Formation and Characterization of Crystalline Molecular Arrays of Gas Molecules in a 1-Dimensional Ultramicropore of a Porous Copper Coordination Polymer

Abstract

Molecules and atoms confined in a nanospace may have properties distinctly different from those of the bulk fluid, owing to the formation of a specific molecular array characteristic of nanospace. In situ synchrotron powder X-ray diffraction measurements have been used to observe confined guest molecules such as N2, O2, Ar, and CH4 in the well-regulated ultramicropore of a copper coordination polymer, 1 ([Cu2(pzdc)2pyz]: pzdc = 2,3-pyrazinedicarboxylate and pyz = pyrazine). The obtained crystal structures indicate that guest molecules are confined in a linear fashion to form crystalline-like regular ordered arrays, in contrast to the situation in the gas and liquid state, even at temperatures above the boiling point, and the ordered arrays are characteristic of the kind of gas molecule and the geometrical and potential properties of the ultramicropore of 1.

Chemistry of coordination space of porous coordination polymers

“…In this section, we focus on a series of compounds as porous coordination pillared layer structures (CPLs), [Cu 2 (pzdc) 2 (P)] n (pzdc = pyrazine-2,3-dicarboxylate, P = pillar ligands) [44][45][46][47][48][49][50][51][52][53][54]. The CPL series is one representative example of porous coordination polymers with high designability.…”

“…Fig. 9 shows adsorption isotherms of Ar, CH 4 , N 2 , and O 2 at 77 K and CO 2 at 195 K on CPL-1 [47]. The isotherms display a steep rise in the low relative pressure region followed by a plateau.…”

“…However, we were not successful in many attempts to form 1D arrays of these paramagnetic gas molecules through confinement of the molecules in porous coordination polymers [68] or in microporous carbon materials [57,69]. Therefore, to form a regular assembly of these simple molecules in a nanochannel, it is important that we use not only the strong confinement effect of nanospace but also the commensurability between the host structure and guest molecule mentioned above, the amount adsorbed in each unit pore of CPL-1 shows precisely integral value [46,47]. This commensurate adsorption clearly indicates the formation of molecular arrays in the one-dimensional channel of CPL-1.…”

Selective CO2 Adsorption by a Triazacyclononane‐Bridged Microporous Metal–Organic Framework

“…[1][2][3][4] In the last decade, many crystalline porous coordination polymers have led to a new class of porous materials with the potential for a range of applications, [2,[5][6][7][8][9][10] and they have also provided flexible platforms for developing well-designed gas molecule adsorbents, [1,4,11,12] in particular, for CO 2 capture with high selectivity. [13][14][15][16][17][18][19][20][21][22][23][24] To enhance the adsorption capacity, microporous materials with open metal sites, such as Cu 3 A C H T U N G T R E N N U N G (BTC) 2 [25] (BTC = 1,3,5-benzenetricarboxylate) and M 2 A C H T U N G T R E N N U N G (DOTP) (CPO-27M; M = Ni, Mg, DOTP = 2,5-dioxyterephtalate), [26,27] were studied and their high capacity for CO 2 adsorption was shown thanks to strong electrostatic interactions with the exposed metallic ions. [26,27] The Lewis acid character of the coordinatively unsaturated metal ions was taken advantage of by using zeolites and Cu 3 A C H T U N G T R E N N U N G (BTC) 2 for the separation of gas mixtures with high selectivity, [28,29] and the CPO-27M materials were shown to be among the best sorbents for CO 2 separation close to 1 atm.…”

Molecular Interactions for Modeling of Oxygen System Using van der Waals Density Functional Approach

“…In these systems, construction of the pair potential between molecules promotes a development on material physics. It may also suggest a new insight on the molecular system confined in metal-organic solids [5][6][7].…”