Single-Pore versus Dual-Pore Bipyridine-Based Covalent-Organic Frameworks: An Insight into the Heterogeneous Catalytic Activity for Selective CH Functionalization

Harsh Vardhan; Abdullah M Al-Enizi; Ayman Nafady; Yanxiong Pan; Zhongyu Yang; Humberto R Gutiérrez; Xiaolong Han; Shengqian Ma

doi:10.1002/smll.202003970

Single-Pore versus Dual-Pore Bipyridine-Based Covalent-Organic Frameworks: An Insight into the Heterogeneous Catalytic Activity for Selective CH Functionalization

Small. 2021 Jun;17(22):e2003970. doi: 10.1002/smll.202003970. Epub 2020 Sep 11.

Authors

Harsh Vardhan¹, Abdullah M Al-Enizi², Ayman Nafady², Yanxiong Pan³, Zhongyu Yang³, Humberto R Gutiérrez⁴, Xiaolong Han⁵, Shengqian Ma^{1

6}

Affiliations

¹ Department of Chemistry, University of South Florida, 4202 E. Fowler Avenue, Tampa, FL, 33620, USA.
² Department of Chemistry, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia.
³ Department of Chemistry and Biochemistry, North Dakota State University, 1231 Albrecht Blvd., Fargo, ND, 58108, USA.
⁴ Department of Physics, University of South Florida, Tampa, FL, 33620, USA.
⁵ School of Chemical Engineering, Northwest University, Xi'an, Shaanxi, 710069, China.
⁶ Department of Chemistry, University of North Texas, 1508 W Mulberry St, Denton, TX, 76201, USA.

PMID: 32914540
DOI: 10.1002/smll.202003970

Abstract

Exponential growth in the field of covalent-organic frameworks (COFs) is emanating from the direct correlation between designing principles and desired properties. The comparison of catalytic activity between single-pore and dual-pore COFs is of importance to establish structure-function relationship. Herein, the synthesis of imine-linked dual-pore [(BPyDC)]_x _% -ETTA COFs (x = 0%, 25%, 50%, 75%, 100%) with controllable bipyridine content is fulfilled by three-component condensation of 4,4',4″,4'″-(ethene-1,1,2,2-tetrayl)tetraaniline (ETTA), 4,4'-biphenyldialdehyde, and 2,2'-bipyridyl-5,5'-dialdehyde in different stoichiometric ratio. The strong coordination of bipyridine moieties of [(BPyDC)]_x _% -ETTA COFs with palladium imparts efficient catalytic active sites for selective functionalization of sp² CH bond to CX (X = Br, Cl) or CO bonds in good yield. To broaden the scope of regioselective CH functionalization, a wide range of electronically and sterically substituted substrates under optimized catalytic condition are investigated. A comparison of the catalytic activity of palladium decorated dual-pore frameworks with single-pore imine-linked Pd(II) @ Py-2,2'-BPyDC framework is undertaken. The finding of this work provides a sporadic example of chelation-assisted CH functionalization and disclosed an in-depth comparison of the relationship between superior catalytic activity and core properties of rationally designed imine linked frameworks.

Keywords: C H functionalization; covalent-organic frameworks; heterogeneous catalysis; palladium; pore surface engineering.

Abstract

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