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As promising photonic material, phototheranostics can be activated in the laser irradiation range of tumor with sensitivity and spatiotemporal precision. However, it is difficult to completely eradicate solid tumors due to their irregularity and limited laser irradiation area. Herein, multi-stimulus responsive HA-Ce6@SWNHs were constructed with single-walled carbon nanohorns (SWNHs) and chlorine e6 (Ce6) modified hyaluronic acid (HA) via non-covalent binding. This SWNHs-based phototheranostics not only exhibited water dispersion but also could target tumor and be activated by near-infrared light for photodynamic therapy (PDT) and photothermal therapy (PTT). Additionally, HA-Ce6@SWNHs could be degraded by hyaluronidase in residual tumor cells, causing HA-Ce6 to fall off the SWNHs surfaces to restore autofluorescence, thus precisely guiding the programmed photodynamic treatments for residual tumor cells after the initial phototherapy. Thus, this work provides a rationally designed multiple-stimulus-response strategy to develop smart SWNHs-based phototheranostics for precise PDT/PTT and post-treatment imaging-guided PDT of residual tumor cells.

This work discloses a zwitterionic approach for selective copolymerization of carbon dioxide (CO₂) and propylene oxide (PO), producing poly(propylene carbonate) (PPC), a biodegradable polymer with broad applications. Small-molecule catalysts composed of triethylamine (TEA) and trialkyl boranes are effective for CO₂/PO copolymerization with an alternating degree of >99% and a productivity of 171 g PPC/g catalyst. A diamine N,N,N′,N′-tetraethyl ethylenediamine (TEED) paired with trialkyl borane exhibited improved activity and productivity (up to 216 g PPC/g catalyst). By adjusting the Lewis acid–base pair, the PPC selectivity can be regulated to 99%. In addition, PPCs have medium regioregularity with a head-to-tail diad content of 80–82% and number-average molecular weights of up to 56.0 kg/mol with narrow polydispersity (below 1.2). The overall catalytic performance of these readily available simple molecules is better than that of previously reported organic catalysts for CO₂/PO copolymerization. Successive insertion of PO and CO₂ into the Lewis pair leads to the formation of an end-to-end zwitterion featuring a TEB-masked anion and an onium cation, which is highly selective to the alternating copolymerization, as demonstrated by quantum mechanical calculations.

Carbonized polymer dots (CPDs) have received great interest from researchers in recent years. However, the solid-state photoluminescence quenching of CPDs is a big challenge owing to the resonance energy transfer or π–π* interaction. Herein, we report a new type of carbon dioxide (CO2) derived CPD exhibiting quantum yields of 46.2% in solution and 11.3% as a solid. These CPDs were prepared using ethylenediamine and trimethylolpropane tri(cyclic carbonate)ether synthesized from the reaction of carbon dioxide (CO2) and trimethylolpropane triglycidyl ether as precursors in ethanol. Gel permeation chromatography results revealed that the formation of CPDs involved the polymerization of small molecules and then the transformation of the polymers to CPDs. The solid-state fluorescence is attributed to the self-passivation of poly(hydroxyurethane) chains on the surface of the carbon core. Particularly, the synthesis of CPDs consumed nearly 26.7 wt% CO2, thus providing a new method for fixing CO2 to functional carbon materials. We have also demonstrated the application of CO2-derived CPDs by the fabrication of multicolor light-emitting diodes (LEDs), and a warm white LED is obtained when CPDs are applied as single phosphors by changing the amount of CPDs and the type of chip.

The synthesis of high-molecular-weight (MW) polyesters from the copolymerization of maleic anhydride (MA) and epoxides remains a challenge. Herein, we describe the copolymerization of MA with propy...

Preparation of non-conjugated polymers with long-wavelength emission and high quantum yield (QY) is still a huge challenge. Herein, we report the first example of linear non-conjugated polyester exhibiting yellow-green clusteroluminescence (CL) and a high QY of 38 %. We discovered that the polyester P3 with balanced flexibility and rigidity showed the longest CL wavelength and highest QY. Systematically photophysical characterization unravel the key role of ester cluster in the CL and the cluster formation via the aggregate of ester units was visualized. Moreover, P3 was demonstrated to be a highly selective, quick-responsive (ca. 1.2 min) and sensitive detector (detection limit is 0.78 μM) for irons owing to the fast disassociation of clusters by irons. This work not only gains further mechanistic insight into CL but also provides a new strategy to design high-efficiency and long-wavelength CL, meanwhile, enlightens the glorious application prospect of luminescent polyester.

