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ISSN: 2056-9890

Synthesis and crystal structure of catena-poly[[aqua­zinc(II)]-bis­­[μ2-4-(phenyl­diazen­yl)benzoato-κ2O:O′]]

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aKey Laboratory of Catalysis and Materials Sciences of the State Ethnic Affairs Commission & Ministry of Education, College of Chemistry and Material Science, South-Central Minzu University, Wuhan, 430074, People's Republic of China, and bSchool of Materials Science and Engineering, Central South University, Changsha, 410083, People's Republic of China
*Correspondence e-mail: [email protected]

Edited by X. Hao, Institute of Chemistry, Chinese Academy of Sciences (Received 18 March 2026; accepted 16 May 2026; online 5 June 2026)

In the title compound, [Zn(C13H9N2O2)2(H2O)]n or [Zn(pba)2(H2O)]n (pba = 4-(phenyl­diazen­yl)benzoate, the Zn2+ ions are coordinated by one water mol­ecule and four oxygen atoms from four different pba ligands to form a [ZnO5] trigonal bipyramid. The Zn ion and the water O atom lie on a twofold axis. The trigonal bipyramids are bridged by the pba ligands, extending the structure into chains propagating along the b-axis direction. The chains are connected through hydrogen-bonding inter­actions.

1. Chemical context

Azo­benzene, as a classical photoswitchable mol­ecule, has gained great attention in designing stimuli-responsive supra­molecular system due to its unique photochromic properties arising from reversible E and Z geometric isomerism (Feng et al., 2025View full citation; Golzani et al., 2026View full citation; Hao et al., 2017View full citation). In recent years, metal–organic frameworks (MOFs) and their derivatives have become widely used in many fields such as separation, catalysis, detection and electrochemical reduction (Liang et al., 2024View full citation; Zhao et al., 2022View full citation, 2026View full citation; Zhong et al., 2025View full citation). Incorporating azo­benzene derivatives into MOFs represents a frontier strategy for constructing stimuli responsive systems in materials science. For example, Nitschke and co-workers successfully developed light-responsive metal–organic capsules by incorporating azo­benzene-based ligands (Ghosh et al., 2026View full citation) while Tadjarodi and co-workers fabricated a sacrificial nanozyme-based MOF capable of detecting and qu­anti­fying Hg2+ ions in aqueous solutions by using an azo­benzene-4,4-di­carboxyl­ate ligand (Golzani et al., 2026View full citation). However, theoretically, the mol­ecular motion will be certainly restricted by steric constraints and lattice strain in crystalline MOFs. To supply more examples of functional compounds incorporation by azo­benzene derivatives, the title compound, (1), with a one-dimensional chain structure, was obtained.

2. Structural commentary

The asymmetric unit of (1) one Zn ion (site symmetry 2), one pba anion and one water mol­ecule (O atom site symmetry 2) (Fig. 1[link]). The Zn—O bond lengths are in the range 1.954 (5)–2.150 (3) Å (Table 1[link]). All the data are comparable to those reported for other related ZnII–polycarboxyl­ate compounds (Gu et al., 2023View full citation; Liu et al., 2025View full citation; Zhao et al., 2024View full citation). Each Zn center is five-coordinated by four oxygen from four different pba anions and one coordinated water mol­ecule, forming a trigonal–bipyramidal geometry. The equatorial plane is occupied by atoms O1, O1i and O3. The pba ligand bridges two ZnII ions through its carboxyl O atoms, and two ZnII ions are bridged by two pba ligands to form a binuclear Zn2(COO)2 unit. The two ZnII ions and the two carboxyl carbon atoms are in the same plane. The neighboring Zn2(COO)2 unit is distorted and the angle between the binuclear units is 77.3 (1)° (the plane is defined by two ZnII ions and two carboxyl carbon atoms).

