Mechanical Bond-Protected Stable Bisradicals

NU 2020-049

INVENTORS
J Fraser Stoddart*
Kang Cai

ABSTRACT
Traditional organic radicals are not stable in air, and NIR dyes with absorption wavelength longer than 1300 nm is difficult to obtain.  Northwestern researchers have developed two new highly positively charged catenanes that display highly stable mono-and diradical states under ambient conditions and with good NIR absorbing ability longer than 1300 nm.  Their results demonstrate that “mechanical-bond-induced-stablization” is an efficient way to achieve highly stable mono-and diradicals. The mixed-valence nature of the [2]catenanes endow them interesting redox and optic properties.  Two  new  highly  charged  [2]catenanes—namely, mHe[2]C•6PF6and mHo[2]C•6PF6—were  synthesized. Electrochemical studies indicate that the first two reduction peaks of these two [2]catenanes are significantly positively shifted, a feature which is responsible for their extraordinary stabilities in air. The mixed-valence nature of the mono-and bis-radical states endows them with unique NIR-absorption properties, e.g. NIR absorption bands for the monoradical and bisradical states observed at ~1800 nm and ~1450 nm, respectively.

APPLICATION

• NIR photothermal conversion
• Advanced materials:  UV/Vis/NIR multiple-state electrochromic materials, spin-electronic materials
• Multiple-state memory devices

ADVANTAGES

• More convenient and efficient synthetic protocol
• Extremely stable mono- and bisradical states
• Measurable NIR absorption properties of the mono-and bisradical forms

PUBLICATION
Cai K, Mao H, Liu WG, Qiu Y, Shi Y, Zhang L, Shen D, Chen H, Jiao Y, Wu H, Liu Z, Feng Y, Stern C, Wasielewski M, Goddard W and Stoddart JF (2020) Highly Stable Organic Bisradicals Protected by Mechanical Bonds. J Am Chem Soc 142(15):7190-7197.

IP STATUS
Provisional and PCT applications have been filed.