Morphological characterization of fullerene–androsterone conjugates

Abstract

SummaryHere we report on the self-organization characteristics in water of two diastereomer pairs of fullerene–androsterone hybrids that have the hydrophobic C60 appendage in the A and D ring of the androsterone moiety, respectively. The morphology and particle size in aqueous solution were determined by transmission electron microscopy (TEM) and dynamic light scattering (DLS), with satisfactory agreement between both techniques. In general, these fullerene derivatives are shown to organize into spherical nano-scale structures with diameters in the ranges of 10–20 and 30–50 nm, respectively.

Steroid–Fullerene Hybrids from Epiandrosterone: Synthesis, Characterization and Theoretical Study

“…When the fullerene cage is present in the C3-ethylmalonate functionality, this dihedral angle has a value of -162.3°and -172.3°for 10 and 11, respectively, and 161.4°and -158.6°when the fullerene moiety is present at the C17-ethylmalonate fragment in 10 and 12, respectively. Same results were found in a previous work, [22] and was eventually demonstrated by X-ray analysis. These results are in agreement with those previously reported by us after a conformational search on similar systems.…”

“…These results are in agreement with those previously reported by us after a conformational search on similar systems. [22] Moreover, theoretical calculations predict that the relative disposition of hydrogens H3 and H17 of the corresponding rings A and D of the steroid moiety and the closest carbonyl groups to each one is nearly similar in all cases. Same results were found in a previous work, [22] and was eventually demonstrated by X-ray analysis.…”

“…[22] Moreover, theoretical calculations predict that the relative disposition of hydrogens H3 and H17 of the corresponding rings A and D of the steroid moiety and the closest carbonyl groups to each one is nearly similar in all cases. Same results were found in a previous work, [22] and was eventually demonstrated by X-ray analysis. [49] These results show that the pres-ence of a hydrogen bond, in all cases, has a major role in the final geometry of the ethylmalonate fragment together with the presence or not of the fullerene moiety, previously noted.…”

“…Steroids show a broad biological activity profile and, due to their rigid skeleton and potential for varying levels of functionalization, they have become ideal structures for the development of hybrid molecules. [22] The hybrids thus formed not only may modulate the properties of each one of the components, but also allow obtaining chimeric molecular entities with completely new properties and functions. [15][16][17] In particular, the roles of sterols in diverse biological systems have been widely studied, and it has been determined that hydroxyl groups have a strong impact in the interaction with the receptor.…”

“…[17,18,20,21] Gathering these two entities has allowed these conjugates to be more soluble than pristine [60]fullerene in aqueous medium as well as in organic solvents. [22] The hybrids thus formed not only may modulate the properties of each one of the components, but also allow obtaining chimeric molecular entities with completely new properties and functions. [23] The synthetic methods for preparing hybrid steroid-fullerenes are based on the electrophilic character of C 60 , the most common reactions reported for the modifications of fullerenes being the cycloadditions.…”