近红外原位研究杂多酸引发的环氧-四氢呋南阳离子聚合

用近红外光谱原位跟踪的方法,研究了杂多酸催化的环氧树脂和四氢呋喃的阳离子聚合过程.发现在低环氧树脂含量下,环氧消耗速率在整个聚合过程中维持不变;而在高环氧树脂含量下,环氧消耗速率则随时间有所下降.通过红外光谱在碳氢区域的分峰分析,证明环氧树脂与四氢呋喃发生了共聚反应,二维红外光谱的结果也确证了这一结果.此外,还探讨了环氧转化速率与环氧含量间的关系.     

多级孔NiMo负载TS-1分子筛催化剂的制备及其加氢脱硫性能

钛硅(TS-1)分子筛的微孔孔道严重限制了其在复杂分子催化转化中的应用,为了克服这一问题,通过酸洗脱、碱刻蚀及二者相结合的方法制备了多级孔TS-1分子筛,并采用等体积共浸渍法制备了相应的NiMo负载型催化剂;使用X射线衍射(XRD)、N₂吸附-脱附、吡啶吸附红外光谱(Py-FTIR)、氢气程序升温还原(H₂-TPR)、X射线光电子能谱(XPS)和高分辨透射电子显微镜(HR-TEM)等方法对多级孔TS-1分子筛的理化性质进行了表征;以二苯并噻吩(DBT)为探针对催化剂的加氢脱硫(HDS)性能进行了评价。结果表明,和常规TS-1分子筛相比,多级孔TS-1分子筛保持了MFI拓扑结构,比表面积增大且具有介孔结构,分子筛表面形成了适量的Brønsted酸中心;相应催化剂上活性金属与载体间相互作用得以改善,MoS₂片晶长度和堆垛层数适宜,形成了更多的NiMoS活性相;催化剂活性和选择性均有所提升,尤其是酸洗脱获得的NiMo/AT-TS-1催化剂的活性相较未经处理的NiMo/TS-1催化剂提升了1.2倍,直接脱硫(DDS)路径选择性提升了22%。     

聚醚酰亚胺改性TGDDM环氧树脂的相分离研究

合成了不同化学结构的聚醚酰亚胺(PEI)并用于4,4′-二氨基二苯甲烷四缩水甘油醚(TGDDM)环氧树脂的增韧改性,以DSC,TRLS和SEM等方法研究了体系相分离过程中相容性和熔融粘度对相分离过程和结构的影响,对固化反应诱导相分离中相结构的控制提出初步的看法.     

Coordination-Induced Emission from Tetraphenylethylene Units and Their Applications

Thanks to the potential of aggregation-induced emission (AIE) phenomena, improved stabilities, and the good selectivity and sensitivity of the chemical responses exhibited by the products, coordination-driven self-assembly with tetraphenylethylene (TPE) units has recently received much attention and has been widely investigated for application in chemical sensors, cell imaging agents, light-harvesting systems, and others. Several reviews have emerged on the topics of AIE chemistry and aggregation-induced emission luminogen (AIEgen)-based supramolecular assembles, however, there is still a distinct lack of full overviews of emission enhancement from the viewpoint of metal-coordination effects. Thus, this minireview offers recent advances that have been made in the design and application of TPE-based metallacycles, metallacages, metal-organic frameworks (MOFs) and coordination polymers (CPs).     

Supramolecular Construction of a [16]-Imidazolium Cage via a Quadruple [2+2] Photocycloaddition and Its Selective Fluorescent Recognition of Pyranine (HPTS)

Polyimidazolium-based cages are considered promising materials based on their fascinating properties and potential applications. These three-dimensional functional structures are highly desirable for the recognition of particular guest molecules, however, their synthesis remains challenging. In this work, we have designed and synthesizes a pure [n]-imidazolium (n=16) cage, the hexadecakisimidazolium salt H₁₆- 2 (PF₆)₁₆, from tetragonal octakisimidazolium salt H₈- 1 (PF₆)₈. The synthetic method involves formation of metal-carbene templates, a quadruple photochemical [2+2] cycloaddition reaction and subsequent removal of metal ions. Specifically, the synthesized cage, featuring sixteen imidazolium moieties, demonstrated high efficiency for the selective fluorescent recognition of 8-hydroxy-1,3,6-pyrene trisulfonate (HPTS). The present work not only further develops the metal-carbene template strategy by exploiting a new type of polyimidazolium cage, but also provides encouraging prospects for the design of versatile imidazolium-based functional acceptors.     

Numerical analysis for the effcacy of nasal surgery in obstructive sleep apnea hypopnea syndrome

In the present study, we reconstructed upper airway and soft palate models of 3 obstructive sleep apnea–hypopnea syndrome(OSAHS) patients with nasal obstruction. The airflow distribution and movement of the soft palate before and after surgery were described by a numerical simulation method. The curative effect of nasal surgery was evaluated for the three patients with OSAHS. The degree of nasal obstruction in the 3 patients was improved after surgery. For 2 patients with mild OSAHS, the upper airway resistance and soft palate displacement were reduced after surgery. These changes contributed to the mitigation of respiratory airflow limitation. For the patient with severe OSAHS, the upper airway resistance and soft palate displacement increased after surgery, which aggravated the airway obstruction. The effcacy of nasal surgery for patients with OSAHS is determined by the degree of improvement in nasal obstruction and whether the effects on the pharynx are beneficial. Numerical simulation results are consistent with the polysomnogram(PSG) test results, chief complaints, and clinical findings, and can indirectly reflect the degree of nasal patency and improvement of snoring symptoms, and further,provide a theoretical basis to solve relevant clinical problems.     

