A thiadiazole copper complex and a method for synthesizing the same

Abstract

This invention discloses a copper thiadiazole complex and its synthesis method. The copper thiadiazole complex has the chemical formula [C3H5ClCuN3S] and belongs to the monoclinic crystal system. A novel copper 2-amino-5-methyl-1,3,4-thiadiazole complex was synthesized using a solvothermal method with 2-amino-5-methyl-1,3,4-thiadiazole as the ligand and copper chloride as the transition metal. The complex provided by this invention was confirmed by UV-Vis absorption spectroscopy and fluorescence spectroscopy to be able to electrostatically bind to calf thymus DNA and to exhibit hydrophobic interactions with human serum albumin (HSA), showing potential applications in chemical biology research.

Description

Technical Field

[0001] This invention relates to the field of chemistry, specifically to a thiadiazole copper complex and its synthesis method. Background Technology

[0002] Copper, as an endogenous element, is a fundamental element for most aerobic organisms. It exhibits less toxicity to normal cells than to cancer cells, causing fewer side effects than traditional cisplatin-based anticancer drugs. Utilizing this characteristic of copper, researchers have synthesized numerous copper complexes. Studies have revealed that some copper complexes can generate large amounts of reactive oxygen species (ROS), which cause oxidative damage to mitochondria and biomolecules, thus demonstrating strong anticancer activity. This has shown great potential in the field of inorganic antitumor therapy and has become a hot topic in research on DNA-small molecule interactions. In recent years, transition metal complexes have been widely used as anticancer drugs in DNA structural probes, DNA molecular photoswitches, DNA disruptors, and anticancer agents. Many scientists have used transition metals such as copper to replace traditional cisplatin-based drugs, using DNA as a target for cancer prevention and treatment. Summary of the Invention

[0003] This invention addresses the shortcomings of existing technologies by providing a thiadiazole copper complex and its synthesis method.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A copper thiadiazole complex with the chemical formula [C3H5ClCuN3S] belongs to the monoclinic crystal system and has the space group [C3H5ClCuN3S]. P 21 / c, cell parameters are as follows: a =6.3605(3) Å, b =11.4549(5) Å, c =9.3600(5) Å, α =90°, β =100.607(5)°, γ =90°, V =670.31(6) Å 3 , Z =4, ρ calc g=2.122 cm 3 , μ =3.871 mm -1 , F (000) = 424.0, Cu1 is coordinated in a four-coordinate manner with N1 and N2 from the 2-amino-5-methyl-1,3,4-thiadiazole ligand. i Cl1 on CuCl2 iiCl1 coordinates to form a distorted tetrahedral CuN2Cl2 configuration.

[0006] Furthermore, the one-dimensional chain structure of the thiadiazole copper complex is in the shape of the letter "H". The central ion of a single complex molecule, the copper ion, coordinates with the N atom on the ligand 2-amino-5-methyl-1,3,4-thiadiazole and is bridged with the chlorine atom to form an infinitely linked one-dimensional chain diagram. The ligand 2-amino-5-methyl-1,3,4-thiadiazole connects two adjacent Cu(I) ions through bidentate coordination.

[0007] A method for synthesizing a thiadiazole copper complex, comprising the following steps:

[0008] (1) Weigh the reactant raw materials according to a molar ratio of 2-amino-5-methyl-1,3,4-thiadiazole to CuCl2 of 2.0~2.2.

[0009] (2) Measure ethanol according to the ratio of 2-amino-5-methyl-1,3,4-thiadiazole: ethanol volume = 1 mmol : 7 mL, and measure water according to the ratio of 2-amino-5-methyl-1,3,4-thiadiazole: ethanol volume = 1 mmol : 2 mL.

[0010] (3) Place the 2-amino-5-methyl-1,3,4-thiadiazole weighed in step (1) into a reaction vessel, add the ethanol and water measured in step (2) as solvents into the reaction vessel, and stir at room temperature until completely dissolved.

