Sage Journals: Discover world-class research

Abstract

Three new complexes, {[Ni₂(3-PCA)₂(DMAP)₄(H₂O)₂]·2H₂O}₂, [Cu₂(3-PCA)₂(4-PP)₂·2H₂O]_n, and [Cu₂(4-PCA)₂(2,2′-bpy)₂·2H₂O]_n, are synthesized by the solvothermal method with pyrazole-3-carboxylic acid or pyrazole-4-carboxylic acid as the main ligands and 2,2′-bipyridine, 4-dimethylaminopyridine, or 4-phenylpyridine as auxiliary ligands. The crystal structures of the three complexes are determined by single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis, and Fourier transform infrared analysis. The magnetic detection proves that the three complexes are all antiferromagnetic.

Keywords

coordination compounds crystal structures magnetic properties pyrazole-3-carboxylic acid pyrazole-4-carboxylic acid

Introduction

Coordination compounds are highly valued by the scientific community because of their various spatial structures and excellent properties.¹ They not only play an important role in promoting the development of inorganic and organic chemistry, but also have important research value and significance in scientific fields such as materials science and bio-pharmacology.^2–4 Complexes have the characteristics of self-assembly, and they can form multifunctional materials with different sizes and different characteristics. Coordination compounds having infinite structures have been intensively studied, with significant progress having been made in the fields of materials science and coordination chemistry.^5–11

It is well known that many factors such as synthetic methods, central metals, ligands, and pH can influence the final structures of complexes.^12,13 Heterocyclic carboxylic acids are important intermediates in the synthesis of nitrogen-containing biologically active compounds, pharmaceuticals, and agrochemicals.¹⁴ Pyrazole carboxylic acids can coordinate with metals via nitrogen and oxygen atoms. They play a crucial role in modern coordination chemistry due to their stability, accessibility, and versatile coordination modes, making them important ligands for complexes with interesting magnetic, sorption or luminescent properties.^15–17 Meanwhile, Jiang reported two pyrazole-3-carboxylic acid (3-PCA) complexes and they exhibit excellent heterogeneous catalytic performance. One complex is a binuclear copper structure of 3-PCA without any auxiliary ligands, the other compound is a mononuclear manganese complex of 3-PCA with 2,2′-bipyridine auxiliary ligand.¹⁸ Here, three new metal-organic carboxylic acid complexes based on pyrazole-carboxylic-formic acid (Scheme 1), {[Ni₂(3-PCA)₂(DMAP)₄(H₂O)₂]·2H₂O}₂ (1), [Cu₂(3-PCA)₂(4-PP)₂·2H₂O]_n (2), and [Cu₂(4-PCA)₂(2,2′-bpy)₂·2H₂O]_n (3), have been successfully obtained under different conditions. The (1) is a binuclear nickel compound with 3-PCA as the ligand and DMAP as the ancillary ligand. The (2) and (3) are copper polymers with 3-PCA or 4-PCA as the ligand and 4-PP or 2,2′-bpy as the ancillary ligand. We report the synthesis, crystal structures, and magnetic properties of these compounds in this work.

Scheme 1

The structures of 3-PCA and 4-PCA.

Results and discussion

Synthesis of compounds 1–3

Compounds 1–3 were synthesized by a solvothermal method. Compounds 1 and 2 were synthesized using 3-PCA as the main ligand and 4-dimethylaminopyridine (4-DMAP) and 4-phenylpyridine (4-PP) as auxiliary ligands. Compounds 3 was synthesized using pyrazole-4-carboxylic acid (4-PCA) as the main ligands and 2,2′-bipyridine (2,2′-bpy) as auxiliary ligands.