Unravelling the Roles of Solvophobic Effects and π⋅⋅⋅π Stacking Interactions in the Formation of [2]Catenanes Featuring Di-(N-Heterocyclic Carbene) Building Blocks

A series of [2]catenanes has been prepared from di-NHC building blocks by utilizing solvophobic effects and/or π⋅⋅⋅π stacking interactions. The dinickel naphthobiscarbene complex syn-[ 1 ] and the kinked biphenyl-bridged bipyridyl ligand L² yield the [2]catenane [ 2-IL ](OTf)₄ by self-assembly. Solvophobic effects are pivotal for the formation of the interlocked species. Substitution of the biphenyl-linker in L² for a pyromellitic diimide group gave ligand L³ , which yielded in combination with syn-[ 1 ] the [2]catenane [ 3-IL ](OTf)₄. This assembly exhibits enhanced stability in diluted solution, aided by additional π⋅⋅⋅π stacking interactions. The π⋅⋅⋅π stacking was augmented by the introduction of a pyrene bridge between two NHC donors in ligand L⁴ . Di-NHC precursor H₂- L⁴ (PF₆)₂ reacts with Ag₂O to give the [Ag₂ L⁴ ₂]₂ [2]catenane [ 4-IL ](PF₆)₄, which shows strong π⋅⋅⋅π stacking interactions between the pyrene groups. This assembly was readily converted into the [Au₂ L⁴ ₂]₂ gold species [ 5-IL ](PF₆)₄, which exhibits exceptional stability based on the strong π⋅⋅⋅π stacking interactions and the enhanced stability of the Au-C_NHC bonds.     

Twisted intramolecular charge-transfer state of trans-3-(N,N-Dimethylamino)-4'-cyanostilbene: The C−C bond twisting

Whether a twisted intramolecular charge-transfer (TICT) state is formed is an important issue for understanding the fluorescence properties of a push-pull organic dye. Here we report a position effect of the donor substituent on the TICT state formation of aminostilbenes: namely, trans-3-(N,N-dimethylamino)-4′-cyanostilbene ( mDCS ) behaves differently from its TICT-free para isomer DCS and forms a TICT state in acetonitrile (MeCN). The TICT state of mDCS also differs from that of many previously reported aminostilbenes by twisting a C−C bond instead of a C−N bond. In addition, among the ring-bridged model compounds mDCS-N , mDCS-C1 , and mDCS-C2 , we observed an unusual electronic effect of the ring-bridging in mDCS-C2 that mitigates the impact of the TICT state on the fluorescence properties. Both the C−C bond twisting in mDCS and the ring-bridging electronic effect in mDCS-C2 provide new insights into the TICT chemistry of aminostilbenes.     

CO2-based Biodegradable Supramolecular Polymers with Well-tunable Adhesive Properties

Supramolecular adhesives that enable debonding on-demand are of significant research interest for the development of adaptive and smart materials,yet,biodegrable supramolecular adhesives have been rarely exploited.Herein,telechelic,three-armed and four-armed CO₂-based polyols with close molecular weights and various content(or carbonate unite content)have been synthesized via a zinc-cobalt double metal cyanide complex catalyzed ring-opening copolymerization of CO₂ and propylene oxide,and further exploited as sustainable and biodegradable building blocks for supramolecular polymers(SMPs)with 2-ureido-4[1H]-pyrimidinone(UPy)motifs.Notably,the orthogonal modulation of the CO₂ content and the topology of CO₂-based polyols provide a unique opportunity to fine-tune the surface energy as well as the cohesive strength of the resulting CO₂-based SMPs.Notably,a three-armed SMP with 44%CO₂(3UPy-CO₂-44%)can well balance the trade-off between surface energy and cohesive strength,therefore bestowing a high adhesive strength of 7.5 and 9.7 MPa towards stainless steel and wood substrates respectively by testing the corresponding single lap joints.Moreover,the light-responsive adhesion property of 3UPy-CO₂-44%has been demonstrated exemplarily by blending with a UV sensitizer.     

Frustrated molecular packing in highly ordered smectic phase of side-chain liquid crystalline polymer with rigid polyacetylene backbone

Using poly(5-{[(4'-heptoxy-4-biphenylyl)carbonyl]oxy}-1-pentyne) as an example, we demonstrate the incorporative accommodation of the rigid polyacetylene backbones and the mesogenic pendants, which leads to a highly ordered smectic (Sm) phase with a frustrated structure. The polymer exhibits a recognizable sheetlike molecular shape due to its rigid backbone and relatively short spacer (three methylene units), and the building block of the liquid crystalline (LC) phase is the whole molecule. In the LC phase, five layers of the molecules stack as a smectic A (SmA) block, and adjacent SmA blocks glide halfway of the molecular width from one to another. In scanning tunneling microscopy (STM) experiments, the STM tip scrape is found to generate a regular nanopattern with periodic electron conductivity, of which the spacing is determined by the side-chain length.