[0011] (4) Add the CuCl2 weighed in step (1) to the above reaction vessel and stir until completely dissolved.

[0012] (5) Adjust the pH to 8 using triethylamine solution, then stir to mix thoroughly, cover the reaction vessel, and install the iron sleeve.

[0013] (6) Place in an oven at 75~85 ℃ for 3 days to react.

[0014] (7) Cool to room temperature for 12 h, open the kettle and filter to obtain reddish-brown crystals, wash with ethanol 3 times, dry under natural conditions, and store in a sealed container.

[0015] Further steps are as follows:

[0016] (1) Weigh 0.5 mmol (0.0576 g) of 2-amino-5-methyl-1,3,4-thiadiazole and place it in a reaction vessel. Add 7 mL of ethanol and 1 mL of water as solvents. Add a stir bar and stir with a magnetic stirrer at room temperature for about 30 min until completely dissolved.

[0017] (2) Weigh 0.25 mmol (0.0426 g) of CuCl2 and add it to the above reaction vessel, stirring until completely dissolved.

[0018] (3) Adjust the pH to 8 using triethylamine solution, then stir for 30 min to mix thoroughly. Remove the stir bar, cover the reaction vessel, and install the iron sleeve.

[0019] (4) Place in an 80℃ oven and react for 3 days.

[0020] (5) Cool to room temperature for 12 h, open the kettle and filter to obtain reddish-brown crystals, wash with ethanol 3 times, dry under natural conditions, and store in a sealed container.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention employs a solvothermal method to synthesize a novel 2-amino-5-methyl-1,3,4-thiadiazole copper complex using 2-amino-5-methyl-1,3,4-thiadiazole as a ligand and copper chloride as a transition metal. The complex was characterized and its structure analyzed using infrared spectroscopy, elemental analysis, and X-ray single-crystal diffraction. The interaction mechanisms between the complex and CT-DNA and HSA were investigated, revealing the bonding and reaction mechanisms between the transition metal complex and DNA. UV-Vis absorption spectroscopy and fluorescence spectroscopy confirmed that the complex can electrostatically bind to calf thymus DNA and exhibit hydrophobic interactions with human serum albumin (HSA), demonstrating potential applications in chemical biology research. Attached Figure Description

[0023] Figure 1 This is a one-dimensional chain diagram of the thiadiazole copper complex.

[0024] Figure 2 The image shows the infrared spectrum of the thiadiazole copper complex.

[0025] Figure 3 The image shows a comparison of the infrared spectra of the raw material and the thiadiazole copper complex.

[0026] Figure 4 The image shows the UV-Vis spectrum of the interaction between the thiadiazole copper complex and CT-DNA.

[0027] Figure 5 The image shows the fluorescence of the interaction between the thiadiazole copper complex and EB-CT-DNA.

[0028] Figure 6 The image shows the UV-Vis spectrum of the interaction between the thiadiazole copper complex and HSA.

[0029] Figure 7The image shows the fluorescence spectrum of the reaction between the thiadiazole copper complex and HSA.

[0030] Figure 8 The Hirshfeld surface force diagram of the thiadiazole copper complex is shown.

[0031] Figure 9 This is a two-dimensional fingerprint map of the surface interaction of the thiadiazole copper complex. Detailed Implementation

[0032] The technical solution of the present invention will be further illustrated below through embodiments.

[0033] Example 1

[0034] 1 Experiment

[0035] 1.1 Main Instruments and Reagents

[0036] Experimental instruments: XTL-220 microscope (Shanghai Tiansheng, China), Spectrum 65 Fourier transform infrared spectrometer (PerkinElmer, USA), Smart ApexII CCD X-ray single crystal diffractometer (Bruker, Germany), RF-5301 PC fluorescence spectrophotometer (Shimadzu, Japan), VarioEL III elemental analyzer (Eleman, Germany), UV-8000 ultraviolet-visible spectrophotometer (Shanghai Yuanxi Instruments, China).

