Studies On Cations Recognition Sensors Based On Naphthalene Diimide And Pillararenes

With the continuous development of supramolecular chemistry,host-guest chemistry and self-assembly systems are becoming more and more familiar to scientists.Among them,cation recognition has become an important part of host-guest chemistry.In recent years,with the joint efforts of scientific researchers,significant progress and achievements have been made in the field of ion identification research.Each new sensor molecule not only accelerates the development of host-guest chemistry in ion recognition,but also expands the research scope of supramolecular chemistry,which greatly enriches the research content in this field.Nevertheless,with the continuous development of scientific research,designing and synthesizing novel cationic sensors is still very challenging for scientific researchers.Up to now,in the previous literature reports,there are few ion-recognition subjects with high selectivity,low cost,simple synthesis steps,and effective application,and only a few of them can be in solutions with high water content.Even pure water performs specific ion recognition.In the first part,we summarize the synthesis of sensors based on 1,8naphthalimide derivatives and columnar aromatics and their applications in cation recognition.In the second part,the selective recognition of target ions in water is very important and the development of novel water soluble chemosensor is still an intriguing challenge.Herein,a novel water soluble fluorescent sensor based on aspartic acid（Asp）functionalized 1,8-naphthalimide derivative（Asp-NI）has been designed and synthesized.The sensor Asp-NI could dissolve in water and successively detect Fe³⁺and H₂PO₄^-in water solution with high selectivity and sensitivity.The detection limits are 4.97×10^-7M f or Fe³⁺and 5.27×10^-6M for H₂PO₄^-.Other coexistent competitive metal ions(Hg²⁺,Ag⁺,Ca²⁺,Cu²⁺,Co²⁺,Ni²⁺,Cd²⁺,Pb²⁺,Zn²⁺,Cr³⁺and Mg²⁺)showed no interference in the Fe³⁺detection process.The sensor Asp-NI could act as a Fe³⁺and H₂PO₄^-controlled“On-Off-On”fluorescent switch.More interestingly,the Fe³⁺induced fluorescence quenching process could be totally reversed by the addition of H₂PO₄^-,this“On-Off-On”switching process could be repeated several times with little fluorescence loss.Notably,the actual usage of sensor Asp-NI was further demonstrated by test kits.In the third part,a novel pillar[5]arene-based thioacetohydrazone functionalized fluorescent polymer was designed and synthesized.This polymer not only contains pillar[5]arene units as the fluorophore（signal transducer）but also embedded the thioacetohydrazone group as the ionophore（cation receptor）.Therefore,it displays specificity response for mercury ion over other common cations(Mg²⁺,Ca²⁺,Zn²⁺,Co²⁺,Fe³⁺,Pb²⁺,Cd²⁺,Ni²⁺,Tb³⁺,Cu²⁺,Eu³⁺,Fe²⁺,Cr³⁺,Ag⁺and La³⁺)in DMSO/H₂O（1:1,v/v）.Competitive cations did not show any significant changes in emission intensity and the fluorescence spectra detection limit was 8.12×10^–7M,indicating the high selectivity and sensitivity of the polymer to Hg²⁺.Meanwhile,this polymer can efficiently remove Hg²⁺from water.In the fourth part,we designed and synthesized a bis-pillararene DP5,and explored the properties of the bis-pillararene DP5 in ion recognition.By fluorescence spectroscopy,we found that the bis-pillararene DP5 can respond to the fluorescence quenching of Fe³⁺and Cu²⁺in solution,and other ions have no obvious effect on this stimuli response.We calculated the minimum detection limits of Fe³⁺and Cu²⁺by DP5 to be 2.6×10^-77 M and 8.69×10^-77 M,respectively.