Supramolecular Complexation of Alkali Cations through Mechanochemical Reactions between Crystalline Solids

Abstract

The organometallic zwitterion [Co(III)(eta(5)-C(5)H(4)COOH)(eta(5)-C(5)H(4)COO)] reacts quantitatively as a solid polycrystalline phase with a number of crystalline alkali salts MX (M = K(+), Rb(+), Cs(+), NH(4) (+); X = Cl(-), Br(-), I(-), PF(6)(-), although not in all cation/anion permutations) to afford supramolecular complexes of the formula [Co(III)(eta(5)-C(5)H(4)COOH)(eta(5)-C(5)H(4)COO)](2).M(+)X(-). In some cases, the mechanochemical complexation requires kneading of the two solids with a catalytic amount of water. The characterization of the solid-state products has been achieved by a combination of X-ray single-crystal and powder-diffraction experiments. The hydrogen-bonding interactions have been investigated by solid-state NMR spectroscopy. The mechanochemical reactions imply a profound solid-state rearrangement accompanied by breaking and forming of O-H...O hydrogen-bonding interactions between the organometallic molecules. All compounds could also be obtained by solution crystallization of the inorganic salts in the presence of the organometallic unit. The solid-state complexation of alkali cations by the organometallic zwitterion has been described as a special kind of solvation process taking place in the solid state.

Solid‐State NMR Investigation of Ligand Mobility and Reactivity in Transition Metal Complexes

“…This shift has been related to the lengthening of the O···O HB that occurs by increasing the cation size inside the cage. [98] The solid-state complexation of alkali cations by the organometallic zwitterion has been described as a special kind of solvation process taking place in the solid state.…”

Surfactant-Stabilized Single-Walled Carbon Nanotubes Using Triphenylene Derivatives Remain Individually Dispersion in Both Liquid and Dried Solid States

“…Figure 5(b) shows the ratio of (9,4) / (7,6) for SWNTs dispersed in D 2 O with C6, C8, and C10. In the solution with C10, the ratio of thick SWNTs [ (9,4); diameter: 0.92 nm] was higher than that of thin SWNTs [(7,6); diameter: 0.90 nm]. For C8, the ratios of these two types of SWNTs were almost the same.…”

“…For C8, the ratios of these two types of SWNTs were almost the same. However, for C6, which has the shortest alkyl chain among the tested surfactants, the ratios were inverted: the PL intensity of (7,6) was greater than that of (9,4). Thus, the larger diameter SWNTs apparently were better dispersed with C10, which has a longer alkyl chain, and the smaller diameter SWNTs were better dispersed with C6, which has a shorter alkyl chain.…”

Dealing with Crystal Forms (The Kingdom of Serendip?)

“…Relevant portions of the IR spectra are shown in Scheme 4. The extension of this reaction to the family of alkali halides afforded a wealth of new co-crystals of general formula [Co III (h 5 -C 5 H 4 COOH)(h 5 -C 5 H 4 COO)] 2 ·MX with M + = K + , Rb + , Cs + , NH 4 + and X À = Cl À , Br À , I À , PF 6 À , characterized by the presence of a supramolecular cage formed by four or- [31] More recently, we have come across an analogous situation involving barbituric acid. [30] The investigation of the co-crystallization product of the reaction both in solution and in the solid state between the organometallic molecules and KBr revealed quantitative formation of the co-crystal [Co III (h 5 -C 5 H 4 COOH)(h 5 -C 5 H 4 COO)] 2 ·KBr.…”

“…Alternating melting points for co-crystals of dicarboxylic acids with dinitrogen bases: a) even numbers of carbon atoms, b) odd number of carbon atoms. [31] More recently, we have come across an analogous situation involving barbituric acid. Griesser et al [32] had observed that the IR spectrum of the anhydrous form II of barbituric acid in KBr showed an additional absorption band at 3500 cm À1 , which could only be explained by assuming that some solid-state transformation had occurred.…”