Synthesis Of A Small Fluorescent Probe Of Spiropyran And Its Metal Ion Recognition Performance

As important light-responsive molecules,spiropyrans are important in optoelectronic switches,optical information storage technology,logic gate digital display,camouflage materials,nonlinear optical materials,photochromic materials,and metal ion detection in living cells.It has attracted the attention of more and more researchers,and has become the direction for more and more researchers to conduct research and exploration.In this paper,benzothiazole and its derivatives,benzimidazol e and benzindoline are used as raw materials,and 2-hydroxy-3-methoxy-5-nitrobenzaldehyde is formed by a reaction similar to aldol condensation4 different compounds.The product was represented by FI,Nuclear Magnetic Resonance(¹H NMR,¹³C NMR)and other methods,and then the metal ion detection were analyzed by ultraviolet and fluorescence spectrophotometer.In order to be able to select excellent spiropyran photochromic materials for photochromic performance research and metal ion detection applications,we successfully synthesized 8'-methoxy-3-methyl-6'-nitro-3H-spiro[benzo[d]thiazole-2,2'-chromene](SP1),3-benzyl-8'-methoxy-6'-nitro-3H-spiro[benzo[d]thiazole-2,2'-chromene](SP2),two kinds of spir-opyran compounds containing benzothiazole and methoxy.The main difference in structure between the two compounds is that SP2 has one more benzyl functional group than SP1.Subsequently,the photochromic performance of SP1 and SP2 and the recognition performance of metal ions were experimentally studied.Through metal ion selectivity experiments,it is found that both SP1 and SP2 can quickly and effectively identify trivalent metal ions iron,chromium,and aluminum,and the compound will fade after complexing with metal ions,which has a good naked eye recognition effect.Through the metal ion anti-interfere-nce experiment,it is found that SP2 has better anti-interfere-nce perform-ance than SP1,and the linear correlation coefficient of the fitting curve is closer to 1,indicating that the fitting is good.Through kinetic experiment-ts,it is found that the response time of SP1 and SP2 to iron,chromium,and aluminum metal ions is shorter and fast.In contrast,the response time of SP2 is within 15 s,and the response time of SP1 is within 20 s,which is slightly faster.a little.Through reversibility experiments,it was found that SP2 compounds are reversible more than three times,SP1compounds are reversible more than once,and SP2 spiropyran compounds have a more stable structure than SP1 spiropyran compounds.Finally,using SP2 as an example,the spiropyran compound is used in the calculation of molecular logic gates.The additio-n of iron,chromium,aluminum and EDTA is used as the input signal,and the absorbance at the maximum absorption wavelength is used as the output signal.In addition to the signal logic gate circuit.In general,SP2 is better than SP1 for detecting metal ions.In order to obtain a compound with a single recognition of trivalent metal ions,8'-methoxy-1,3-dimethyl-6'-nitro-1,3-dihydrospiro[benzo[d]imidazole-2,2'-chromene](SP3)and 2-(8-methoxy-3',3'-dimethyl-6-nitrospiro[chromr nr-2,2'-indolin]-1'-yl)ethan-1-ol(SP4).Change the S atom of benzothiazo le in the structure of SP1 and SP2 into N atom and C atom.SP3 still recognizes metal ions iron,chromium and aluminum,but SP4 can recogn ize iron and chromium ions very well,but does not recognize aluminum ions.As a result,the synthesis of SP4 lays the foundation for further exploration of compounds with a single function of recognizing trivalent metal ions.