[0037] Experimental reagents: 2-Amino-5-methyl-1,3,4-thiadiazole (Shanghai Maclean Biochemical Technology Co., Ltd.), copper chloride (Tianjin Xingfu Technology Development Co., Ltd.), calf thymus DNA (CT-DNA, Sigma), tris(hydroxymethyl)aminomethane (Tris, Wuhan Hengwo Technology Co., Ltd.), human serum albumin (HAS, Sigma).

[0038] 1.2 Synthesis of coordination compounds

[0039] Weigh 0.5 mmol (0.0576 g) of 2-amino-5-methyl-1,3,4-thiadiazole and place it in a reaction vessel. Add 7 mL of ethanol and 1 mL of water as solvents. Add a stir bar and stir with a magnetic stirrer at room temperature for about 30 min until completely dissolved. Weigh 0.25 mmol (0.0426 g) of CuCl2 and add it to the above reaction vessel. Stir until completely dissolved. Adjust the pH to 8 using triethylamine solution, and stir for another 30 min to ensure homogeneity. Remove the stir bar, cover the reaction vessel, attach the iron sleeve, and place it in an oven (80℃) for 3 days. Cool to room temperature for 12 h, open the vessel, and filter to obtain reddish-brown crystals. Since they are insoluble in ethanol, they can be washed three times with a small amount of ethanol. Dry under natural conditions and store in a sealed container.

[0040] 1.3 Determination of the crystal structure of the coordination compound

[0041] A crystal of suitable size (0.15 mm × 0.13 mm × 0.12 mm) was placed on a Smart Apex II CCD X-ray surface probe diffractometer. The diffraction source was a graphite monochromatic Mo-Ka (λ = 0.71073 nm), the temperature was 297.40 (10) K, and the data collection angle range was 5.68° < 2θ < 52.732°. 7577 diffraction points were collected, of which 1354 were independent diffraction points. Structural analysis and refinement were performed according to the methods described in the literature and using SHELXS-97, SHLEXL-97, and Olxe2 programs. Table 1 shows the crystallographic data of the thiadiazole copper complex, and Table 2 shows some bond lengths and bond angles in the single crystal structure of the thiadiazole copper complex.

[0042] Table 1. Crystallographic data of the thiadiazole copper complexes.

[0043]

[0044] Table 2 shows some bond lengths and bond angles in the single-crystal structures of the thiadiazole copper complexes.

[0045]

[0046] 1.4 Interaction between the complex and CT-DNA

[0047] 1.4.1 Common Solution Preparations

[0048] Tris-HCl / NaCl buffer solution: Weigh 5 × 10 -3 mol (0.6057 g) of Tris and 5 × 10 -2 Dissolve 2.9102 g of NaCl in a beaker by stirring, and adjust the pH to 7.38 (7.2-7.5) with dilute HCl.

[0049] CT-DNA solution: Dissolve an appropriate amount of CT-DNA in Tris-HCl / NaCl buffer solution. The solution must not contain protein. Then determine A. 260 / A 280 The solution is suitable for experimental use when the ratio is between 1.8 and 1.9. The calculation formula is as follows:

[0050] (1)

[0051] To calculate its concentration, where K This indicates the dilution factor. CT-DNA solution should be stored in a refrigerator at 4°C for no more than 3 days.

[0052] 1.4.2 Ultraviolet-Visible Absorption Spectroscopy

[0053] Baseline correction was performed using Tris-HCl / NaCl buffer solution to subtract blank background. 5.0 mL of buffer solution and 0.65 μmol / L sodium chloride solution were added to both the reference and sample cells. L -1 The complex solution was prepared by pipetting equal volumes (30 μL) of CT-DNA (2.0 mmol·L⁻¹) into both chambers. -1 The concentration ratio of CT-DNA to complex was continuously increased by adding CT-DNA solution. After each addition of CT-DNA solution, the mixture was blown and mixed, and allowed to stand for 5 min. The solution was then scanned in the wavelength range of 190-350 nm.

