Executive Summary : | Recent studies in optoelectronics and non-linear optics (NLO) highlight the significant role of through space conjugation (TSC) in functional materials. The tradeoff between nonlinear optical properties and crystal transparency is a significant challenge for NLO materials, limiting their practical applications. However, connecting potent D/A groups or highly conjugated chains with TSC core structures leads to elevated NLO responses but small impact on transparency. This is an advantage of TSCT type molecules as NLO materials and a powerful way to remedy the contradiction between NLO responses and transparency. Despite the development of novel structures of TSC molecules for various optoelectronic applications, there has been no comprehensive study on the regulation of NLO response on these systems. This has encouraged researchers to develop new ideas for the design and optimization of new NLO materials. They are particularly interested in octopolar systems with multi-donor/acceptor molecules, as changing the number and orientation of peripheral fused benzene units can enhance dipolar or octupolar contribution to the second-order NLO response. To analyze NLO activities of the designed structures, gas-phase electronic structure calculations will be carried out using DFT and TDDFT methods. Density Functional Theory will be used to calculate the first and higher orders of static and dynamic hyperpolarizabilities. The presence of TBCT and TSCT will be identified using natural transition orbital (NTO) analysis using Multiwfn software package and Natural Population Analysis (NPA). |