121st General Meeting of the KCS

Type Award Lecture in Division
Area Recent Trends in Computational Chemistry: Bigdata and Artificial Intelligence
Room No. Room 402
Time FRI 14:30-:
Code PHYS3-1
Subject Computational studies on sensors, spin couplings in diradicals, and metal oxide nanoparticles
Authors Jin Yong Lee
Department of Chemistry, Sungkyunkwan University, Korea
Abstract I will introduce the computational studies on fluorescent sensors, magnetic couplings in organic diradicals, and metal oxide nanoparticles. The fluorescent chemosensors have been played an important role in cell dynamics due to the high sensitivity. The working mechanism for the fluorescent sensors can be classified into two major groups, intramolecular charge transfer (ICT) and photo-induced electron transfer (PET). I will show representative examples for each case. Organic diradicals are considered the basic unit for organic magnetic materials. We investigated spin coupling interaction in simple organic diradicals, and tried to get a simple rule for the determination of ground spin state. Finally, we proposed a simple but useful rule to determine the ground spin state of diradicals without a full calculation. Finally, I will show you our recent studies on the influence of size and shape on the electronic structures of 0.5-3.2 nm diameter TiO2 nanoparticles using density functional theory calculations. Our results generally confirm that that nanoparticle ground state and excited state electronic structure has a significantly more pronounced structure dependency than size dependency. Then, we track the optical and electronic band gap of a set of (TiO2)n nanoparticles ranging from small non-bulk-like clusters with n=4, 8 and 16, to larger nanoparticles with n=35 and 84 derived from cuts from the anatase bulk crystal structure. We also found that the enhanced catalytic activity of TiO2 nanoparticles by oxygen vacancy was due to the existence of singly occupied orbitals in between the HOMO and LUMO. We provide a predictive map of how the anatase-rutile level alignment varies from the smallest nanoparticles to the bulk. Our results predict that other level alignments which are less favorable for photocatalysis will emerge when the diameter of the TiO2 NPs is reduced below ~15 nm. The exciton dynamics also shows important information on the catalytic activity.
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