biostudies-literatureIshida SJapan Agency for Medical Research and DevelopmentMinistry of Education, Culture, Sports, Science and Technology36https://www.ebi.ac.uk/biostudies/studies/S-EPMC11934680biostudies-literatureUnknown17(1)Recent advancements in artificial intelligence (AI)-based molecular design methodologies have offered synthetic chemists new ways to design functional molecules with their desired properties. While various AI-based molecule generators have significantly advanced toward practical applications, their effective use still requires specialized knowledge and skills concerning AI techniques. Here, we develop a large language model (LLM)-powered chatbot, ChatChemTS, that assists users in designing new molecules using an AI-based molecule generator through only chat interactions, including automated construction of reward functions for the specified properties. Our study showcases the utility of ChatChemTS through de novo design cases involving chromophores and anticancer drugs (epidermal growth faJournal of cheminformaticsLarge language models open new way of AI-assisted molecule design for chemists.PMC11934680no.JP22ama121023JPMXP1122683430no.JP23nk0101111Sato THonma TTerayama KIshida SfalseLarge language models open new way of AI-assisted molecule design for chemists.Recent advancements in artificial intelligence (AI)-based molecular design methodologies have offered synthetic chemists new ways to design functional molecules with their desired properties. While various AI-based molecule generators have significantly advanced toward practical applications, their effective use still requires specialized knowledge and skills concerning AI techniques. Here, we develop a large language model (LLM)-powered chatbot, ChatChemTS, that assists users in designing new molecules using an AI-based molecule generator through only chat interactions, including automated construction of reward functions for the specified properties. Our study showcases the utility of ChatChemTS through de novo design cases involving chromophores and anticancer drugs (epidermal growth fa2025-01-01T00:00:00Z2025 Mar2026-06-03T02:36:14.995Z2025-07-09T03:04:51.487ZS-EPMC119346804012878810.1186/s13321-025-00984-8