Acylhydrazone sensor, preparation method thereof and application of acylhydrazone sensor in fluorescence detection of aluminum ions

Abstract

The invention discloses an acylhydrazone sensor, a preparation method thereof and an application of the acylhydrazone sensor in fluorescence detection of aluminum ions, 4, 4 '-diaminodiphenyl ether-2, 2'-dicarboxamide and 2-hydroxy-1-naphthaldehyde are used as precursors, and a sensing molecule with a rigid conjugated structure is constructed through an efficient aldehyde amine condensation one-step reaction; the synthesis route shows excellent atom economy and process stability. The GW sensor disclosed by the invention shows specific recognition capability on Al < 3 + >, the detection response time of the GW sensor is shorter than 15 seconds, and gt is still kept in the presence of 15 competitive ions such as La < 2 + > and Cu < 2 + >; and the identification efficiency is 95%. Through a time-resolved fluorescence spectrum and an ultraviolet-visible titration experiment, a synergistic coordination mechanism of Al < 3 + > and carbonyl oxygen and imine nitrogen atoms in the sensor is disclosed. The sensor has excellent analysis performance, and a new method is provided for on-site detection of trace aluminum pollutants in environmental water.

Description

Technical Field

[0001] The invention belongs to the field of chemical synthesis and relates to an acylhydrazone sensor for cation selective fluorescence detection, in particular to an acylhydrazone sensor and a preparation method thereof and an application method thereof in fluorescence detection of aluminum ions. Background Art

[0002] With the rapid development of industrialization and urbanization, heavy metal pollution in water bodies has become a global environmental challenge. According to the World Health Organization (WHO), about 23% of the world's surface water is contaminated by Pb. 2+ Cr 6+ 、Hg 2+ 、Cd 2+ Pollution from toxic heavy metal ions such as cadmium and cadmium is primarily caused by human activities such as electroplating wastewater (38%), mine tailings (27%), and agricultural runoff (19%). These bioaccumulative pollutants can amplify effects through the food chain, inducing neurodegenerative diseases (such as Alzheimer's disease) and organ dysfunction. For example, cadmium pollution can have an enrichment factor of up to 10 in aquatic organisms. 3 -10 4 magnitude, seriously threatening the safety of ecosystems and human health. Current heavy metal detection technologies mainly include inductively coupled plasma mass spectrometry (ICP-MS, LOD ~ 0.1ppb), anodic stripping voltammetry (ASV, RSD < 5%) and X-ray fluorescence spectroscopy (XRF). However, these methods generally have problems such as expensive instruments (ICP-MS equipment costs > $500,000), complex pre-treatment (such as ASV requires pre-enrichment) and limited on-site detection. In contrast, fluorescence sensing technology has become a research hotspot in the field of environmental monitoring due to its high sensitivity (up to nm level), real-time response (<60s) and portable detection advantages. Acylhydrazone compounds have attracted widespread attention due to their unique molecular design: ① Rigid conjugated skeleton (such as Schiff base structure) gives them excellent fluorescence quantum yield (Φ>0.65); ② Multi-site coordination ability (N, O donor) can achieve specific recognition of metal ions; ③ Modular synthesis strategy facilitates functional modification. Recent studies have confirmed that naphthyloylhydrazone derivatives have a strong affinity for Al 3+ The detection limit can reach 0.05μm (Inorg. Chem. Front. 2023, 10), and its two-photon absorption characteristics (δ ~ 500GM) further expand its potential for bioimaging applications. These advances provide important theoretical basis and technical support for the development of a new generation of intelligent sensing platforms.

[0003] Acylhydrazone compounds are a class of organic compounds with a naphthaleneimide structure. They are compounds obtained by replacing one or more hydrogen atoms on the naphthalene ring, and are generally represented by N-naphthaleneimide. In general, acylhydrazone compounds have the following main characteristics: (1) Fluorescence properties: Acylhydrazone compounds usually exhibit good fluorescence properties. They can produce strong fluorescence emission under ultraviolet light excitation, have a long fluorescence lifetime and a high fluorescence quantum yield. (2) Structural diversity: The structure of acylhydrazone compounds has certain flexibility and diversity. The properties and functions of acylhydrazone compounds can be adjusted by introducing different substituents on the naphthalene ring, adjusting the carbon chain length or changing the substituents on the N atom of naphthaleneimide. (3) Selective recognition performance: Due to the diversity of structure, acylhydrazone compounds can achieve selective recognition of target compounds by adjusting the molecular structure and the introduction of functional groups. (4) Reactivity: Acylhydrazone compounds have certain reactivity and can undergo various types of chemical reactions, such as redox reactions, coordination reactions, acid-base neutralization reactions, etc. Based on the above characteristics, acylhydrazone compounds are widely used in the development of fluorescent chemical sensors in the fields of molecular recognition, molecular imaging, bioorganic chemistry, analytical chemistry, materials chemistry, biology and medicine. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for detecting metal ions Al by fluorescence. 3+ Acylhydrazone sensor and preparation method thereof.

