Low-dimensional organic-inorganic hybrid halide for nitrobenzene detection

Abstract

The invention discloses a low-dimensional organic-inorganic hybrid halide for nitrobenzene detection, and relates to the technical field of chemistry, and the technical key points are as follows: ACPP is protonated 1-amino-4-cyclopentyl piperazine ([ACPP] 2Cu4Br8) halide, and the halide shows multiple advantages in optical performance, water stability and application as a fluorescent probe. The method is used for nitrobenzene detection.

Description

Technical Field

[0001] The invention relates to the technical field of chemistry, and in particular to a low-dimensional organic-inorganic hybrid halide for nitrobenzene detection. Background Art

[0002] Three-dimensional (3D) lead halide perovskite nanocrystals (PNCs) are considered to be a new generation of photoluminescent (PL) functional materials in solid-state optoelectronic devices due to their tunable emission wavelength, ultrahigh quantum yield (PLQY) and narrow emission linewidth in the entire visible spectrum. Low-dimensional organic-inorganic hybrid metal halides have become a strong alternative candidate to 3D PNCs due to their unique advantages such as abundant material sources, diverse structures, excellent PLQY and low toxicity. In recent years, luminescent low-dimensional metal halides have attracted widespread attention due to their unique electronic structures and optical properties.

[0003] The geometrical diversity of organic cations and metal halide anions contributes to their unprecedented optoelectronic properties. Organic cations (such as aliphatic or aromatic) and central metal ions (such as In 3+ , Mn 2+ , Cu + , Sb 3+ ,Bi 3+ , Sn 4+ , Sn 2+ The wide selection of low-dimensional metal halides enables them to achieve excellent luminescence performance required in emerging applications such as light-emitting diodes (LEDs), sensors, and scintillators. To date, a variety of low-dimensional luminescent materials with broadband emission have been developed for LED applications to replace rare earth phosphors.

[0004] With toxic Pb 2 + ions and unstable Sn 2+ ,Ge 2+ Compared with perovskites, low-dimensional hybrid metal halides can accommodate a large number of environmentally friendly metal ions, such as Cu + 、Zn 2+ , Mn 2+ 、In 3+ , Sb 3+ 、Zr 4+etc., which show lower toxicity and higher stability in extreme environments. Cuprous halides have developed rapidly with their low toxicity, low cost and excellent luminescence properties, becoming a bright candidate for the new generation of luminescent materials. In addition, most low-dimensional hybrid cuprous-based materials perform well in PLQY, such as [N(C2H5)4]2Cu2Br4 and (MA)4Cu2Br6. In particular, the discrete metal halide species as the luminescence center are completely separated from the organic cations with strong quantum confinement effects, which enables the low-dimensional hybrid metal halides to provide tightly localized carriers and ultra-high PLQY.

[0005] Among these low-dimensional hybrid halides, cuprous phases have attracted much attention due to their low toxicity, abundant material sources, flexible coordination modes, and high luminescence efficiency. However, the high water solubility of inorganic metal salts and organic ammonium salts makes them exhibit poor stability in water, which poses a major challenge to practical applications.

[0006] To this end, the present invention aims to provide a low-dimensional organic-inorganic hybrid halide for nitrobenzene detection to solve the above problems. Summary of the invention

[0007] The purpose of the present invention is to solve the above problems and provide a low-dimensional organic-inorganic hybrid halide for nitrobenzene detection. The halide is [ACPP]2Cu4Br8. The halide has photoluminescence properties, water stability properties and small molecule fluorescent probe properties and can be used for nitrobenzene detection.

[0008] In order to achieve the above object, the technical solution of the present invention is as follows:

[0009] The invention provides a low-dimensional organic-inorganic hybrid halide for nitrobenzene detection. The halide is 1-amino-4-cyclopentylpiperazine in which ACPP is protonated, and the structural formula of the halide is [ACPP]2Cu4Br8.

[0010] The preparation method of the halide comprises: washing and dissolving 1-amino-4-cyclopentylpiperazine ACPP and hydrobromic acid HBr with anhydrous ethanol, and after recrystallizing 1-amino-4-cyclopentylpiperazine ACPP and hydrobromic acid HBr in anhydrous ethanol, vacuum drying them to obtain ACPP salt;

[0011] 1.436 g of purified copper bromide (CuBr) was added to a mixture of 10 mL of hydrobromic acid and hypophosphorous acid (H3PO2) and stirred in a beaker. 40 mL of ethanol solution was then added. After the CuBr was completely dissolved, the salt of ACPP was added and heated until a clear solution was formed. The solution was then placed in an oven at 80 °C for 120 hours.

[0012] The solution was then cooled to 20°C, the supernatant was filtered and evaporated in a glove box at 20°C to obtain white crystals precipitated from the solution. The crystals were taken out of the glove box, collected by filtering, and dried in a vacuum oven to obtain the halide [ACPP]2Cu4Br8.