Description of the structure of 1

The X-ray crystallographic data show that complex 1 consists of two dinuclear Ni(II)-units as shown in Figure 1(a). Every two Ni(II) ions are connected by two 3-PCA ligands, and each Ni(II)-unit consists of two Ni(II) cations, two 3-PCA ligands, four 4-DMAP ligands, two coordinated water molecules, and two free water molecules. In the complex, each Ni(II) ion is six-coordinate in a distorted octahedral environment. Two nitrogen atoms of the auxiliary 4-DMAP ligands, one nitrogen atom of the 3-PCA ligand, and one oxygen atom of a water molecule are located at the equatorial positions. One oxygen atom and one nitrogen atom from two different 3-PCA ligands coordinate Ni(II) cations in axial positions (Figure 1(b)). The Ni-O distances vary from 2.105(7) Å to 2.108(7) Å, while the Ni-N distances vary from 2.050(8) Å to 2.171(7) Å (Table 1). As shown in Figure 1(a), the Ni(II) ions interact with each other and exhibit short Ni···Ni interactions of 4.0823 (17) Å and 4.0887 (17) Å. There is a strong C-H···π-accumulation effect between complex 1 molecules (C-H···π interaction distance of 3.158 Å) (Figure 1(c)). Furthermore, the three-dimensional spatial structure of complex 1 is formed by weak interactions such as hydrogen bonding and intermolecular forces (Figure 1(d)). Selected hydrogen bonds and angles are listed in Table 2.

Figure 1.

(a) Coordination environment of the Ni(II) ions in 1, (b) coordination geometry of the Ni(II) ion, (c) view of the 1D chain, (d) 3D framework structure.

Table 1.

Selected bond lengths (Å) and angles (°) for complex 1.

Ni1—N3	2.171 (7)	Ni1—N2^A	2.060 (7)
Ni1—N5	2.162 (7)	Ni1—O1^A	2.108 (7)
Ni1—N1	2.050 (8)	Ni1—O3	2.105 (7)
N2A—Ni1—N3	90.1 (3)	N1—Ni1—O1^A	176.3 (3)
N2A—Ni1—O1^A	80.0 (3)	N1—Ni1—O3	94.9 (3)
O1A—Ni1—N3	87.3 (3)	N2^A—Ni1—N5	95.4 (3)
O3—Ni1—N3	84.6 (3)	N2^A—Ni1—O3	167.8 (3)
O3—Ni1—O1^A	88.7 (3)	O1^A—Ni1—N5	87.3 (3)
N1—Ni1—N2^A	96.4 (3)	O3—Ni1—N5	88.8 (3)

Symmetry codes: A: −x+2, −y+1, −z.

Table 2.

The hydrogen bond lengths (Å) and angles (°) of complex 1.

D—H···A	d(D—H)	d(H···A)	d(D···A)	D—H···A
O3—H3^A···O8^B	0.89	1.89	2.712(11)	153
O3—H3^B···O5	0.89	1.88	2.689(10)	151
O4—H4^A···O8^B	0.85	1.83	2.650(11)	161
O6—H6^A···O4^C	0.85	2.09	2.648(11)	123
O6—H6^B···O2^D	0.85	2.11	2.715(10)	127
O5—H5^A···O2^D	0.85	2.04	2.684(12)	132

Symmetry codes: B: −x+1, −y+1, −z+1; C: x−1, y, z; D: −x+1, −y+1, −z.

Description of the structure of 2

The X-ray crystallographic data reveal that the minimum structure unit of complex 2 (Figure 2(a)) consists of two Cu(II) cations, two 3-PCA ligands, two 4-PP ligands, two coordinate water molecules and two free water molecules. The Cu(II) ions (Cu1 and Cu1A) are in a five-coordination environment. The Cu(II) ion is coordinated by two nitrogen atoms from 3-PCA anions, one nitrogen atom from 4-PP anions, one oxygen atom from 3-PCA anions, and one oxygen atom from a coordinated water molecule. The Cu–O bond lengths range from 1.965(4) Å to 2.380 (4) Å and the Cu–N bond lengths range from 1.938 (3) Å to 1.954 (3) Å (Table 3). The five coordination atoms form an irregular tetragonal cone configuration around the copper ion (τ = 0.301, Figure 2(b)). The two-dimensional (2D) layer structure is formed by bridging 3-PCA anions (Figure 2(c)), which is further progressed into a three-dimensional (3D) supramolecular framework through π···π stacking interactions (Figure 2(d)).

Figure 2.

(a) Coordination environment of the Cu(II) ions in 2, (b) coordination geometry of the Cu(II) ion, (c) view of the 2D-layered structure, (d) 3D framework structure.

Table 3.

Selected bond lengths (Å) and angles (°) for complex 2.

