Crystal structure of the inclusion complex of β-cyclodextrin with mefenamic acid from high-resolution synchrotron powder-diffraction data in combination with molecular-mechanics calculations

Abstract

The crystal structure of the inclusion complex of beta-cyclo-dextrin with mefenamic acid has been determined from a combination of high-resolution synchrotron powder-diffraction data and molecular-mechanics calculations. A grid search indicates two possible solutions, which are corroborated by molecular-mechanics calculations, while Rietveld-refinement results suggest the crystal structure that is more likely to be formed in the solid state. Mefenamic acid is partially included in beta-cyclodextrin with either the xylyl or the benzoic-acid moiety being inside its cavity. In both solutions mefenamic acid and beta-cyclodextrin form a monomeric complex in a herringbone packing scheme.

Characterization of aspartame–cyclodextrin complexation

“…The initial structures of the cyclodextrins were based on structural data found in the literature [30] and on structures in the Brookhaven Protein Database [31,32]. Optimization applied the MMFF94 s force field [33,34] with 8.0 Å cut-off distance for the non-bonded interactions, 0.7 hydrogen-bond scaling factor and distance dependent dielectric function (ε = 78.3), until 0.01 RMS gradient was reached with the BFGS algorithm.…”

The protection of Nifedipin from photodegradation due to complex formation with β-cyclodextrin

“…As such, the wider side of the cavity is surrounded by secondary hydroxyl groups, i.e., the outer side of cyclodextrin is hydrophilic and, therefore, soluble in aqueous media. Conversely, the inner cavity of cyclodextrin is much more hydrophobic in character because the free electron pairs of the glycoside bridge oxygens are within the cavity [14,15]. Various organic molecules can be encapsulated in the cyclodextrin cavity, forming so-called inclusion complexes.…”

Crystal Structure of Melaminium Orthophosphate from High‐Resolution Synchrotron Powder‐Diffraction Data

“…The ease of solving crystal structures from powder-diffraction data is no longer restricted to small, fairly rigid, (in)organic molecules like the moieties presented here. Indeed, in the last few years, structures of much larger and more flexible molecules have been solved in our laboratory, e.g., the inclusion complex of b-cyclodextrin with mefenamic acid [29].…”