A Combined Theoretical−Experimental Study of the Inclusion of Niobocene Dichloride in Native and Permethylated β-Cyclodextrins

Abstract

Inclusion complexes comprising niobocene dichloride, Cp 2 NbCl 2 , and either native -cyclodextrin ( -CD) or permethylated -CD (TRIMEB) were prepared with a host:guest molar ratio of 1:1. The adducts were characterized in the solid state by powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), 13 C{ 1 H} CP/MAS NMR, FTIR, and FT Raman spectroscopies. Ab initio calculations were performed in order to elucidate the possible inclusion geometries and calculate vibrational frequencies for Cp 2 NbCl 2 in the region 100-1800 cm -1 . The vibrational spectra indicated that neither the hosts nor the guest were chemically modified upon inclusion complexation. Small wavenumber shifts in C-H, C-C, and metal-ligand vibrational modes were attributed to the effect of the host-guest interaction. Powder XRD showed that the -CD adduct was of low crystallinity, while the TRIMEB adduct was quite crystalline. The powder XRD pattern of the TRIMEB adduct could be satisfactorily indexed in the monoclinic system with the space group P2 1 . A hypothetical structural model for the crystal packing was obtained through Monte Carlo optimizations using a reported TRIMEB geometry comprising a distorted elliptical cavity. An unrestrained Rietveld refinement of the structural model could not be carried out due to the relatively low quality of the experimental powder XRD pattern. However, the plausibility of the host-guest interaction geometry, involving inclusion of one of the guest Cp ligands inside the CD cavity, was fully supported by the ab initio calculations.

Cyclodextrins improve the antimicrobial activity of the chloride salt of Ruthenium(II) chloro-phenanthroline-trithiacyclononane

“…Nevertheless, we found that it works particularly well for the methylated cyclodextrin, TRIMEB, due to its high solubility in these media. In fact, the same method has been previously successfully employed by some of us (Braga et al 2006a;Pereira et al 2007). The adduct b-CDÁ[Ru( [9]aneS 3 )phenCl]Cl (4) was prepared by co-dissolution in water/ethanol (50/50) followed by freeze-drying to obtain an orange microcrystalline solid.…”

“…Recent work on CD inclusion of the compounds Cp 2 MCl 2 (Cp = cyclopentadienyl, M = Nb, Mo) (Pereira et al 2007;Braga et al 2005Braga et al , 2001 showed an enhanced antitumoral action, in particular for TRIMEBÁCp 2 MoCl 2 (Braga et al 2005). b-CD was also shown to enhance the cytotoxic activity of trans Pt(dipyridine)Cl 2 by improvement of its aqueous solubility (Horvath et al 2008).…”

Spectroscopic and thermal characterization of the host–guest interactions between α‐, β‐ and γ‐cyclodextrins and vanadocene dichloride

“…On a recent study, Goncalves and co-workers found, using ab initio calculations, that geometries A and B as well as a third geometry where the chloride is inserted into the cavity with a shallow penetration of the Cp rings could exist at room temperature. [34] The most likely geometry of the CD-Cp 2 VCl 2 host-guest complex will be investigated by molecular mechanics calculation.…”

Computer‐aided drug design to explore cyclodextrin therapeutics and biomedical applications

“…[46] Today, hundreds of computational calculations describe drug-CD complexes reports. Table 1 classifies a number of present research studies in this field: molecular docking, [47][48][49] MD, [50][51][52][53] quantitative structure-activity/ property relationships (QSARs/QSPRs), [54][55][56] quantum mechanics (QM), [57][58][59] Monte Carlo (MC) simulations, [60][61][62] and machine learning.…”

“…β-CD and four derivatives of β-CD Luteolin [47] Molecular docking HP-β-CD and methylated β-CD Voriconazole [58] β-CD 4,4′-Dihydroxybiphenyl [59] β-CD 57 Guest molecules [50] Molecular dynamics (MD) β-and γ-CD Amphotericin B [51] α-, β-, and γ-CD Cumene hydroperoxide [52] α-and β-CD 1-Alkanols, substituted phenols, and substituted imidazoles [53] α-CD Benzene derivatives [54] Quantitative structure-activity/ property relationships (QSARs/QSPRs) β-CD Multiple compounds [55] β-CD 233 Molecules [56] β-CD Dopamine and epinephrine [57] Quantum mechanics (QM) α-CD Carboplatin, oxaliplatin, nedaplatin [58] β-CD Aflatoxin B1 [59] β-CD Praziquantel [60] Monte Carlo (MC) simulations β-CD and methylated β-CD Niobocene dichloride [61] α-CD Water [62] Sulfobutylether β-CD Diverse organic molecules [63] Machine learning…”