Chiral Phosphorescent Carbonized Polymer Dots Relayed Light-Harvesting System for Color-Tunable Circularly Polarized Room Temperature Phosphorescence.

Carbonized polymer dots (CPDs) with a circularly polarized fluorescence property have received increasing attention in recent years. However, it is still a great challenge to construct circularly polarized room-temperature phosphorescence (CPRTP) CPDs. Herein, a simple approach to the synthesis of intrinsically CPRTP CPDs for the first time by utilizing sodium alginate and l-/d-arginine as precursors under relatively mild reaction conditions is presented. Notably, the CPDs exhibit both chirality and green RTP in solid states. Furthermore, color-tunable CPRTP is successfully achieved by engineering chiral light-harvesting systems based on circularly polarized phosphorescence resonance energy transfer (C-PRET) where the CPDs with green RTP function as an initiator of chirality and light absorbance, and commercially available fluorescent dyes with different emission colors ranging from yellow to red serve as the terminal acceptors. Through one-step or sequential C-PRET, the light-harvesting systems can simultaneously furnish energy transfer and chirality transmission/amplification. Given the multicolor long afterglow, lifetime-tunable, and CPRTP properties, their potential applications in multiple information encryption are demonstrated.

Room Temperature Phosphorescence Carbon Dots: Preparations, Regulations, and Applications.

Room temperature phosphorescence (RTP) materials have drawn considerable attention by virtue of their outstanding features. Compared with organometallic complexes and pure organic compounds, carbon dots (CDs) have emerged as a new type of RTP materials, which show great advantages, such as moderate reaction condition, low toxicity, low cost, and tunable optical properties. In this review, the important progress made in RTP CDs is summarized, with an emphasis on the latest developments. The synthetic strategies of RTP CDs will be comprehensively summarized, followed by detailed introduction of their performance regulation and potential applications in anti-counterfeiting, information encryption, sensing, light-emitting diodes, and biomedicine. Finally, the remaining major challenges for RTP CDs are discussed and new opportunities in the future are proposed.

Self-assembly of fullerene C60-based amphiphiles in solutions.

Fullerene C60 is an all-carbon cage molecule with rich physicochemical properties. It is highly symmetric and hydrophobic, which can be used as a building block for the preparation of amphiphiles that self-assemble into diverse supramolecular structures in aqueous solutions. Meanwhile, C60 is also lipophobic, which is different from the alkyl chains in traditional surfactants. By attaching alkyl chains to the C60 sphere, a new type of lipophobic-lipophilic amphiphiles can be constructed which undergo self-assembly in n-alkanes. When inorganic clusters such as polyoxometalate are linked to the C60 sphere, organic-inorganic hybrids will be obtained which can self-assemble in polar organic solvents. Pristine C60 has also been modified by polar groups such as hydroxy and carboxy, which are linked to hydrophobic moieties and form a new class of amphiphiles. In this review, the self-assembly of C60-based amphiphiles in aqueous and nonaqueous solutions will be summarized. The characteristics exhibited by C60-based amphiphiles during the self-assembly will be discussed with close comparison to traditional surfactants, and the influences of the aggregate formation on the physicochemical properties of the C60 sphere will be described. Finally, a brief summary will be given together with a promising perspective in near future.

Aggregation Behavior and Antioxidant Properties of Amphiphilic Fullerene C60 Derivatives Cofunctionalized with Cationic and Nonionic Hydrophilic Groups.

Amphiphilic derivatives of fullerene C60 are attractive from viewpoints of supramolecular chemistry and biomedicine. The establishment of relationships among the molecular structure, aggregation behavior and properties such as scavenging radicals of the amphiphilic C60 derivatives is the key to push these carbon nanomaterials to real applications. In this work, six monosubstituted C60 derivatives were synthesized by a one-step quaternization of their neutral precursors, which bear Percec monodendrons terminated with oligo(poly(ethylene oxide)) (o-PEO) chain(s). The main difference among the C60 derivatives lies in the number and substituted position of the o-PEO chain(s) within the Percec monodendron. Derivative with a 4-substitution of the o-PEO chain still showed limited solubility in water. Other derivatives possessing two or three o-PEO chains exhibited much improved solubilities and rich aggregation behavior in water. It was found that the formation of aggregates is regulated both by the number and the substituted pattern of the o-PEO chains. Typical morphologies include nanosheets, nanowires, vesicles, nanotubes, and nanorods. Although the structures of the C60 derivatives are different from those of traditional surfactants, their aggregation behavior can be also well explained by applying the theory of critical packing parameter. Interestingly, the capabilities of the C60 derivatives to scavenge the hydroxyl radicals (OH·-) followed the same order of their solubility in water, where the compound bearing three o-PEO chains with a 2,3,4-substitution got the champion quenching efficiency of ∼97.79% at a concentration of 0.15 mg·mL-1 (∼0.11 mmol·L-1).

