Miura Hiroki, Bon Volodymyr, Senkovska Irena, Ehrling Sebastian, Watanabe Satoshi, Ohba Masaaki, Kaskel Stefan
Department of Inorganic Chemistry, Technische Universität Dresden, Bergstrasse 66, D-01062 Dresden, Germany.
Dalton Trans. 2017 Oct 17;46(40):14002-14011. doi: 10.1039/c7dt02809a.
Controlled nucleation in a micromixer and further crystal growth were used to synthesize Ni(2,6-ndc)dabco (2,6-ndc - 2,6-naphthalenedicarboxylate, dabco - 1,4-diazabicyclo[2.2.2]octane), also termed DUT-8(Ni) (DUT = Dresden University of Technology), with narrow particle size distribution in a range of a few nm to several μm. The crystal size was found to significantly affect the switching characteristics, in particular the gate opening pressure in nitrogen adsorption isotherms at 77 K for this highly porous and flexible network. Below a critical size of about 500 nm, a type Ia isotherm typical of rigid MOFs is observed, while above approximately 1000 nm a pronounced gating behaviour is detected, starting at p/p = 0.2. With increasing crystal size this transition gate becomes steeper indicating a more uniform distribution of activation energies within the crystal ensemble. At an intermediate size (500-1000 nm), the DUT-8(Ni) crystals close during activation but cannot be reopened by nitrogen at 77 K possibly indicating monodomain switching.
在微混合器中进行可控成核并进一步进行晶体生长,用于合成Ni(2,6-ndc)dabco(2,6-ndc - 2,6-萘二甲酸酯,dabco - 1,4-二氮杂双环[2.2.2]辛烷),也称为DUT-8(Ni)(DUT = 德累斯顿工业大学),其粒径分布狭窄,范围从几纳米到几微米。发现晶体尺寸对开关特性有显著影响,特别是对于这种高度多孔且灵活的网络,在77 K下氮气吸附等温线中的门开启压力。在约500 nm的临界尺寸以下,观察到刚性金属有机框架典型的Ia型等温线,而在约1000 nm以上,在p/p = 0.2时检测到明显的门控行为。随着晶体尺寸的增加,这个转变门变得更陡峭,表明晶体集合体内活化能的分布更均匀。在中等尺寸(500 - 1000 nm)时,DUT-8(Ni)晶体在活化过程中关闭,但在77 K下不能被氮气重新打开,这可能表明单畴开关。