[0054] 1.4.3 Fluorescence spectrum

[0055] 8.0 μmol·L -1 Ethidium bromide (EB) and 10.0 μmol·L⁻¹ -1 The EB-CT-DNA solution was mixed in equal volumes and reacted for 12 h. 3.0 mL of EB-CT-DNA solution was added to the sample cell, and the excitation wavelength (EX) was set to 470 nm. Scanning was performed in the wavelength range of 490–900 nm. 5 μL of 0.0015 mmol / L EB-CT-DNA solution was added dropwise to the EB-CT-DNA system. L -1 The complex solution was reacted for 5 minutes, and its emission spectrum was measured.

[0056] 1.5 Interaction between the complex and HSA

[0057] 1.5.1 Ultraviolet-Visible Absorption Spectrum

[0058] Add 5 mL of buffer solution to both the sample cell and the blank cell to calibrate the baseline. Replace the buffer solution in the sample cell with 5 μmol / L buffer solution. L -1 HSA solution was analyzed and scanned at wavelengths of 190-350 nm. 30.0 μL of the complex solution (0.65 μmol) was added using a pipette. L -1 Mix thoroughly by blowing and stirring. After standing at room temperature for 5 minutes, scan within the same wavelength range, adding the complex solution a total of 10 times.

[0059] 1.4.1 Fluorescence spectrum

[0060] Add 3 mL of 5 μmol to the sample cell L -1The optimal excitation wavelength (EX) for the HSA solution was 286 nm, and scanning was performed within the range of 306–586 nm. 30.0 μL of the complex solution (0.0015 mmol) was added using a pipette. L -1 Mix thoroughly by blowing and stirring, and let stand at room temperature for 5 minutes. Then scan within the same wavelength range. Add the complex solution a total of 10 times.

[0061] 2 Results and Discussion

[0062] 2.1 Infrared Spectroscopy Analysis

[0063] like Figure 2 As shown, in the range of 3129~3270 cm -1 The absorption peak at 1616 cm⁻¹ is generated by the stretching vibration of the NH group on the five-membered heterocycle of thiadiazole. -1 The characteristic absorption peak produced by C=N is at 1527 cm⁻¹. -1 1498 cm -1 1355 cm -1 The characteristic absorption peak at 1212 cm⁻¹ is produced by -CH₃. -1 1151 cm -1 It is a characteristic peak generated by the vibration within the bending plane of CH, at 700 cm⁻¹ in the infrared spectrum. -1 515 cm -1 The absorption characteristic peak of the target product Cu-N appeared at the point, which can be used to determine that the copper ion has coordinated with the nitrogen atom on the ligand. The data results of the infrared spectrum and the single crystal structure are basically consistent.

[0064] 2.2 Crystal Structure Description

[0065] The crystal system of the complex [C3H5ClCuN3S] is monoclinic, and its space group is [space group number missing]. P 21 / c, cell parameters are as follows: a =6.3605(3) Å, b =11.4549(5) Å, c =9.3600(5) Å, α =90°, β =100.607(5)°, γ =90°, V =670.31(6) Å 3 , Z =4, ρ calc g=2.122 cm 3 , μ =3.871 mm -1 , F(000) = 424.0. Under basic hydrothermal conditions, Cu 2+ It is easily reduced to Cu + Furthermore, based on the principle of molecular electroneutrality and the typical Cu-N bond in coordination compounds, the oxidation state of the copper ion is determined to be +1. Figure 2 It can be seen that Cu1 is coordinated in a four-coordinate manner with N1 and N2 from the 2-amino-5-methyl-1,3,4-thiadiazole ligand. i Cl1 on CuCl2 ii The Cu1-N1 bond coordinates with Cl1 to form a distorted tetrahedral CuN2Cl2 configuration. Table 2 shows that the bond length of the Cu1-N1 bond is 2.0197(16) Å, and the Cu1-N2 bond... i The bond length is 1.9952(16) Å, Cu1-Cl1 ii The bond length of the Cu1-Cl1 bond is 2.6930(6) Å, and the bond length of the Cu1-Cl1 bond is 2.3385(5) Å. The one-dimensional chain structure of the complex is in the shape of the letter "H". The central ion of a single complex molecule, the copper ion, coordinates with the N atom of the ligand 2-amino-5-methyl-1,3,4-thiadiazole and is bridged with the chlorine atom to form an infinitely linked one-dimensional chain diagram. Among them, the ligand 2-amino-5-methyl-1,3,4-thiadiazole connects two adjacent Cu(I) ions through bidentate coordination.

