Idarubicin (IDA) is the analog of daunorubicin (DNR). The absence
of the methoxy group at position 4 of IDA remarkably improved lipophilicity,
which is responsible for extra cellular uptake, higher DNA-binding
ability, and considerable cytotoxicity in correlation with doxorubicin
(DOX) and DNR. In this paper, we conceived two principal objectives:
we realized the crystal structure of IDA by X-ray diffraction measurements
on single crystals at room temperature (monoclinic, space group <i>P</i>2<sub>1</sub>, <i>a</i> = 5.1302(2) Å, <i>b</i> = 9.9122(5) Å, <i>c</i> = 24.8868(11) Å;
β = 91.425(4)°; <i>V</i> = 1265.14(10) Å<sup>3</sup>) with refinements of the structure converged to the final <i>R</i> = 3.87%. The second objective has been to develop gold
nanoparticles encapsulated with idarubicin through an original methodology
in which gold salt (HAuCl<sub>4</sub>) is chelated with IDA and diacid
polymer (PEG) to form hybrid nanoparticles called IDA IN PEG-AuNPs
in which drug solubility was enhanced. The computational studies were
in agreement with the experimental observations. These hybrid nanoparticles
and their precursors were analyzed by Raman, UV–Vis, <sup>1</sup>H NMR, and transmission electron microscopy (TEM). The main results
are completed by a theoretical approach to understand the whole process.