[0005] 1. Acylhydrazone sensors and their preparation methods

[0006] The acylhydrazone sensor of the present invention has the molecular formula C 38 H 30 N4O6, named GW, has the structural formula:

[0007]

[0008] The preparation method of the acylhydrazone sensor of the present invention comprises the following steps: using ethanol as a solvent, using 4,4'-diaminodiphenyl ether-2,2'-diformamide and 2-hydroxy-1-naphthaldehyde as substrates, controlling the feed ratio at 1:3, adding glacial acetic acid, and reacting under reflux at 80°C for 12 hours, monitoring the reaction progress by TLC (thin layer chromatography), and after the reaction is completed, recrystallizing in anhydrous ethanol for 3-4 times to finally obtain the acylhydrazone sensor molecule GW.

[0009] The synthetic route of GW is:

[0010]

[0011] The hydrogen spectrum and mass spectrum of the acylhydrazone sensor molecule GW prepared by the above method are shown in Figure 1 and Figure 2 .

[0012] Another object of the present invention is to provide the use of the above-mentioned acylhydrazone sensor in fluorescence detection of aluminum ions.

[0013] 2. Selective detection of Al by acylhydrazone sensors 3+ Specific applications

[0014] In the dimethyl sulfoxide suspension in which the acylhydrazone sensor molecules GW were uniformly distributed, various metal ions (Mg 2+ ,Co 2+ ,Cu 2+ ,Ca 2+ ,Zn 2+ ,Al 3+ ,Fe 3+ ,Cr 3+ ,Pb 2+ ) in an aqueous solution.

[0015] It was found that only Al 3+ The addition of DMSO can significantly enhance the fluorescence of the sensor GW suspension (see Figure 3 ), while the addition of other cations could not cause significant changes in the fluorescence of the sensor GW. This phenomenon shows that the acylhydrazone sensor GW has achieved the goal of 3+ Selective detection.

[0016] (1) Acylhydrazone sensor GW for metal ion Al 3+ Determination of the limit of detection (LOD)

[0017] Fluorescence titration experiments were used to determine the effect of dimethyl sulfoxide suspension of sensor GW on Fe 3+ The lowest detection limit (LOD) of aqueous solution (1M) was obtained, and the data were linearly fitted (LOD determination diagram is shown in Figure 4 , LOD linear fitting diagram see Figure 5 ), calculate the sensor GW to Al 3+ The LOD is 2.34×10 -7 M.

[0018] (2) Analysis of the detection mechanism of acylhydrazone sensors GW

[0019] X-ray photoelectron spectroscopy (XPS) was used to characterize the GW and GW-Al 3+ The interaction mode and electronic structure of the sensor are analyzed to explore the GW sensing mechanism:

[0020] like Figure 6 As shown, Al is added to the sensor GW 3+ After that, the C of -C=N- 1sThe binding energy is from 285.40eV ( Figure 6 a) move to 285.5eV ( Figure 6 c) Similarly, after metal ions are added to the sensor GW, the N 1s The binding energy is 398.6eV ( Figure 6 b) moves to 398.2eV ( Figure 6 d) The above results show that there is a strong coordination effect between aluminum atoms and C atoms and N atoms. However, in GW, GW-Al 3+ In CC / CH 1s The binding energy did not change before and after the addition of metal ions, indicating that CC / CH did not participate in the coordination reaction.

[0021] like Figure 7 As shown, high-resolution Al 2p The electron energy spectrum consists of two characteristic binding energy peaks at 71.4eV and 72.7eV, corresponding to GW-Al 3+ Al 3+ and Al 0 , indicating the presence of trivalent aluminum ions.

[0022] The above results further confirm that the sensor GW and metal ion Al 3+ Sensing mechanism.

[0023] (3) X-ray diffraction (XRD) of GW and GW-Al 3+ Testing and analysis

[0024] like Figure 8 As shown, GW exhibits a diffraction peak at 2θ=23.55°, which indicates the existence of π-π stacking non-covalent interaction between GW molecules. 3+ The diffraction peak at 2θ=23.63° still appears in the 3+ The addition of does not destroy the π-π stacking interaction between GW molecules.

[0025] In summary, the present invention has the following advantages:

[0026] 1. This invention uses a clever design to select 4,4'-diaminodiphenyl ether-2,2'-dicarbonamide and 2-hydroxy-1-naphthaldehyde as the main starting materials to successfully synthesize a new type of fluorescent chemical sensor GW, which can achieve the specific metal ion Al 3+ Ultrasensitive and selective detection.

