Fluorescence probe molecule as well as preparation method and application thereof to hypochlorite ion detection

[0034] A method for synthesizing fluorescent probe molecules, comprising the following steps:

[0035] Reaction of 4-bromo-1,8-naphthalic anhydride with methylamine yields compound 2.

[0036] Substitution reaction of compound 2 with hydrazine hydrate yields compound 3.

[0037] After reacting rhodamine B with phosphorus oxychloride, continue to react with compound 3 to generate the fluorescent probe molecule shown in structural formula A.

[0038] The synthetic route is as follows:

[0039]

[0040] Further, the steps of reacting 4-bromo-1,8-naphthalene dicarboxylic anhydride and methylamine to generate compound 2 are:

[0041] Dissolving 4-bromo-1,8-naphthalene dicarboxylic anhydride in methylamine, reacting at 50-100°C for 0.5-2 hours to obtain compound 2. The preferred reaction condition is to react at 10-40° C. for 1.5-3 hours.

[0042] Further, the step of generating compound 3 by substitution reaction of compound 2 with hydrazine hydrate is:

[0043] Compound 2 was

[0053] Synthesis of compound 2

[0054]Add 4-bromo-1,8-naphthalic anhydride (5 g, 18 mmol) into a 100 mL round bottom flask, add 54 mL of 33% methylamine solution to dissolve, and stir at 85° C. for 1 h. The reaction was stopped, and the solid crude product was obtained by filtration. After the solid was fully dried, it was recrystallized with chlorobenzene to obtain 4.43 g of off-white compound 2 with a yield of 83%.

[0055] m.p.172-174°C; 1 H NMR (400MHz, CDCl 3 )δ3.56(s,3H),7.86(dd,J=8.4Hz&J=0.8Hz,1H),8.05(d,J=7.6Hz,1H),8.43(d,J=8.0Hz,1H),8.58 (dd, J=8.4Hz&J=1.2Hz,1H),8.67(dd,J=8.4Hz&J=1.2Hz,1H).

[0056] Synthesis of compound 3

[0057] In a 100 mL round bottom flask, compound 2 (2.4 g, 8 mm01) and hydrazine hydrate (80%, 25 mL) were sequentially added, and the reaction was stirred at 130° C. for 1 h. Stop the reaction and cool to room temperature, add a large amount of water to the solution, a yellow solid precipitates, filter and wash with water to obtain 1.66g of