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Macrocycles are key tools for molecular recognition and self‐assembly. However, traditionally prevalent macrocyclic compounds exhibit specific cavities with diameters usually less than 1 nm, limiting their range of applications in supramolecular chemistry. The efficient synthesis of giant macrocycles remains a significant challenge because an increase in the monomer number results in cyclization‐entropy loss. In this study, we developed a low‐entropy‐penalty synthesis strategy for producing giant macrocycles in high yields. In this process, long and rigid monomers possessing two reaction modules were condensed with paraformaldehyde via Friedel–Crafts reaction. A series of giant macrocycles with cavities of sizes ranging from 2.0 to 4.7 nm were successfully synthesized with cyclization yields of up to 72%. Experimental results and theoretical calculations revealed that extending the monomer length rather than increasing the monomer numbers could notably reduce the cyclization‐entropy penalty and avoid configuration twists, thereby favoring the formation of giant macrocycles with large cavities. Significantly, the excellent self‐assembly capacity of these giant macrocycles promoted their assembly into organogels. The xerogels exhibited enhanced photoluminescence quantum efficiencies of up to 83.1%. Mechanism investigation revealed the excellent assembly capacity originated from the abundant π–π interactions sites of the giant macrocycles. The outstanding emission enhancement resulted from the restricted nonradiative decay processes of rotation/vibration and improved radiative decay process of fluorescence. This study provides an effective and general method for achieving giant macrocycles, thereby expanding the supramolecular toolbox for host–guest chemistry and assembly applications. Moreover, the intriguing assembly and photophysical properties demonstrate the feasibility of developing novel and unique properties by expanding the macrocycle size. [ABSTRACT FROM AUTHOR]

Diels-Alder (DA) addition is an efficient method to repair damages at mild conditions. It is often used in self-healing polyurethanes and epoxy resins and seldom used in cross-linked polyamides (cPAs). Michael addition becomes a useful method to synthesize cPAs. However, no efficient way has been established to conduct double-addition of primary amines. In this work, organic catalyzed Michael addition and polycondensation were established to prepare polyamide oligomers with furan pendent groups (pFU-PAs), and a DA addition was adopted to prepare self-healing cross-linked polyamides (SH-cPAs). A bulk double Michael addition of furfurylamine and methyl acrylate was performed at 30-70[degrees]C in the presence of 1,5,7-triazabicyclo[4.4.0] dec-5-ene (TBD), 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD), or 4-(N,N-dimethylamino) pyridine (DMAP), and a high yield of furfurylamine-N,N-bis(methyl propionate) (FA-BMP) was prepared. The catalytic activity order is MTBD>TBD >> DMAP in Michael addition. Melt polycondensation of FA-BMP with bis(2-aminopropyl) polypropyleneglycol and hexamethylene diamine was catalyzed by MTBD and N,N'-diphenylthiourea. The DA addition of 1,5-bismaleimido-2-methylpentane and pFU-PAs was monitored by FT-IR, [sup.1]H NMR, DSC, polarizing optical microscopy, and gel content. In these catalyzed processes, the structures of FA-BMP, pFU-PAs, and SH-cPAs were controlled easily, and the SH-cPAs showed good mechanical property and excellent self-healing performance of 88%-98%. KEYWORDS Diels-Alder addition, Michael addition, organic catalysts, polycondensation, self-healing polyamides, 1 | INTRODUCTION Thermoset polymers have a three-dimensional cross-linked structure, and they exhibit remarkable advantages, such as solvent resistance, heat resistance, dimensional stability, and excellent mechanical properties. [1-3] During their [...]

In order to study the influence of stretching process parameters on the safety performance of modified double base propellant molding process, the compression melting section, melt conveying section and die forming section are modeled as a whole, the density, rheological properties of the modified double base propellant slurry are determined, the mesh independ¬ence of the fluid domain is verified based on Polyflow software, and the safety characteristics of the stretch molding process of the modified double base propellant slurry under non-isothermal conditions are studied. The results show that the increase of screw speed increases the temperature, pressure and shear rate of the slurry, and there is a risk of ignition and explosion, in or¬der to ensure the safety, the appropriate screw speed in the stretching molding process is 10 r/min. With the increase of screw temperature, the shear rate decreases, the plasticization degree of the material becomes worse, and the increase of screw temperature is easy to decompose the material, combined with the composition characteristics of the sensitive material of mod¬ified double base propellant, the screw temperature is relatively safe at 85 °C . Compared with the screw temperature, the change of sleeve temperature has little influence on the material flow field, and combined with the actual production conditions of modified double base propellant, the sleeve holding temperature of 70 °C is suitable for the production of modified double base propellant. Based on the simulation results, it is concluded that the effects of rapid changes in pressure and temperature should be paid attention to in the propellant production process. [ABSTRACT FROM AUTHOR]

