Amino-Functionalized Cage-Opened C₆₀ Derivatives

Abstract

The amino-functionalized cage-opened [60]fullerene derivatives were synthesized by reactions with phenylenediamine. In this reaction, the diamine undergoes direct addition to the α,β-unsaturated carbonyl moiety. Further C−C bond scission is promoted by the intramolecular S N 2 reaction. These amino-functionalized derivatives possess high-lying highest occupied molecular orbital levels as suggested by electrochemical analyses. These compounds showed intense near-infrared absorption bands that tail to 900 nm, reflecting the optical transition with π−π* and charge transfer character.

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

“…, C(1)C(2) and C(3)C(4). According to our previous study on a reaction of 1 with o -phenylenediamine, 7 a cleavage of the C(3)C(4) bond is unable to proceed due to a steric demand. In addition, NMR spectral feature of 2 showed a close resemblance with that for the product obtained by the reaction with o -phenylenediamine.…”

“…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 Open-[70]Fullerenes with a Fused Azaacene

“…In the initial step, the aromatic diamine undergoes nucleophilic addition to the C(1)C(2) bond where the high LUMO coefficients are suggested by theoretical calculations (Figure S18). The intramolecular S N 2 addition by the NH 2 group in A then leads to the formation of spiro intermediate B via a C(1)–C(2) bond cleavage . The subsequent 1,2-shift of one of the amino groups affords C and/or D .…”

“…The intramolecular S N 2 addition by the NH 2 group in A then leads to the formation of spiro intermediate B via a C(1)−C(2) bond cleavage. 15 The subsequent 1,2-shift of one of the amino groups affords C and/or D. In the case of 1,2-diaminoacenes with a stronger nucleophilicity, further bond cleavage in C would proceed to give π-extended open-[60]fullerenes such as 2 and 3. The weaker nucleophilicity is, however, expected to increase the activation barrier of this C−C bond cleavage process, whereas a ring-opening reaction of the aziridine unit in D might proceed to give E with the release of strain as a driving force.…”

π-Extended Fullerenes with a Reactant Inside

“…In 2012, Peng and Ding reported the first π-extended fullerenes by introducing an external chromophore on the basis of an effective planar–curved π conjugation which renders low-energy transitions electric dipole-allowed, thereby pushing its absorption into the near-infrared (NIR) region (Figure ). Afterward, Gan and our group independently designed and synthesized fullerene-based donor–acceptor-type NIR dyes upon merging a planar π-system with a partially disrupted C 60 cage (Figure ). Importantly, these π-extended fullerenes can be regarded as precisely size-regulated molecular nanocarbon hybrids.…”