Influence of Halogen Substituent on the Self-Assembly and Crystal Packing of Multicomponent Crystals Formed from Ethacridine and Meta-Halobenzoic Acids

Abstract

In order to determine the influence of halogen substituent on the self-assembly of the 6,9-diamino-2-ethoxyacridinium cations and 3-halobenzoate anions in the crystals formed from ethacridine and halobenzoic acids, the series of ethacridinium meta-halobenzoates dihydrates: ethacridinium 3-chlorobenzoate dihydrate (1), ethacridinium 3-bromobenzoate dihydrate (2), and ethacridinium 3-iodobenzoate dihydrate (3), were synthesized and structurally characterized. Single-crystal X-ray diffraction measurements showed that the title compounds crystallized in the monoclinic P21/c space group and are isostructural. In the crystals of title compounds, the ions and water molecules interact via N–H⋯O, O–H⋯O and C–H⋯O hydrogen bonds and π–π stacking interactions to produce blocks. The relationship between the distance X⋯O between the halogen atom (X=Cl, Br, I) of meta-halobenzoate anion and the O-atom from the ethoxy group of cation from neighbouring blocks and crystal packing is observed in the crystals of the title compounds.

The Influence of Solvent on the Crystal Packing of Ethacridinium Phthalate Solvates

“…The crystal of 3 is the only one that contains an alcohol molecule, whereas the crystal of compound 4 is the only one that contains a water molecule in its basic structural motifs (heterotetramers or heterohexamers). motif is the cyclic heterohexamer, previously observed in the crystals of 6,9-diamino-2-etoxyacridiu meta-halobenzoates dihydrates [10], yet they differ from each other. In the crystal of compound 3, t 6,9-diamino-2-etoxyacridine cation interacts with the phthalic acid anion through the N(9-amin H Table 3).…”

“…A different situation arises in the case of crystals of 6,9mino-2 ethoxyacridinium phthalate isobutanol solvate (3) and 6,9-diamino-2-ethoxyacridinium halate tert-butanol solvate monohydrate (4) (Figure 2c,d and Table 2). Here, the basic structural tif is the cyclic heterohexamer, previously observed in the crystals of 6,9-diamino-2-etoxyacridium a-halobenzoates dihydrates [10], yet they differ from each other. In the crystal of compound 3, the diamino-2-etoxyacridine cation interacts with the phthalic acid anion through the N(9-amino)-O(carboxy)…”

“…In crystals 3 and 4, the neighbo π-stacking interactions between aromatic rings of acridine m the mean plane of the acridine skeleton and of neighbo compound 3 than for compound 4 in these heterohexame contains an alcohol molecule, whereas the crystal of compou molecule in its basic structural motifs (heterotetramers or he hydrogen bond, whereas one isobuta etoxyacridine cation and the phthalic acid anion vi hydrogen bonds, to produce a centrosymmetric het the crystal of compound 4, the 6,9-diamino-2-etox anion through the N(9-amino)-H hydrogen bond, whereas one iso etoxyacridine cation and the phthalic acid anio hydrogen bonds, to produce a centrosymmetr the crystal of compound 4, the 6,9-diamino-2 anion through the N(9-amino)-H a-halobenzoates dihydrates [10], yet they differ from each other. In the crystal of compound 3, the diamino-2-etoxyacridine cation interacts with the phthalic acid anion through the N(9-amino)-O(carboxy) hydrogen bond, whereas one isobutanol molecule interacts with both 6,9-diamino-2yacridine cation and the phthalic acid anion via N(acridine)-H Table 3).…”

“…The crystal of 3 is the only one that contains an alcohol molecule, whereas the crystal of compound 4 is the only one that contains a water molecule in its basic structural motifs (heterotetramers or heterohexamers). diamino-2 ethoxyacridinium phthalate isobutano phthalate tert-butanol solvate monohydrate (4) (F motif is the cyclic heterohexamer, previously obser meta-halobenzoates dihydrates [10], yet they differ 6,9-diamino-2-etoxyacridine cation interacts with H •••O(carboxy) hydrogen bond, whereas one isobuta etoxyacridine cation and the phthalic acid anion v hydrogen bonds, to produce a centrosymmetric he the crystal of compound 4, the 6,9-diamino-2-eto anion through the N(9-amino)-H rotetramers is smaller for compound 1. A different situation arises in the case of crystals of 6,9mino-2 ethoxyacridinium phthalate isobutanol solvate (3) and 6,9-diamino-2-ethoxyacridinium halate tert-butanol solvate monohydrate (4) (Figure 2c,d and Table 2).…”

“…From a structural point of view, ethacridine is a poorly known compound. A search of the Cambridge Structure Database (CSD version 5.41, update March 2020) shows that there are only six known crystal structures containing the ethacridinium cation, including ethacridinium lactate monohydrate (REFCODE: BIMJUC) [ 8 ], two polymorphs of ethacridinium lactate (REFCODE: COVSUD, COVZOE) [ 9 ] and three dihydrates of ethacridinium halobenzoates: 3-chlorobenzoate, 3-bromobenzoate, and 3-iodobenzoate [ 10 ]. The reason for such a small number of structures is the difficulty of obtaining single crystals of high purity and appropriate quality of XRD experiments.…”