[0027] 2. The sensor of the present invention is based on naphthalimide fluorescent group, which has stable performance and excellent fluorescence characteristics; GW sensor is sensitive to Al 3+It showed specific recognition ability, with a detection limit of 30.7nM for Al3+ (fluorescence method) and a detection response time of less than 15 seconds. 2+ 、Co 2+ The recognition efficiency is still >95% in the presence of competing ions. 3+ The method has high sensitivity, fast response speed, and can be completed without complex operations and expensive equipment. Therefore, the acylhydrazone sensor GW has a good application prospect.

[0028] 3. The novel acylhydrazone-based aluminum ion fluorescence sensor GW developed in this study features readily available, low-cost raw materials, a simple preparation process, and high product yield, aligning with the principles of green chemistry. GW exhibits high sensitivity and excellent selectivity. Synergistic analysis of time-resolved fluorescence spectroscopy and UV-visible titration reveals the synergistic coordination mechanism of Al3+ with carbonyl oxygen (C=O) and imine nitrogen (C=N) atoms in the sensor. This sensor exhibits excellent analytical performance, providing a new method for the rapid detection of trace aluminum contamination in environmental waters. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is the hydrogen spectrum of the acylhydrazone sensor molecule GW of the present invention;

[0030] Figure 2 This is the mass spectrum of the acylhydrazone sensor molecule GW of the present invention;

[0031] Figure 3 This is the fluorescence spectrum of the acylhydrazone sensor GW of the present invention for selective detection of metal ions;

[0032] Figure 4 The acylhydrazone sensor GW of the present invention detects Al 3+ Fluorescence titration diagram of

[0033] Figure 5 The acylhydrazone sensor GW of the present invention detects Al 3+ Linear fitting graph of ;

[0034] Figure 6 The acylhydrazone sensor GW of the present invention detects Al 3+ XPS graph;

[0035] Figure 7 Al 2p XPS spectrum of

[0036] Figure 8 The acylhydrazone sensor GW of the present invention detects Al 3+ XRD pattern of

[0037] Figure 9Photos of gel GW with different metal ions added under visible light and UV light. DETAILED DESCRIPTION

[0038] The following is a specific example of the preparation of the acylhydrazone sensor molecule GW and the fluorescence detection of metal ions Al 3+ The application is further explained.

[0039] Example

[0040] Preparation of the acylhydrazone sensor molecule GW: Using ethanol as the solvent, 4,4'-diaminodiphenyl ether-2,2'-dicarboxamide and 2-hydroxy-1-naphthaldehyde as substrates at a feed ratio of 1:3, glacial acetic acid was added, and the reaction was refluxed at 80°C for 12 hours. The reaction progress was monitored by TLC (thin-layer chromatography). After the reaction, the product was recrystallized 3-4 times from anhydrous ethanol to obtain the acylhydrazone sensor GW. The yield was 84%. (Hydrogen and mass spectra are shown in Figure 2). Figure 1 and Figure 2 ).

[0041] Application Examples

[0042] The sensor GW prepared in the embodiment respectively detects Al by fluorescence. 3+ :

[0043] Take 0.2 mL of dimethyl sulfoxide suspension of the sensor molecule GW in the example in a small reagent bottle; add various metal ions (Mg 2+ ,Co 2+ ,Cu 2+ ,Ca 2+ ,Zn 2+ ,Al 3+ ,Fe 3+ ,Cr 3+ ,Pb 2+ The fluorescence was observed by ultraviolet light (365nm) and under visible light. The results showed that the addition of metal ions Al 3+ The fluorescence of the suspension changed significantly, while the rest did not change, such as Figure 9 shown.

[0044] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An acylhydrazone sensor having the structural formula:

2. A method for preparing an acylhydrazone sensor according to claim 1, characterized in that: Using ethanol as solvent, 4,4'-diaminodiphenyl ether-2,2'-diformamide and 2-hydroxy-1-naphthaldehyde as substrates, glacial acetic acid was added, and the mixture was refluxed at 80°C for 12 hours. The reaction progress was monitored by TLC. After the reaction was completed, the mixture was recrystallized from anhydrous ethanol for 3-4 times to obtain an acylhydrazone sensor.

3. The method for preparing an acylhydrazone sensor according to claim 2, wherein The molar ratio of 4,4'-diaminodiphenyl ether-2,2'-dicarboxamide to 2-hydroxy-1-naphthaldehyde is 1:1.5-1:

3.

4. Use of the acylhydrazone sensor obtained by the preparation method as claimed in claim 2 or 3 in fluorescence detection of Al3+.

5. The use of the acylhydrazone sensor according to claim 4 in fluorescence detection of Al3+, characterized in that: When Al3+ was added to the dimethyl sulfoxide suspension of the acylhydrazone sensor, the fluorescence of the sensor was enhanced.

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