A hybrid bismuth-chloride material and its reversible photochromic application

Abstract

The present invention discloses an inorganic-organic bismuth-chloride hybrid material and its preparation method and application. The hybrid material has the molecular formula (Hhpt)3(BiCl6), where (Hhpt) + It is a protonated 2-(4-hydroxyphenyl)thiazole with a positive charge. Using BiCl₃, 2-(4-hydroxyphenyl)thiazole, HCl, and ethanol as the reaction materials, single crystals of the compound (Hhpt)₃(BiCl₆) were obtained under solvothermal conditions. This compound exhibits highly efficient reversible photochromic properties and is suitable for fabricating light-controlled switches.

Description

Technical Field

[0001] The present invention relates to the field of photochromism, and in particular to a hybrid bismuth chloride material (Hhpt)3(BiCl6) and its application of reversible photochromic properties, wherein (Hhpt) + It is a protonated 2-(4-hydroxyphenyl)thiazole. Background Art

[0002] Photochromism refers to the molecular structure of certain compounds changing under the influence of light of a certain wavelength and intensity, resulting in a corresponding change in the material's light absorption peak, or color. Optically functional molecular materials with photochromic properties have enormous application prospects in new materials fields such as optical switches, sensors, and intelligent information storage. Hybrid metal halides, as an emerging class of high-efficiency photochromic materials, have attracted widespread attention over the past 20 years due to their excellent performance and wide range of applications.

[0003] In recent years, the research interest in photochromic materials has continued to increase, and more and more products using photochromic materials are being used in our daily lives. Organic photochromic materials can be easily prepared into flexible films, but they have many disadvantages, such as poor heat resistance and stability, which limit their practical applications. Inorganic photochromic materials have excellent oxidation resistance and thermal stability, but also have the disadvantage of structural instability. Compared with organic and inorganic photochromic materials, hybridization of organic and inorganic materials to reduce the impact of their respective limitations on material performance is gradually becoming a promising research direction. Lead-based hybrid photochromic materials have always been a research hotspot, but lead has problems such as environmental pollution and health hazards. Therefore, replacing lead with non-toxic bismuth provides a feasible method to effectively solve the toxicity problem. Summary of the Invention

[0004] The purpose of the present invention is to provide a bismuth chloride inorganic-organic hybrid material with reversible photochromic behavior, overcoming the shortcomings of traditional organic photochromic materials, such as poor thermal stability and difficult processing of inorganic photochromic materials. In addition, the use of bismuth as an inorganic metal source solves the problem of lead toxicity in lead-based perovskite materials. The selection of protonated 2-(4-hydroxyphenyl)thiazole as the organic cation greatly enhances the sensitivity of the photoresponse. The material synthesis method is simple, and the material itself has the characteristics of low cost, non-toxicity, and reversible photochromic behavior.

[0005] The technical solution of the present invention includes the following contents:

[0006] 1. A bismuth-chlorine inorganic-organic hybrid material (Hhpt)3(BiCl6), where (Hhpt) +Represents protonated 2-(4-hydroxyphenyl)thiazole. This compound crystallizes in the monoclinic system in the P21 non-centrosymmetric space group and contains three crystallographically independent (Hhpt) + , 1 crystallographically independent Bi 3+ and 6 Cl – , each Bi 3+ With independent 6 Cl – Coordinated to form a regular octahedral mononuclear (BiCl6) 3– Single-nuclear cluster.

[0007] 2. A method for preparing an inorganic-organic bismuth chloride hybrid material, characterized in that: BiCl3 and 2-(4-hydroxyphenyl)thiazole are weighed in a molar ratio of 1:1 and placed in a mixture of HCl and ethanol in a volume ratio of 1:1. Under solvothermal conditions, light yellow strip-like crystals are obtained, namely the compound (Hhpt)3(BiCl6).

[0008] 3. The use of the inorganic-organic bismuth chloride hybrid material as described in item 1, characterized in that the compound has efficient reversible photochromic properties and can be used to make light-controlled switches.

[0009] The beneficial effects of the present invention are that the synthesis conditions of the product are simple, easy to control and pollution-free. By precise regulation at the molecular level, the advantageous properties of inorganic and organic components are combined to achieve reversible photochromism of inorganic-organic bismuth-chloride hybrid materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is the molecular structure diagram of the inorganic-organic bismuth-chloride hybrid material (Hhpt)3(BiCl6).