[Scheme 1]

Table 1
Selected geometric parameters (Å, °)

Zn1—O1 1.964 (3) Zn1—O2iii 2.150 (3)
Zn1—O1i 1.964 (3) Zn1—O3 1.954 (5)
Zn1—O2ii 2.150 (3)    
       
O1—Zn1—O1i 142.3 (2) O3—Zn1—O1i 108.85 (11)
O1—Zn1—O2iii 87.11 (12) O3—Zn1—O1 108.85 (10)
O1i—Zn1—O2iii 94.66 (13) O3—Zn1—O2iii 87.26 (9)
O1i—Zn1—O2ii 87.11 (12) O3—Zn1—O2ii 87.26 (9)
O1—Zn1—O2ii 94.66 (13) C1—O1—Zn1 121.4 (3)
O2iii—Zn1—O2ii 174.51 (18) C1—O2—Zn1ii 125.4 (3)
Symmetry codes: (i) Mathematical equation; (ii) Mathematical equation; (iii) Mathematical equation.
[Figure 1]
Figure 1
The extended asymmetric unit of (1) showing the coordination environment of the Zn2+ cation and the ligand. Displacement ellipsoids are drawn at the 30% probability level. [Symmetry codes: (A) −x + 1, −y + 1, −z + 1; (B)−x + 1, y, −z + Mathematical equation; (C) x, −y + 1, z + Mathematical equation.]

3. Supra­molecular features

In the crystal, The units are extended along the c-axis direction, generating a one-dimensional zigzag chain (Fig. 2[link]). The ligand hangs along the chain towards different directions (Fig. 3[link]). O—H⋯O hydrogen bonds are observed (Table 2[link]). The packing is shown in Fig. 4[link].

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O3—H3⋯O2iv 0.87 1.78 2.588 (4) 154
Symmetry code: (iv) Mathematical equation.
[Figure 2]
Figure 2
The one-dimensional zigzag chain.
[Figure 3]
Figure 3
The one-dimensional chain constructed by ZnII ions and the carboxyl groups.
[Figure 4]
Figure 4
Packing diagram of (1), showing hydrogen-bonding inter­actions (dashed lines).

4. Synthesis and crystallization

A mixture of Zn(NO3)2·6H2O (29.5 mg, 0.1 mmol) and pba (45.2 mg, 0.2 mmol) in 5 mL DMF was sealed in a Teflon lined autoclave and heated to 393 K for 48 h, then gradually cooled down to room temperature. Pale-yellow block-shaped crystals were obtained.

5. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 3[link]. The hydrogen atom of the coordinated water mol­ecule was located from a difference-Fourier map, and refined using a riding model with isotropic displacement parameters Uiso(H) = 1.5Ueq(O). C-bound H atoms were positioned geometrically (C—H = 0.95 Å) and refined with as riding with Uiso(H) = 1.2Ueq(C).

Table 3
Experimental details

Crystal data
Chemical formula [Zn(C13H9N2O2)2(H2O)]
Mr 533.83
Crystal system, space group Monoclinic, C2/c
Temperature (K) 100
a, b, c (Å) 51.1233 (13), 6.1213 (2), 7.2534 (3)
β (°) 90.788 (3)
V3) 2269.68 (13)
Z 4
Radiation type Cu Kα
μ (mm−1) 1.91
Crystal size (mm) 0.35 × 0.34 × 0.34
 
Data collection
Diffractometer ROD, Synergy Custom DW system, HyPix
Absorption correction Multi-scan (CrysAlis PRO; Rigaku Oxford Diffraction, 2023View full citation)
Tmin, Tmax 0.683, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections 12079, 2310, 1997
Rint 0.074
(sin θ/λ)max−1) 0.629
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.064, 0.188, 1.09
No. of reflections 2310
No. of parameters 164
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 0.98, −0.79
Computer programs: CrysAlis PRO (Rigaku OD, 2023View full citation), SHELXT (Sheldrick, 2015aView full citation), SHELXL2018/3 (Sheldrick, 2015bView full citation) and OLEX2 (Dolomanov et al., 2009View full citation).

