Science China Chemistry最新文献

Macrocyclic liquid crystals combine the unique property of liquid crystals and excellent supramolecular assembly ability of macrocyclic compounds. It is a significant challenge to make rational use of the advantages of macrocyclic compounds to prepare new macrocyclic mesogens. Pillararenes, a type of macrocycles with rigid pillar-shaped frameworks and easy-to-functionalize property, are excellent building blocks to fabricate liquid crystal materials. However, the site-selective modification property of pillararene has been rarely exploited to tailor liquid crystal behaviors. Previously reported pillararene-based liquid crystal systems are almost prepared by per-functionalized pillararenes. Herein, we report the regulation of chiral liquid crystal behaviors by different derivatization of pillararene. Lyotropic and thermotropic liquid crystals with different chirality were obtained by self-assembly of pillararene with different numbers of cholesterol groups. The bridge between thermotropic liquid crystal and lyotropic liquid crystal based on pillararene is built. In addition, the chirality of the mesogens can be amplified through supramolecular self-assembly driven by noncovalent interactions. Based on the different liquid crystal behaviors, the optical signal of the pillararene-based chiral liquid crystals was used to fabricate an information encryption system. This work provides a simple strategy to regulate liquid crystal behaviors via pillararene-based mesogens and realizes information encryption through the combination of different types of liquid crystals.

Hypoxia is a common characteristic of tumors and associated with poor outcome in most cancer types, thus hypoxia-triggered combined therapeutic systems with well-defined structure hold significant promise for achieving specific and effective tumor destruction. Herein, a water-soluble perylene diimide (PDI) cyclophane “Gemini Box” (GBox-1⁴⁺) is demonstrated as both a hypoxia-responsive photothermal agent and a drug capsule for tumor-specific combination therapy. First, owing to the covalent enclosure of PDI chromophore by double-sided molecular straps, GBox-1⁴⁺ can significantly stabilize labile PDI radical anions generated through bioreduction at the lesion site of hypoxic tumors, leading to high-efficiency near-infrared photothermal ablation of tumors. Meanwhile, GBox-1⁴⁺ can act as a molecular capsule to bind water-insoluble antitumor drugs camptothecin and hydroxycamptothecin in 1:1 host–guest stoichiometry with high affinities, greatly enhancing the water solubility of drugs. Eventually, such drug-loading cyclophane system as a hypoxia-activated photothermal/drug combined therapeutic platform exhibits more effective inhibition of tumor growth than the single treatment under identical conditions. This study significantly extends the application range of host–guest cyclophane systems and opens a promising avenue to structurally uniform combined therapeutic agents against hypoxic tumors with improved specificity.

Chiral hybrid metal halides with high photoluminescence quantum yield (PLQY) and superior dissymmetry factor (g_lum) are promising candidates for circularly polarized luminescence (CPL) emitting sources. However, it is a great challenge to achieve both high g_lum and large PLQY. Here, we report a new supramolecular strategy to fabricate chiral hybrid Cu(I)-halides with near-unity quantum yields and intense CPL emissions. The dissymmetry factor can be dramatically modulated by tuning the host-guest complexations. Attributing to the chirality and variable conformations of the host-guest complexes, a series of chiral [G@L^R/S]₂Cu₄I₆ have been prepared. The incorporation of different cations within the chiral L^R/S hosts leads to variations of packing modes along the c-axis and different extent of distortions in the [Cu₄I₆]²⁻polyhedra. Among them, [H₃O@L^R/S]⁺ cations are stacked based on Van der Waals interactions and hierarchically self-assemble into a right/left-handed helix in [H₃O@L^R/S]₂Cu₄I₆, which results in a high g_lum of −7×10⁻³ and a large PLQY of 96.92%. Notably, [G@L^R/S]₂Cu₄I₆ shows promising applications in single-component white light emitting diodes (WLEDs), exhibiting a maximum dissymmetry factor of −1.2×10⁻³. The effective host-guest complexation and oriented hierarchical self-assembly provide an effective strategy for the development of high-performance CPL materials.

