Abstract <p>This study presents a comprehensive theoretical investigation of a novel graphene-based fractal nanostructure modeled on the Sierpinski triangle undergoing atomic substitution with boron. Using Density Functional Theory at the B3LYP/6-31G level via Gaussian 09. According to we systematically study the effects of mono-, di-, and multi-site boron doping on the geometric stability, electronic structure, vibrational behavior, and chemical reactivity of the system. The optimized geometries were confirmed to be true energy minima through the absence of imaginary frequencies in IR spectra. The Highest Occupied Molecular Orbital and Lowest Unoccupied Molecular Orbita (energy gap) was significantly reduced upon boron substitution, decreasing from 2.98 eV (pure structure) to 0.93 eV in the most heavily doped configurations. This reduction is revealing of enhanced electrical conductivity and tunability, relevant for applications in nano-electronic and sensing devices. Infrared spectral analysis revealed additional characteristic peaks corresponding to B–C and B–H stretching, confirming successful doping and local bonding changes. Global reactivity descriptors, such as electronegativity, chemical hardness, softness, and electrophilicity index, were also evaluated and correlated with the degree of substitution, highlighting increased reactivity in doped systems. Overall, the results suggest that boron-doped Sierpinski graphene structures are promising candidates for use in gas-sensing technologies and optoelectronic devices due to their modifiable electronic and vibrational characteristics. Future work may explore the interaction of these nanostructures with target analytes (substances with known chemical, physical, and other properties) and their integration into functional devices.</p>