FROM MOLECULES TO MATERIALS: UNDERSTANDING FUNCTIONAL NANOMATERIALS FROM FIRST-PRINCIPLES APPROACHES

Functional nanomaterials represent a rapidly expanding class of systems characterized by properties that emerge from their structural organization at the nanoscale. Their relevance spans a broad range of applications, including energy conversion, chemical sensing, and molecular recognition. Understanding and predicting the atomistic or molecular interactions that govern their formation and properties has become an essential step toward developing efficient and targeted design strategies. This Thesis addresses this challenge by adopting a fully computational perspective, based on first-principles approaches, to investigate how molecular-level interactions can be modulated and exploited to engineer functional nanomaterials with controlled physicochemical behavior. The central goal of this work is to demonstrate that the rational design of functional nanomaterials can be achieved by understanding molecular interactions along three distinct, yet conceptually related, molecule-to-material strategies: (i) fragmentation of molecular precursors, (ii) encapsulation in confined nanospaces, and (iii) surface adsorption. Taken together, these strategies enable the investigation of different aspects of nanomaterial formation, each corresponding to a specific condition, ranging from gas-phase reactivity to molecular confinement and surface interactions. In this context, rather than treating these studies as isolated case analyses, this Thesis proposes a unified framework in which fragmentation, confinement, and surface binding are regarded as different manifestations of the same principal outcome: control at the molecular scale determines the structure and function of the resulting nanomaterial. The work relies on a combination of first-principles computational approaches, with Density Functional Theory (DFT) as the methodological core. Time-Dependent DFT (TD-DFT) is employed to study electronic excitations in photoactive systems, while periodic DFT calculations are used to model extended solid-state structures and molecule-surface interfaces. This multi-method approach enables the characterization of complex systems under realistic conditions and provides access to detailed information on structure, energetics, charge distribution, and electronic behavior. In particular, the computational investigation provides insights into structure-function relationships that are often not directly accessible by experimental techniques, and thus plays a crucial complementary role in understanding the material behavior at the atomic scale.