Studies on polymorph conversion in a new cyclodextrin inclusion compound

Abstract

A novel β-cyclodextrin (βCD) inclusion compound was prepared using 4-phenylpyridine N-oxide (PPNO) as the organic guest. The inclusion compound, βCD·PPNO, was characterised both in solution and the solid state using numerous techniques. 1 H NMR in aqueous solution allowed the determination of a 1:1 stoichiometry and an association constant of 164±21 M -1 . Powder and singlecrystal X-ray diffraction studies evidenced the formation of two distinct crystal phases, appearing at different timings. Over time, one of the crystal phases converts spontaneously into the other. This work is the first to monitor the conversion of different polymorphs of cyclodextrin inclusion compounds in real time.

Inclusion of Pentamidine in Carboxylated Pillar[5]arene: Late Sequential Crystallization and Diversity of Host–Guest Interactions

“…8 Unfortunately, the experimental crystal structure data highlighting various binding geometries and intermolecular interaction modes between the same host and guest rarely mirror the whole structural host−guest landscape. 9,10 In this work we showcase an artificial supramolecular system as an ensemble of three host−guest complexes where not all interactions occur at the same time.…”

“…Therefore, the protein–ligand complex is better described as a superposition or ensemble of different structures. , The molecular recognition event between a protein and ligand is a delicate balance of multiple attractive and repulsive interactions affected inter alia by solvation/desolvation phenomena and conformational changes of one or both molecular partners. , The same can refer to the simpler supramolecular host–guest systems composed of flexible partners with multiple binding interactions . Unfortunately, the experimental crystal structure data highlighting various binding geometries and intermolecular interaction modes between the same host and guest rarely mirror the whole structural host–guest landscape. , In this work we showcase an artificial supramolecular system as an ensemble of three host–guest complexes where not all interactions occur at the same time.…”

Association of aescin with β- and γ-cyclodextrins studied by DFT calculations and spectroscopic methods

“…In the evaluation of the interaction of cyclodextrin with a guest molecule in aqueous solution, one first needs to investigate the stoichiometry [ 26 ]. For this, the continuous variation method (Job plot) [ 27 ] was employed.…”

Facilitating Nitrification Inhibition through Green, Mechanochemical Synthesis of a Novel Nitrapyrin Complex

“…Through the preparation of β-CD inclusion complexes it is generally then possible to (i) improve the water solubility/stability of the guest molecules, (ii) perform a controlled release of the included molecules, and (iii) increase the bio-and ecocompatibility of the guest molecules. 25 As a result of these properties, β-CD has been widely employed as a drug carrier in the pharmaceutical field, 26 as well as in the food industry and in the environmental sciences. 27,28 Interestingly, although the preparation of β-CD inclusion complexes with agrochemicals has been reported, 29−32 there are no studies concerning the stabilization of AMO inhibitors by inclusion into the β-CD cavity.…”

“…β-Cyclodextrin (β-CD, see Scheme ) belongs to the family of cyclodextrins, cyclic oligosaccharides with glucose units6 (α-cyclodextrins), 7 (β-cyclodextrins), or 8 (γ-cyclodextrins)bonded via α-1,4 glycosidic bonds; all cyclodextrins possess a hydrophobic cavityable to include apolar guestsand a hydrophilic surface, which makes the resulting inclusion compounds soluble in water. Through the preparation of β-CD inclusion complexes it is generally then possible to (i) improve the water solubility/stability of the guest molecules, (ii) perform a controlled release of the included molecules, and (iii) increase the bio- and ecocompatibility of the guest molecules . As a result of these properties, β-CD has been widely employed as a drug carrier in the pharmaceutical field, as well as in the food industry and in the environmental sciences. , Interestingly, although the preparation of β-CD inclusion complexes with agrochemicals has been reported, − there are no studies concerning the stabilization of AMO inhibitors by inclusion into the β-CD cavity.…”