| Amphiphic molecules with novel structures and function groups,especially those with ?-conjugated groups,are a hotspot of research in colloid and interface science.Due to the rigid planarity,strong p-p interaction and Van der Waals force,?-conjugated amphiphiles show a distinction to those traditional ones with flexible alkyl chains.More importantly,the existence of ?-conjugated groups endowed amphiphiles with unique properties of luminescence,electrics and magnetics?-conjugated amphiphiles adopt both electron-rich(such as naphthalene,anthracene,pyrene)and electron-deficient(such as NDI,PBI)conjugated groups,and larger conjugated structures,even oligomers or polymers with repeated conjugates units are also induced to amphiphiles.The novel luminescent properties and self-assembly capability of conjugated amphiphiles have attracted researchers for their potentials in materials and applications.Conjugated amphiphiles could assemble to liquid crystal materials and nano-devices with photoelectric functions,or form micro-vehicles,such as vesicles.Besides,conjugated amphiphiles are wide used as semiconductors,fluorescent probes and biological monitorsGenerally speaking,as the conjugated group becomes larger,both of the excitation and emission spectra would have a red shift,accompanies with significant enhancement of fluorescence intensity and quantum yield.However,a larger conjugated structure can cause severe ?-? interaction,leading a poor solubility in water and other nonpolar organic solvent,which restrict the application of those?-conjugated molecules in self-assembly and other fields.The build of amphiphiles from conjugated groups could enlarge the solubility and provides opportunities of forming aggregates,which mainly by the way of attaching linear aliphatic chains or alkoxy chains.We have paid attention to the branched chains modified ?-conjugated molecules,recently.Those molecules showed better solubility and amphipathy than the ones mentioned above,and more easily to form aggregation structures in solution.Furthermore,branched chains,especially asymmetric ones,break the orderly arrangement of molecules,resulting a markedly decrease of melting point(mp),even forming room temperature liquids.Given all that,we raised our design of new?-conjugated amphiphiles:We adopted different conjugated groups as head,which is attached with a imidazolium cation,and the cation with modified by branched alkyl chains in different length.In most cases,Br-is used to be the counteranion,and the properties could be adjusted by exchange of counteranion.Room temperature ionic liquids(RTIL)were easily obtained by this method.My thesis contains 7 chapters.The major research was the supramolecular assembly of our synthesized ionic compounds,both in solution and solvent-free state,and we also make explorations the photoelectric applications of those materials.In chapter I,we introduced the molecule design of ?-conjugated amphiphiles,as well as their development in colloid and interface chemistry,nanotechnology,soft materials and supramolecular assembly.We emphasized on the supramolecular assembly behaviors of ?-conjugated amphiphiles.In solvent-free state,they could develop functional molecular or ionic fluid or liquid crystal.In solvent,they could aggregate as vesicles or nanoparticles,or form materials such as gels and films.We also summarized their applications in detectors,photoelectrics and biology.At last,we introduced why selecting the tile and the significance of studying the topic,and the main contents of the research.In chapter II,we aimed on a series of luminescent ILs on the basis of naphthyl head group in Chapter 2 to Chapter 4.The ILs have naphthamide and branched alkyl chains attached on the both nitrogen of imidazolium,which are balanced by Br-.In Chapter 2,we studied the co-assembly of these ILs and POMs,which focused on the one with longest alkyl chain and {Mo72Fe30}.Owing to the electrostatic interaction between imidazolium and {Mo72Fe30}? and the hydrophobicity of naphthyl and branched alkyl chains,ILs would combine with {Mo72Fe30} to form encapsulated structure,in which {Mo72Fe30)and imidazolium are stay interiorly while naphthyl and branched alkyl leave outside.The structure is same as surfactants encapsulated POMs(SEPs),and could form highly ordered honeycomb pattern on the interfaces of air/water or air/solid,by breath figure method.The honeycomb films manufactured by luminescent ILs,have good emission properties and electrochemical properties.Such supramolecular