Fullerenols Revisited: Highly Monodispersed Photoluminescent Nanomaterials as Ideal Building Blocks for Supramolecular Chemistry.

Fullerenols have been known for decades; however, the photoluminescent (PL) properties and applications in supramolecular chemistry of these molecules have not been well addressed. Herein, a strategy has been developed to purify the as-prepared fullerenols, and the photoluminescence and capabilities of these molecules to form supramolecular self-assemblies were systematically studied. It was found that fullerenols show wavelength-dependent emission with an absolute fluorescent quantum yield of approximately 3.5 %. The PL characteristics are reminiscent of carbon dots, especially those obtained by using the top-down method. The studied fullerenols can be used to detect Cu2+ ions with a limit of detection down to 3.50 µm. In addition, the amphiphilicity of the fullerenols can be readily tuned by ionic complexation with cationic surfactants, such as 1-tetradecyl-3-methylimidazoliumbromide (C14 mimB) and tetradecyltrimethylammonium bromide (TTAB). On increasing the concentration of the surfactant, the transition of aggregates was induced from highly ordered vesicles to honeycomb-structured crystals and finally to giant micelles. After the formation of supramolecular self-assemblies, enhancement of photoluminescence was observed, which can be ascribed to the suppression of intramolecular vibrations and motion combined with the loosely packed self-assembly array. This study provides a facile way to generate PL nanoarchitectures, which may find applications in fluorescent sensing, drug delivery, and optoelectronics.

Naphthalene-Functionalized, Photoluminescent Room Temperature Ionic Liquids Bearing Small Counterions.

Obtaining π-conjugated room temperature ionic liquids (RTILs) is difficult because of the relatively strong π-π interaction among the π-moieties. Existing strategies by using bulky counterions greatly hindered further property optimization and potential applications of these intriguing functional fluids through simple ion exchange. Herein, four naphthalene-functionalized, π-conjugated RTILs with small counterions (Br(-) ) have been facilely synthesized with high yields. Our strategy is to attach branched alkyl chains to the cationic backbone of the target compounds (2 a-d), which effectively tune inter- and intramolecular interactions. Compounds 2 a-d have satisfactory thermal stability (up to 300 °C) and low melting points (<-19 °C). Rheological measurements revealed the fluid character of 2 a-d, whose viscosity decrease with the increase of the alkyl chain length and temperature. The presence of the π-conjugated naphthalene moiety imparts 2 a-d photoluminescent properties in bulk solutions. Moreover, the absence of strong π-π stacking among the naphthalene units in solvent-free states enables them to be used as a new generation of photoluminescent inks.

Self-Organization and Vesicle Formation of Amphiphilic Fulleromonodendrons Bearing Oligo(poly(ethylene oxide)) Chains.

