In this work, 4-formyl-3-hydroxybenzoic acid (FHBA), which does not contain a large conjugated ring structure, exhibited aggregation-induced emission (AIE) in aqueous solvents. On this basis, FHBA and a metal-organic framework material (i.e., ZIF-8) form into a complex (FHBA@ZIF-8), which presents the AIE characteristics of FHBA. Then, lanthanide metal (i.e., Eu³⁺) coordinates with guanosine 5′-monophosphate disodium (GMP) salt to synthesize a coordination polymer (LnCP), which combines with FHBA@ZIF-8 do afford a novel double-emitting fluorescence probe (FHBA@ZIF-8@Eu-GMP, FZE) for tetracycline antibiotics (TCAs). TCAs coordinate with Eu³⁺ and act as antenna ligand. Thus, an “antenna effect” comes into being and effectively enhances the emission intensity of Eu³⁺ at 616 nm. Moreover, the UV–vis spectra of TCAs largely overlap with the excitation spectrum of FHBA, resulting in an inner filter effect (IFE) and quenching of blue-green fluorescence from FHBA molecules at 473 nm. The ratio of fluorescence signal (F₆₁₆/F₄₇₃) showed a good linear relationship with the concentration of tetracycline hydrochloride (TC) in the range of 0.1–200.0 μM, and the detection limit was 60 nM (S/N = 3). This fluorescence probe can also effectively respond to oxytetracycline hydrochloride (OTC) and chlortetracycline hydrochloride (CTC). The probe was applied to determine TC in milk, and the recoveries ranged from 94.0% to 101.4%, indicating the application potential of this method. This study provides a novel idea for the construction of ratiometric fluorescence sensing platforms and shows the application potential of the AIE effect of FHBA.

在这项工作中，不含大共轭环结构的 4-甲酰基-3-羟基苯甲酸 (FHBA) 在水性溶剂中表现出聚集诱导发射 (AIE)。在此基础上，FHBA与金属有机骨架材料（即ZIF-8）形成复合物（FHBA@ZIF-8），呈现出FHBA的AIE特性。然后，镧系金属（即 Eu ³⁺）与鸟苷 5'-磷酸二钠（GMP）盐配位合成配位聚合物（LnCP），与 FHBA@ZIF-8 结合提供了一种新型的双发射荧光探针（ FHBA@ZIF-8@Eu-GMP, FZE) 用于四环素类抗生素 (TCA)。TCA 与 Eu ³⁺协调并充当天线配体。于是，“天线效应”应运而生，有效增强了Eu ³⁺的发射强度在 616 纳米。此外，TCA 的紫外-可见光谱与 FHBA 的激发光谱在很大程度上重叠，导致内部过滤效应 (IFE) 和 FHBA 分子在 473 nm 处的蓝绿色荧光猝灭。荧光信号比（F ₆₁₆ / F ₄₇₃)与盐酸四环素(TC)的浓度在0.1-200.0 μM范围内呈良好的线性关系，检出限为60 nM (S/N = 3)。这种荧光探针还可以有效响应盐酸土霉素（OTC）和盐酸金四环素（CTC）。该探针用于测定牛奶中的TC，回收率为94.0%~101.4%，表明该方法具有应用潜力。本研究为比例荧光传感平台的构建提供了新思路，并展示了FHBA AIE效应的应用潜力。