In the pursuit of high-performance single-molecule magnets (SMMs), incorporating intramolecular magnetic coupling emerges as a pivotal strategy. Among these, d-f SMMs have garnered significant attention due to their remarkable versatility, which lies in their ability to tune coordination environments and facilely substitute metal centers. However, achieving performance-centric d-f SMMs through the synergistic interplay between highly anisotropic f ions and d-f magnetic interactions remains a formidable challenge. While mononuclear hexagonal bipyramidal (D_6h) Dy^III SMMs have been successfully isolated, the exploration of d-f SMMs featuring D_6h-lanthanide metal centers remains uncharted territory. In this study, we employed planar bipodal ligands in conjunction with “staple-like” axial phenoxide ligands to synthesize the first hexagonal bipyramidal d-f SMM. Remarkably, this compound exhibits alternating-current magnetic susceptibilities peaking up to 68 K with an energy barrier surpassing 1,200 K, thus establishing a new benchmark within the heterometallic d-f SMM landscape inclusive of complexes with diamagnetic d metals and paramagnetic f ions. Notably, the ferromagnetic interaction at the d-f sites engenders oscillating relaxation times contingent on the magnetic field — a characteristic distinct from mononuclear SMMs. These findings shed light on a deliberate design approach for d-f SMMs, emphasizing the cooperative utilization of high-barrier lanthanide modules alongside d ions through magnetic interactions. This synergy significantly enhances and diversifies the magnetic dynamics of these intriguing molecular systems.

The transition-metal-catalyzed migratory functionalization has emerged as a robust protocol for the building of C–C bonds remote from the “initiation” position. However, a similar strategy for the construction of quaternary carbon centers is still underdeveloped and only a limited number of reports exist. Herein, we report a nickel-catalyzed migratory hydrocyanation of unconjugated dienes to construct remote cyano-substituted quaternary carbon centers. This transformation features exceptional regioselectivity, mild reaction conditions, broad substrate scope and high yields. The synthetic utility of this method has been highlighted by a series of product derivatizations, and the potential of this transformation has been extended to synthesize TRPV1 antagonist and the key intermediate in the total synthesis of quebrachamine. Density functional theory (DFT) studies unveiled that the specific catalytic pocket assumed a significant role in the selective formation of cyano-substituted quaternary carbon centers.

Polymeric materials have penetrated all aspects of society and play an irreplaceable role. However, there is an inherent contradiction between their mechanical properties and processing behavior. Here, inspired by cement, a crucial construction material renowned for its excellent fabricating behavior and self-strengthening properties, we have developed dynamic cross-linked poly(oxime-urethane) (CPOU). The synthesized CPOU showed good self-healing ability and 3D printability owing to the dynamic dissociation and re-association of oxime-carbamate bonds. Simple objects printed through the fused deposition modeling technique were able to be readily assembled into complex architectures through intrinsic self-healing. Furthermore, the self-strengthening of CPOU was successfully realized through multiple-step tandem reactions. The dissociation of dynamic oxime-carbamate bonds produced–NCO groups, which reacted with the surrounding water to form polar urea bonds in the polymer network, leading to an increase in the tensile strength of CPOU from 11.95 to 19.37 MPa. This work not only develops the polymers with combined self-healing, facile fabricating, and self-strengthening properties but also provides a new molecular strategy to modulate the properties of polymers, which could be potentially applied in diverse areas.

Nanocatalytic therapy shows great potential for therapeutic interventions. However, therapeutic efficiency is often limited by unsatisfactory enzyme activity and lack of the coordination of immune system. Therefore, engineering nanozymes activity enhancement while activating immune system will be an effective strategy to achieve efficient tumor therapy. Herein, we synthesize a DSPE-PEG-FA modified manganese dioxide-based dual-atom nanozyme (MDF), on which iridium and platinum atoms are anchored. The obtained MDF can simultaneously mimic four enzyme activities of catalase, oxidase, peroxidase, and glutathione oxidase, set off a reactive oxygen species (ROS) storm, cause tumor cell death. The enzyme activity of MDF can be enhanced by its own photothermal effect. Meanwhile, MDF can consume intracellular glutathione and release Mn²⁺, which can prevent generated ROS from consumption and further activate cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes (cGAS-STING) pathway and promote the secretion of type I interferon, which will help promote dendritic cells maturation, present antigens to T lymphocytes to help kill tumor cells. Ultimately, MDF shows excellent tumor suppressive effects. This work provides a new paradigm for the field of nanozymes and offers a new reference for involvement of cGAS-STING pathway activation in tumor catalytic therapy.

