Constructions And Properties Of Supramolecular Chiral Assemblies Based On Phthalocyanine

In recent years,the research of supramolecular chirality has aroused great interest especially in its generatation,regulation and functionalization.The fundamental point of the research in supramolecular chiral assemblies is the choice of building block.On the one hand,there should be strong enough noncovalent interactions among building blocks for forming supramolecular assembly.On the other hand,the building blocks should have some good properties to ensure the potential functional applications of formed supramolecular system.Phthalocyanine molecules with the special conjugated structure and good planarity could induce strong ?-? interaction and tight aggregation.Furthermore,the numerous substituent sites around the phthalocyanine ring enrich the molecular structure,which result in the regulation of structure and property of supermolecular assembly.These characteristics make the phthalocyanine a good choice for the construction of chiral supramolecular assemblies.Sandwich-type phthalocyanine complex,formed through the connection of single-deck phthalocyanine molecules by metal ion,has the larger conjugated system,which improve the electrical conductivity.Moreoever,the additional substituent sites within the sandwich-type complex provide more potential for the regulation of supramolecular structure.The supramolecular assembly based on sandwich-type phthalocyanine has been widely used in photics,electrics and magnetics.In addition,although some researches have been performed on the chiral supramolecular systems contructed by sandwich-type phthalocyanine recently,the generation mechanism,regulation,and application of those chiral supramolecular assemblies still need further research.The research works included in this thesis were conducted based on these issues.1.At the air/water interface,achiral phthalocyanine with crown ether substituents(H2Pc(15C5)4)could co-assemble with positively charged poly-L-lysine and negatively charged DNA respectively,using Langmuir-Blodgett(LB)technology.During the assembling process,the chirality of biomacromolecule can be transferred to assembly,which endow the assembly good optical activity.Moreover,for different biomacromolecule,the chirality of formed assembly is also unlike.Furthermore,using steady-state fluorescence method,the H2PC(15C5)4/poly-L-lysine co-assembly is applied in chiral recognition of small molecules and realize a good discriminating for multiple chiral isomers of amino acids as well as epimer of sugars.This result opens a new strategy for multiobject chiral recognition by using simple supramolecular assemblies.2.The achiral phthalocyanine(H2Pc(15C5)4)is used as host building block to co-assemble respectively with several kinds of alkali metal ions at the air/water interface by using LB technology.The results show that the achiral H2Pc(15C5)4 can form chiral assembly through self-assembly.When co-assembled with different alkali metal ions,the intensity of chirality of corresponding assemblies change variously due to the different host-guest interaction.Resulting from the size-matching effect between cavity of crown ether and alkali metal ions,H2Pc(15C5)4 could form helical nanostructures upon interaction with potassium ions,which enhance the supramolecular chirality greatly,whereas the sodium ions have no abvious impact on that.However,the smaller lithium ions cannot induce this achiral phthalocyanine form chiral assemblies.This work realizes the regulation of supramolecular chirality and helps to fabricate tunable supramolecular chiral assemblies from achiral phthalocyanine building blocks.3.In the previous study,we found that the poly-L-lysine had a strong interaction with phthalocyanine cotaining crown ether substituents at the air/water interface.Therefore,the host building block is changed to sandwich-type double-decker phthalocyanine containing four crown ether and eight butoxy substituents Eu[Pc(12C4)4][Pc(OC4H9)8](EuPc2),which can co-assemble with guest poly-L-lysine to form single-molecule-diameter(1.7nm)1D nanofibers using LB technology.These nanofibers were found to have compartmentalized internal space.EuPc2/poly-l-lysine nanofibers can also be electrochemical sensors both in water for NO2-and in gas phase for NO2.Moreover,sensing nitrite in water shows a low limit of detection(LOD)(0.046?M),high sensitivity(16?A mM-1)and a large linear concentration range with strong anti-interfering ability.This research also suggests a different influencing mechanism in water and gas phase due to the complex inner strcture within nanofibers.This work provide a new strategy for the fabrication of multifunctional 1 D nanofibers with complex inner structure.4.In order to enhance the hydrophobicity of host molecule,on the basis of previous studies,we use the double-decker phthalocyanine containing four crown ether and eight octanoxy substituents Eu[Pc(12C4)4][Pc(OC8H17)8](EuPc2-8)as host building block,which has the longer oxygen carbon chains with stronger hydrophobicity.The EuPc2-8 can be co-assembled with poly-L-lysine to form single-molecule-diameter(1.25 nm)1D helical nanofibers.The research shows that the formed EuPc2-8/poly-L-lysine co-assembling nanofibers are equipped with obvious optical activity,though the EuPc2-8 is achiral.Furthermore,the EuPc2-8/poly-L-lysine co-assembling system can be used in electrochemically chiral recognition and realize a good discrimination for tryptophan enantiomer.