The possibility of modulating the electronic configurations of the innermost atoms inside a nanospace, nano sheath with chemical modification was investigated using synchrotron X-ray photoelectron spectroscopy. Systems of definite nanostructures were chosen for this study. Systematic variations in energy, intensity, and width of pi and sigma O 1s core level spectra, in absorption characteristics of C 1s-->pi transition, in photoabsorption of pre-edge and resonance regions of the Gd 4d-->4f transition, were observed for Gd@C(82) (an isolated nanospace for Gd), Gd@C(82)(OH)(12) (a modified nanospace for Gd), and Gd@C(82)(OH)(22) (a differently modified nanospace for Gd), and the reference materials Gd-DTPA (a semi-closed space for Gd) and Gd(2)O(3). A sandwich-type electronic interaction along [outer modification group]-[nano sheaths]-[inner metallic atom] was observed in the molecules of modifications. This makes it possible to control electron-donation directions, either from the innermost metallic atom toward the outer nano sheaths or the reverse. The results suggest that one may effectively tune the fine structures of electronic configurations of such a metallic atom being astricted into nanostructures through changing the number or category of outer groups of chemical modifications. This may open a door to realizing the desired designs for electronic and magnetic properties of functionalized nanomaterials.