[0013] The halides shown have photoluminescence properties, water stability properties and small molecule fluorescent probe properties and can be used for nitrobenzene detection.

[0014] Compared with the prior art, this solution has the following beneficial effects:

[0015] The ACPP of the present invention is a protonated 1-amino-4-cyclopentylpiperazine ([ACPP]2Cu4Br8) halide that exhibits multiple advantages in optical properties, water stability and application as a fluorescent probe, marking the development of a new cuprous halide fluorescent probe for detecting C6H5NO2, thereby promoting the detection application based on metal halide luminescent materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the lifespan of [ACPP]2Cu4Br8 crystal at different temperatures in an embodiment of the present invention;

[0017] Figure 2 Schematic diagram of the fluorescence emission spectrum of [ACPP]2Cu4Br8 at different temperatures in an embodiment of the present invention;

[0018] Figure 3 is a graph of Ea in an embodiment of the present invention;

[0019] Figure 4 This is a thermogravimetric analysis diagram of an embodiment of the present invention;

[0020] Figure 5 Schematic diagram of the stability results of [ACPP]2Cu4Br8 in the embodiment of the present invention, wherein a is an optical photograph after immersion in water for 1 / 2 / 3 / 4 weeks; b is the photoluminescence emission spectra of different weeks; c is the PXRD after immersion in water;

[0021] Figure 6 The optical photographs (a) and fluorescence data (b) of [ACPP]2Cu4Br8 in various solvents in the embodiments of the present invention;

[0022] Figure 7 is a PL spectrum diagram of the C6H5NO2 / C6H5Br solution in the concentration range from 60ppm to 900ppm in an embodiment of the present invention;

[0023] Figure 8It is a schematic diagram of the change in PL emission intensity of [ACPP]2Cu4Br8 microcrystals in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solution of the present invention will be further described in detail below in conjunction with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0025] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0026] Example 1: Photoluminescence (PL) properties of [ACPP]2Cu4Br8

[0027] Under ultraviolet light excitation, the crystals of [ACPP]2Cu4Br8 exhibit bright yellow luminescence and show a clear absorption edge cutoff wavelength of 480nm. The luminescence properties of [ACPP]2Cu4Br8 crystals were studied by photoluminescence (PL) spectroscopy. Under ultraviolet light excitation, [ACPP]2Cu4Br8 crystals emit broad-spectrum yellow light. In addition, time-resolved PL spectra were obtained to further study the emission mechanism. At 300K, the average PL decay lifetime of [ACPP]2Cu4Br8 crystals was 54.93μs. As the temperature decreased, the radiation intensity increased to 96.32μs and 137.99μs at 200K and 80K, respectively (e.g. Figure 1 shown).

[0028] The observed parallax in the PL emission is almost negligible, indicating that the spectra between microscale particles and bulk crystals are not affected by surface defects. The results show that [ACPP]2Cu4Br8 crystals have good spectral stability and structural stability. Thermogravimetric analysis showed that [ACPP]2Cu4Br8 still remains in bulk crystals at temperatures up to 535K. The extended lifetime indicates that these broad-spectrum emissions originate from the radiative recombination of STEs, which has been previously observed in many 0D hybrid metal halides, and the linear correlation between the excitation power density and the emission intensity further supports this assertion. In order to confirm the behavior of STEs, the temperature dependence of the PL emission spectra at the same temperature was studied (such as Figure 2The emission wavelength has a weak dependence on temperature, which may be due to the effect of band gap change or thermal expansion, which only slightly affects the emission characteristics. In addition, when the temperature is reduced from 290K to 80K, the emission intensity increases consistently, indicating that there is no radiative recombination rate during the thermal quenching process.

[0029]

[0030] The thermal activation energy (Ea) is calculated from the integrated emission intensity and the Arrhenius equation, where I PL represents the integrated emission intensity at temperature T, I0 represents the intensity at 0K, k B is the Boltzmann constant, E a is the exciton binding energy. Calculations show that E a reaches 31.72 meV, and the thermal dissociation energy of free excitons at 300 K is about 26 meV (e.g. Figure 3 This result indicates that there are bound excitons inside [ACPP]2Cu4Br8. The emission spectrum gradually broadens with increasing temperature, which is mainly attributed to the EP coupling effect. This unique 0D hybrid halide structure enhances the PL efficiency and reduces the non-radiative recombination pathway.

[0031] Example 2: Water Stability Properties of [ACPP]2Cu4Br8

[0032] To evaluate its stability, [ACPP]2Cu4Br8 crystals were immersed in deionized water for four weeks. Under ultraviolet irradiation at 365nm, [ACPP]2Cu4Br8 still maintained stable yellow visible light emission and showed no obvious attenuation after prolonged immersion (e.g. Figure 5 a). The spectrum of [ACPP]2Cu4Br8 after 28 days in deionized water shows that the yellow emission intensity is well preserved (as shown in Figure 5 b). Further study of its luminescence stability and structural stability in water was conducted through PXRD patterns (as shown in Figure 5 c) EDS and XPS analysis confirmed that water treatment had little effect on the structure and cuprous element of [ACPP]2Cu4Br8. The presence of organic cations significantly enhanced the water resistance, and its hydrophobic weak hydrogen bonds contributed to its good water stability.

