Solvent-Controlled Phase Transition of a CoII-Organic Framework: From Achiral to Chiral and Two to Three Dimensions.
An unprecedented reversible dynamic transformation is reported in a metal-organic framework involving bond formation, which is accompanied by two important structural changes; achiral to chiral and two- to three-dimensions. Using two bent organic ligands (diimpym=4,6-di(1H-imidazol-1-yl)pyrimidine; H2npta=5-nitroisophthalic acid) and CoII(NO3)2⋅6 H2O the coordination polymer Co(diimpym)(npta)⋅CH3OH, (1⋅CH3OH), was obtained solvothermally. Its structure consists of knitted pairs of square layers (44-sql net) of five-coordinated Co and disordered methanol, and it crystallized in the achiral Pbca space group at room temperature. It undergoes a single crystal to single crystal (SC-SC) transformation to a 3D interpenetrated framework (α-polonium-type net, pcu) of six-coordinated Co and ordered methanol in the chiral P212121space group below 220 K. Most unusual is the dynamic temperature-dependent shortening of a Co⋅⋅⋅O connection from a non-bonded 2.640 Å (298 K) to a bonded 2.347 Å distance (100 K) transforming the square pyramidal cobalt polyhedron to a distorted octahedron. The desolvated crystals (1) obtained at 480 K retain the full crystallinity and crystallize in the achiral Pbca space group between 100 and 298 K but the dynamic shortening of the Co⋅⋅⋅O distance connecting the layers into the 3D pcu framework structure is observed. Following post-synthetic insertion of ethanol (1⋅CH3CH2OH) it does not exhibit the transformation and retains the knitted 2D achiral Pbca structure for all temperatures (100-298 K) and the ethanol is always disordered. The structural analyses thus conclude that the ordering of the methanol induces the chirality while the available space controls the dynamic motion of the knitted 2D networks into the 3D interpenetrated framework. Consequently, 1 selectively adsorbs CO2to N2and exhibits Type-III isotherms indicating dynamic motion of the 2D networks to accommodate the CO2at 273 and 298 K in contrast to the rigidity of the 3D framework at 77 K preventing N2from penetrating the solid. The magnetic properties are also reported.
Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, P. R. China.
Xing-Po
XP
Wang
Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, P. R. China.
Wen-Miao
WM
Chen
Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, P. R. China.
Hao
H
Qi
Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, P. R. China.
Xiao-Yi
XY
Li
Department of Chemistry, FPV, University of Ss. Cyril and Methodius, 917 01, Trnava, Slovakia.
Cyril
C
Rajnák
Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, P. R. China.
Zhen-Yu
ZY
Feng
Institut de Chimie de Strasbourg, Université de Strasbourg, CNRS-UMR 7177, 4 rue Blaise Pascal, 67008, Strasbourg Cedex, France.
Mohamedally
M
Kurmoo
Department of Chemistry, FPV, University of Ss. Cyril and Methodius, 917 01, Trnava, Slovakia.
Roman
R
Boča
Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, P. R. China.
Chun-Jiang
CJ
Jia
Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, P. R. China.
Chen-Ho
CH
Tung
Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, P. R. China.
Di
http://orcid.org/0000-0001-5966-1207
D
Sun
gas adsorption; magnetism; metal-organic frameworks; single-crystal-to-single-crystal transformation