一种含有N,N'-二乙基甲酰胺（DEF）溶剂化镉簇二级结构单元的柔性金属有机框架中包含非常规吡啶基配体。

Unconventional Pyridyl Ligand Inclusion within a Flexible Metal-Organic Framework Bearing an N,N'-Diethylformamide (DEF)-Solvated Cd Cluster Secondary Building Unit.

作者信息

Chao Meng-Yao, Chen Jing, Wu Xiao-Yu, Wang Rui-Yao, Wang Pei-Pei, Ding Lifeng, Young David J, Zhang Wen-Hua

机构信息

College of Chemistry Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, China.

Department of Chemistry, Xi'an Jiaotong-Liverpool University, Suzhou, 215123, China.

出版信息

Chempluschem. 2020 Mar;85(3):503-509. doi: 10.1002/cplu.202000127.

DOI:10.1002/cplu.202000127

PMID:32187841

Abstract

A cationic three-dimensional (3D) metal-organic framework (MOF) sustained by an N,N'-diethylformamide (DEF)-solvated zigzag-shaped Cd cluster secondary building unit (SBU), [Et NH ] [Cd (BTB) (DEF) ] ⋅ 4.75DEF (1 a, H BTB=benzene-1,3,5-tribenzoic acid) shows flexible framework behavior and undergoes solvate exchange with CHCl to yield [Et NH ] [Cd (BTB) (DEF) ] ⋅ xCHCl (1 b) accompanied by changes to pore sizes and shapes. Unexpectedly, the DEF solvates coordinated to the central Cd could not be replaced by strongly donor pyridyl and dipyridyl ligands. Additionally, more electron-deficient pyridyls preferentially coordinated to the flanking Cd of the Cd SBU, as exemplified by [Et NH ] [Cd (BTB) (DEF) (PyCHO) ] ⋅ xSol (2 a, PyCHO=4-pyridinealdehyde) and [Et NH ] [Cd (BTB) (DEF) (PyAc) ] ⋅ xSol (2 b, PyAc=4-acetylpyridine). Density functional theory (DFT) calculations were used to understand these counterintuitive observations.

摘要

一种由N，N'-二乙基甲酰胺（DEF）溶剂化的锯齿形镉簇二级构筑单元（SBU）支撑的阳离子三维（3D）金属有机框架（MOF），[Et₂NH₂][Cd₃(BTB)₂(DEF)₂]⋅4.75DEF（1a，H₃BTB = 苯-1,3,5-三苯甲酸）表现出框架柔性行为，并与CHCl₃发生溶剂交换，生成[Et₂NH₂][Cd₃(BTB)₂(DEF)₂]⋅xCHCl₃（1b），同时伴随着孔径和形状的变化。出乎意料的是，与中心镉配位的DEF溶剂化物不能被强供体吡啶基和联吡啶基配体取代。此外，电子缺乏程度更高的吡啶基优先与镉SBU的侧翼镉配位，如[Et₂NH₂][Cd₃(BTB)₂(DEF)(PyCHO)]⋅xSol（2a，PyCHO = 4-吡啶甲醛）和[Et₂NH₂][Cd₃(BTB)₂(DEF)(PyAc)]⋅xSol（2b，PyAc = 4-乙酰基吡啶）所示。采用密度泛函理论（DFT）计算来理解这些与直觉相悖的观察结果。