Aniline‐Mediated Imination and Reduction of a Cage‐Opened C₆₀ Derivative

Abstract

The imination of a cage‐opened fullerene C60 derivative was examined using N,N‐dimethyl‐1,4‐phenylenediamine. The desired imine derivative showed a remarkably intense near‐infrared (NIR) absorption band (λedge=1050 nm). According to theoretical calculations, the longest wavelength absorption is assignable to the HOMO→LUMO transition with a strong charge‐transfer character, in which the HOMO localizes on the introduced imine moiety while the high LUMO coefficients can be seen over the entire C60 skeleton. It should be noted that the two reduced compounds bearing an amine or methylene group were also formed in the reaction producing the imine derivative, the former of which again showed NIR absorption tailing to 1200 nm. In this reduction, the hydride source is considered to be α‐hydrogen of the diamine so that the use of N,N,N’,N’‐tetramethyl‐1,4‐phenylenediamine increased the yield of the methylene derivative up to 20%.

Open-[60]fullerene–aniline conjugates with near-infrared absorption

“…1). 6 Recently, we reported a dehydrative condensation of a carbonyl group on the [60]fullerene orifice with o - and p -substituted aromatic diamines, which afford NIR-absorbing dyes showing absorption edges at 900 nm (benzonitrile) 7 and 1050 nm (toluene), 8 respectively. In these molecules, the aniline moiety is conjugated with the [60]fullerene skeleton by an imino group.…”

π-Extended Fullerenes with a Reactant Inside

“…For the facile π-extension of fullerenes, we focused on open-[60]­fullerene 1 bearing a 1,2-dicarbonyl moiety which would be a potential scaffold to extend its π-conjugation via tandem condensation reactions (Figure a). Thus, an o -dichlorobenzene (ODCB) solution containing 1 and excessive diamines were heated at 180 °C for 4 h in a sealed glass tube.…”