structure with organic-inorganic hybrids have the merits of both side.In Chapter III,we deprotonated tta with NaOH,and formed complex anion Eu(tta)4-with coordination of Eu(tta)4-.The anion of amphiphlic ILs mentioned above was changed to Eu(tta)4-,generated a series of Eu-componds lEu(tta)4-4Eu(tta)4,with bright fluorescence.The f-f transition of lanthanide(III)ions is Laporte-forbidden,and dissociative Eu3+ could hardly emit in solution environments,while Eu complex Eu(tta)4-is with strong fluorescence in solution.Nevertheless,Eu(tta)4-would still be quenched in high water content environments.It is essential to prevent Eu(tta)4-form high polar solvent molecules,on the purpose of avoiding solvent quenching,increasing the fluorescence intensity.We used the methods of self-assembly in the mixture of good and poor solvent of lEu(tta)4 and prepared a kind of aggregates with obvious fluorescence enhancement.The aggregates encapsuled Eu(tta)4-interiorly,which avoid the energy dissipation by coordination of water molecules.In chapter IV,we also reported the research of assembly of four imidazolium bromides ILs in Chaper 4.This design creates a new type of amphiphilic ionic liquids with apolar-polar-apolar structure and a low melting point(mP,<-20?),which has not been achieved by reported counterparts.In solvent-free states,microphase segregation occurs with polar and apolar domains arrange bicontinuously as proved by molecular dynamics simulations.When dispersed in water,the bicontinuous structure still survived,forming self-stabilized giant aggregates with swollen polar channels and ultrahigh colloidal stability(up to years),which was verified by experiments and MD simulation.In chapter V,we synthesized a new kind of ionic compounds with high luminescent efficiency,by exchanging naphthyl head group to naphthalimide.Due to the high symmetric structure of naphthalimide and stronger ?-? interaction,these compounds balanced by Br-are with high mp,and no longer room temperature liquids We chose the one of lowest mp and exchanged the counteranion to larger NTf2-,and obtained supercool luminescent ionic liquid,which maintain liquid state for periods even the temperature is lower than mp.With the simply mixing of IL and fluorochrome dopants,resonance energy transfer would occur,resulting in multiple emission under single excitation.The emission of IL composite was highly adjustable by changing the molar ratio of IL and dopants,even gained white emission composite.In view of high viscosity and good adhesion of the IL,it was used as white emission ink and fluorescent coating of white emission OLEDIn chapter VI,we mainly studied the properties of naphthaimide ionic compounds with Br-counterion,which have high melting points.Compounds with linear alkyl were also prepared to be the reference of branched alkyl modified ones.In fact,the series of compounds performed unique assembly behavior in solvent-free state and maintained highly ordered structure.Among them,those with long branched alkyl chained were considered to be thermotropic liquid crystal,while those with linear alkyl chains would remain supercool amorphous during the cooling procedure.We tried to load the compounds on quartz plates and measured the third order nonlinear properties of them,and the results showed good reverse saturated absorption.In general,most of the organic NLO molecules have D-?-A structure,to create a large dissymmetric delocalized ?-electron system.Our molecular structures seemed not to have the typical configuration of NLO molecules.Those with unique Alkyl-p-A were also demonstrated to have NLO properties,which widen the scope of NLO organic molecules.In chapter VII,we newly synthesized a series of ionic compounds with the core of NDI,and modified NDI with imidazolium on the both side.The halogenated hydrocarbons show low reactivity in the alkylation of imidazolium,so both compounds of monosubstitutes and disubstitutes were gained.We discovered the monosubstitutes with long branched alkyl chains could form stable gels in binary solvents.The existence of NDI cores granted gels of unique photochromic properties The phenomena were also found in the solid of monosubstitutes with different alkyl length.Electron spin resonance(ESR)measurements showed that NDI would form stable radicals after short term of irradiation,resulting color deepening of those compounds.Our results are meaning for the development of photochromic soft materials. |
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