Synthesis and properties of open-cage fullerene C₆₀ derivatives: impact of the extended π-conjugation

Abstract

Novel open-cage fullerene C60 derivatives with extended π-conjugation bearing thiophene rings exhibit long wavelength absorption due to characteristic intramolecular charge transfer transitions.

Amino-Functionalized Cage-Opened C60 Derivatives

“…In 2012, Gan and co-workers pronounced that a cage-opened C 60 derivative having an enamine moiety showed an intense green color in solution with the longest absorption band tailing to 850 nm (Figure ). Compared with π-extended cage-opened C 60 derivatives showing an intense near-infrared (NIR) absorption, amino functionalization seems to be a promising strategy for readily preparing fullerene-based NIR dyes as in the case of phosphorus functionalization . Because of multiple functional groups on the rims of orifices, amines often undergo nucleophilic addition to olefins and/or carbonyl groups though the detailed reaction mechanism remains unclear .…”

“…The amino functionalization of 1 caused the intense absorption up to 900 nm for 2 . Compared with 1 , 5 showed an intense reddish orange color in solution with higher absorption coefficients in the UV and visible regions, likely arising from the π-extension upon introduction of the quinoxaline unit. The amino functionalization of 5 again results in the NIR absorption tailing to 900 nm for 6 .…”

Singlet Oxygen: Discovery, Chemistry, C60‐Sensitization†

“…In an extended work of the same research group, the development of a methodology for the preparation of open-cage fullerene C 60 derivatives with expanded p-conjugation was also reported. Again, the key step for the synthesis of the open-cage fullerene derivative was the self-sensitized photooxygenation path (251).…”

Nonclassical Abramov Products Formed on Orifices of Cage‐Opened C60 Derivatives

“…Next, we applied the similar reactionc onditions to 9, [26] in which C(2)=O(2) andC (3)=O(3) carbonyl groups in 1 are protected asabis(hemiketal) moiety [27] (Scheme 3). In this reaction, methylene derivative 11 was obtainedi n2%y ield, suggestive of in situd eprotection of 9,f ollowed by the hydrolysis of transiently-formed b-oxo-phosphorus ylide whicha lso gave 10 as am ajor product (64 %) via stepwise deoxygenation reactions.…”