A simple and green method was established to prepare self-healing crosslinked nonisocyanate polyurethanes (SH-cNIPUs) from biobased diglycerol bis(cyclic carbonate) (DGDC). Two nonisocyanate polyurethane prepolymers with furan terminal groups (tFU-NIPUs) were synthesized through a ringopening reaction of DGDC with furan methylamine and trimethylolpropane tris(poly[propylene glycol], amine terminated) ether, or tris(2-aminoethyl) amine under mild conditions. The SH-cNIPUs were prepared via a Diels-Alder reaction between tFU-NIPUs and a bismaleimide. SH-cNIPUs were characterized by ATI-FTIR, 'H NMR, differential scanning calorimetry, polarized optical microscope, and tensile strength after being damaged and healed. SH-cNIPUs with glass transition temperature from 8 to 49[degrees]C, tensile strength up to 21 MPa, and self-healing efficiency from 67 to 80% were successfully synthesized. KEYWORDS biobased, Diels-Alder reaction, nonisocyanate route, self-healing polyurethanes, 1 | INTRODUCTION Cross-linked polymers are used widely in our daily lives and in different industrial fields due to their dimensional stability and excellent mechanical properties. However, cross-linked polymers have [...]

The separation of toluene (Tol) and pyridine (Py) azeotropes is significant in the chemical industry. Herein, we present a new method for the energy-efficient separation of Tol and Py using pillar[5]arene-based adaptive macrocycle co-crystals (MCCs) that can selectively separate Py from a Py/Tol equimolar mixture with 99.2% purity, accompanied by vapochromic behavior from white to yellow. [ABSTRACT FROM AUTHOR]

Effective tiller number (ETN) directly affects panicle number and is closely related to wheat grain yield. Mining quantitative trait loci (QTLs) associated with wheat tiller number and analyzing the correlation between tiller number and other important agronomic traits can provide the theoretical basis for molecular breeding. In this study, we first proposed and established a novel genetic analysis framework of "multiple environmental assessments-depth analysis of individual traits-comprehensive evaluation of various traits-friendly marker development-verification in different backgrounds". Using this approach, low-tillering QTLs were identified and validated base on an F6 recombinant inbred line population (MC population) derived from the low-tillering plant msf and Chuannong 16 (CN16), phenotypic data of effective tillers from multiple environments, and a 16K chip-based constructed genetic linkage map. QTL mapping results showed that there were four QTLs controlling tillering on chromosomes 1A, 5A, and 6D, respectively. Qltn.sau-MC-1A was a stable and major low-tillering QTL explaining 13.39%--60.40% of the phenotypic variation rate, and its positive allele was from msf. Phenotypic analysis showed that ETN of the lines carrying the positive allele of Qltn.sau-MC-1A was significantly less than those with the negative alleles. Correlation analysis showed that ETN had a significantly positive correlation with plant height (PH), and a significantly negative correlation with thousand kernel weight (TKW), kernel number per spike (KNPS), kernel weight per spike (KWPS), and flag leaf width (FLW), but no significantly correlation with flag leaf length (FLL) and anthesis date (AD). Genetic analysis showed that positive allele of Qltn.sau-MC-1A had a significant effect on increasing KNPS, KWPS, and TKW, but delaying AD. Validation results in different backgrounds suggested that the ETN of lines carrying positive alleles from Qltn.sau-MC-1A could be significantly decreased. Collectively, we established a new genetic mapping approach and further used it to identify and validate a major QTL controlling low-tiller number, Qltn.sau-MC-1A, which laid a foundation for further fine mapping and understanding the mechanism of tiller formation. [ABSTRACT FROM AUTHOR]

Two novel species within the family Dictyosporiaceae are described and illustrated from terrestrial habitats on dead culms of bamboo and an unidentified plant, respectively. Through morphological comparisons and the multi-locus phylogenetic analyses of combined LSU , ITS , SSU , and tef1-α sequence dataset, two species, Gregarithecium bambusicola, Pseudocoleophoma paraphysoidea are identified. Phylogenetically, both species clustered into a monophyletic clade with strong bootstrap support. Gregarithecium bambusicola sp. nov. can be distinguished from other species within the genus based on its almost straight ascospores. Pseudocoleophoma paraphysoidea sp. nov. differs from other species in its conidiogenous cells intermixed with paraphyses, longer conidiogenous cells and larger conidia. The identification of this lineage contributes to our understanding of the classification of Dictyosporiaceae. [ABSTRACT FROM AUTHOR]