Young Ho Jhon

Reversible Interpenetration in a Metal-Organic Framework Triggered by Ligand Removal and Addition

Interpenetration is known for the structures of many minerals and ice; most notably for ice, it exists in doubly interpenetrating (VI, VII, and VIII) and non-interpenetrating (Ih) forms with the latter being porous and having nearly half of the density of the former. In synthetic materials, specifically in metal–organic frameworks (MOFs), interpenetration is generally considered undesirable because it reduces porosity. However, on the contrary, many advantageous properties also arise when MOFs are interpenetrated, such as selective guest capture, stepwise gas adsorption, enhanced framework robustness, photoluminescence control, and guest-responsive porosity. Therefore, various strategies have been suggested to control interpenetration during synthesis. However, once these extended network materials are prepared as interpenetrating or non-interpenetrating structures, the degree of interpenetration generally remains unchanged, because numerous chemical bonds must be broken and subsequently reformed in a very concerted way during the process unlike some interlocked coordination compounds in solution (Figure 1a).

Crystal structure and electronic properties of 2-amino-2-methyl-1-propanol (AMP) carbamate

A crystal structure of a carbamate of 2-amino-2-methyl-1-propanol (AMP-carbamate) has been elucidated and its structural and electronic properties investigated by density functional theory calculations and natural bond orbital analyses.

Nucleophilicity and accessibility calculations of alkanolamines: applications to carbon dioxide absorption reactions.

Both nucleophilicities and accessibilities of three alkanolamines [monoethanolamine (MEA), (2-(methylamino)ethanol (MAE), and 2-amino-2-methyl-1-propanol (AMP)] were calculated to predict their reactivities with CO(2). After DFT geometry-optimization calculations, the global, group, and atomic nucleophilicities of each amine were obtained using MP2 quantum mechanical calculations. Only global nucleophilicity matched an experimental pK(a) order (MAE > AMP > MEA). However, it failed to predict the slow rate of the sterically hindered AMP and the order of rate constants, MAE > MEA > AMP. The accessibilities of amines to CO(2) have been calculated by MD simulations by monitoring collisions at the reaction centers: N atoms in amines and C in CO(2). The accessibility results indicate that global nucleophilicity needs quantitative correction for steric effects to predict better reactivities of amines with CO(2).

Poly[bis­(μ4-2,3,5,6-tetra­fluoro­benzene-1,4-di­carboxyl­ato-κ4O1:O1′:O4:O4′)bis­(tetra­hydro­furan-κO)dizinc]

The title compound, [Zn2(C8F4O4)2(C4H8O)2]n, has a three-dimensional metal-organic framework structure. The asymmetric unit consists of two ZnII atoms, two tetrahydrofuran ligands, one 2,3,5,6-tetrafluorobenzene-1,4-dicarboxylate ligand and two half 2,3,5,6-tetrafluorobenzene-1,4-dicarboxylate ligands, which are completed by inversion symmetry. One ZnII atom has a distorted trigonal–bipyramidal coordination geometry, while the other has a distorted octahedral geometry. Two independent tetrahydrofuran ligands are each disordered over two sets of sites with occupancy ratios of 0.48 (4):0.52 (4) and 0.469 (17):0.531 (17).

Poly[bis­(N,N-dimethyl­formamide)(μ-formato)(μ5-4-oxidoisophthalato)dizinc(II)]

The title compound, [Zn2(CHO2)(C8H3O5)(C3H7NO)2]n, is a three-dimensional metal–organic framework, of which two independent ZnII atoms (denoted Zn1 and Zn2) are linked by both 4-oxidoisophthalate and formate bridging ligands. The 4-oxidoisophthalate ligands link two Zn1-type and three Zn2-type atoms, forming a corrugated sheet roughly parallel to the ac plane. The formate ions join two neighboring sheets along the b axis, forming a three-dimensional network. Two independent dimethylformamide ligands are coordinated to separate ZnII atoms and fill the voids provided by the framework. Both types of ZnII atoms have a distorted trigonal-bipyramidal coordination geometry.