TY - JOUR
T1 - A Porous and Solution-Processable Molecular Crystal Stable at 200 °c
T2 - The Surprising Donor-Acceptor Impact
AU - Cheng, Shengxian
AU - Ma, Xiaoxia
AU - He, Yonghe
AU - He, Jun
AU - Zeller, Matthias
AU - Xu, Zhengtao
N1 - Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2019/12/4
Y1 - 2019/12/4
N2 - We report a curious porous molecular crystal that is devoid of the common traits of related systems. Namely, the molecule does not rely on directional hydrogen bonds to enforce open packing, and it offers neither large concave faces (i.e., high internal free volume) to frustrate close packing, nor any inherently built-in cavity like in the case of organic cages. Instead, the permanent porosity (as unveiled by the X-ray crystal structure and CO2 sorption studies) arises from the strong push-pull units built into a Sierpinski-like molecule that features four symmetrically backfolded side arms. Each side arm consists of the 1,1,4,4-tetracyanobuta-1,3-diene acceptor coupled with the dimethylaminophenyl donor, which is conveniently installed by a cycloaddition-retroelectrocyclization reaction. Unlike the poor/fragile crystalline order of many porous molecular solids, the molecule here readily crystallizes, and the crystalline phase can be easily deposited into thin films from solutions. Moreover, both the bulk sample and thin film exhibit excellent thermal stability with the porous crystalline order maintained even at 200 °C. The intermolecular forces underlying this robust porous molecular crystal likely include the strong dipole interactions and the multiple C···N and C···O short contacts afforded by the strongly donating and accepting groups integrated within the rigid molecular scaffold.
AB - We report a curious porous molecular crystal that is devoid of the common traits of related systems. Namely, the molecule does not rely on directional hydrogen bonds to enforce open packing, and it offers neither large concave faces (i.e., high internal free volume) to frustrate close packing, nor any inherently built-in cavity like in the case of organic cages. Instead, the permanent porosity (as unveiled by the X-ray crystal structure and CO2 sorption studies) arises from the strong push-pull units built into a Sierpinski-like molecule that features four symmetrically backfolded side arms. Each side arm consists of the 1,1,4,4-tetracyanobuta-1,3-diene acceptor coupled with the dimethylaminophenyl donor, which is conveniently installed by a cycloaddition-retroelectrocyclization reaction. Unlike the poor/fragile crystalline order of many porous molecular solids, the molecule here readily crystallizes, and the crystalline phase can be easily deposited into thin films from solutions. Moreover, both the bulk sample and thin film exhibit excellent thermal stability with the porous crystalline order maintained even at 200 °C. The intermolecular forces underlying this robust porous molecular crystal likely include the strong dipole interactions and the multiple C···N and C···O short contacts afforded by the strongly donating and accepting groups integrated within the rigid molecular scaffold.
UR - http://www.scopus.com/inward/record.url?scp=85075667379&partnerID=8YFLogxK
U2 - 10.1021/acs.cgd.9b01488
DO - 10.1021/acs.cgd.9b01488
M3 - Article
AN - SCOPUS:85075667379
SN - 1528-7483
VL - 19
SP - 7411
EP - 7419
JO - Crystal Growth and Design
JF - Crystal Growth and Design
IS - 12
ER -