[0066] 2.3 Analysis of the interaction between the complex and CT-DNA

[0067] 2.3.1 Analysis of Ultraviolet Absorption Spectra

[0068] Depend on Figure 4 It can be observed that as the concentration of CT-DNA increases, the absorption peak of the complex at 208 nm gradually weakens, exhibiting a slight hypochromic effect, but the wavelength of the absorption peak hardly shifts. If insertion is considered as the interaction mechanism between the complex and DNA, a more pronounced hypochromic effect and red shift in the absorption peak occur. This is because the complex and DNA base pairs undergo electron stacking and coupling, resulting in an electronic energy level transition and a decrease in wavelength. Therefore, it is speculated that the interaction between the complex and CT-DNA is not insertion, but rather trenching or electrostatic interaction. The binding constant of the complex to DNA... K b Available formulas:

[0069] (2)

[0070] Calculated (where C) DNA Expressed as the concentration of CT-DNA, ε a Represented as A obsd / CCu +, ε b This represents the molar absorptivity of the fully combined complex. ε f (Indicates the molar absorptivity of the complex that has not interacted with CT-DNA), expressed in C1. DNA / ( ε a - ε f ) for C DNA Plot the graph and calculate the binding constant of the complex with CT-DNA using formula (2). K b = 2.42×10 3 L mol -1 .

[0071] 2.3.2 Analysis of fluorescence spectra

[0072] Depend on Figure 5 It is known that EB-CT-DNA has a strong fluorescence absorption peak at 609 nm. With the continuous addition of the complex, the fluorescence intensity decreases as the complex concentration increases, from an initial fluorescence intensity of 93.75% to 80.08%. The fluorescence absorption peak does not show a significant shift in position. Therefore, we conclude that the interaction between the complex and EB-CT-DNA is not insertional, but likely electrostatic, causing DNA contraction and the EB molecule to be expelled from the DNA double helix, resulting in a decrease in the fluorescence intensity of EB-DNA. This is consistent with the conclusions from the UV data, thus we speculate that the interaction between DNA and the complex is electrostatic. According to the classical Stern-Volmer equation:

[0073] (3)

[0074] In the formula F 0 represents the fluorescence intensity of the EB-CT-DNA system without the addition of a complex. F This indicates the fluorescence intensity of the EB-CT-DNA system when the complex is added. K q Let be the rate constant for the molecular quenching process. K sv Let represent the quenching constant, τ0 be the average lifetime of the fluorescent molecule in the absence of the quencher, and [Q] represent the concentration of the complex. The calculation yields... K sv =6.94×10 4 L·mol -1 extinguishing rate constant K q =6.94×10 12 L·mol-1 ·s -1 Much larger than the mechanistic dynamic quenching rate constant (2×10⁻⁶). 10 L·mol -1 Therefore, the fluorescence quenching of CT-DNA by the complex is static quenching. This can be determined using the formula:

[0075] (4)

[0076] In the formula K a is the binding constant, n is the binding site, and the binding rate constant between the complex and CT-DNA during static quenching is calculated. K a =285.1 L·mol -1 The binding site n=0.564.