Supporting information


Computing details top

catena-Poly[[aquazinc(II)]-bis[µ2-4-(phenyldiazenyl)benzoato-κ2O:O']] top
Crystal data top
[Zn(C13H9N2O2)2(H2O)]F(000) = 1096
Mr = 533.83Dx = 1.562 Mg m3
Monoclinic, C2/cCu Kα radiation, λ = 1.54184 Å
a = 51.1233 (13) ÅCell parameters from 5128 reflections
b = 6.1213 (2) Åθ = 1.7–75.3°
c = 7.2534 (3) ŵ = 1.91 mm1
β = 90.788 (3)°T = 100 K
V = 2269.68 (13) Å3Block, colourless
Z = 40.35 × 0.34 × 0.34 mm
Data collection top
ROD, Synergy Custom DW system, HyPix
diffractometer
2310 independent reflections
Radiation source: Rotating-anode X-ray tube, Rigaku (Cu) X-ray Source1997 reflections with I > 2σ(I)
Mirror monochromatorRint = 0.074
Detector resolution: 10.0000 pixels mm-1θmax = 75.8°, θmin = 1.7°
ω scansh = 6363
Absorption correction: multi-scan
(CrysAlisPro; Rigaku Oxford Diffraction, 2023)
k = 77
Tmin = 0.683, Tmax = 1.000l = 99
12079 measured reflections
Refinement top
Refinement on F2Primary atom site location: dual
Least-squares matrix: fullHydrogen site location: mixed
R[F2 > 2σ(F2)] = 0.064H-atom parameters constrained
wR(F2) = 0.188 w = 1/[σ2(Fo2) + (0.0833P)2 + 14.3419P]
where P = (Fo2 + 2Fc2)/3
S = 1.09(Δ/σ)max < 0.001
2310 reflectionsΔρmax = 0.98 e Å3
164 parametersΔρmin = 0.78 e Å3
0 restraints
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Zn10.5000000.68636 (12)0.7500000.0348 (3)
O10.46580 (5)0.5827 (6)0.6597 (5)0.0429 (8)
O20.48302 (5)0.2968 (5)0.5191 (4)0.0395 (7)
O30.5000001.0056 (8)0.7500000.0614 (15)
H30.5014501.0919180.8448600.092*
N10.35958 (6)0.1029 (6)0.4436 (5)0.0366 (8)
N20.35633 (7)0.0988 (6)0.4260 (5)0.0380 (8)
C10.46353 (8)0.4063 (8)0.5720 (6)0.0363 (9)
C20.40772 (8)0.0371 (7)0.4283 (6)0.0363 (9)
H20.4052380.1051170.3785530.044*
C30.29970 (9)0.4379 (8)0.2927 (7)0.0428 (10)
H3A0.2966450.5784100.2410220.051*
C40.28344 (8)0.0956 (9)0.4070 (7)0.0437 (11)
H40.2691010.0034910.4356320.052*
C50.43271 (8)0.1173 (8)0.4591 (7)0.0377 (10)
H50.4474010.0305930.4277140.045*
C60.43656 (8)0.3233 (7)0.5352 (6)0.0353 (9)
C70.38625 (8)0.1666 (7)0.4710 (6)0.0345 (9)
C80.41509 (8)0.4531 (7)0.5779 (6)0.0357 (9)
H80.4176550.5932380.6314250.043*
C90.27874 (9)0.3010 (9)0.3321 (7)0.0461 (11)
H90.2613140.3477830.3077900.055*
C100.30859 (8)0.0238 (8)0.4405 (6)0.0381 (10)
H100.3116070.1170810.4915080.046*
C110.32956 (8)0.1596 (7)0.3988 (6)0.0366 (10)
C120.38991 (8)0.3773 (8)0.5420 (6)0.0369 (10)
H120.3752470.4679400.5656220.044*
C130.32514 (9)0.3678 (8)0.3294 (7)0.0399 (10)
H130.3394700.4625130.3069960.048*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Zn10.0210 (4)0.0272 (4)0.0562 (6)0.0000.0029 (3)0.000
O10.0247 (14)0.0444 (19)0.060 (2)0.0063 (13)0.0040 (12)0.0118 (15)
O20.0221 (13)0.0465 (19)0.0500 (18)0.0000 (12)0.0034 (12)0.0032 (14)
O30.096 (4)0.027 (2)0.061 (3)0.0000.017 (3)0.000
N10.0252 (16)0.0325 (19)0.052 (2)0.0029 (14)0.0021 (14)0.0003 (16)
N20.0267 (17)0.036 (2)0.052 (2)0.0029 (15)0.0044 (14)0.0000 (16)
C10.0256 (19)0.039 (2)0.044 (2)0.0017 (17)0.0039 (16)0.0033 (19)
C20.0277 (19)0.032 (2)0.049 (2)0.0001 (16)0.0024 (17)0.0010 (18)
