Preparation And Optical Properties Of POSS Luminescent Gel

Nanomaterials extracted from agricultural and forestry wastes rich in silicon have excellent optical properties.Therefore,the existence of Si-O-Si structure can greatly improve the optical properties of the materials.Polyhedral Oligomeric Silsesquioxane（POSS）is a special new organic-inorganic hybrid nanomaterial with multiple active sites.Its Si-O-Si rigid framework can effectively improve the luminescence performance and the photothermal stability of the luminescent materials.In this paper,3-aminopropyl triethoxy silane（APTE）was used as raw material to synthesze a series of irregular aminopropyl silsesquioxanes to optimize the coordination environment and energy conversion efficiency of Eu³⁺.In addition,cage-like octapropyl siloxane（OAP-POSS）was synthesized and amidated to obtaine aggregation-induced luminescence（AIE）materials.To expand the application of functionalized POSS molecules,multifunctional agarose hydrogel was prepared which can not only be used to detect and adsorb ions in water,but also has excellent photothermal properties.1.The coordinatiol environment around Eu³⁺ plays an important role in the optical properties of the complex.Therefore,structure-controllable oligomeric silsesquioxane ligands was introduced to optimize the coordination environment and energy conversion efficiency of Eu1+,thereby significantly improving the photoluminescence properties of the complexes.More importantly,the photo luminescent properties of the product will be altered because of the formation of the Si-O-Si structure.In addition,the observed trend of Judd-Ofelt intensity parameters was used to justify the coordination environment of Eu³⁺ ions.The experimental results reveal that the sol-gel reaction of the ligands can not only effectively promote intramolecular energy transfer,but also make the coordination environment of rare earth ions into a low-symmetric coordination environment to enhance the luminescence efficiency of rare earth ions.In order to further explore the relevant mechanism,theoretical calculations were conbined with experiments,the results show that the sol-gel reaction will induce the separation of the distribution of excited holes and electrons,leading to an efficient charge-transfer（CT）process.Consequently,the sol-gel reaction occurring among ligands will be attributed to an efficient CT process,leading to a strong luminescence intensity,as observed experimentally.2.Besides,during the experiment,it was discovered that irregular POSS has a certain fluorescence effect.Fluorescence spectroscopy was used to determine the emission peak at 525 nm when excited by ultraviolet light with a wavelength of 435 nm.In order to further explore this fluorescence phenomenon,we selected octaaminopropyl cage silsesquioxane（OAP-POSS）as the substrate.By the amidation of OAP-POSS,we obtained a series of aggregation-induced luminescence（AIE）materials（PAOP,CAOP）.Through the combination of experiments and theoretical calculations,we found that although the POSS-core rarely participate in the excited state charge transfer,the core structure will restrict the π-π staking of the chromophores to enhance the monomer emission in dilute solution and the strong self-assembly properties after organic modification will strengthen aggregate induce emission.In addition,PAOP has high selectivity and sensitivity to monomer emission enhancement of fluorine ion（F-）.3.Inspired by the unique adsorption properties of hydrogel,we prepared functionalized POSS and loaded them into the framework of agarose gel matrix to expand the application of functionalized POSS molecules.According to the spectroscopic change after the docking between AIE probes with agarose hydrophobic region,the interaction of the AIE-active probe and polysaccharide structures were discussed.This provides unique evidence to decipher the condition and photophysical nature of the molecules in interpenetrated networks.In addition,the adsorption of agarose can be used to detect and adsorb ions in water and the composite hydrogel after adsorption has excellent photothermal properties..