Portal de Periódicos da CAPES

Specific πδ+–πδ- interaction enables conjugated microporous polymers for highly selective capture of Pd(II)

2022; Elsevier BV; Volume: 437; Linguagem: Inglês

10.1016/j.cej.2022.135367

1873-3212

Xin Sheng, Hui Shi, Deng You, Xuan Ding, Mingming Peng, Penghui Shao, Liming Yang, Haozhi Wang, Xubiao Luo, Shenglian Luo,

Molecular Sensors and Ion Detection

Specific π δ+ –π δ- interaction between –C≡C– with vertical π bond in conjugated microporous polymers and electron-rich Pd center with π 5 8 δ - in PdCl 4 2- is constructed, resulting in highly selective capture of PdCl 4 2- in coexistence systems of heavy metals. It provides a novel design principle for efficient and targeted heavy metal adsorbents in acid wastewater. • Three kinds of CMPs adsorbents were prepared by S-H coupling reactions. • The –C≡C– groups of CMPs were identifified as the adsorption sites of PdCl 4 2- . • Strong π δ+ –π δ- interaction was formed between the –C≡C– and PdCl 4 2- . • CMPs exhibited an excellent PdCl 4 2- selectivity in acid water. The targeted capture of heavy metals from wastewater is urgently necessary in response to strategic demands of sustainable resource utilization, but it is severely hampered by the formation of specific adsorbent-adsorbate interactions. Herein, the conjugated microporous polymer CMP-1 with –C≡C– binding sites is introduced for the adsorption of PdCl 4 2- in acid wastewater. The matched interaction between –C≡C– with vertical π bond and electron-rich Pd center with π 5 8 δ - exhibits exceptional PdCl 4 2- selectivity in competitive systems with coexisting heavy metals. To regulate the electron density of π bond in –C≡C– to further reinforce the π δ+ –π δ- interaction, p -FCMP and o -FCMP adsorbents are rationally designed through the substitution of electro-withdrawing F group at different positions. A joint experimental-simulation exploration reveals that the F-induced electron oriented migration in –C≡C– results in the decreased π-electron density, therefore enhancing the binding of PdCl 4 2- . Notably, o -FCMP possesses the maximum positive charge density at –C≡C– binding sites, which greatly promotes the charge transfer between –C≡C– and PdCl 4 2- for stronger bonding interaction, achieving an optimal adsorption capacity of 447.7 mg g −1 as well as enhanced selectivity. This work provides unique insights into the efficiently targeted removal of heavy metals.