Strategic Exploration of Quinoline-Based Materials

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K14670
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 33010:Structural organic chemistry and physical organic chemistry-related
• Research Institution: Keio University
• Principal Investigator: XU Wei 慶應義塾大学, 薬学部(芝共立), 助教 (80869272)
• Project Period (FY): 2022-04-01 – 2024-03-31
• Keywords: TEtraQuinoline / TEQ / quinoline / In2Q2 / macrocyclic compounds

Outline of Final Research Achievements

In this study, we designed and synthesized a cyclic quinoline tetramer, TEtraQuinoline (TEQ), which features a 16-membered ring skeleton. TEQ is an N4-type macrocyclic molecule similar to porphyrin, but it is characterized by its saddle-shaped structure and neutral nature when acting as a ligand. TEQ forms complexes with a series of transition metals (Fe2+, Co2+, Ni2+, Cu2+, Zn2+, and Pd2+), as confirmed by X-ray crystallography. A TEQ/Fe(II) complex exhibited high catalytic activity, promoting the dehydrogenation of benzylamine with catalyst amounts as low as 0.1 mol%. TEQ also demonstrated strong fluorescence upon protonation and in the presence of Zn(II) cations, indicating potential applications as structurally robust probes for acids and zinc. Additionally, we synthesized a novel nitrogen macrocyclic ligand, In2Q2, consisting of two indoles (In) and two quinolines (Q). Its saddle-shaped structure and formation of Zn complexes have been confirmed.

Free Research Field

Structural organic chemistry, Organic synthesis

Academic Significance and Societal Importance of the Research Achievements

The cyclic quinoline tetramer TEQ is a novel nitrogen ligand that can be regarded as a non-planar porphyrinoid. It coordinates with a range of transition metals, showing great potential in catalysis, including asymmetric transformations. Additionally, it shows promise as a fluorescent material.