[0033] Example 3: [ACPP]2Cu4Br8 small molecule fluorescent probe properties

[0034] The unique and multifunctional properties of this 0D halide framework were extensively explored to reveal its potential as a fluorescent switch triggered by small chemical molecules as an effective fluorescent probe. The PL emission was monitored to evaluate the sensing ability of [ACPP]2Cu4Br8 microcrystals by adding various organic solvents into the microcrystals. 1mL of aromatic hydrocarbon derivatives were used as detection targets, including benzene (C6H6), toluene (C6H5CH3), ethylbenzene (C6H5C2H5), nitrobenzene (C6H5NO2), chlorobenzene (C6H5Cl), bromobenzene (C6H5Br) and iodobenzene (C6H5I). The emission spectrum showed that the PL emission intensity dropped sharply to 0.64% due to the quenching effect of C6H5NO2; while there was no obvious change in other solvents (such as Figure 6 a and 6b).

[0035] In addition, the quenching response of PL to these stimuli was evaluated by using a variety of organic solvents with different functional groups as external chemical perturbations. These solvents included cyclohexane, tetrahydrofuran, acetonitrile and various alcohols. It was observed that even after injection of these organic solvents for more than 24 hours, the spectral distribution and intensity of the freshly prepared samples were almost the same as the initial data, indicating that no fluorescence quenching occurred in these cases. The detection limit as a key parameter of the detection capability was evaluated by a series of fluorescence titration experiments with diluted C6H5NO2 / C6H5Br, with the concentration range of toluene solution ranging from 60ppm to 900ppm. Optical images and PL spectra (such as Figure 7 As shown in Figure 2, the fluorescence quenching is significant until the concentration of C6H5NO2 / C6H5Br solution drops to 60ppm. 18 H 42 After the fluorescence of [ACPP]2Cu4Br8 microcrystals weakened, it was completely restored by washing with C6H5Br, and the restored fluorescence intensity was close to the initial value. This fully demonstrated the reversible PL switching ability of [ACPP]2Cu4Br8 to C6H5NO2. In order to verify the consistency of this reversible quenching-recovery process, the changes in the PL emission intensity of [ACPP]2Cu4Br8 microcrystals were monitored during the immersion-cleaning cycle. The optical images of the microcrystals showed consistent quenching and recovery cycles. After three cycles, the reduction in its emission intensity was minimal, showing excellent repeatability and reversibility (such as Figure 8 The reversible fluorescence quenching observed in [ACPP]2Cu4Br8 upon exposure highlights its potential as an effective fluorescent probe for the detection of C6H5NO2 with high reproducibility, selectivity, and sensitivity. This marks the development of a new cuprous halide fluorescent probe for the detection of C6H5NO2, promoting the detection application based on metal halide luminescent materials.

[0036] The above specific embodiments are merely explanations of the present invention and are not limitations of the present invention. After reading this specification, those skilled in the art may make modifications to the embodiments without any creative contribution as needed. However, such modifications are protected by the patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A low-dimensional organic-inorganic hybrid halide for nitrobenzene detection, characterized in that: The halide is ACPP, which is protonated 1-amino-4-cyclopentylpiperazine, and the structural formula of the halide is [ACPP]2Cu4Br8.

2. A low-dimensional organic-inorganic hybrid halide for nitrobenzene detection as claimed in claim 1, characterized in that: The halides are used for nitrobenzene detection.

3. A low-dimensional organic-inorganic hybrid halide for nitrobenzene detection as claimed in claim 1, characterized in that: The preparation method of the halide comprises: washing and dissolving 1-amino-4-cyclopentylpiperazine ACPP and hydrobromic acid HBr with anhydrous ethanol, and after recrystallizing 1-amino-4-cyclopentylpiperazine ACPP and hydrobromic acid HBr in anhydrous ethanol, vacuum drying them to obtain ACPP salt; 1.436 g of purified copper bromide (CuBr) was added to a mixture of 10 mL of hydrobromic acid and hypophosphorous acid (H3PO2) and stirred in a beaker. 40 mL of ethanol solution was then added. After the CuBr was completely dissolved, the salt of ACPP was added and heated until a clear solution was formed. The solution was then placed in an oven at 80 °C for 120 hours. The solution was then cooled to 20°C, the supernatant was filtered and evaporated in a glove box at 20°C to obtain white crystals precipitated from the solution. The crystals were taken out of the glove box, collected by filtering, and dried in a vacuum oven to obtain the halide [ACPP]2Cu4Br8.

Images