Cu1—N3	1.994 (3)	Cu1—O2^A	2.380 (4)
Cu1—O1	1.965 (3)	Cu1—N2^B	1.938 (3)
Cu1—N1	1.954 (3)	N2^B—Cu1—N3	94.09 (14)
N3—Cu1—O2^A	100.67 (12)	N2^B—Cu1—O1	178.26 (14)
O1—Cu1—N3	84.41 (12)	N2^B—Cu1—N1	99.57 (12)
O1—Cu1—O2^A	92.71 (11)	N2^B—Cu1—O2^A	86.70 (12)
N1—Cu1—O2^A	94.39 (10)

Symmetry codes: A: x+1/2, −y+3/2, z; B: −x, −y+1, −z+1.

Description of the structure of 3

The X-ray crystallographic data show that the molecular structure of complex 3 (Figure 3(a)) consists of two Cu(II) cations, two 4-PCA ligands, two 2,2′-bpy ligands, two coordinated water molecules, and two free water molecules. The Cu(II) ions (Cu1 and Cu1A) are in a five-coordination environment. The Cu(II) ion is coordinated by two nitrogen atoms from 4-PCA anions, two nitrogen atoms from the 2,2′- bpy ligand, and one oxygen atom from the coordinated water molecule. The Cu–O bond lengths are 2.023 (4) Å and the Cu–N bond lengths range from 1.979 (5) Å to 2.174 (6) Å (Table 4). The five coordination atoms form an irregular square pyramidal configuration around the copper ion (τ = 0.460, Figure 3(b)). The 2D layer structure is formed by bridging 4-PCA acid ions (Figure 3(c)), which is further progressed into a 3D supramolecular framework through π···π stacking interactions (Figure 3(d)).

Figure 3.

(a) Coordination environment of the Cu(II) ions in 3, (b) coordination geometry of the Cu(II) ion, (c) view of the 2D-layered structure, (d) 3D framework structure.

Table 4.

Selected bond lengths (Å) and angles (°) for complex 3.

Cu1—N3	2.057 (5)	Cu1—N2^A	1.979 (5)
Cu1—N4	2.050 (5)	Cu1—O2^B	2.023 (4)
Cu1—N1	2.174 (6)	N2^A—Cu1—O2^B	95.3 (2)
N3—Cu1—N1	95.2 (2)	O2^B—Cu1—N3	87.1 (2)
N4—Cu1—N3	79.2 (2)	O2^B—Cu1—N4	145.0 (2)
N4—Cu1—N1	116.7 (2)	O2^B—Cu1—N1	96.4 (2)
N2^ACu1—N1	91.5 (2)

Symmetry codes: A: −x, −y, z; B: x+1/2, −y+1/2, −z+1.

Figure 4.

IR spectra of complexes 1–3.

IR spectra

IR spectroscopy is an excellent approach to characterize and study crystallization. The IR spectra of complexes 1–3 in the 4000–500 cm⁻¹ region were studied. The peaks at 3321, 3466, and 3421 cm⁻¹ for the three compounds can be assigned to the ν_O–H stretching vibrations. Strong characteristic bands due carboxylic groups are observed in the region of 1626, 1586, and 1598 cm⁻¹. Skeletal vibrations for the phenyl and N-heterocyclic rings appear at 786, 768, and 729 cm⁻¹.

Thermal analyses

Thermogravimetric analyses were carried out for complexes 1–3 in order to characterize the compounds more fully in terms of their thermal stability. As shown in Figure 5, for complex 1, the weight loss is mainly divided into two stages. Before 120 °C, the weight loss rate is 6.62% (theoretical value is 8.07%), which is caused by the loss of coordinated water molecules and free water molecules. As the temperature increases, the framework begins to collapse until the temperature reaches 410 °C, at which point the weight loss curve begins to flatten, the remaining amount is 17.85% (theoretical value 16.63%), and the residual product is presumed to be NiO.

Figure 5.

TGA curves of complexes 1–3.

For complex 2, the weight loss is mainly divided into two stages. When the temperature reaches 127 °C, the weight loss rate is 5.67% (theoretical value is 5.19%), which is caused by the loss of free water molecules. When the temperature reaches 140 °C, the framework begins to collapse. The weight loss curve begins to stabilize when the temperature reaches 510 °C. The remaining amount is 19.49% (theoretical value 23.06%), and the residual product is thought to be CuO.

