynamically favorable. On the other hand, in the 6–6 bonding configuration, such a process is inhibited because the LE states on ZnPc are the lowest ones. More detailed mechanisms are elucidated from nonadiabatic dynamics simulations. In the 6–6 bonding configuration, no excitation energy transfer was observed. In contrast, in the 5–6 bonding configuration, several LE and charge‐transfer (CT) excitons were shown to participate in the energy‐transfer process. Further analysis reveals that the photoinduced energy transfer is mediated by a CT exciton, such that electron‐ and hole‐transfer processes take place in a concerted but asynchronous manner in the excitation energy transfer. It is also found that high‐level electronic structure methods including exciton effects are indispensable to accurately describe photoinduced energy‐ and electron‐transfer processes. Furthermore, this work opens up new avenues for regulating the excited‐state properties of molecular donor–acceptor dyads by means of chemical bonding.