Influences of Molecular Structure on Supramolecular Selection during Cocrystallization of Polypyridyl Metal Complexes

Abstract

Heteroleptic complexes of the type [RuL2L′]­(PF6)2 (L, L′ = combinations of 1,10-phenanthroline (phen) and 2,2′-bipyridine (bipy)) were found to cocrystallize with [Ni­(phen)3]­(PF6)2 to produce cocrystals of [Ni­(phen)3] x ­[RuL2L′]1–x ­(PF6)2. In this report we show that the ability of the complexes to cocrystallize is influenced by the number of common ligands between complexes in solution. Supramolecular selection is a phenomenon caused by molecular recognition through which cocrystals can grow from the same solution but contain different ratios of the molecular components. It was found that systems where L = phen displayed less supramolecular selection than systems where L = bipy. With increasing supramolecular selection, the composition of cocrystals was found to vary significantly from the initial relative concentration in the cocrystallizing solution, and therefore it was increasingly difficult to control the final composition of the resultant cocrystals. Consequently, modulation of concentration-dependent properties such as phase was also found to be less predictable with increasing supramolecular selection. Notwithstanding the complication afforded by the presence of supramolecular selection, our results reaffirm the robustness of the [M­(phen)3]­(PF6)2 structure because it was maintained even when ca. 90% of the complexes in the cocrystals were [Ru­(phen)­(bipy)2]­(PF6)2, which in its pure form is not isomorphous with [M­(phen)3]­(PF6)2. Experiments between complexes without common ligands, i.e., [Ru­(bipy)3]­(PF6)2 cocrystallized with [Ni­(phen)3]­(PF6)2, were found to approach the limit to which molecular recognition processes can be confused into cocrystallizing different molecules to form single cocrystals. For these systems the result was the formation of block-shaped crystals skewered by a needle-shaped crystals.

Role of Anions and Mixtures of Anions on the Thermochromism, Vapochromism, and Polymorph Formation of Luminescent Crystals of a Single Cation, [(C6H11NC)2Au]+

“…As the data in Table show, the As:P ratio in the crystals reflects the As:P ratio in the solution used for crystal growth. Although previous studies of such mixed crystals have also shown that the compositions of the crystals and solutions from which they were grown were similar, there are cases known where supramolecular selection occurs and the compositions of the crystals and the growth solutions differ. , …”

“…Although previous studies of such mixed crystals have also shown that the compositions of the crystals and solutions from which they were grown were similar, 38 there are cases known where supramolecular selection occurs and the compositions of the crystals and the growth solutions differ. 39,40 In general, the Au 2 Au](PF 6 ) 0.50 (AsF 6 ) 0.50 shows both P−F vibrations at 828 and 556 cm −1 and As−F vibrations at 687 and 392 cm −1 . Similar infrared spectra have been obtained for the other salts shown in Table 2.…”

Porous Cubic Cesium Salts of Silicododecatungstate(molybdate)/Borododecatungstate Blends: Synthesis and Molecular Adsorption Properties

“…This monoclinic salt was likely to be the thermodynamically preferred product from the reaction of the cesium salt and BW . Then, we focused on the synthetic concept of making a “molecular alloy” (or “co-crystal”). − It is known that the molecular alloy (co-crystal) of two molecules with similar molecular structures (A and B, forming A x B 1– x ) can be formed with either the A or B crystal structure when the crystal structures of A and B are different. , The crystal structure preference would be determined by the relative stability. In addition, the chemical and physical properties of the molecular alloy (or co-crystal) can be controlled by its composition.…”

“…60−62 It is known that the molecular alloy (co-crystal) of two molecules with similar molecular structures (A and B, forming A x B 1−x ) can be formed with either the A or B crystal structure when the crystal structures of A and B are different. 61,62 The crystal structure preference would be determined by the relative stability. In addition, the chemical and physical properties of the molecular alloy (or co-crystal) can be controlled by its composition.…”