Synthesis And Properties Of Water-soluble Binaphthol Fluorescent Molecules

Chiroptical functional materials exhibiting circularly polarized luminescence(CPL)are attracting more and more interest due to their wide application in various fields of research such as fluorescent probes,3D optical imaging,photoelectric devices and so on.Early CPL materials were mainly derived from covalent bond-modified small chiral organic molecules and polymers,which were difficult to be synthesized and highly cost.How to efficiently obtain a CPL system and achieve effective improvement and tunable of luminescence performance is very difficult in this research field.On the other hand,due to the reversibility,diversity and flexibility of noncovalent interactions,they have been applied in the assembly of supramolecular CPL materials in recent years.Cucurbit[n]urils(Q[n]s or CB[n]s)are among the macrocyclic hosts known to date besides crown ethers,cryptands,cyclodextrins,and calixarenes,compared to the others macrocycles,Q[n] has advantages as following:(1)Q[n]s has a more rigid geometric structure,which make it has a better selectivity and a large complex constant for guest.As a result,various stable water-soluble supramolecular self-assembly systems of Q[n]with guest molecules were constructed through noncovalent bonds such as hydrophobic effect,hydrogen bonds,ionic dipoles,etc;(2)Q[n]s can significantly modify the physicochemical properties of guest molecules upon complexation such as enhanced fluorescent emission in the hydrophobic cavities;(3)Q[8],a large homologue of the Q[n] family,is unique because of its ability to bind two hetero-and homo guests in its cavity.The above characteristics of Q[n]s make it have a widely application in supramolecular host-guest chemistry.However,few CPL assemblies with optically tunable features have been fabricated via Q[n]-based host-guest interaction.In this thesis,R-and S-binaphthol as chiral precursors and a series of bispyridinium fluorescent guests were synthesized.UV-vis absorption spectroscopy,fluorescence emission spectroscopy,nuclear magnetic resonance technology,circular dichroism and other methods were explored to study the effect of solvents,metal ions and Q[n]-based host-guest interactions on the chiral signal of those guests.The main research contents are as follows:1.A series of bispyridinium fluorescent guests with electron push-pull effect(DA)were synthesized from R-binaphthol scaffold.The results showing that the fluorescence of those molecules exhibited obviously solvent effect,and the AIE effect of fluorescent molecules is further evaluated with different volume fractions of water and ethanol solvents.At the same time,the study found that unmodified pyridine fluorescent molecules have remarkable fluorescent response on aluminum ions in ethanol,which further leading to the change of chiral signal of fluorescent molecules by CD study.Theoretical calculation was performed to evaluate the structure effect for CD signals.2.Properties of host-guest interaction and the resulting fluorescence changes of those bispyridinium fluorescent guests with Q[7] and Q[8] were investigated in aqueous solution.The results indicated remarkable fluorescent emission changes were triggered after the host-guest complexations.Generally,enhancing fluorescence emission was observed in Q[7]-based host-guest interactions,and red-shift fluorescent emission was observed in Q[8]-based host-guest interactions.However,the results of CD spectra showed that the host-guest self-assembly did not significantly change the signal of the guest molecule.