A new series of N-methylfulleropyrrolidines bearing oligo(poly(ethylene oxide))-appended Percec monodendrons (fulleromonodendrons, 4a-f) have been synthesized. The substituted position of the oligo(poly(ethylene oxide)) chain(s) on the phenyl group of the Percec monodendron for 4a-f was varied, which is at the 4-, 2,4-, 3,5-, 3,4,5-, 2,3,4- and 2,4,6- position, respectively. 4a-e are obtained as solids at 25 °C and can self-organize into lamellar phases as revealed by X-ray diffraction (XRD) and small-angle X-ray scattering (SAXS) measurements, while 4f appears as a viscous liquid. The substitution patterns of the oligo(poly(ethylene oxide)) chain(s) also significantly influence the solubility of 4a-f, especially in ethanol and water. Formation of self-organized supramolecular structures of 4d and 4e in water as well as 4d in ethanol is evidenced from UV-vis and dynamic light scattering (DLS) measurements. Further studies in water using various imaging techniques including transmission electron microscopy (TEM), freeze-fracture TEM (FF-TEM), cryo-TEM and atomic force microscopy (AFM) observations revealed the formation of well-defined vesicles for 4d and plate-like aggregates for 4e, indicating that the aggregation behavior of the fulleromonodendrons is highly dependent on their molecular structures. For 4d in ethanol, only irregular aggregates were noticed, indicating the solvent also plays a role on regulating the aggregation behavior. After functionalization with the Percec monodendrons, 4a-f can preserve the intriguing electrochemical properties of pristine C60 as revealed by cyclic voltammetries. The thermotropic properties of 4a-f have also been investigated. It was found that all of them show good thermal stability, but no mesophases were detected within the investigated temperature ranges.

Achieving long-lived white circularly polarized luminescence from carbonized polymer dots via phosphorescence resonance energy transfer.

Achieving white-light emission, especially long-lived white circularly polarized luminescence, is challenging. Herein, chiral phosphorescent carbonized polymer dots (CPDs) have been prepared by using chiral polymer sodium alginate and chiral small molecule L-lysine as precursors. Benefiting from the efficient triplet-to-singlet phosphorescence resonance energy transfer (PRET), CPD-based long-lived warm white CPL has been achieved for the first time. This study provides a universal strategy for the convenient and efficient preparation of CPD-based long-lived white CPL materials.

Chiral Aggregation-Induced Emission Carbon Dot-Based Multicolor and Near-Infrared Circularly Polarized Delayed Fluorescence via a Light-Harvesting System.

Circularly polarized luminescence (CPL) materials are the research frontier of chiral luminescence. As a kind of luminescent carbon material, carbon dots (CDs) are expected to become excellent candidates for the construction of CPL materials. However, the construction of CD-based circularly polarized afterglow emission, especially multicolor and near-infrared emission, remains a great challenge due to aggregation-caused quenching and the instability of triplet excitons. In this work, we synthesized chiral CDs with aggregation-induced emission using dithiosalicylic acid and l/d-arginine as precursors through a one-step solvothermal method. Notably, the CDs exhibit green delayed fluorescence (DF) in poly(vinyl alcohol) films. Furthermore, multicolor and near-infrared circularly polarized delayed fluorescence is successfully realized via engineering a chiral light-harvesting system in which the CDs with green DF emission act as energy donors and fluorescent dyes with emission colors ranging from yellow to the near infrared serve as energy acceptors.

Effect of new-style anterior and posterior vaginal wall repair combined with modified ischial spine fascia fixation on patients with pelvic organ prolapse and their postoperative quality of life.

Objective: This study aims to explore the effect of new-style anterior and posterior vaginal wall repair combined with modified ischial spine fascia fixation on patients with pelvic organ prolapse (POP) and their postoperative quality of life. Methods: A total of 88 patients with POP and elective surgery admitted to Anqing Hospital affiliated to Anhui Medical University from March 2018 to March 2021 were retrospectively analyzed. According to their surgical methods, patients were divided into an observation group [44 cases, all underwent new-style anterior and posterior vaginal wall repair combined with modified ischial spine fascia fixation (new-style APVR-modified ISFF)] and a control group [44 cases, all underwent traditional anterior and posterior vaginal wall repair combined with sacrospinous ligament fixation (traditional APVR- SLF)]. The perioperative indicators were compared between the two groups. The pelvic floor function, pelvic organ prolapse quantification (POP-Q) classification, and quality of life were observed before operation, 3 months after operation, and 6 months after operation. All patients were followed-up. Results: Compared with the control group, the observation group had more advantages in intraoperative blood loss, operation time, urinary catheter indwelling time, postoperative anal exhaust time, and hospitalization time (P < 0.05). In terms of pelvic floor function, patients of both groups showed significant improvement at 3 months and 6 months after surgery (P < 0.05). In terms of quality of life, the two groups exhibited significant improvement at 6 months after surgery (P < 0.05). PFIQ-7, PFDI-20, and UDI-6P of the observational group were lower than those of the control group, while PISQ-12 was higher than that of the control group but all with no significant difference (P > 0.005). In addition, the total complication rate of the observation group was 2.27% (1/44), which was significantly lower than 22.73% (10/44) of the control group (P < 0.05). Conclusion: New-style APVR-modified ISFF can effectively treat POP and improve the quality of life of such patients, with less postoperative complications and high safety.

