Science China Chemistry最新文献

Active organic optical waveguide materials (OOWMs) incorporating room temperature phosphorescence (RTP) hold significant promise for diverse applications in photonic and optoelectronic devices. Despite this potential, realizing active RTP optical waveguides with large-sized ordered structures and minimal light loss remains a formidable challenge. To address this issue, we present a groundbreaking thermoplastic active OOWM with low light loss, leveraging room temperature phosphorescent liquid crystalline polymer (LCP). This innovative material can be easily synthesized through the copolymerization of phosphorescent and liquid crystalline monomers. The resulting RTP copolymer exhibits a nematic liquid crystal phase with a phosphorescence lifetime of approximately 0.15 ms and an afterglow duration of around 1 second. Leveraging the excellent processability of LCP, we successfully produce meter-scale fibers via melt spinning. These RTP LCP fibers, characterized by a high orientation of mesogens along the fiber axis, demonstrate superior light confinement and efficient light conduction compared to unoriented samples, resulting in a low optical loss coefficient of 0.13 dB/mm. Furthermore, the thermal responsiveness of the RTP LCP optical waveguide enables its use as a photo switch. This pioneering work paves the way for the design of new OOWMs tailored for advanced photonics and optoelectronics devices.

Constructing charge transfer (CT) state by introducing donor (D) and acceptor (A) is an efficient strategy to regulate the photophysical properties of luminescent materials. Traditional CT-type luminophores are built on π-conjugated fused-ring structures, which always show hybrid CT/locally excited (LE) states and luminescence quenching effect in the aggregate state. In this work, eight conjugated biphenyl (BP) and nonconjugated diphenylmethane (DPM) derivatives with different donors and acceptors are synthesized to investigate the CT properties. Systematic photophysical characterization and theoretical calculation demonstrate that the through-space CT (TSCT) in nonconjugated DA-DPM exhibit superior photophysical performance than the conjugated DA-BP with through-bond CT (TBCT), the main manifestations are as follows: (1) TSCT luminophores produce longer maximum emission wavelength (λ_em) than the corresponding TBCT ones. For example, the longest λ_em of DMA-CN-DPM (DMA, dimethylamino) is 621 nm but the corresponding λ_em of DMA-CN-BP is only 480 nm. (2) TSCT-based DA-DPM demonstrates more sensitive responsiveness to environmental stimuli such as temperature and polarity. (3) Complete separation of the the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) distribution exists in all kinds of conformation of DA-DPM, which was hard to realize in conjugated DA-BP.

The impact of underwater bubbles on solid surfaces with a gradient wettability is important for fundamental science and technological applications. Despite progress in the translational motion of underwater bubbles on asymmetric surface, a fundamental dynamic understanding of asymmetrical bounce behavior of the underwater bubble needs to be further improved. Herein, we investigate asymmetrical bounce of underwater bubbles after impacting the wettability gradient copper mesh surface. Asymmetrical bounce of the underwater bubble on the wettability gradient mesh (WGM) surface is composed by asymmetrical spread in the spread process and asymmetrical recoil in the recoil process, which induce the unidirectional movement behavior. Additionally, effective bubble-size manipulation can be easily implemented due to different volumes of bubbles remaining at different locations of WGM surface. We envision that this work will provide a new understanding of asymmetrical bounce behavior of the underwater bubble on the wettability gradient surface, and propose a novel and feasible strategy for constructing the underwater bubble manipulation system.

Herein, a nickel-catalyzed arylcyanation of unactivated alkenes via cyano group translocation with aryl boronic acids has been developed. These transformations provided a robust approach to constructing structurally diverse 1,n-dinitriles or 4-amino nitriles from easily prepared and commercially available starting materials. The cyano group translocation was achieved, involving the addition into the intramolecular C–N triple bond followed by the retro-Thorpe reaction. Mechanistic studies revealed that high temperature and CsHCO₃ as the base were crucial for the cyano group translocation.

Circularly polarized luminescence (CPL) materials have received widespread attention due to their remarkable performance and broad applications. However, current CPL material research primarily focuses on tunable color, intensity, and reversibility. Constructing CPL with adjustable lifetime remains a significant challenge. Herein, a series of CPL polymeric materials with tunable lifetime were obtained by employing phosphorescent terephthalic acid and chiral organic small molecule R/S-BNAF (a luminescent binaphthol derivative) to copolymerize with acrylamide in different ratios. It was verified that this performance results from the different energy transfer efficiency between luminophores with varying ratios of the monomers for copolymerization. This strategy to realize CPL with tunable lifetime by modulating the energy transfer efficiency will provide a new perspective to broaden the applications of CPL materials.