This work reports a unique one-pot/one-step route to rapidly produce poly(thioether)s from poly(monothiocarbonate) (PMTC), a sulfur-containing polymer, using commercially available organic bases. The process started with the degradation of PMTC to a cyclic monothiocarbonate that generated an episulfide via a decarboxylative reaction. Then the episulfide underwent ring-opening polymerization. Organic bases catalyzed the degradation of PMTC and initiated the ring-opening of the generated cyclic monothiocarbonate. This process was successfully expanded to transform several PMTCs to the corresponding poly(thioether)s. The resultant poly(thioether)s exhibited higher thermal decomposition temperatures (up to 311 °C), higher refractive indexes (ca. 1.62) and lower glass transition temperatures (−48 °C) than those of the corresponding PMTCs. This work provides a polymer-to-polymer pathway for repurposing poly(monothiocarbonate)s.

This work describes an organic double-site Lewis pair with exceedingly high activity for the copolymerization of carbonyl sulfide (COS) with propylene oxide (PO). Fully alternating poly(monothiocarbonate)s can be produced with >99% regioregularity in a living manner. Molecular weight of the copolymers can be tuned in the range of 3.8–103.1 kg mol−1 (PDI: 1.09–1.18). Importantly, the on–off character of this system was also investigated and proved to be an effective way to regulate the copolymerization and synthesize block copolymers.

The copolymerization of carbon dioxide (CO2) with epoxides via organocatalysis is still a big challenge. This work reports the selective copolymerization of CO2 and epoxides bearing a phenyl group, i.e., phenyl glycidyl ether (PGE) and styrene oxide (StO), catalyzed by a combination of Lewis bases (LBs) and excess triethyl borane (TEB). The resultant CO2/PGE copolymers presented a molar fraction of carbonate units (FCO2) of more than 99%, with a regioregularity of ca. 92%. The weight percentage of the cyclic carbonate (WCC) was less than 1 wt%. The turnover frequency (TOF) was as high as 38 h−1 for producing the CO2/PGE copolymer with a number-average molecular weight (Mn) of 16.6 kg mol−1 and a dispersity (Đ) of 1.2. What is of importance is that the dosage of TEB had a strong impact on the selectivity, where the regioregular copolymer or cyclic carbonate could be selectively produced by simply tuning the TEB/LB molar ratios, as revealed by in situ FT-IR spectroscopy. It is proposed that excess TEB could either promote the equilibrium to generate the TEB-coordinated growing anion or activate the epoxide for enhancing the reactivity. Both copolymers are promising optical materials as colorless solids with a high refractive index (nd) of 1.55–1.56 (590 nm, 20 °C, cast film).

The fast and living ring-opening polymerization (ROP) of propylene oxide (PO) by metal-free catalysis is reported. By using triethyl borane (TEB) and organic Lewis bases (LBs, e.g.: phosphazene base, amidine and guanidine) as the catalysts, various alkyl alcohols can effectively initiate the ROP of PO, yielding tailor-made poly(propylene oxide)s (PPOs) with high regioregularity, predictable molecular weights, and narrow dispersity approaching Poisson distribution. The TEB/LB catalysts present unprecedentedly high activity (turnover frequency of up to 7500 h-1 ) and a truly living character for the polymerization, as evidenced by kinetic studies that showed fast initiation and growth, unobserved chain-transfer to PO, chain extension reactions, and the synthesis of various PPO-based block copolymers with narrow dispersities (Đ

Ring-opening polymerization (ROP) of the bioderived and nonstrained γ-butyrolactone (γ-BL) is an emerging approach to produce recyclable polymers. It remains a big challenge to synthesize high molecular weight linear poly(γ-butyrolactone)s (PγBLs) in a highly active and selective manner. In this report, we developed dual organocatalysts for the ROP of γ-BL, using symmetrical (thio)ureas with electron-donating groups to buffer the growing anions that were generared by the superbase phosphazene (P4). Linear PγBLs were selectively obtained with high apparent rate constant (ca. 39 times than single P4), and high number-average molecular weights of up to 64.3 kg/mol (ca. 3 times than single P4). The turnover frequencies of these P4/(thio)urea pair-catalyzed processes were as high as 125 h–1. High molecular weight PγBLs exhibited dramatically improved mechanical properties.

Metal-free synthesis of fully alternating polycarbonates from carbon dioxide (CO2) and epoxides is highly desired but a huge challenge. Here, we disclose the combination of tertiary amines with trialkyl boranes for completely alternating copolymerization of CO2 with epoxides. Triethylamine (TEA) pairing with triethyl borane (TEB), the simplest catalyst for the copolymerization of CO2 and propylene oxide (PO), afforded fully alternating poly(propylene carbonate) (PPC) with a turnover frequency (TOF) of 54 h-1 at 60 oC. Remarkably, diamine such as, N,N,N',N'-tetraethylethylenediamine (TEED) and triamine such as N,N,N',N'',N''-pentamethyldiethylene triamine (PMDETA) pairing with TEB exhibited improved the copolymer selectivity of up to 99%. Supplementally, the effect of trialkylborane structure on the copolymerization were also investigated. Moreover, PPCs prepared from these tertiary amines/ trialkyl boranes Lewis pairs showed the head-to-tail diad content of around 80%. The number-average molecular weight of PPC was up to 56.0 kg/mol with narrow distribution (Đ =1.16) and could be easily adjusted by simply varying the feeding ratios. The 1H NMR spectra and MALDI-TOF-MS spectra suggest that both tertiary amine-activating CO2 and TEB-masked end anions cooperatively promote the fully alternating CO2/epoxide copolymerization. This work provides an organocatalytic platform for well-defined CO2/epoxide copolymers using simple small molecules with high atomic utilization.

