Study On The Design, Synthesis And Properties Of A New Series Of Organic Functional Small Molecule Fluorescent Probes

There is a critical extension of human perception of the world in many aspects.This is largely because we are much less sensitive!;〇the chemical or biological environment thane physical environment.However,appropriate chemical or biological compositions aretightly linkede quality of life.For example,the pKsence of certain molecules and ions and their COncentrations inside a human body reflect the person,s health,while chemicals inthe environment can affect human health.Therefore development of highly sensitive and selective method to recognize important analytes has long been a focus of research in many areas.Traditional methods often suffer from extensive and time-con suming procedures that involve the use of sophisticated instrumentation. Thus, simple, inexpensive and convenient techniques for analytes detection are still in demand. Fluorescent sensors are reagents that can interact with analytes accompanied by the changes of their spectroscopic properties; on thebasis of such changes,the analytes can thus be determined Fhioiescent sensei’s have drawn substantial interests of researchers owing to their advantageous features. Those features COd include simplicity, low cost, high sensitivity, adaptation to automation, real-time analysis, and diverse signal output modes. To date, various fluorescent sensors have been extensively investigated and widely used in many fieldsased on the mentioned above,the specific contents of this paper include the following:(1)Two kinds of uorescent sensors(Ila and Ilb) for iron ion bearing benzimidazole/benzothiazole-coumarion derivatives have been designed and synthesized. We introducednitrogen/ sulphurand oxygen heteroatoms as chelating skes and eth)d-7-hydroxycoumarin-3-carboxyIate group was introduced as fluorophore to achieve recognitions. Both Ila and lib displayed high selectivity and sensitivity for iron ion in a very short time,which served as an ON-OFF type sesor. Sensors Ila and lib were designed with ease of synthesis and low cost. Therefore,these sensors have potential applications inphysiological and environmental systems for iron ion detection.(2)Introducing nitrogen and oxygen heteroatoms as chelating sites,a copper ion fluorescent sensor nia was designed and synthesised. After that, an OFF-ON fluorescence change of nia-Cu(II) was observed by addition of cysteine. This fluorescence change was caused by the decomplexation of Cu(II) ion from non-fluorescent complextion, following by hydrolytic cleavage of the resulted Schiff base give a strongly fluorescent compound 4.Sensor DIa-Cu(n) displayed excellent selectivity for cysteine. Even homosysteine and glutathione which often show strong interference to cysteine detection did not show any in our conditions. It is thus the contention that this novel finding would be a brand new guideline in designing reaction-bed fluorescent turn-on sensors for the biologically wlevant thiols.(3) Using intramolecular charge transfer(ICT) as signaling mechanism scris of hybrid coumarin-hemicyanine compounds were synthesized as chemosensors for cyanide detection.The recognition of cyanide can be achieve by cyanides strong affinity toward the polarized C=N bond of the hetnicyanine group. All the sensors had good sensitivity and high selectivity toward cyanide. Among the four sensors, the reaction between cyanide and IVc resulted in an obvious color and spectral change in a very short time. Thus the test strip based on IVc was fabricated,which could act as convenient and efficient cyanide test kits mes the real-time, simple-to-use and naked-eye detection of cyanide possible.(4)Fluorescent sensors in the near-infrared region(NIR)are favorable as NIR light leads to less photodainage,deep tissue penetration,and minimum background fluorescence interference.Ratiometric method can enable the measurement of fluorescent intensity at two differit wavekgthsd providebuilt-in correction.Based on these design strategim,we have developed江series of ratiometric NIR fluorescent sensors Vsic,Usinghybrid rhodamine-fluorescein as fluorophore and hemi-cyanine as receptor,there are two fluorescent emission bands of Va-c and the ICT band of Vc cant be as long as 675 nm.There,these sensors have potential applications in complicated systems for cyanide detection.