Synthesis Of Halloysite Nanotubesbased Conjugated Materials And Conjugated Tetracoordinate Organoboron Compounds

Recently,the development of conjugated nanomaterials has drawn tremendous attention in polymer materials and nanomaterials fields.The surface modification by conjugated compounds is one of the main approaches to prepare conjugated nanomaterials.Halloysite nanotubes?HNTs?are natural tubular materials.A number of advantages such as the unique micro-spatial structure,large length-diameter ratio,large cavity volume,biocompatibility and low-cost make them to be promising materials in the fields of energy,catalysis,bio-medical,environmental protection and many so others.In this study,a serious of HNTs-based conjugated materials were prepared via the surface modification method,which expanded the application in the fields of bio-medicine and fluorescent materials.Two types of tetracoordinate organoboron compounds and relating conjugated polymers were also synthesized in order to provide the infrastructural support to enhance the fluorescent performance of the HNTs-based conjugated materials.The main work is as follows:Chapter I: The development of HNTs was briefly introduced.Chapter II: The amino-modified halloysite nanotubes?HNTs-NH2?were obtained by treating HNTs with KH550?,a commercial available silane coupling agent,and then reacted with 2-bromoisobutyryl bromide and sodium azide to give the azide-functionalized HNTs.The poly?alkylfluorene?derivative bearing terminal acetylenic hydrogens was grafted onto the azide-functionalized HNTs via “click” chemistry.The synthesized poly?alkylfluorene?-grafted HNTs exhibited good fluorescence property.Chapter III: An efficient method was developed by functionalize the 1-pyrenylboronic acid?PBA?onto the inner surface of HNTs by the dehydration condensation between arylboronic acid and vicinal diol group.The tube's outer siloxane surface was almost not changed during the reaction.The obtained PBA-modified HNTs showed good fluorescence property and water dispersibility.The established B-C linkage gave a highly specific and sensitive H₂O₂-sensitivity to HNTs.As a result PBA-modified HNTs can serve as a fluorescence probe for the detection of hyperoxide.Chapter IV: 1,4-Phenylenediboronic acid was conjugated to the alumina surface of HNTs to give the phenylenediboronic acid-modified HNTs.Pentoxifylline,a non-steroid antiinflammatory drug?NSAID?and has been proven to be an antitumor agent in the latest studies,was load into the lumen of the phenylenediboronic acid-modified HNTs.The arylboronic acid groups near the openings of drug-loaded HNTs were capable of crosslinking polysaccharides via the dehydration condensation between arylboronic acid and vicinal diol group,and then gave a uniform chemical hydrogel.The drug-loaded hydrogel showed a H₂O₂-sensitive release behavior and a reduction effect on the “initial burst effect”.Chapter V: An intermediate compound bearing two N,O-bidentate ligands was synthesized via a benzoin condensation reaction.Then two types of conjugated tetracoordinate organoboron compounds were synthesized by treating the intermediate compound with BF3 and BPh3,respectively.The crystal structure of BF2-chelated conjugated tetracoordinate organoboron compound was given in the text.The synthesized organoboron compounds exhibit good fluorescence property and thermostability.A photoswitching device was then fabricated based on a thin film of BF2-chelated conjugated tetracoordinate organoboron compound spincoated onto single walled carbon nanotubes,which produced a steady and reproducible photocurrent response.Chapter VI: The boron-chelated conjugated polymers were synthesized by the SuzukiMiyaura coupling reaction.The obtained polymers showed good solubility in CH2Cl2,CHCl3,tetrahydrofuran,and some other common organic solvents.The boron-chelated conjugated polymers showed good fluorescence property in both solution and film state.The investigations of the HNTs-based nanocomposites bearing the synthesized organoboron compounds or their derivatives will be focus on in the coming studies.