Structural analysis and multipole modelling of quercetin monohydrate – a quantitative and comparative study

Abstract

The multipolar atom model, constructed by transferring the charge-density parameters from an experimental or theoretical database, is considered to be an easy replacement of the widely used independent atom model. The present study on a new crystal structure of quercetin monohydrate [2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-chromen-4-one monohydrate], a plant flavonoid, determined by X-ray diffraction, demonstrates that the transferred multipolar atom model approach greatly improves several factors: the accuracy of atomic positions and the magnitudes of atomic displacement parameters, the residual electron densities and the crystallographic figures of merit. The charge-density features, topological analysis and electrostatic interaction energies obtained from the multipole models based on experimental database transfer and periodic quantum mechanical calculations are found to compare well. This quantitative and comparative study shows that in the absence of high-resolution diffraction data, the database transfer approach can be applied to the multipolar electron density features very accurately.

Insights into the Inhibition of the p90 Ribosomal S6 Kinase (RSK) by the Flavonol Glycoside SL0101 from the 1.5 Å Crystal Structure of the N-Terminal Domain of RSK2 with Bound Inhibitor

“…The benzopyran moiety (rings A and C) is, as expected, planar within experimental error. However, unlike the situation in the free, non-glycosylated flavonols, where the B-ring is coplanar with benzopyran, 56 in the present structure, the B-ring is twisted from the plane of benzopyran by 26.1 °, to avoid a clash with O6 (the glycosidic oxygen). The rhamnose ring adopts an expected 1 C 4 chair conformation, as observed in free α-L-rhamnose 57 and in α-L-rhamnopyranosides.…”

Probing Weak Intermolecular Interactions by Using the Invariom Approach: A Comparative Study of s‐Tetrazine

“…Among other options, transferred multipolar models were developed, one of them being based on a recently introduced concept of invarioms 2. They were devised to replace an independent atom model (IAM)3, 4 by using database entries of multipolar parameters obtained within the Hansen–Coppens aspherical‐atom formalism5 from X‐ray measurements of high quality6 or from quantum chemical calculations 2. 7 As well as taking as less time than IAM to employ,8, 9 their use allows reaching the accuracy of conventional multipole refinement against high‐resolution data 8.…”

Experimental and theoretical study of quercetin complexes formed on pure silica and Zn-modified mesoporous MCM-41 and SBA-16 materials

“…Our samples show identical patterns with their sample called QCTc heat treated at 40 °C, but the exact crystalline structure was not identified. Single crystal data can be found only on di-and monohydrate forms [43,44], however only the powder diffraction pattern generated by the CIF file of dihydrate form (Cambridge Structural Database Fef-bex01) is identical with our parent quercetin sample. Based on their X-ray powder diffraction, 13 C, 1 H NMR, and quantum chemical computations data Filip et al [36] proposed a reliable crystal structure model of anhydrous quercetin with monoclinic system and space group of P21/a.…”