Variable Temperature Fluorescence Research Articles

Flexible AIE/PCM composite fiber with biosensing of alcohol, fluorescent anti-counterfeiting and body thermal management functions

Alcohol sensing plays a critical role in medical detection and personal health management. AIE materials with high sensitivity, selectivity and fast response have been widely used in biosensing, but their application in the field of alcohol sensing still needs further research and development. Furthermore, developing flexible phase change materials (PCMs) is significant for the research of human-body thermal management. In this study, a kind of flexible polyacrylonitrile (PAN)/polyvinylpyrrolidone (PVP)/polyethylene glycol (PEG)/Py-CH (pyrene-based AIE molecule)/SiO2@h-BN composite fiber textile (PAB) with alcohol sensing performance, writable fluorescence property, and human body thermal management function has been prepared via electrospinning technique. The PAN/PVP fiber matrix successfully integrated AIE fluorescent sensing material and PCM into a multi-functional composite with great shape stability. Owing to the introduction of novel pyrene-based Py-CH with AIE characteristic, this innovative textile exhibited wonderful fluorescent properties, including sensitive alcohol fluorescence sensing, writable fluorescence performance and variable temperature fluorescence. Furthermore, proposed PAB textile delivered a high energy storage density of 87∼90 J/g, excellent thermal reliability, great comprehensive mechanical flexibility and enhanced thermal conductivity for flexible human body thermal management. Hence, this flexible multifunctional AIE/PCM composite sensing textiles can be widely used in alcohol sensing, fluorescence anti-counterfeiting and flexible body thermal management.

Silver/Antimony-Base Multifunctional Double Perovskite with H/F Substitution Enhance Properties.

Two-dimensional double perovskites have experienced rapid development due to their outstanding optoelectronic properties and diverse structural characteristics. However, the synthesis of high-performance multifunctional compounds and the regulation of their properties still lack relevant examples. Herein, we synthesized two multifunctional compounds, (C6H14N)4AgSbBr8 (1) and (F2-C6H12N)4AgSbBr8 (2), which exhibit high solid-state phase transition temperature, bistable dielectric constant switching, second harmonic generation (SHG), and bright emission. Through H/F substitution, the transition temperature increases and achieves a smaller band gap attributed to reduced interlayer spacing. Furthermore, we investigated the broad emission mechanism of the compounds through first-principles calculation and variable-temperature fluorescence, confirming the presence of the STE1 emission. Our work provides insight into the further development of multifunctional compounds and chemical modification that enhances compound properties.

Synthesis and characterization of N-TMS-2-pyridinamine dimethyl-aluminum: A dormant precursor

An aluminum precursor (N-TMS-2-pyridinamine dimethyl-aluminum) with the dormant property was synthesized. Dormant precursor's structure, the change of structure with temperature, and thermodynamic property were verified by Single-crystal XRD, NMR, variable-temperature NMR, elemental analysis, variable-temperature fluorescence, and TG/DSC. Single-crystal XRD proved that N-TMS-2-pyridinamine dimethyl-aluminum is dimer(dormant) at room temperature. 1H NMR showed that N-TMS-2-pyridinamine dimethyl-aluminum exists as monomer, dimer, and trimer in C6D6. Variable-temperature NMR demonstrates that temperature changes alter the structure of dormant precursor, and that increasing the temperature cause dormant precursor to form monomer. Dimer(dormant) depolymerize rapidly to monomer at 105 °C(The LnP-T−1 curve of the dimer shows that the evaporation enthalpy ΔHvapour of the dimer decreases rapidly around 105 °C), dimer slowly depolymerizes to monomer at 50 °C (isothermal TG shows that the weight loss rate increases obviously at about 300 min). TG shows that both dimer and monomer have good thermal stability and volatility(residual mass < 1.5%, Tvapor pressure at p=1 Torr of dimer = 90 °C, Tvapor pressure at p=1 Torr of monomer = 38 °C), the volatility of monomer is better than that of dimer. N-TMS-2-pyridinamine dimethyl-aluminum can convert the dormant state(dimer) to the better volatile active form (monomer) by adjusting its configuration by temperature, which can provide a case study for the development of dormant precursors.