It is highly desirable to develop simple organocatalysts for the controlled ring-opening alternating copolymerization (ROAC) of epoxides and cyclic anhydrides, leading to high molecular weight polyesters. Hence, a phosphazenium salt, namely tri[tris (dimethylamino)phosphoranylidenamino]phosphonium chloride (P₄⁺Cl⁻), is developed as a catalyst for the ROAC of epoxides and cyclic anhydrides. Surprisingly, the combination of P₄⁺Cl⁻ with a protonic initiator, such as 1,4-benzenedimethanol (BDM) exhibited high efficiency in the copolymerization of propylene oxide (PO) and phthalic anhydride (PA). This led to the production of polyester with an exceptional high molecular weight (M_n) of up to 126 kDa, which represented a rare example of poly(PO-alt-PA) with M_n surpassing 100 kDa. Note that the core P atom is trivalent status and the tris[tris(dimethylamino)] phosphoranyl group will share one proton in the P₄⁺Cl⁻ salt. Once combined with protonic species, the P₄⁺Cl⁻ will not only serve as a proton acceptor but also as a hydrogen bonding donor for the cyclic anhydrides. Therefore, it was assumed that the P₄⁺ plus proton served dual role in mimic of base/urea pair to effectively catalyze ROAC, which was supported by density functional theory (DFT) calculations.

Flexible ion-conductive materials exhibit intriguing advantages for applications in flexible electronic devices. Currently, the further enhancement of their conductivity within environmental limitations is an urgent demand for the development of flexible electronic devices, yet remains as a great challenge. Herein, we report a “dual-acid” strategy, via the encapsulation of two acids, H₃PW₁₂O₄₀ (HPW) and NH₂SO₃H (SA), with synergistic interaction into poly(vinyl alcohol)-glycerol (PVA-Gly) hydrogel, to achieve polyoxometalate(POM)-based flexible materials with superionic conductivity under various environmental conditions. As a representative example, the prepared PVA-Gly/HPW-SA-20% hydrogel presents an ultrahigh proton conductivity ranging from −30 °C (3.33×10⁻² S cm⁻¹) to room temperature (2.78×10⁻¹ S cm⁻¹) under ambient humidity. Moreover, the PVA-Gly/HPW-SA-20% hydrogel exhibits remarkable advantages in anti-freezing, mechanical flexibility and self-adhesiveness, making it a promising multifunctional electrolyte for flexible electronic devices. Both experimental results and molecular dynamics (MD) simulations jointly demonstrate that SA bridges HPW clusters to form a dense proton transport pathway induced by multiple electrostatic and hydrogen bonding interactions between SA and HPW counterparts, which contributes to the high-level proton conductivity of the PVA-Gly/HPW-SA-20% hydrogel. This work provides new insights into the design of POM-based flexible materials with superionic conductivity.

α-Imino metal carbenes are versatile intermediates in organic synthesis, and have broad applications in the assembly of divergent N-heterocycles. However, the catalytic enantioselective desymmetrization based on α-imino metal carbenes has not been developed to date. Herein, we disclose an enantioselective desymmetrizing C(sp²)–H functionalization of azide-ynamides via α-imino copper carbenes, leading to the efficient assembly of divergent chiral indoloazepines in generally moderate to excellent yields with high enantioselectivities. Notably, this reaction represents the first enantioselective desymmetrization based on α-imino metal carbenes. Further synthetic transformations and biological tests show the potential utility of this method. Moreover, computational studies are employed to elucidate the reaction mechanism and the origin of enantioselectivity.

The central-to-axial chirality conversion represents a fascinating class of chemical processes consisting of the destruction of stereogenic centers and the simultaneous installation of axial chiral elements, which provides efficient methods for the preparation of axially chiral compounds. However, developing catalytic asymmetric approaches for constructing these central chirality precursors and the efficient central-to-axial chirality conversion remains a challenge due to the requirement of aromatization or elimination process. In this work, we have developed an unprecedented enantioselective intramolecular Friedel-Crafts alkylation with unactivated-ketone carbonyls from which a chiral tertiary alcohol was generated with high efficiency and excellent enantioselectivity. In addition, the central-to-axial chirality conversion strategy has been successfully applied to the synthesis of enantioenriched biaryls via a less-explored carbocation-initiated rearrangement and aromatization under the promotion of Lewis acid. This methodology provided a straightforward and sustainable access to a broad range of biaryl-2-carboxylic acid and in excellent yields (up to 92%) and excellent central-to-axial chirality conversion (up to 99% conversion percentage). This work could be a great model for developing new methods for synthesizing axially chiral biaryls and a general protocol for the rearrangement and aromatization of carbocations for further functionalization.

Metal phthalocyanines (MPcs) have gained considerable research attention as hole-transport materials (HTMs) in perovskite solar cells (PSCs) because of their superb stability. However, the photovoltaic performance of MPc-based HTMs in PSCs is still lagging behind their small molecule and polymeric counterparts, largely due to their relatively low hole mobility. Here, we report for the first time the application of a copper naphthalocyanine derivative (namely tBu-CuNc) as a hole-transport material (HTM) in perovskite solar cells (PSCs), and systematically study its optoelectronic and photovoltaic property compared with its CuPc analog (tBu-CuPc). Combined experiments disclose that the extension of π-conjugation from Pc to Nc core leads to not only an enhanced hole-carrier mobility associated with a stronger intermolecular interaction, but also an elevated glass transition temperature (T_g) of 252 °C. The resultant PSCs employing tBu-CuNc deliver an excellent power conversion efficiency of 24.03%, which is the record efficiency reported for metal complex-based HTMs in PSCs. More importantly, the encapsulated tBu-CuNc-based devices also show dramatically improved thermal stability than the devices using the well-known Spiro-OMeTAD, with a T₈₀ lifetime for more than 1,000 h under damp-heat stress. This study unfolds a new avenue for developing efficient and stable HTMs in PSCs.