[0011] Figure 2 This is the spatial stacking diagram of inorganic-organic bismuth chloride hybrid material (Hhpt)3(BiCl6) molecules along the a-axis in a unit cell.

[0012] Figure 3 The powder diffraction patterns of the newly synthesized inorganic-organic bismuth chloride hybrid material (Hhpt)3(BiCl6) are completely consistent with the single crystal simulated diffraction results.

[0013] Figure 4 Emission spectra (top) and color coordinates (bottom) of the inorganic-organic bismuth chloride hybrid material (Hhpt)3(BiCl6) at excitation wavelengths of 260, 275, 305, and 348 nm.

[0014] Figure 5 This is the infrared spectrum of the inorganic-organic bismuth chloride hybrid material (Hhpt)3(BiCl6).

[0015] Figure 6Solid-state UV absorption spectrum of inorganic-organic bismuth-chloride hybrid material (Hhpt)3(BiCl6).

[0016] Figure 7 This is the thermogravimetric analysis diagram of the inorganic-organic bismuth chloride hybrid material (Hhpt)3(BiCl6).

[0017] Figure 8 These are pictures of the inorganic-organic bismuth-chlorine hybrid material (Hhpt)3(BiCl6) compound before and after color change.

[0018] Figure 9 The overall and partial DOS diagrams of the inorganic-organic bismuth chloride hybrid material (Hhpt)3(BiCl6).

[0019] Figure 10 This is the UV-vis absorption spectrum of the inorganic-organic bismuth chloride hybrid material (Hhpt)3(BiCl6) compound before and after color change. DETAILED DESCRIPTION

[0020] Synthesis of compound (Hhpt)3(BiCl6)

[0021] 0.079 g of BiCl₃ and 0.044 g of 2-(4-hydroxyphenyl)thiazole were placed in a 25 mL polytetrafluoroethylene (PTFE) liner. 3 mL of HCl and 3 mL of ethanol were added. The PTFE liner was then placed in a stainless steel reactor, tightened, and heated in a 120°C oven. After three days of constant temperature, the mixture was allowed to cool naturally to room temperature, yielding light yellow, strip-like crystals, the compound (Hhpt)₃(BiCl₃).

[0022] Reversible photochromic test of compound (Hhpt)3(BiCl6)

[0023] When (Hhpt)3(BiCl6) was continuously irradiated with a 300 W xenon lamp in air at room temperature, the sample exhibited a color change from light yellow to orange-yellow within 18 hours. When the orange-yellow product was placed in the dark, it reversed after three days, returning to its pre-discoloration light yellow.

Claims

1. An inorganic-organic bismuth-chloride hybrid material, characterized in that The molecular formula of the material is (Hhpt)3(BiCl6), where hpt represents 2-(4-hydroxyphenyl)thiazole, (Hhpt) + It means that the protonated 2-(4-hydroxyphenyl)thiazole, inorganic-organic bismuth chloride hybrid material (Hhpt)3(BiCl6) crystallizes in the P21 non-centrosymmetric space group in the monoclinic system, and the unit cell parameters are α=90(1)°,β=94.06(3)°,γ=90(1)°,the molecular structure contains three crystallographically independent (Hhpt) + , 1 crystallographically independent Bi 3+ and 6 Cl – , each Bi 3+ With independent 6 Cl – Coordinated to form a regular octahedral mononuclear (BiCl6) 3– of single-nuclear clusters.

2. A method for preparing the inorganic-organic bismuth-chloride hybrid material according to claim 1, characterized in that: BiCl3 and 2-(4-hydroxyphenyl)thiazole in a molar ratio of 1:1 were weighed and placed in a mixed solution of HCl and ethanol in a volume ratio of 1:

1. After constant temperature reaction under solvent thermal conditions at 120°C, the mixture was naturally cooled to room temperature to obtain light yellow strip crystals, which are inorganic-organic bismuth chloride hybrid materials (Hhpt)3(BiCl6).

3. Use of the inorganic-organic bismuth-chloride hybrid material according to claim 1, characterized in that: The material has reversible photochromic properties and can be used to make light-controlled switches.

Images