For complex 3, the weight loss is mainly divided into two stages. Between 133 °C and 250 °C, the weight loss rate is 4.12% (theoretical value is 5.31%), which is caused by the loss of free water molecules. As the temperature rises, the framework begins to collapse. However, it is not until 630 °C that the weight loss curve begins to stabilize. The weight loss rate is 79.45% (theoretical value 79.18%). This is due to the main ligand 3-PCA and the auxiliary ligand. Both 2,2′-bipyridine are decomposed and volatilized at this stage. The remaining amount is 16.43% (theoretical value is 18.88%), and the residual product is presumed to be Cu atoms.

Powder X-ray diffraction analysis

The purities of the synthesized complexes were determined by powder X-ray diffraction (PXRD). Cu-Kα was chosen as a monochromatic light diffraction source, the scanning range is 5–50°, and diffraction data are collected. The theoretical diffraction peaks were calculated using Mercury software, and the actual diffraction peaks obtained experimentally were plotted and compared. It was found that the actual diffraction peaks were basically consistent with the simulated diffraction peaks (Figure 6), indicating that the synthesized complexes are pure samples.

Figure 6.

PXRD patterns of complexes 1–3.

Hirshfeld surface analysis for complex 1

Hirshfeld surface (HS) analysis is a useful tool for the in-depth visualization of aspects of crystal packing and supramolecular arrangements in crystal lattices. The color mapping of functions describing specific properties of the HS allows for intuitive recognition and quantitative analysis of interactions between molecules.^19–22 For a deeper understanding of the molecular structure of complex 1, the intermolecular interactions were examined by HS analysis, and the corresponding fingerprints were recorded.

The results of the HS analysis of complex 1 are shown in Figure 7. In HS analysis, the white surface indicates contacts with distances equal to the sum of the van der Waals radii, whereas red or blue surfaces represent distances shorter or longer than the van der Waals radii, respectively. The d_norm surface range is −0.702 to 1.495 Å, which indicates close contacts arising from O–H···O donor–acceptor interactions between carboxyl groups and free water molecules.²³ Hirshfeld 2D fingerprint plots allow rapid and easy identification of the significant intermolecular interactions map on the molecular surface.^24,25 As shown in Figure 8, the proportions of H···H and C···H are 57.5% and 20.6%, respectively, which shows that van der Waals forces play a major role, and that the intermolecular hydrogen bond is small. In addition, the proportions of O···H and N···H interactions are 17.8% and 3.2%, respectively, indicating that O–H···O from carboxyl and water molecules are the main hydrogen bonds in the molecular structure.

Figure 7.

Hirshfeld surface mapped with d_norm for complex 1.

Figure 8.

Fingerprint plots for the H···H (a), C···H (b), O···H (c), and N···H (d) contacts of complex 1.

Magnetic properties

The temperature dependences of the magnetic susceptibilities for the three complexes were measured in the 2–300 K temperature range under an applied field of 1000 Oe. The χ_M, χ_MT versus T plots are illustrated in Figure 9. For complex 1, the χ_MT value at 300 K is 2.15 cm³⋅K⋅mol⁻¹ (Figure 9(a)), which is close to the theoretical χ_MT value of 2 cm³⋅K⋅mol⁻¹. As the temperature decreases, χ_mT shows a slow downward trend. When the temperature reaches 2 K, the minimum value of χ_mT is 0.04 cm³·K·mol⁻¹, which preliminarily indicates that there is a certain degree of antiferromagnetic interaction between the Ni(II) cations in complex 1. Between 25 and 300 K, the magnetic susceptibilities can be fitted to the Curie–Weiss law with θ = −5.12 K, and C = 2.24 cm³·K·mol⁻¹. This further indicates that there is a weak antiferromagnetic interaction between the Ni(II) cations of complex 1.²⁶

Figure 9.

Temperature dependence of χ_m, χ_mT, and χ_m⁻¹ for complexes 1–3 (a–c).