[0077] 2.4 Analysis of the interaction between the complex and HSA

[0078] 2.4.1 Analysis of Ultraviolet Absorption Spectra

[0079] Depend on Figure 6 It is observed that HSA produces a characteristic absorption peak at 207 nm. With increasing HSA to complex concentration ratio, the absorption peak at 207 nm gradually weakens, exhibiting a hypochromic effect, and the absorption peak wavelength shifts to longer wavelengths, resulting in a redshift. This is because the addition of the complex opens the hydrophobic pocket, exposing the hydrophobic groups originally encapsulated within the protein to the aqueous solution, thus altering the polarity of the amino acid microenvironment. Therefore, it can be inferred that the complex and HSA interact.

[0080] 2.4.2 Analysis of fluorescence spectra

[0081] Depend on Figure 7 It can be seen that the strong absorption peak of HSA is at 353 nm. With the continuous addition of complexes, the fluorescence intensity decreases with the increase of complex concentration, showing a significant hypochromic effect. At the same time, the wavelength shifts to shorter wavelengths, resulting in a blue shift. This is due to the enhanced hydrophobicity, indicating that the interaction between the complex and HSA is a hydrophobic interaction. From formula (3), we can obtain... K sv =1.79×10 4 L·mol -1 quenching rate constant K q =1.79×10 12 L·mol -1 ·s -1 It can be known that K q =1.79×10 12 L·mol -1·s -1 >2.0×10 10 L·mol -1 ·S -1 (The collisional quenching constant of maximum diffusion between small drug molecules and biomacromolecules) indicates that the fluorescence quenching of HSA by the complex is static quenching. (Using C...) DNA / ( ε a - ε f ) for C DNA Plot the graph and calculate the binding constant between the complex and HSA using formula (3). K a =39.54 L·mol -1 The number of binding sites is n=0.419.

[0082] 2.5 Hirshfeld Surface Analysis

[0083] Hirshfeld surface analysis was performed using CrystalExplorer 3.1 software with the CIF file containing the crystal parameters of the complex as the data source. The results yielded density function (Dnorm), shape index (-1.000-1.000 nm), and curvature maps (-4.000-0.400 nm) ranging from -0.643 to 0.996 nm. Stronger surface interactions appeared at the red spots in the Dnorm.

[0084] The intermolecular forces in a crystal are analyzed using 2D fingerprinting to determine the relative proportions of different molecular types. From... Figure 9 (2D fingerprint image) It can be seen that the H…H interaction accounts for the largest proportion in the complex molecule at 20.2%. The fingerprint region is relatively evenly distributed in the middle, indicating that the short-range interactions of the complex are stable. The Cl…H interaction accounts for 18.7%, and the two ends of the fingerprint region are wing-like, corresponding to the hydrogen bond donor and acceptor, respectively. In addition, the S…H / H…S interaction accounts for 12.7%, the N…H / H…N interaction accounts for 12.3%, and the Cu…N interaction accounts for 9.1%.

[0085] 3. Conclusion

[0086] This invention synthesizes a novel Cu(I) complex C3H5ClCuN3S with 2-amino-5-methyl-1,3,4-thiadiazole as a ligand. This metal complex belongs to the monoclinic crystal system and has a space group of [missing information]. P 21 / c. Central ion Cu +A tetrahedralic ligand configuration was employed, with each copper atom coordinating with two nitrogen atoms from a 2-amino-5-methyl-1,3,4-thiadiazole ligand and two chlorine atoms from a transition metal, forming a distorted tetrahedral configuration. Hirshfeld surface analysis data showed that the H…H interaction (20.2%) and Cl…H interaction (18.7%) were dominant. The interactions between the complex and CT-DNA and HSA were investigated using UV and fluorescence spectroscopy. The fluorescence quenching of both CT-DNA and HSA by the complex was static. A hypochromic effect was observed when the complex interacted with CT-DNA, but the absorption peak position did not shift, indicating that the complex interacted with CT-DNA via electrostatic interactions. The binding constant of the complex to CT-DNA was also determined. K b =2.42×10 3 L mol -1 , K a =285.1 L mol -1 The binding site n = 0.564. The binding constant of the complex with HSA. K a =39.54 L mol -1 quenching rate constant K q =1.79×10 12 L mol -1 S -1 The number of binding sites is n=0.419.

