Influence of the Ammonium Cation and 18-Crown-6 Guest on the Supramolecular Networks of 1,3,5-Cyclohexanetricarboxylic Acid

Abstract

The title acid 1,3-cis,5-cis-cyclohexanetricarboxylic acid (H 3 CTA) forms a three-dimensional anionic host framework via O-H‚‚‚O -hydrogen bonds with 11.2 × 12.7 Å square channels for the inclusion of 18-crown-6 (18-C-6) and NH 4 + cation in a Russian doll assembled guest∩cavitand⊂clathrand crystal structure, H 2 CTA -‚H 2 O‚NH 4 + ‚18-C-6 (1). Differences in the binding of the ammonium cation to the crown ether and OHNH 3 + cation result in a two-dimensional network of H 2 CTA -anions in H 2 CTA -‚OHNH 3 + ‚18-C-6 (2) that resemble the black phosphorus topology. In contrast to ionic structures 1 and 2, crystal structure of the neutral complex H 3 CTA‚(18-C-6) 0.5 (3) is sustained by a size/shape fit of the crown macrocycle in the 14.5 × 14.5 Å hexagonal cavity of the triacid host and 12 C-H‚‚‚O interactions.We recently described crystal structures of 1,3-cis,5-cis-cyclohexanetricarboxylic acid (H 3 CTA) with some amine bases to give H 2 CTA -‚RNH 3 + salts (R ) H, NH 2 , OH, Me, Et). 1 The role of cation template was noted to be crucial in these structures. Tetrahedral ammonium cations, such as NH 4 + , OHNH 3 + , and NH 2 -NH 3 + with four strong NH/OH groups, direct a supramolecular tetrahedron of H 2 CTA -anions stabilized by O-H‚‚‚O -hydrogen bonds which in turn grows to the adamantane network. On the other hand, the MeNH 3 + counterion with only three donor groups results in a hexagonal layer structure of black phosphorus topology. Ammonium cation is known to perch on the 18-crown-6 macrocycle bonded via three N + -H‚‚‚O hydrogen bonds. 2 We reasoned that the fourth H bonding group on the hydrophobic outside-hydrophilic inside ammonium ion-18-C-6 complex would direct the organization of H 2 CTA -anions and furthermore the chairlike conformation of 18-C-6 in the solid state would match with that of cyclohexane tricarboxylic acid. This indeed turns out to be the case. H 2 CTA -‚ H 2 O‚NH 4 + ‚18-C-6 (1) has a three-dimensional channel structure of H 2 CTA -through the inclusion of water; the channels house a crown ether and NH 4 + counterion resembling the Russian nesting doll superanion capsule-metal ion complexes reported by Atwood and Raston. 3 The anions form undulated sheets in H 2 CTA -‚ OHNH 3 + ‚18-C-6 (2) with supercations intercalating the charged layers. The crystal structure of neutral host-guest complex H 3 -CTA‚(18-C-6) 0.5 (3) has a large hexagonal, chicken wire network of triacid molecules that is filled by the crown ether and stabilized via numerous C-H‚‚‚O interactions. Ermer 4 had targeted the isolation of a symmetric supramolecular hexagon in complexes of crown ether with trimesic acid (H 3 TMA) and H 3 CTA but instead obtained hydrated structures.Equimolar amounts of H 2 CTA -‚NH 4 + salt and 18-C-6 were dissolved in EtOH by gentle heating and crystallized at room temperature. Diffraction quality single crystals of hydrate 1 appeared after one week, which were solved and refined in the noncentrosymmetric space group Pna2 1 . 5 There are two molecules each of H 2 CTA -, NH 4 + , 18-C-6, ...

A C3‐Symmetric Macrocycle‐Based, Hydrogen‐Bonded, Multiporous Hexagonal Network as a Motif of Porous Molecular Crystals

“…To date, 3D assemblies based on porous H-HexNets have been constructed from molecules such as 1,3,5-substituted benzene derivatives, [3,4] aliphatic tricarboxylic acids, [5] hexasubstituted benzene derivatives, [6] phosphazene derivatives, [7] and others.…”

Nested [Na6(H2O)]6+ encapsulation of nickel(II) coordination framework assembled from pyridyl-2,6-dicarboxylic acid

“…Relatively, those of concurrent holding ion and molecule are much less known. The capsule-metal complexes reported by Atwood and Raston are the rare examples of such MOFs, whose channels host crown ether-NH þ 4 supercation within [6]. The cases demonstrated a novel layered 1-1 ionmolecule inclusion in coordination framework.…”

“…doi:10.1016/j.inoche.2006.12.014 as a secondary building unit (SBU) for the whole construction(shortened as [Ni 2 ]). Through the O c@o -Ni links, six SBU units combine into a corolla-like pore dodecanickel wheel(shortened as [Ni 2 ]6 ), as shown inFig. 2.…”

Packing Similarities and Synthon Variabilities in Aminopyridinium Sulfoisophthalates

“…[1][2][3][4][5][6][7][8][9][10][11][12] In this view molecular co-crystals are of growing interest because of their relevance to pharmaceutical formulations, solid-state organic synthesis, and control of polymorphs. 13-21 However, crystal engineering of organic salts [22][23][24][25][26][27][28][29][30][31] is also becoming popular because they contain more easily predicted, ionic, hydrogen-bonded supramolecular synthons [32][33][34][35][36][37][38] and because these synthons are generally more robust than those in neutral organics. Salt formation is pertinent to the study of 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 ...…”