Mechanochromic Emission in Ternary CB[8]TPA2 Array. Insights into the Role of Host-Interaction Nature

The formation of host-guest aggregates favors the enhancement of molecular properties owing to the molecular confinement into a suitable cavity. This report provides an overview of the binding and emission features in ternary host-guest systems, with a particular focus on cucurbituril (CB[8]) systems. Our results reveal the crucial role of host-guest interactions in modulating mechano-chromic luminescent properties through various organic compounds, such as TPA derivatives. Advanced computational methodologies, including density functional theory (DFT), time-dependent DFT (TDDFT), and Energy Decomposition Analysis based on Natural Orbitals for Chemical Valence (EDA-NOCV), are employed to analyze orbital density of transitions, energy interactions, charge transfer mechanisms, and the stability of these complexes. Key findings highlight the contributions of electrostatic, orbital, and dispersion interactions, which enhance our understanding of photophysical behavior. In this sense, the host-guest interaction is predominantly from the ΔE_elstat term, which retains 54% to 57% in attractive forces, and the ΔE_disp term goes from 24% to 27%. Additionally, the CB-encapsulation demonstrates its potential application in innovative materials and MCL response, highlighting the possible significance of molecular design. This report aims to provide a comprehensive understanding of the intricate dynamics within these systems.