**4. Conclusions**

In this work, we presented a structural study of a Cu(II)-H2dtp-based MOF system, in which the rational assembly of Cu(II), dtp2<sup>−</sup> or Hdtp<sup>−</sup> as well as auxiliary bdc2<sup>−</sup> linker give birth to two new MOF materials with the formulae of {[Cu(dtp)](H2O)2}n (**1**) and [Cu(Hdtp)(bdc)0.5]n (**2**). The harvest of 2D "wave-shaped" networks in **1** benefits from the five-coordinative Cu(II), which suggests a low metal ion coordination number in controlling

the formation of the 2D Cu(II)-dtp2<sup>−</sup> network. The introduction of bdc2<sup>−</sup> into the Cu(II) dtp2<sup>−</sup> system results in a 1D chain structure with a "ladder-shape" in **2**. A unique 2D supermolecular layer with a thickness of 7.9 Å is formed by the orderly array of the 1D chain, which may help to broaden the horizon for the assembly of 2D materials through the intermolecular interactions. The air stability of two MOFs is witnessed by PXRD, and the TGA indicates that the thermal stability of the two MOFs is as high as 300 ◦C. The unique structure and relatively good stability of these Cu(II)-MOFs inspired us to further isolate the 2D structures of **1** and **2** as 2D materials for further research.

**Supplementary Materials:** The following supporting information can be downloaded at: https:// www.mdpi.com/article/10.3390/cryst12050585/s1, Table S1: Hydrogen-bonding parameters in **1**; Table S2: Hydrogen-bonding parameters in **2**; Table S3: Selected bond lengths (Å) and angles (o) for **1**; Table S4: Selected bond lengths (Å) and angles (o) for **2**. CCDC 2164393 (**1**) and 2164388 (**2**) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data\_request/cif (accessed on 5 April 2022), by emailing data\_request@ccdc.cam.ac.uk, or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, U. K.; Fax: +44-1223-336033.

**Author Contributions:** Conceptualization, Z.-W.Z. and L.-Q.W.; methodology, Z.-W.Z., L.-Q.W. and J.-J.L.; validation, J.-J.L., X.-X.C., Q.-W.C. and Y.Q.; formal analysis, J.-J.L., X.-X.C.; Q.-W.C. and Y.Q.; investigation, Z.-W.Z. and L.-Q.W.; resources, Z.-W.Z., L.-Q.W. and J.-J.L.; data curation, J.-J.L.; writing—original draft preparation, Z.-W.Z. and L.-Q.W.; writing—review and editing, Z.-W.Z., L.-Q.W. and Q.C.; visualization, Q.C.; supervision, Z.-W.Z. and L.-Q.W.; project administration, Z.-W.Z. and L.-Q.W.; funding acquisition, Z.-W.Z., L.-Q.W. and J.-J.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by National Natural Science Foundation of China grant number 22161009, Thousands of Young and Middle-aged Backbone Teachers Training Project of Guangxi Colleges and Universities grant number Gui-Jiao 2020-58, University innovation foundation of Guangxi Medicine grant number Gui-Degree 2021 No. 6, Collaborative Innovation Center of Zhuang and Yao Ethnic Medicine grant number 2013 No. 20, Guangxi University of Chinese Medicine Key Project of First-class Discipline Construction grant number 2018XK050, Guangxi Natural Science Foundation grant number 2022GXNSFAA035477.

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

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

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

#### **References**