Claims

1. A thiadiazole copper complex, characterized in that, Its chemical formula is [C3H5ClCuN3S], it belongs to the monoclinic crystal system, and its space group is […]. P 21 / c, cell parameters are as follows: a =6.3605(3) Å, b =11.4549(5) Å, c =9.3600(5) Å, α =90°, β =100.607(5)°, γ =90°, V =670.31(6) Å 3 , Z =4, ρ calc g=2.122 cm 3 , μ =3.871 mm -1 , F (000) = 424.0, Cu1 is coordinated in a four-coordinate manner with N1 and N2 from the 2-amino-5-methyl-1,3,4-thiadiazole ligand. i Cl1 on CuCl2 ii Cl1 coordinates to form a distorted tetrahedral CuN2Cl2 configuration. Table 1 shows the crystallographic data of the thiadiazole copper complex, and Table 2 shows some bond lengths and bond angles in the single crystal structure of the thiadiazole copper complex. Table 1 shows the crystallographic data of the thiadiazole copper complexes. Table 2 shows some bond lengths (Å) and bond angles (°) in the single-crystal structures of the thiadiazole copper complexes.

2. The thiadiazole copper complex according to claim 1, characterized in that, The one-dimensional chain structure of the thiadiazole copper complex is in the shape of the letter "H". The central ion of a single complex molecule, the copper ion, coordinates with the N atom on the ligand 2-amino-5-methyl-1,3,4-thiadiazole and is bridged with the chlorine atom to form an infinitely linked one-dimensional chain diagram. The ligand 2-amino-5-methyl-1,3,4-thiadiazole connects two adjacent Cu(I) ions through bidentate coordination.

3. A method for synthesizing the thiadiazole copper complex as described in claim 1, characterized in that, The steps are as follows: (1) Weigh the reactant raw materials according to a molar ratio of 2-amino-5-methyl-1,3,4-thiadiazole to CuCl2 of 2.0~2.

2. (2) Measure ethanol according to the ratio of 2-amino-5-methyl-1,3,4-thiadiazole: ethanol volume = 1 mmol : 7 mL, and measure water according to the ratio of 2-amino-5-methyl-1,3,4-thiadiazole: ethanol volume = 1 mmol : 2 mL. (3) Place the 2-amino-5-methyl-1,3,4-thiadiazole weighed in step (1) into a reaction vessel, add the ethanol and water measured in step (2) as solvents into the reaction vessel, and stir at room temperature until completely dissolved. (4) Add the CuCl2 weighed in step (1) to the above reaction vessel and stir until completely dissolved. (5) Adjust the pH to 8 using triethylamine solution, then stir to mix thoroughly, cover the reaction vessel, and install the iron sleeve. (6) Place in an oven at 75~85 ℃ for 3 days to react. (7) Cool to room temperature for 12 h, open the kettle and filter to obtain reddish-brown crystals, wash with ethanol 3 times, dry under natural conditions, and store in a sealed container.

4. The method for synthesizing the thiadiazole copper complex as described in claim 3, characterized in that, The steps are as follows: (1) Weigh 0.5 mmol (0.0576 g) of 2-amino-5-methyl-1,3,4-thiadiazole and place it in a reaction vessel. Add 7 mL of ethanol and 1 mL of water as solvents. Add a stir bar and stir with a magnetic stirrer at room temperature for about 30 min until completely dissolved. (2) Weigh 0.25 mmol (0.0426 g) of CuCl2 and add it to the above reaction vessel, stirring until completely dissolved. (3) Adjust the pH to 8 using triethylamine solution, then stir for 30 min to mix thoroughly. Remove the stir bar, cover the reaction vessel, and install the iron sleeve. (4) Place in an 80℃ oven and react for 3 days. (5) Cool to room temperature for 12 h, open the kettle and filter to obtain reddish-brown crystals, wash with ethanol 3 times, dry under natural conditions, and store in a sealed container.

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