TY - JOUR
T1 - Investigation of Missing-Cluster Defects in UiO-66 and Ferrocene Deposition into Defect-Induced Cavities
AU - Shan, Bohan
AU - McIntyre, Sean M.
AU - Armstrong, Mitchell R.
AU - Shen, Yuxia
AU - Mu, Bin
N1 - Funding Information:
We gratefully acknowledge the National Science Foundation (Grant Number CBET-1748641 and CMMI-1825594). We gratefully acknowledge the use of facilities within the Leroy Eyring Center for Solid State Science at Arizona State University and ASU SEMTE lab manager Fred Pena for continued support. We also appreciate that Dr. Lenore Dai provided the TGA analyzer and Yifei Xu and Wendy Lin for the technical support.
Publisher Copyright:
© Copyright 2018 American Chemical Society.
PY - 2018/10/24
Y1 - 2018/10/24
N2 - Advancing our understanding of the defect formation mechanism in metal-organic frameworks (MOFs) is critical for the rational design of the material's structure. In particular, the defects in the UiO-66 framework have been shown to have a significant impact on the framework functionality and stability. However, the effects of synthesis conditions on defect formation are elusive and our understanding of missing-ligand and missing-cluster defects in UiO-66 is far from clear. In this work, we demonstrate that the formation of missing-cluster (MC) defects is due to the large number of partially deprotonated ligands in synthesis solution. The proposed mechanism is verified by a series of syntheses controlling the defect formation. The results show that the quantity of MC defects is sensitive to deprotonation reagents, synthesis temperature, and reactant concentration. The pore size distribution derived from the N2 adsorption isotherm at 77 K allows accurate and convenient characterization of the defects in UiO-66. The existence of defects in the UiO-66 framework can cause significant deviations in its pore size distribution from the results derived from the theoretically perfect crystal structure. The extra cavities generated by MC defects are demonstrated to allow deposition of a large functional molecule, ferrocene (3.5 Å × 4.5 Å × 4.5 Å). The successful incorporation is proven by the tuning of the original N2-selective framework to become an O2-selective framework.
AB - Advancing our understanding of the defect formation mechanism in metal-organic frameworks (MOFs) is critical for the rational design of the material's structure. In particular, the defects in the UiO-66 framework have been shown to have a significant impact on the framework functionality and stability. However, the effects of synthesis conditions on defect formation are elusive and our understanding of missing-ligand and missing-cluster defects in UiO-66 is far from clear. In this work, we demonstrate that the formation of missing-cluster (MC) defects is due to the large number of partially deprotonated ligands in synthesis solution. The proposed mechanism is verified by a series of syntheses controlling the defect formation. The results show that the quantity of MC defects is sensitive to deprotonation reagents, synthesis temperature, and reactant concentration. The pore size distribution derived from the N2 adsorption isotherm at 77 K allows accurate and convenient characterization of the defects in UiO-66. The existence of defects in the UiO-66 framework can cause significant deviations in its pore size distribution from the results derived from the theoretically perfect crystal structure. The extra cavities generated by MC defects are demonstrated to allow deposition of a large functional molecule, ferrocene (3.5 Å × 4.5 Å × 4.5 Å). The successful incorporation is proven by the tuning of the original N2-selective framework to become an O2-selective framework.
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U2 - 10.1021/acs.iecr.8b03516
DO - 10.1021/acs.iecr.8b03516
M3 - Article
AN - SCOPUS:85054827189
SN - 0888-5885
VL - 57
SP - 14233
EP - 14241
JO - Industrial and Engineering Chemistry Research
JF - Industrial and Engineering Chemistry Research
IS - 42
ER -