For complex 2, the experimental χ_MT value at 300 K is 0.775 cm³⋅K⋅mol^–1 (Figure 9(b)), which is close to the theoretical χ_MT value of 0.750 cm³⋅K⋅mol⁻¹. As the temperature decreases, the χ_mT value decreases to reach a minimum of 0.006 cm³⋅K⋅mol⁻¹ at 2 K. This preliminarily shows that there is a certain degree of antiferromagnetic interaction between the Cu(II) cations in complex 2. In the high-temperature region, the magnetic susceptibility of 2 follows the Curie–Weiss law with θ = −535.6 K and C = 2.11 cm³·K·mol⁻¹. This indicates weak antiferromagnetic coupling between the Cu(II) cations in complex 2 in the high-temperature region.²⁷

For complex 3, the χ_MT value at 300 K is 0.836 cm³⋅K⋅mol^–1 (Figure 9(c)), which is close to the theoretical χ_MT value of 0.750 cm³⋅K⋅mol^–1. On decreasing the temperature, the χ_mT value declines to a minimum of 0.029 cm³·K·mol⁻¹ at 2 K, which preliminarily indicates that there is a certain degree of antiferromagnetic interaction between the Cu(II) cations in complex 3. The magnetic susceptibilities of 3 in the range of 25–300 K obey the Curie–Weiss law with a Weiss constant θ = −0.77 K and C = 0.86 cm³·K·mol⁻¹. This indicates that there is a weak antiferromagnetic interaction between the Cu(II) cations of complex 3.²⁸

Conclusion

In summary, three new complexes, {[Ni₂(3-PCA)₂(DMAP)₄(H₂O)₂]•2H₂O}₂ (1), [Cu₂(3-PCA)₂(4-PP)₂•2H₂O]_n (2), and [Cu₂(4-PCA)₂(2,2′-bpy)₂•2H₂O]_n (3), have been synthesized by the solvothermal method with pyrazole carboxylic acid. The single-crystal X-ray structures show that 1 is a dinuclear Ni(II)-complex, and that the binuclear Cu(II) units in complexes 2 and 3 form a 2D-layered structure through the carboxyl groups. HS analysis shows that van der Waals forces play a major role in the packing of complex 1. Magnetic studies show that there are antiferromagnetic interactions between the metal ions in complexes 1, 2, and 3. This indicates that the three complexes may have potential value in the field of magnetic materials.

Experimental

Instruments and reagents

All commercial chemicals and solvents were used without purification. The structures of the complexes were also been confirmed by single-crystal X-ray (Agilent G8910A CCD) diffraction analyses. IR spectra were recorded on a PE Spectrum One FT-IR Spectrometer (KBr pellet). PXRD data were obtained on a Bruker D8 Advance X-ray diffractometer. The thermogravimetric measurements were performed with an SDTQ 600 apparatus. Magnetic measurements were recorded on an MPMS SQUID magnetometer.

Preparation of the complexes

{[Ni₂(3-PCA)₂(DMAP)₄(H₂O)₂]•2H₂O}₂ (1)

A mixture of Ni(SO₄)₂·6H₂O (0.0526 g, 0.2 mmol), 3-PCA (0.0244 g, 0.2 mmol), DMAP (0.0610 g, 0.5 mmol), CH₃OH (5 mL), H₂O (10 mL), and triethylamine (40 μL) was stirred at room temperature for 10 min, and then sealed in a 25-mL Teflon-lined stainless-steel container. The mixture was heated at 110 °C for 72 h. After slowly cooling to room temperature, the product was washed with ethanol/distilled water several times and filtered to afford blue needle-like crystals. Yield: 53% based on Ni. anal. calcd. for C₃₆H₄₈N₁₂Ni₂O₆·2(H₂O): C, 49.58; H, 5.85; N, 17.19. Found (%): C, 48.44; H, 5.69; N, 17.12. IR (KBr, cm⁻¹): 3321 (br), 1626 (s), 1562 (m), 1537 (w), 1447 (w), 1380 (s), 1228 (s), 1138 (m), 1063 (m), 1010 (s), 786 (m), 530 (w).

[Cu₂(3-PCA)₂(4-PP)₂·2H₂O]_n (2)

A mixture of Cu(NO₃)₂·3H₂O (0.0483 g, 0.2 mmol), 3-PCA (0.0244 g, 0.2 mmol), 4-PP (0.0621 g, 0.4 mmol), CH₃OH (5 mL), and H₂O (10 mL) was stirred at room temperature for 10 min, and then sealed in a 25-mL Teflon-lined stainless-steel container. The mixture was heated at 90 °C for 72 h. After slowly cooling to room temperature, the product was washed with ethanol/distilled water several times and filtered to afford blue needle-like crystals. Yield: 61% based on Cu. anal. calcd. for (C₃₀H₂₂Cu₂N₆O₄)·2(H₂O): C, 51.95; H, 3.78; N, 12.12. Found (%): C, 50.74; H, 3.71; N, 12.62. IR (KBr, cm⁻¹): 3466 (br), 1586 (s), 1515 (w), 1459 (w), 1368 (s), 1273 (w), 1224 (m), 1146 (m), 1073 (m), 1034 (w), 824 (w), 768 (m), 693 (w).

