Porous coordination polymer with flexibility imparted by coordinatively changeable lithium ions on the pore surface.
Solvothermal reactions of equimolar zinc acetate, lithium acetate, and 1,3,5-benzenetricarboxylic acid (H(3)btc) in different mixed solvents yielded isostructural three-dimensional frameworks [LiZn(btc)(cG)].lG [cG and lG denote coordinated and lattice guests, respectively; cG = (nmp)(0.5)(H(2)O)(0.5), lG = (EtOH)(0.5) (1a); cG = H(2)O, lG = EtOH (1b); nmp = N-methyl-2-pyrrolidone] with one-dimensional channels occupied by guest molecules and solvent-coordinated, extrusive Li(+) ions. Thermogravimetry analyses and powder X-ray diffraction measurements revealed that both 1a and 1b can lose all lattice and coordinated guests to form a desolvated phase [LiZn(btc)] (MCF-27, 1) and almost retains the original framework structure. Gas adsorption measurements on 1 confirmed its permanent porosity but suggested a structural transformation from 1a/1b to 1. It is noteworthy that only 1a can undergo a single-crystal to single-crystal (SCSC) transformation into 1 upon desolvation. The crystal structure of 1 revealed that the Li(+) ions were retracted into the channel walls via complementary coordination to the carboxylate oxygen atoms in the framework rather than being exposed on the pore surface. Single-crystal X-ray diffraction analyses were also performed for N(2)- and CO(2)-loaded samples of 1, revealing that the framework remained unchanged when the gases were adsorbed. Although the gas molecules could not be modeled, the residue electrons inside the channels demonstrated that the retracted Li(+) ions still behave as the primary interacting site for CO(2) molecules. Nevertheless, solvent molecules such as H(2)O can readily compete with the framework oxygen atom to retrieve the extrusive Li(+) ions, accompanying the reverse structural transformation, i.e., from 1 to 1a/1b.
Xie
Lin-Hua
LH
MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, State Key Laboratory of Optoelectronic Materials, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, China.
Lin
Jian-Bin
JB
Liu
Xiao-Min
XM
Wang
Yu
Y
Zhang
Wei-Xiong
WX
Zhang
Jie-Peng
JP
Chen
Xiao-Ming
XM
D007477:Ions / Q000737:chemistry; D008094:Lithium / Q000737:chemistry*; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D016062:Porosity; D033362:Powder Diffraction; D013499:Surface Properties; D013818:Thermogravimetry; D014233:Tricarboxylic Acids / Q000737:chemistry; D015032:Zinc / Q000737:chemistry
D007477:Ions; D009942:Organometallic Compounds; D011108:Polymers; D014233:Tricarboxylic Acids; D008094:Lithium; D015032:Zinc; C069849:trimesic acid