Design,Synthesis And Application Of Functional Molecules Based On Isoquinoline Framework

Isoquinoline alkaloids are a class of nitrogen-containing heterocyclic compounds with diverse structures and are important components of many biologically active products.The discovery and various applications of natural isoquinoline alkaloids and the synthesis of isoquinoline derivatives are organic and pharmaceutical hot issues in the field of chemistry.In this study,isoquinoline was used as the parent ring structure,and derivatives of three systems were prepared by different synthetic methods,which have different properties and application values.Therefore,this paper will elaborate on the following three aspects:First,the tandem reaction of peroxide-mediated oxidation/radical addition/cyclization builds the isoquinoline skeleton.In this reaction,under mild metal-free catalysis conditions,di-tert-butyl peroxide is used as an initiator to induce indole to generate free radicals,and a series of addition and cyclization reactions occur to synthesize a series of aromatic heterocyclic substituted isotopes.Quinoline compounds,the reaction has a wide substrate range,good functional group tolerance and high atom economy,and the yield is good.The study also verified the mechanism of free radicals in the reaction system.The free radical intermediates were captured by TEMPO and tracked and confirmed by mass spectrometry（TOF-MS）.Second,the design,synthesis and application of a novel ratiometric fluorescent probe driven by isoquinolinium salt aromatization.In this reaction,AgNO₃ is used as a catalyst to make 2-ethynylbenzaldehyde and benzylamine undergo a cyclization reaction to obtain benzylisoquinolinium salt,and a functional group with good fluorescence properties is selected to prepare probe BIQS.The application shows that the probe has high selectivity and sensitivity to fluoride.Fluoride induces a tandem reaction of hydroxyl deprotection and 1,6-oxidative elimination,and causes significant fluorescence enhancement.Relative fluorescence intensity(I₃₉₈/I₅₂₂)increased linearly with F-concentration in the range of 0-9.0μmol L^-1.The detection limit is very low（3.7 nM）due to the intrinsic aromatization drive of the F-induced probe.The identification mechanism was demonstrated by mass spectrometry（MS）and 1H NMR.In vitro imaging results show that the novel probe BIQS is membrane permeable and can be applied to the determination of fluoride ions in living cells.Third,the design and synthesis of aggregation-induced luminescent molecules based on isoquinoline structure.Tetraphenylene has a good aggregation-induced luminescence effect（AIE）.Benzoxazine dye is a stable fluorescent dye containing nitrogen and oxygen heterocycles.It uses isoquinoline as a bridge to integrate two fluorophores.The design and synthesis of isoquinoline a series of target products with high yields were obtained under mild reaction conditions as a new type of double AIE molecule with tetraphenylene（TPE）and benzoxazine structure as one parent.The detection of fluorescence properties showed that the probe with chlorine as a substituent had a good AIE effect,and the effect was better than that of the single molecule containing only tetraphenylene or benzoxazine structure,the fluorescence intensity was higher,and the fluorescence emission wavelength was certain.It has a good application prospect in the field of fluorescent materials.