C30.038 (2)0.036 (2)0.054 (3)0.0103 (19)0.0004 (19)0.001 (2)
C40.029 (2)0.049 (3)0.054 (3)0.0010 (19)0.0047 (18)0.005 (2)
C50.0241 (19)0.037 (2)0.053 (3)0.0038 (17)0.0060 (17)0.0018 (19)
C60.0241 (19)0.035 (2)0.047 (2)0.0017 (16)0.0042 (16)0.0042 (18)
C70.0231 (18)0.034 (2)0.046 (2)0.0031 (16)0.0027 (16)0.0051 (17)
C80.0269 (19)0.034 (2)0.047 (2)0.0034 (16)0.0026 (16)0.0004 (18)
C90.029 (2)0.056 (3)0.053 (3)0.011 (2)0.0004 (19)0.003 (2)
C100.0284 (19)0.037 (2)0.049 (2)0.0006 (17)0.0032 (17)0.0022 (19)
C110.028 (2)0.036 (2)0.046 (3)0.0060 (16)0.0035 (17)0.0014 (18)
C120.0259 (19)0.036 (2)0.049 (3)0.0034 (16)0.0058 (17)0.0035 (19)
C130.034 (2)0.032 (2)0.054 (3)0.0024 (17)0.0068 (19)0.0020 (19)
Geometric parameters (Å, º) top
Zn1—O11.964 (3)C3—C91.393 (7)
Zn1—O1i1.964 (3)C3—C131.392 (6)
Zn1—O2ii2.150 (3)C4—H40.9500
Zn1—O2iii2.150 (3)C4—C91.389 (7)
Zn1—O31.954 (5)C4—C101.377 (6)
O1—C11.258 (6)C5—H50.9500
O2—C11.265 (5)C5—C61.390 (6)
O3—H30.8700C6—C81.393 (6)
O3—H3i0.8700C7—C121.400 (6)
N1—N21.252 (5)C8—H80.9500
N1—C71.430 (5)C8—C121.389 (6)
N2—C111.429 (5)C9—H90.9500
C1—C61.490 (6)C10—H100.9500
C2—H20.9500C10—C111.393 (6)
C2—C51.384 (6)C11—C131.388 (6)
C2—C71.392 (6)C12—H120.9500
C3—H3A0.9500C13—H130.9500
O1—Zn1—O1i142.3 (2)C10—C4—C9120.9 (4)
O1—Zn1—O2iii87.11 (12)C2—C5—H5119.6
O1i—Zn1—O2iii94.66 (13)C2—C5—C6120.8 (4)
O1i—Zn1—O2ii87.11 (12)C6—C5—H5119.6
O1—Zn1—O2ii94.66 (13)C5—C6—C1120.4 (4)
O2iii—Zn1—O2ii174.51 (18)C5—C6—C8119.9 (4)
O3—Zn1—O1i108.85 (11)C8—C6—C1119.7 (4)
O3—Zn1—O1108.85 (10)C2—C7—N1124.5 (4)
O3—Zn1—O2iii87.26 (9)C2—C7—C12120.3 (4)
O3—Zn1—O2ii87.26 (9)C12—C7—N1115.1 (4)
C1—O1—Zn1121.4 (3)C6—C8—H8120.0
C1—O2—Zn1ii125.4 (3)C12—C8—C6119.9 (4)
Zn1—O3—H3127.4C12—C8—H8120.0
Zn1—O3—H3i127.408 (2)C3—C9—H9120.1
H3—O3—H3i105.2C4—C9—C3119.7 (4)
N2—N1—C7114.1 (4)C4—C9—H9120.1
N1—N2—C11113.4 (4)C4—C10—H10120.3
O1—C1—O2122.7 (4)C4—C10—C11119.4 (4)
O1—C1—C6117.5 (4)C11—C10—H10120.3
O2—C1—C6119.8 (4)C10—C11—N2123.6 (4)
C5—C2—H2120.3C13—C11—N2116.1 (4)
C5—C2—C7119.4 (4)C13—C11—C10120.3 (4)
C7—C2—H2120.3C7—C12—H12120.2
C9—C3—H3A120.2C8—C12—C7119.7 (4)
C13—C3—H3A120.2C8—C12—H12120.2
C13—C3—C9119.6 (4)C3—C13—H13120.0
C9—C4—H4119.5C11—C13—C3120.0 (4)
C10—C4—H4119.5C11—C13—H13120.0
Zn1—O1—C1—O27.8 (6)C2—C5—C6—C81.3 (7)
Zn1—O1—C1—C6170.5 (3)C2—C7—C12—C83.0 (7)
Zn1ii—O2—C1—O195.8 (5)C4—C10—C11—N2179.1 (4)
Zn1ii—O2—C1—C686.0 (5)C4—C10—C11—C131.9 (7)
O1—C1—C6—C5172.2 (4)C5—C2—C7—N1179.3 (4)
O1—C1—C6—C87.6 (6)C5—C2—C7—C120.8 (7)
O2—C1—C6—C56.1 (7)C5—C6—C8—C120.8 (7)
O2—C1—C6—C8174.0 (4)C6—C8—C12—C72.9 (7)
N1—N2—C11—C1017.8 (7)C7—N1—N2—C11180.0 (4)
N1—N2—C11—C13163.1 (4)C7—C2—C5—C61.3 (7)
N1—C7—C12—C8178.5 (4)C9—C3—C13—C112.3 (7)
N2—N1—C7—C218.8 (6)C9—C4—C10—C110.2 (7)
N2—N1—C7—C12162.7 (4)C10—C4—C9—C31.0 (7)
N2—C11—C13—C3177.8 (4)C10—C11—C13—C33.1 (7)
C1—C6—C8—C12179.3 (4)C13—C3—C9—C40.2 (7)
C2—C5—C6—C1178.5 (4)
Symmetry codes: (i) x+1, y, z+3/2; (ii) x+1, y+1, z+1; (iii) x, y+1, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H3···O2iv0.871.782.588 (4)154
Symmetry code: (iv) x+1, y+1, z+3/2.
 