The development of CO₂ separation membranes with high permeability and high selectivity, as well as ultra-thin selective layers, has always been challenging. Herein, a molecular-scaled co-assembly strategy is employed to fabricate the Pebax-Mo₁₃₂ (Pebax = polyether-block-amide copolymer; Mo₁₃₂ = (NH₄)₄₂[Mo₇₂^VIMo₆₀^VO₃₇₂(CH₃COO)₃₀(H₂O)₇₂]) membranes. The optimal self-standing membrane, Pebax-Mo₁₃₂-5%, shows a CO₂ permeability of ∼384 Barrer and an ultra-high ideal CO₂/N₂ selectivity of ∼244, outperforming most membranes reported in the literature. The CO₂ permeability and ideal CO₂/N₂ selectivity are increased by 70% and 367%, respectively, compared with the pristine Pebax membrane. A thin-film composite membrane prepared by spin-coating technique on a support membrane with gutter layers also exhibits a CO₂ permeance of 838 GPU and a CO₂/N₂ selectivity of 136. Such excellent performance can be attributed to the following reasons: (1) strong hydrogen bonding interactions between {Mo₁₃₂} clusters and Pebax confer excellent interfacial compatibility to the mixed matrix membranes; (2) incorporation of hollow {Mo₁₃₂} clusters into the Pebax molecular chain decreases the crystallinity of Pebax, and thereby accelerates the chain dynamics and increases the free volume of the membrane; (3) in situ diffuse reflectance infrared Fourier-transform spectroscopy demonstrates that the {Mo₁₃₂} clusters can effectively catalyze the hydration reaction of CO₂ and promote the transport of CO₂; (4) furthermore, the 0.35 nm pores of the crown ether-type {Mo₉O₉} allow the accurate size sieving of CO₂ (0.33 nm) and N₂ (0.36 nm) molecules.

Single-molecule magnets (SMMs) are a kind of nanosized magnetic materials that are capable of storing massive bytes of information. Strongly coupling the spin centers in a proper manner is a usual approach to promote the working temperature (or blocking temperature) for SMMs. Electron delocalized radicals have been widely employed to accomplish this job. Here, we show a new manner by using weak but multiple B–H^δ− ⋯ Dy³⁺ inverse hydrogen bonding (IHB) interactions to control the magnetic couplings in a series of dimeric dysprosiacaborane SMMs. This approach leads to a record high T^100s_B of 10 K among non-radical bridged dimeric SMMs, which is mainly ascribed to strong ferromagnetic coupling (4.38 cm⁻¹) and the proper alignment of the magnetic principle axes of the adjacent dysprosium(III) ions. In verifying by theoretical calculations, these results demonstrate that IHB interactions can be used to construct strong axial ferromagnetic coupling and enhancing magnetic blocking temperature for SMMs.

Organelle-targeted imaging can provide information on cellular functions and intracellular interactions, being significant for disease diagnosis. The use of room-temperature phosphorescence (RTP) in organelle-targeted imaging can fully utilize its unique characteristics of long wavelength and deep penetration. However, this technology has long been plagued by insufficient probe targeting and limited luminous intensity. In this work, we prepared a series of complexes composed of multicationic persulfurated arenes and biomacromolecules via electrostatic interactions in 1:1 stoichiometry for high-contrast mitochondrial-targeted RTP imaging. Such an electrostatic interaction design effectively prevented the self-aggregation of the probes, which is not conducive to mitochondrial targeting. Simultaneously, it suppressed the non-radiative decay to the maximum extent, enabling the probes to exhibit strong RTP signals both in aqueous solution and at the cellular level. Furthermore, the biomacromolecules can serve as carriers for an electrostatic interaction transfer of the persulfurated arenes to mitochondria. This leads to high mitochondrial targeting Pearson’s correlation coefficients of the probes and high-contrast RTP imaging effects, as well as the independence of the co-incubated probe concentration. These results provide new insights for the development of targeted imaging technologies.