[Cu₂(4-PCA)₂(2,2′-bpy)₂·2H₂O]_n (3)

A mixture of CuSO₄·5H₂O (0.0749 g, 0.3 mmol), 4-PCA (0.0244 g, 0.2 mmol), 4-PP (0. 0621 g, 0.5 mmol), CH₃OH (5 mL), and H₂O (10 mL) was stirred at room temperature for 10 min, and then sealed in a 25-mL Teflon-lined stainless-steel container. The mixture was heated at 90 °C for 72 h. After slowly cooling to room temperature, the product was washed with ethanol/distilled water several times and filtered to afford blue needle-like crystals. Yield: 53% based on Ni. anal. calcd. for (C₂₈H₁₈Cu₂N₈O₃)·2(H₂O) 3: C, 49.63; H,3.27; N, 16.54. Found (%): C, 48.74; H, 3.21; N, 16.42. IR (KBr, cm⁻¹): 3421 (br), 1598 (w), 1536 (s), 1470 (w), 1415 (s), 1265 (s), 1162 (m), 1007 (m), 893 (m), 775 (s), 729 (m), 633 (w).

X-ray structure determination

Single-crystal X-ray diffraction analyses of the complexes were carried out on an Agilent Technologies G8910A CCD diffractometer equipped with MoKα radiation (λ = 0.71073 Å) using an ω-scan mode at 293 K. The υ-scan technique was employed to measure intensities. The SADABS program was used to correct the Lorentz and Polarization (LP) factors and semi-empirical absorption of the data.²⁹ For the initial data, the direct method of the SHELXS program³⁰ was used to solve the positions of all non-hydrogen atoms and the theoretical hydrogenation method was used to hydrotreat all hydrogen atoms. The analytical data were refined and improved by the least squares method of the SHELXS program. All data analysis and refinement processes were completed using Olex2.^31,32 Crystal data as well as details of the data corrections and refinements for the three complexes are summarized in Table 5.

Table 5.

Crystallographic and experimental data for complexes 1–3.

Empirical formula	(C₃₆H₄₈N₁₂Ni₂O₆)·2(H₂O)	(C₃₀H₂₂Cu₂N₆O₄)·2(H₂O)	(C₂₈H₂₀Cu₂N₈O₄)·(H₂O)
Formula weight	898.31	693.65	677.61
Crystal system	Triclinic	Orthorhombic	Orthorhombic
Space group	P	Pcab	Pcab
a (Å)	10.3793(10)	7.175(9)	13.4691(8)
b (Å)	11.2061(9)	12.751(9)	10.3701(7)
c (Å)	19.661(2)	30.585(8)	9.0267(6)
α (°)	96.044(9)	90	90
β (°)	90.010(8)	90	90
γ (°)	111.762(8)	90	90
V (Å³)	2110.2(4)	2798	1260.81(14)
F (000)	944	1416	688
Z	2	4	2
D_c (g cm⁻³)	1.414	1.647	1.785
µ (mm⁻¹)	0.96	1.58	1.75
θ range (°)	3.7–22.3	2.1–25.6	3.8–24.9
Reflection measured, independent reflection	14,427/7515	3026/2608	8132/2240
Observed reflection [I>2σ(I)]	4055	948	1933
R _int	0.085	0.075	0.057
R₁ [I⩾2σ(I)]	0.114	0.044	0.042
ωR₂ (all data)	0.287	0.123	0.098
Goodness of fit	1.14	0.68	1.06
Δρ (max, min) (e Å)	0.94/−0.56	0.12/−0.16	0.43/−0.39

Footnotes

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Nature Science Foundation of Guangxi Province of China (no. 2017GXNSFAA198268).

ORCID iD

Xiuqing Zhang

References

Chen

Zhou

, et al. Chin J Struct Chem 2022; 41: 14–22.

Cui

Zhao

, et al. Ultrason Sonochem 2017; 39: 837–844.

