Development of new tools to elucidate modes of action

Small Fluorescent Molecule 1,3a,6a-Triazapentalene

Advances in bioimaging technologies and organic light-emitting devices have created a strong demand for fluorescent molecules with novel functions and practical supply methods. We discovered that triazapentalenes (TAPs), which are unique 10π-system aromatic compounds, are excellent fluorescent chromophores that exhibit strong fluorescence despite their compact structure. We also established a simple synthetic method for TAPs. TAPs exhibit a large Stokes shift and strong solvatochromism. Furthermore, their fluorescence wavelength changes significantly depending on the electronic effects of the substituents, an intriguing property. This enables the creation of innovative, compact fluorescent molecules whose colors can be easily controlled without changing the physical properties of the chromophore. Cell staining reagents based on this technology are currently commercially available. Furthermore, TAP enabled the observation of an antihypertensive agent with a molecular weight of 217 in vascular endothelial cells. This demonstrates TAP's usefulness as a fluorescent labeling group for low-molecular-weight bioactive compounds.

Currently, we are utilizing TAPs to pursue the following research projects.

• Photodynamic cancer immunotherapy using only small molecules
• Development of a simple periodontal disease test kit
• Development of Molecular Probes to Elucidate the Relationship Between Cells and Symbiotic Microorganisms

1. Namba, K.; Osawa, A.; Ishizaka, S.; Kitamura, N.; Tanino, K. J. Am. Chem. Soc. 2011, 133, 11466.
2. Namba, K.; Mera, A.; Osawa, A.; Sakuda, E.; Kitamura, N.; Tanino, K. Org. Lett. 2012, 14, 5554.