An in-silico study of supramolecular interactions between 2,6-diisopropylphenyl derivatives of PDI and their GMP-doped composites to tune their optoelectronic response

Noncovalent interactions (NCI) play a central role in shaping supramolecular assemblies and tailoring their optical responses, yet strategies to enhance nonlinear optical (NLO) performance remain limited. In this work, we explore guanosine monophosphate (GMP) doping of 2,6-diisopropylphenyl-substituted perylene diimide (PDI) derivatives, focusing on how bay-position modifications influence their electronic and photophysical behavior. By introducing F, H, and ethyl groups on the silicon atom, we achieve narrow frontier orbital gaps (1.77–2.43 eV) and broad visible-range absorption (559–862 nm). These features translate into remarkable NLO activity: the γSi-H@G composite exhibits a first-order hyperpolarizability (β₀) of 2389.84 au, while γSi₂-2R@G shows a linear polarizability (α₀) of 925.93 au. Our combined analyses, including NCI, DOS, quantum theory of atoms in molecules (QTAIM), natural bond order (NBO) analysis, transition density matrix (TDM), molecular electrostatic potential (MEP), Infrared, Raman spectroscopy (RS), and Hirschfeld surface analysis demonstrate that GMP doping, coupled with bay-position substitutions at the silicon center, provides a robust pathway to enhance charge transfer, narrow orbital gaps, extend visible absorption, and amplify polarizability. This integrated evidence establishes a rational blueprint for designing PDI-GMP supramolecular systems as promising candidates for next-generation photonic and optoelectronic technologies.