Study and Comparison on Purification Methods of Multicolor Emission Carbon Dots.

Recent years have witnessed a rapid development of carbon dots (CDs), due to their outstanding luminescence properties and excellent biocompatibility. However, the internal structure and photoluminescent (PL) mechanism of CDs are still the subject of considerable debate, which is due to the fact that reaction products usually contain mixtures of several CD fractions as well as molecular intermediate and side products. Therefore, careful purification of the CDs is significant for analysis of structure and luminescence mechanism. Here, multicolor emission CDs were prepared by a one-pot pyrolysis of citric acid in formamide. Then, the precipitation method, dialysis and gel permeation chromatography (GPC) are successively employed to purify the multicolor emission CDs. This post-treatment allowed us to compare the optical properties of CDs obtained by different separation methods and provide a valuable guidance for the purification of CDs.

Superstructures with diverse morphologies and highly ordered fullerene C60 arrays from 1 : 1 and 2 : 1 adamantane-C60 hybrid molecules.

Superstructures from fullerene C60-containing compounds, especially those tethered to rigid functional groups with defined shapes, remain largely unexplored. Being the smallest diamondoid, adamantane (Ad) can be viewed as a promising building block for the construction of well-defined superstructures. Here, we report the syntheses of 1 : 1 (4a) and 2 : 1 (4b) Ad-C60 hybrid molecules, which were then used to construct superstructures in binary solvent mixtures via a modified liquid/liquid interfacial precipitation (LLIP) method using CHCl3 as a good solvent. Typically in the combination of DMSO/CHCl3 with a final concentration (cf) of 1.0 mmol L-1, 4a successively forms spheres, plates, nanoflowers and plicated particles with increasing content of DMSO while 4b forms cuboid blocks and microparticles with hierarchically organized surfaces. Changing from DMSO to other poor solvents including acetone, MeOH and EtOAc leads to variations of the morphology of the superstructures for both 4a and 4b. At the nanometer length scale, 4a and 4b adopt different organizations within the superstructures. While 4a tends to self-organize into lamellae with highly ordered C60 layers, the hexagonal phase is dominant in the superstructures formed by 4b. Wettability tests indicate that films formed by the superstructures of 4a and 4b show anti-wetting properties. Besides the solvent effect, the morphology of the superstructures can be also tuned by concentration. For example, when cf is lowered to 0.5 mmol L-1, a new form of superstructure, i.e., fibers, was detected for 4a. Our results also indicate that besides the solvent-induced aggregate transition, gravity-induced sedimentation and subsequent structure ripening can have a significant influence on the final morphology of the superstructures and the aggregate transition pathways.

Fluorescent vesicles formed by simple surfactants induced by oppositely-charged carbon quantum dots.

We show for the first time that stable fluorescent vesicles can be constructed by mixing oppositely-charged carbon quantum dots (CQDs) and simple surfactants in water, and can be potentially used as a new generation of biomarkers and drug delivery vehicles.

Correction: Fluorescent vesicles formed by simple surfactants induced by oppositely-charged carbon quantum dots.

Correction for 'Fluorescent vesicles formed by simple surfactants induced by oppositely-charged carbon quantum dots' by Xiaofeng Sun et al., Chem. Commun., 2016, 52, 12024-12027.

Spatial aromatic fences of metal-organic frameworks for manipulating the electron spin of a fulleropyrrolidine nitroxide radical.

The electron spin properties of a fulleropyrrolidine nitroxide radical incarcerated in the pores of MOF-177 and MIL-53 respectively were investigated for the first time. It was found that the spatial confinement effect and intramolecular interactions in these two solid-state spin systems lead to dramatically distinctive spin dynamics.

Robust onionlike structures with magnetic and photodynamic properties formed by a fullerene C60-POM hybrid.

We report for the first time the synthesis of a covalently-linked fullerene C60-Dawson POM hybrid, which can form onionlike structures with rich magnetic, electrochemical and photodynamic properties.