3.2.9. Synthesis of Na2(H2O)4{CuMo6O16(OH)2[CH3C(CH2O)3]2}·6H2O (**9**)

The synthetic procedure of compound **9** was similar with that of compound **8** except that the pH of the solution was adjusted to 3.5. Elemental analysis calcd. (%) for Na2(H2O)4{CuMo6O16(OH)2[CH3C(CH2O)3]2}·6H2O (Mw = 1389.58 g mol<sup>−</sup>1): C 8.64%, H 2.90%, Na 3.31%, Cu 4.57%, and Mo 41.43%; found C 8.70%, H 2.94%, Na 3.38%, Cu 4.66%, and Mo 41.52%.

#### **4. Conclusions**

By synthesizing a series of CuII-centered Anderson-Evans POMs modified with triol ligands in the presence of different cations in aqueous solution, ordered assemblies of polyanions from 0D to 2D under cation regulation were successfully realized. The results show that NH4 <sup>+</sup> directs the formation of 0D building blocks, and Cu2+ leads the 1D chain structures, while Na<sup>+</sup> dominates 2D networks. During the assembled process, the charge ratio between cations and anions has an important effect on the assembled structures. When the size of a cation is large, its wider connection range can link the four adjacent polyanions together to form a 2D structure, while when the size of cation is small, the polyanions can only be arranged in a 1D chain. The research work in this section not only provides an important method and idea for the construction of an ordered assembly of polyanions, but also lays the foundation for the development of specific functional systems.

**Supplementary Materials:** The following supporting information is available online at https:// www.mdpi.com/article/10.3390/molecules27092933/s1. Figure S1: The schematic drawing of possible decoration types when triol ligands bind to an Anderson-Evans POM cluster, where the blue octahedron represents {MO6} (M = Mo or W) and yellow octahedron denotes heteroatom-oxygen {XO6}; Figure S2: FT-IR spectra of compounds **1**–**9**; Figures S3–S11: TGA curves of compounds **1**–**9**; Figures S12–S14: XRD patterns of as-synthesized compounds **1**–**9** and their simulated patterns from the corresponding single-crystal X-ray diffraction data; Figure S15: Two possible arrangements of linkers and building blocks with 1:1 charge ratio. Spheres and disks represent linkers and building blocks, respectively. The solid and dotted lines show the interactions between the adjacent components; Figure S16: Ball-and-stick representations of compounds (a) **6** and (b) **7**, showing their neighboring chains. Numbers in the diagram represent the distances of adjacent clusters. All H atoms except those attached to tri-bridging O atoms in polyanions are omitted for clarity. Tables S1–S5: Hydrogen bonds for compounds **1**–**5**.

**Author Contributions:** Conceptualization, B.L.; formal analysis, Y.W.; investigation, F.D. and X.L.; writing—original draft preparation, Y.W.; writing—review and editing, B.L.; supervision, B.L.; funding acquisition, B.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by Natural Science Foundation of China, grant number 22172060.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Crystallographic data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data\_request/cif, accessed on 27 March 2022.

**Conflicts of Interest:** The authors declare no conflict of interest.

**Sample Availability:** Samples of the compounds are available from the authors.

#### **References**

