Supramolecular Chirality And Circularly Polarized Luminescence Of Chiral Organic Molecules Self-assembly Structures

Chirality is a basic characteristic of nature.In nature,chirality can be observed at various scales from molecular to supramolecular and galactic scales.Among these various levels of chirality,supramolecular chirality systems have been aroused much attention and studied by many groups.The supramolecular chirality can be characterized by circular dichroism(CD).Understanding the generation,transmission and amplification of supramolecular chirality are of great significance for uncovering many complex processes in life.In recent years,materials with excited chirality,namely,circularly polarized lunimescence(CPL),have attracted much attention for many researchers due to their wide potential applications in chiroptical devices,3D imaging and sensing.For pure orgnic molecular CPL systems,the emission can be readily tuned by bringing about modulations in their excited state electronic levels.However,the relatively low dissymmetry g factor(glum)of organic systems make it difficult to further utilizing such materials.Therefore,to obtain organic CPL-active materials with relatively high dissymmetry g factor and adjustable emission in a convenient way has great significance for obtaining chiroptical materials.In this thesis,various structures with circularly polarized luminescence based on self-assembly of organic molecules have been obtained.In the process of molecular assembly,the chirality induction,chirality transfer and energy transfer process were studied in detail,which were necessary for obtaining materials with chiroptical activity.The main research contents and achievements are as follows:(1)The morphology regulation of chiral orginic molecular self-assembly with amplification of luminescence dissymmetry factor glum was investigated.Chiral spiro anthracene SPAn molecules could self-assemble into various nanostructures by changing the ratio of THF/H2 O solvent.With increasing of the ratio of water,nanostructures were transformed from 0D spherical structure to 2D and 3D nanosheets.During the structural transformation process,the supermolecular chirality and circular polarization luminescence were amplified.It showed that,with increasing the fraction of water,the intermolecular interaction became stronger which resulted in the formation of orderly and compact arrangement of nanostructures.The well-packed nanostructures induced the strong excimer emission at the excited state,which contribute to the sequential amplification of circularly polarized luminescence.By molecular assembly,we obtained nanomaterials with relative high dissymmetry g factor in pure organic system,which provides an efficient way for fabricating higher dissymmetry factor CPL organic nanomaterials.(2)An axial chiral molecule BIAn was utilized to self-and co-assembly with two achiral dye molecules ThT and AbR to construct nanoparticle structure with full-color circularly polarized luminescence.BIAn molecule could self-assemble into nanoparticle with CD and CPL-active.Moreover,the chiral molecules could co-assembly with dye molecules through intermolecular interactions.In the process of co-assembly,by the cooperation of chirality transfer and energy transfer,the nanoparticles with green and red circularly polarized emitting were obtained.By simply co-assembly of chiral molecules with dye molecules,the nanoparticels with full-color CPL were obtained,which provides a convenit way for preparation of 0D chiral materials without tedious synthetic way.The different colors of the chiral nanoparticles could be mixed in different ratios and the 0D nanostructure with white color circularly porlarized luminescence could successfully obtained by radiation energy transfer between nanoparticels.Furthermore,by decorating chiral nanoparticles with magnetic nanoparticles,the magnetic responsive nanoparticles with CPL-active could be obtained.Meaningfully,the magnetic responsive nanoparticles exhibited flexible control on the separation of the mixed colors nanoparticles.The magnetic-responsive chiral organic nanoparticles with CPL-active based on self-assembly of chiral organic molecules can be a promising candidate for chiroptical materials.(3)Supra-amphiphiles self-assembled nanovesicles with chiroptical activity was studied.Coumarin-substituted diacetylene molecule could form supra-amphiphiles with γ-CD by host-gust interaction.Under UV iiradiation,the polymerized vesicles with chiral optical activity were obtained by self-assembling of the supra-amphiphiles.The orderly arranged supra-amphiphiles of the vesicles could polymerize through topochemical reactions upon UV-irradiation.During the process of polymerization,the induced molecular chirality transferred from the supra-amphiphiles to the polymer backbone,so the chiral polymerized vesicles were obtained.Furthermore,by supramolecular chirality transferred from polymerized vesicle to dye molecule,the composite vesicles of s supra-amphiphiles with dye molecules showed supramolecular chirality and circularly polarized luminescence after photopolymerization.In summary,we have obtained various nanostructures with supramolecular chirality and circularly polarized luminescence by self-and co-assembly of chiral organic molecules with achiral guest molecules and chiral supra-amphiphiles.The supramolecular chirality transfer,amplification of chirality and dissymmetry g factor and energy transfer of the assemblies were investigated in detail.This work will provide an effective strategy and theoretical guidance for the preparation of nanomaterials with chiroptical activity.