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Tuneable Emission of Polyhedral Oligomeric Silsesquioxane‐ Based Nanostructures Self‐Assembled in the Presence of Europium(III) Ions: Reversible trans‐to‐cis Isomerization
摘要： Hybrids nanostructures with switchable and reversible “blue-red-green” emission were efficiently synthesized. The Polyhedral Oligomeric Silsesquioxane (POSS) behaves as a directional nano-cage for the terpyridine-based organic ligands allowing an easy complexation of Europium (III) cations. The complexes were characterized via UV-Vis and fluorescence spectroscopies and the stoichiometry was also confirmed via 1H NMR investigation. The octafunctionalized nano-cages allow forming novel self-assembled 3D architectures in presence of the lanthanide cation displaying a red-emission of particular intensity especially in solid state. The presence of an alkenyl group bridging the inorganic core to the organic moiety was employed to tune the emission properties via trans-cis isomerization of the double bond. In the case of O-POSS nanocages this isomerization was monitored also in presence of Eu(III) cations and was accompanied by an evident modification of the colour which passed from blue (trans-O-POSS) to red (Eu@trans-O-POSS) and finally to green (cis-O-POSS) as consequence of the release of the metal cations. This behaviour, together with the easy dispersion of the dry powder and the possibility of coating it as a film in presence of small amount of solvent, makes the emitting solid promising for applications in materials science.
关键词： europium,luminescence,silsesquioxanes,isomerization,self-assembly
更新于2025-11-14 15:32:45
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[Springer Series on Polymer and Composite Materials] Polymer/POSS Nanocomposites and Hybrid Materials (Preparation, Properties, Applications) || Synthesis Routes of POSS
摘要： The study of the chemistry of materials containing Si–O bonds was in the past mainly applied to both inorganic silica and minerals or to organic silicones ?eld in which the R2SiO unit dominates. However, in the last decade, the ?eld of silsesquioxane chemistry with general composition RSiO3/2 has grown dramatically and many structures have been proposed in the literature. The idea of this chapter is to make an overview of the main synthetic approaches used to prepare completely and partially polyhedral oligomeric silsesquioxanes (POSS), highlighting the advantages and the weakness of each procedure. A brief description of the characterization techniques used to analyze the physicochemical properties of POSS was also carried out.
关键词： Hydrosilylation,Functionalization,Close-cage POSS,POSS synthesis,Open-cage POSS,Polyhedral oligomeric silsesquioxanes,Corner capping,Cleavage
更新于2025-09-23 15:21:01
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Silicon Containing Hybrid Copolymers || Construction of Organic Optoelectronic Materials by Using Polyhedral Oligomeric Silsesquioxanes ( <scp>POSS</scp> )
摘要： Organic optoelectronic materials can be generally divided into small molecular weight semiconductors and conjugated polymers with high opto/electronic performance. This interesting electroluminescence and conducting properties were first discovered in the 1970s, but the real surge of the interest occurred in the past 20 years with significant improvements in material performance through creative material design and high material purification. Small molecular weight semiconductors are interesting because of their high purity, ordered structures, and ideal model for fundamental mechanism studies of excitons and charge carriers. Conjugated polymers are mainly used for device fabrication for their advantages of large‐area device fabrication, high performance, and multiple functions. Currently, organic materials receive considerable attention because of their successful applications in organic light‐emitting diodes (OLEDs), solar cell, liquid crystal display (LCD), thin film transistors, sensors, electrochromic devices, and many others. Thanks to the extensive academic and industrial efforts, the mechanism and the relationship between the molecular structure and optoelectronic properties have been illustrated, and various device structures have been developed. Although organic optoelectronic materials have experienced tremendous progress over the past 10 years in fundamental physics and real applications, more work is necessary such as theoretical descriptions in charge generation and transport, distinction in the contributions of various interactions, thermal stability improvement, and commercialization of existing applications. Various new phenomena are still being discovered every day and device performance is continuing to rise. Among these efforts, the incorporation of polyhedral oligomeric silsesquioxanes (POSSs) into organic optoelectronic materials to achieve improved performances has been attracting attention particularly because of the unique and interesting hybrid structures of POSS.
关键词： Electroluminescence,Organic optoelectronic materials,Polyhedral oligomeric silsesquioxanes (POSS),Liquid crystal display (LCD),Electrochromic materials
更新于2025-09-23 15:19:57
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Functional Silica and Carbon Nanocomposites Based on Polybenzoxazines
摘要： The preparation of organic/inorganic hybrid materials comprising a polybenzoxazine (PBZ) matrix incorporating silicon-based species (e.g., polydimethylsiloxane [PDMS], layered silicates [clays], and polyhedral oligomeric silsesquioxanes [POSS]) and carbon-based materials (e.g., carbon black, carbon fibers, carbon nanotubes, and graphene) has received much attention in recent years because these composites display low water absorption, low surface free energy, low dielectric constants, flame-retardancy, and excellent thermal and mechanical properties. This short review article describes the chemical and physical approaches that are used to prepare PBZs incorporating silica and carbon nanocomposites. In addition, recent reports of their physical properties are discussed, covering their dielectric constants and dynamic mechanical, thermal, electrical, and surface properties.
关键词： benzoxazine monomers,layered silicates,polyhedral oligomeric silsesquioxanes,double decker silsesquioxanes,polybenzoxazines,thermal curing polymerizations,polydimethylsiloxanes
更新于2025-09-10 09:29:36