Construction, Analysis And Application Of Coupling Function Of Coumarin Derivative Functional Fluorescence

Coumarin derivatives are wildly employed not only in pharmaceuticals field but also in the filed of fluorescent dyes as an excellent fluorophore. The fluorescent probes based on coumarin derivatives have the advantages of high quantum yields, large Stokes shifts, low toxicity towards cells and light damage to biological tissue. Therefore, amount of fluorescent probes based coumarin derivatives were developed and they have a bright prospect for further biological application.In this article, the design and synthesis of the novel fluorescent ratiometric probe Cl for H2S detection was achieved, wherein the fluorophore in Cl was a large conjugated system derived from coumarin and benzopyrylium and the recognition site was the group of acyl azide. The design and synthesis of the novel fluorescent probes C2 and C3 for Hg2+ detection was achieved, wherein the fluorophore in C2/C3 was a conjugated system derived from coumarin/naphthalene and benzothiazole and the sulfur atom from benzithiazole and the oxygen atom from coumarin/naphthalene constituted the recognition site for Hg2+. The novel fluorescent probe C4 was designed and synthesized for Cu2+ detection, wherein the fluorophore in C4 was coumarin derivative and the nitrogen and oxygen atom from quinolin-8-ol, the oxygen atom from coumarin and the nitrogen atom from schiff-base constituted the recognition site for Cu+. The main contents list as follows:1. An important reaction intermediate 2-(7-(diethylamino coumarin)-7-diethylam-ino-l-benzopyrylium-4-)benzoic acid (CB) was synthesized by 3-acetyl-7-(diethylam-ino)-2H-coumarin-2-one and 2-(4-(diethylamino)-2-hydroxybenzoyl)-benzoic acid. Then, CB was further activated and modified to obtain the fluorescent probe Cl which can detect H2S selectively. A large conjugated system derived from coumarin and benzopyrylium was used as fluorophore and the recognition site was acyl azide for H2S detection. Compared with other reported fluorescent probes based on azide, the detection time was shortened. Acyl azide was selectively reduced by H2S to obtain acyl amide which further attacked the C-4 from Cl to form the spirocyclization. Therefore, C1 can achieve H2S ratiometric detection. In addition, Cl was suitable for ratiometric fluorescence imaging of H2S in living cells, which brought a bright prospect for further biological application.2. The fluorescent probe C2/C3 was synthesized by ethyl-7-hydroxy-8-formylcou-marin-3-carboxylate/2-hydroxy-l-naphthaldehyde and benzothiazolium. A conjugated system derived from coumarin/naphthaline and benzothiazolium was used as fluorophore. The sulfur atom form benzothiazolium and the oxygen atom from coumarin/naphthaline constituted the recongnition site for Hg2+. C2/C3 contained mercury-coordinating elements such as sulfur which enabled them to achieve high selectivity and sensitivity towards mercury in the presence of other heavy metals especially MeHg+and Ag+. The sulfur and oxygen atoms can coordinate with mercury ions forming 1:1 complex, which was confirmed by Job’s plots. The effect of photo-induced electron/energy transfer can be blocked when Hg2+ coordinated with C2 or C3. Therefore, the fluorescent intensity was increased rapidly. The two probes were successfully applied to detect mercury ions in Michigan cancer foundation-7 cells.3. Quinolin-8-ol as the starting material was substituted by ethyl bromodifluor-oacetate, hydrazinolyzed by hydrazine hydrate and then reacted with ethyl-7-hydroxy-8-formylcoumarin-3-carboxylate to obtain the fluorescent probe C4. Coumarin derivative was used as the fluorophore and the nitrogen and oxygen atom from quinolin-8-ol, the oxygen atom from coumarin and the nitrogen atom from schiff-base constituted the recognition site for Cu2+detection. C4 exhibited very strong fluorescence responses towards Cu+ and higher selectivity towards Cu2+ over than other metal ions. In addition, C4 can coordinate with Cu2+ forming 1:1 complex which was confirmed by Job’s plot. The effect of photo-induced electron/energy transfer can occur when C4 formed complex with Cu2+, which made the fluorescent intensity decrease. C4 has been applied to the detection of the Cu2+ in the simulated water sample.