Crystal structure of a host-guest complex between mephedrone hydro-chloride and a tetra-phospho-nate cavitand

Abstract

A new supra-molecular complex (I) between the tetra-phospho-nate cavitand Tiiii[C₃H₇,CH₃,C₆H₅] [systematic name: 2,8,14,20-tetra-propyl-5,11,17,23-tetra-methyl-6,10:12,16:18,22:24,4-tetra-kis-(phenyl-phospho-nato-O,O')resorcin[4]arene] and mephedrone hydro-choride {C₁₁H₁₆NO⁺·Cl^-; systematic name: meth-yl[1-(4-methyl-phen-yl)-1-oxopropan-2-yl]aza-nium chloride} has been obtained and characterized both in solution and in the solid state. The complex of general formula (C₁₁H₁₆NO)@Tiiii[C₃H₇,CH₃,C₆H₅]Cl·CH₃OH or C₁₁H₁₆NO⁺·Cl^-·C₆₈H₆₈O₁₂P₄·CH₃OH, crystallizes in the monoclinic space group P2₁/c with one lattice methanol mol-ecule per cavitand, disordered over two positions with occupancy factors of 0.665 (6) and 0.335 (6). The mephedrone guest inter-acts with the P=O groups at the upper rim of the cavitand through two charge-assisted N-H⋯O hydrogen bonds, while the methyl group directly bound to the amino moiety is stabilized inside the π basic cavity via cation⋯π inter-actions. The chloride counter-anion is located between the alkyl legs of the cavitand, forming C-H⋯Cl inter-actions with the aromatic and methyl-enic H atoms of the lower rim. The chloride anion is also responsible for the formation of a supra-molecular chain along the b-axis direction through C-H⋯Cl inter-actions involving the phenyl substituent of one phospho-nate group. C-H⋯O and C-H⋯π inter-actions between the guest and adjacent cavitands contribute to the formation of the crystal structure.

Keywords: crystal structure; illicit drugs; inclusion compounds; mephedrone; tetra­phospho­nate cavitands.

Figure 1

ORTEP view of (C₁₁H₁₆NO)@Tiiii[C₃H₇,CH₃,C ₆H₅]Cl (I) with partial atom-labelling scheme and anisotropic displacement parameters drawn at the 20% probability level. The solvent mol­ecules and the H atoms of the cavitand are omitted for clarity; only one orientation of the disordered alkyl chain is shown.

Figure 2

Left: view of the main host–guest supra­molecular inter­actions shown as blue and green dotted lines. Only relevant H atoms are shown, while the alkyl chains, the chloride anion and the methanol lattice mol­ecules have been omitted for clarity. Right: side view of the host–guest complex.

Figure 3

Supra­molecular inter­actions (blue dotted lines) involving the chloride anion (represented as a green sphere) and the disordered methanol lattice mol­ecules.

Figure 4

View of the packing of (I) along the b-axis direction, mediated by C14B—H14B⋯Cl⁻ inter­actions (blue lines). The C and H atoms highlighted in purple are in general positions, while the chloride anion is at the symmetry position −x,  + y,  − z.

Figure 5

View of the packing of (I) mediated by C—H⋯O and C—H⋯π inter­actions between the guests and adjacent cavitands. Symmetry code: (i) 1 − x,  + y,  − z.

Figure 6

The full two-dimensional fingerprint plot (a) and those delineated into H⋯H (b), C⋯H/H⋯C (c), O⋯H/H⋯O (d) and Cl⋯H/H⋯Cl (e) contacts for (I).

Figure 7

³¹P NMR (162 MHz, MeOD, 253 K) spectra of (a) free host Tiiii[C₃H₇, CH₃, Ph]; (b) addition of 0.5 equivalent of mephedrone HCl to the host solution; (c) addition of 1 equivalent of mephedrone HCl to the host solution.

Figure 8

¹H NMR (400 MHz, MeOD, 253 K) spectra of (a) free host Tiiii[C₃H₇, CH₃, Ph]; (b) addition of 0.5 equivalent of mephedrone HCl to the host solution; (c) addition of 1 equivalent of mephedrone HCl to the host solution. The arrows indicate the up-shift of ⁺N—CH₃ protons.

Figure 9

Mol­ecular sketch of the different guests described in the Database survey.