Open AccessAsynchronous Double Schiff Base Formation of Pyrazole Porous Polymers for Selective Pd Recovery
Author(s) -
Garai Mousumi,
Mahato Manmatha,
Hong Yeongran,
Rozyyev Vepa,
Jeong Uiseok,
Ullah Zakir,
Yavuz Cafer T.
Publication year - 2021
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.202001676
Subject(s) - pyrazole , schiff base , chemistry , selectivity , reagent , polymer , monomer , density functional theory , amine gas treating , reactivity (psychology) , polymer chemistry , combinatorial chemistry , inorganic chemistry , catalysis , organic chemistry , computational chemistry , medicine , alternative medicine , pathology
Pyrazole‐linked covalent organic polymer is synthesized using an asynchronous double Schiff base from readily available monomers. The one‐pot reaction features no metals as a building block or reagent, hence facilitating the structural purity and industrial scalability of the design. Through a single‐crystal study on a model compound, the double Schiff base formation is found to follow syn addition, a kinetically favored product, suggesting that reactivity of the amine and carbonyls dictate the order and geometry of the framework building. The highly porous pyrazole polymer COP‐214 is chemically resistant in reactive conditions for over two weeks and thermally stable up to 425 °C in air. COP‐214 shows well‐pronounced gas capture and selectivities, and a high CO 2 /N 2 selectivity of 102. The strongly coordinating pyrazole sites show rapid uptake and quantitative selectivity of Pd (II) over several coordinating metals (especially Pt (II)) at all pH points that are tested, a remarkably rare feature that is best explained by detailed analysis as the size‐selective strong coordination of Pd onto pyrazoles. Density functional theory (DFT) calculations show energetically favorable Pd binding between the metal and N‐sites of COP‐214. The polymer is reusable multiple times without loss of activity, providing great incentives for an industrial prospect.