Acknowledgements

This work was financially supported by the National Natural Science Foundation of China (No. 21271189) and the Natural Science Foundation of Hunan Province of China (No. 2023 J J30685) for their financial support.

Funding information

This work was financially supported by the National Natural Science Foundation of China (No. 21271189) and the Natural Science Foundation of Hunan Province of China (No. 2023 J J30685).

References

Return to citationDolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339–341.  Web of Science CrossRef CAS IUCr Journals Google Scholar
Return to citationFeng, Y., Luan, Q., Zhang, S., Xi, L., Zhang, S., Chen, K., Liu, T. & Hou, L. (2025). Chem. Sci. 16, 16151–16157.  CrossRef CAS PubMed Google Scholar
Return to citationGhosh, A. & Nitschke, J. R. (2026). Acc. Chem. Res. 59, 372–381.  CrossRef CAS PubMed Google Scholar
Return to citationGolzani, M., Tadjarodi, A., Zare-Dorabei, R., Karbalaee Hosseini, A. & Janczak, J. (2026). Inorg. Chem. 65, 26–35.  CrossRef CAS PubMed Google Scholar
Return to citationGu, Y., Li, S., Sun, Q. & Zhang, B. (2023). J. Mol. Struct. 1274, 134598.  Web of Science CSD CrossRef Google Scholar
Return to citationHao, X., Xu, M. M., Hu, J. & Yan, Q. (2017). J. Mater. Chem. C 5, 10545–10554.  Google Scholar
Return to citationLiang, F., Ma, D., Qin, L., Yu, Q., Chen, J., Liang, R., Zhong, C., Liao, H. & Peng, Z. (2024). Dalton Trans. 53, 10070–10074.  CrossRef CAS PubMed Google Scholar
Return to citationLiu, H., Li, S., Zhao, B., Gu, Y., Sun, Q. & Zhang, B. (2025). CrystEngComm 27, 4582–4590.  CrossRef CAS Google Scholar
Return to citationRigaku OD (2023). CrysAlis PRO. Rigaku Oxford Diffraction, Yarnton, England.  Google Scholar
Return to citationSheldrick, G. M. (2015a). Acta Cryst. A71, 3–8.  Web of Science CrossRef IUCr Journals Google Scholar
Return to citationSheldrick, G. M. (2015b). Acta Cryst. C71, 3–8.  Web of Science CrossRef IUCr Journals Google Scholar
Return to citationZhao, B., Li, S., Liu, H., Zhong, X., Sun, Q. & Zhang, B. (2026). Inorg. Chem. Commun. 186, 116239.  CrossRef Google Scholar
Return to citationZhao, B., Li, S.-L., Gu, Y.-N., Sun, Q.-Z. & Liu, H. (2022). J. Mol. Struct. 1270, 133944.  CrossRef Google Scholar
Return to citationZhao, B., Lu, J., Liu, H., Li, S., Sun, Q. & Zhang, B. (2024). CrystEngComm 26, 1319–1327.  CrossRef CAS Google Scholar
Return to citationZhong, B., Liu, J., Liu, G., Zhang, Z., Chen, Y. & Wang, X. (2025). J. Mol. Struct. 1345, 141679.  CrossRef Google Scholar

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