This review highlights recent advances in the synthesis of carbon dioxide (CO 2 )-based copolymers with both linear (di-, tri-, and multi-block, etc.) and non-linear (star-block and grafting) architectures. The corresponding catalytic systems are summarized. The microstructure and polymerization mechanism of various types of CO 2 -based copolymers, including block polycarbonates and block copolymers of polycarbonate with polyester, polyether, polyvinyl, and polydiene are discussed. The junction unit between two blocks, which indicates an abrupt change in the chain microstructure and property, is emphasized to define the microstructure of CO 2 -based block copolymers. Special attention was paid to one-pot terpolymerization for the synthesis of CO 2 -based block and grafting copolymers. Finally, the thermal, mechanical, and degradation properties and self-assembly of CO 2 -based block and grafting copolymers are reviewed. Prospective future research and applications of this new class of polymeric materials are discussed.

Polyester synthesis from the alternating copolymerization of epoxides with cyclic anhydrides via a metal-free route remains a key challenge. This work reports the development of a highly active organocatalytic route for the copolymerization of a spectrum of epoxides and cyclic anhydrides. Fully alternating polyesters were synthesized by a variety of organic Lewis acid–base pairs including organoboranes and quaternary onium salts. The effect of the acidity, type, and size of Lewis pairs on the catalytic activity and selectivity of the copolymerization is presented. The undesirable transesterification and etherification were effectively suppressed even in the case of complete conversion of the cyclic anhydride. This could be ascribed to the formation of a unique tetracoordinate bond-carboxylate (or alkoxide) anion. The Lewis pairs are highly active, with a turnover frequency of 102 and 303 h–1 for the copolymerization of propylene oxide with maleic anhydride and phthalic anhydride, respectively, at 80 °C. B...

This study describes the catalytic formation of alternating and regioregular copolymers from carbonyl sulfide (COS) and epoxides along with eugenol-based glycidyl ether (EGE) and guaiacol-based glycidyl ether (GGE), derived from eugenol and guaiacol, respectively. The (salen)CrCl [salen = N,N′-bis(salicylidene) cyclohexanediimine] complex, accompanied with various organic bases, was highly active towards the EGE/COS, GGE/COS copolymerization and EGE/GGE/COS terpolymerization. The turnover of frequency (TOF) of the (salen)CrCl complex for the EGE/COS copolymerization was up to 12 000 h−1. The number-average molecular weight (Mn) of the resultant EGE/COS copolymer was up to 62.2 kg mol−1. In the presence of 0.5–1.5 mol% chlorohydrin, which was a by-product of the synthetic process of EGE, α-Cl, ω-OH EGE/COS copolymers were obtained. This result suggests that chlorohydrin could act as a very efficient chain transfer agent for the copolymerization. The EGE/COS, GGE/COS, and EGE/GGE/COS copolymers were soluble in most of the common solvents and exhibited a high refractive index of more than 1.58 with high Abbe numbers of up to 40.4. This study provides an unprecedented and sustainable synthetic route for making soluble sulfur-rich polymers with high optical properties.

Polythioesters represent a promising functional polymer owing to the ubiquity and uniqueness of thioester bonds, however, to develop new examples of (functionalized) polythioesters for broadening the range of their applications is a grand challenge. Here, we report a convenient synthesis of a polythioester incorporating both thioester and selenide groups in repeating units via the alternating copolymerization of γ-selenobutyrolactone with episulfides including propylene sulfide and cyclohexene sulfide. This process mediated by a relatively mild phosphazene base of P1 exhibits very high activity with turnover of frequency (TOF) values of up to 1200 h−1, in which the nucleophilic attack of a selenol-type anion to episulfides is convinced as the rate-determining step by kinetic investigations. The prepared poly(thioester-alt-selenide)s have rigorously alternating sequences under optimized reaction conditions, molecular weights of 2.5–12.8 kg/mol, glass-transition temperatures of as low as −45.2 °C. Of unique, this copolymer exhibits remarkably high refractive indices of up to 1.74, suggesting a potential application prospect in optical materials.

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.