posted on 2023-11-29, 21:20authored byWen-Qi Tang, Xuannuo Yi, Hanxi Guan, Xiao-Wei Wang, Yue-Wen Gu, Ying-Jie Zhao, Jia Fu, Wang Li, Yue Cheng, Sha-Sha Meng, Ming Xu, Qing-Hua Zhang, Lin Gu, Xueqian Kong, Da-Huan Liu, Wei Wang, Zhi-Yuan Gu
The
precise modulation of nanosheet stacking modes introduces unforeseen
properties and creates momentous applications but remains a challenge.
Herein, we proposed a strategy using bipolar molecules as torque wrenches
to control the stacking modes of 2-D Zr-1,3,5-(4-carboxylphenyl)-benzene
metal–organic framework (2-D Zr-BTB MOF) nanosheets. The bipolar
phenyl–alkanes, phenylmethane (P–C1) and
phenyl ethane (P–C2), predominantly instigated the
rotational stacking of Zr-BTB–P–C1 and Zr-BTB–P–C2, displaying a wide angular distribution. This included Zr-BTB–P–C1 orientations at 0, 12, 18, and 24° and Zr-BTB–P–C2 orientations at 0, 6, 12, 15, 24, and 30°. With reduced
polarity, phenyl propane (P–C3) and phenyl pentane
(P–C5) introduced steric hindrance and facilitated
alkyl hydrophobic interactions with the nanosheets, primarily resulting
in the modulation of eclipsed stacking for Zr-BTB–P–C3 (64.8%) and Zr-BTB–P–C5 (93.3%)
nanosheets. The precise angle distributions of four Zr-BTB–P
species were in agreement with theoretical calculations. The alkyl
induction mechanism was confirmed by the sequential guest replacement
and 2-D 13C–1H heteronuclear correlation
(HETCOR). In addition, at the single-particle level, we first observed
that rotational stacked pores exhibited similar desorption rates for
xylene isomers, while eclipsed stacked pores showed significant discrepancy
for xylenes. Moreover, the eclipsed nanosheets as stationary phases
exhibited high resolution, selectivity, repeatability, and durability
for isomer separation. The universality was proven by another series
of bipolar acetate-alkanes. This bipolar molecular torque wrench strategy
provides an opportunity to precisely control the stacking modes of
porous nanosheets.