Chen

Suslick

KS.

Coord Chem Rev 1993; 128: 293–322.

Zhang

Liu

Shi

, et al. Nano Energy 2016; 22: 149–168.

Jaćimović

Kosović

Kastratović

, et al. J Therm Anal Calorim 2018; 133: 813–821.

Chen

Han

Sun

, et al. Green Energy Environ 2023; 8: 258–266.

Gołdyn

Komasa

Pawlaczyk

, et al. Acta Cryst C 2021; 77: 713–724.

Rizk

Emara

AAA

Mahmoud

NH.

J Mol Struct 2021; 1246: 131143.

Rong

Song

Gao

, et al. Dalton Transactions 2023; 52: 1962–1969.

10.

Sun

Song

, et al. Cryst. Growth Des 2021; 21: 3668–3676.

11.

Wang

Cheng

, et al. Cryst. Growth Des 2018; 18: 280–285.

12.

Sun

Mei

, et al. J Environ Sci 2022; 115: 392–402.

13.

Higgins

DeGraff

Demas

JN.

Inorg Chem 2005; 44: 6662–6669.

14.

Bala

Kumari

Sood

, et al. J Heterocycl Chem 2019; 56: 1787–1793.

15.

Alexander

PS.

Adv Heterocycl Chem 2001; 80: 157–240.

16.

Pavel

Yuliya

Taisiya

, et al. New J Chem 2021; 45: 7047–7051.

17.

Martha

Eleni

Dimitra

HL.

Molecules 2021; 26: 3439.

18.

Jiang

Rong

Qiu

, et al. Chinese J Inorg Chem 2018; 33: 2303–2310.

19.

McKinnon

Fabbiani

FPA

Spackman

MA.

Cryst Growth Des 2007; 7: 755–769.

20.

Öztürkkan

Özdemir

Akbaba

, et al. J Mol Struct 2021: 1250; 131825.

21.

Shobana

Sudha

Ramarajan

, et al. J Mol Struct 2021; 1250; 131856.

22.

Kunchur

Mondal D

Rao S

, et al. Acta Cryst C 2021; 77: 725–733.

23.

Wang

, et al. Struct Chem 2018; 29: 1013–1023.

24.

Luo

Liu

Yang

, et al. Res Chem Intermed 2015; 41: 7059.

25.

Zhang

Xiao

, et al. Supramol Chem 2016; 28: 231.

26.

Ravindra

Francesc

Rabindranath

Z Anorg Allg Chem 2014; 640: 1086–1092.

27.

Gao

Zhao

Tang

, et al. J Coord Chem 2002; 55: 205–213.

28.

Ivana

Judith

AK.

Howard LE, et al. Inorg Chim Acta 2004; 357: 4528–4536.

29.

Dai

Guo

, et al. Chem Chem Phys 2013; 15: 5208–5214.

30.

Sheldrick

GM.

Acta Cryst A 2008; 64: 112–122.

31.

Dolomanov

Bourhis

Gildea

, et al. J Appl Crystallogr 2009; 42: 339–341.

32.

Bourhis

Dolomanov

Gildea

, et al. Acta Crystallogr Sect A: Found Adv 2015; 71: 59–75.

Synthesis,crystal structures and magnetic properties of Pyrazole-Carboxylic acid complexes

Abstract

Keywords

Introduction

Results and discussion

Synthesis of compounds 1–3

Description of the structure of 1

Description of the structure of 2

Description of the structure of 3

IR spectra

Thermal analyses

Powder X-ray diffraction analysis

Hirshfeld surface analysis for complex 1

Magnetic properties

Conclusion

Experimental

Instruments and reagents

Preparation of the complexes

{[Ni2(3-PCA)2(DMAP)4(H2O)2]•2H2O}2 (1)

[Cu2(3-PCA)2(4-PP)2·2H2O]n (2)

[Cu2(4-PCA)2(2,2′-bpy)2·2H2O]n (3)

X-ray structure determination

Footnotes

Declaration of conflicting interests

Funding

ORCID iD

References

{[Ni₂(3-PCA)₂(DMAP)₄(H₂O)₂]•2H₂O}₂ (1)

[Cu₂(3-PCA)₂(4-PP)₂·2H₂O]_n (2)

[Cu₂(4-PCA)₂(2,2′-bpy)₂·2H₂O]_n (3)