Intense Near-Infrared Optical Absorbing Emerald Green [60]Fullerenes

Abstract

Synthesis of emerald green fullerenes (EF) C60[C(CH3)(CO2Et)2]6 and C60[C(CH3)(CO2-t-Bu)2]6 was performed by using hexaanionic C60 intermediate (C60-6) as a reagent in one-pot reaction for attaching six alkyl ester addends on one C60 cage. These EF compounds exhibit intense optical absorption over 600-940 nm, the longest optical absorption of the C60 cage among many [60]fullerene derivatives synthesized.

Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States

“…Although the [n]trannulenes are considerably higher in energy than the [n]annulene counterparts, a supporting molecular framework may provide a three-dimensional cage to sustain the "in-plane" conjugation in the case of the [4n + 2] trannulenes. Thus, [18]trannulene structures are stable within the 60-fullerene architecture [180][181][182][183] and are part of donor-acceptor dyads for light harvesting [180,184].…”

Double Aromaticity in Monocyclic Carbon, Boron, and Borocarbon Rings Based on Magnetic Criteria

“…[4] The trannulenes (cyclically conjugated trans polyenes; an example is shown in Figure 2) were predicted as a class of in-plane aromatics [4,11,[32][33][34] and an increasing number of experimental verifications now exist. [33,[35][36][37] More recently, Schleyer et al [38] re-examined and analyzed the structures and magnetic properties of the 3,5-dehydrophenyl cation (C 6 H 3 + ) and the closely related cyclo [6]carbon (C 6 ) in greater detail. The six-membered rings of both species had equal CÀC bond lengths, [5,39,40] and enhanced magnetic susceptibility anisotropy.…”

Trannulenes with “In‐Plane” Aromaticity: Candidates for Harvesting Light Energy

“…[14] Currently a total of three trannulenes have been discovered. Trannulenes 3-5 arise from three distinct preparative routes and exhibit three distinct topologies and p-conjugated substructures, which will most likely transcribe into quite distinct and tunable physicochemical properties.…”

“…For example, the presence of an [18]trannulene moiety in the nonhalogenated trannulene 5 leads to significant absorptions in the near-IR region (l max = 760 and 850 nm), although the first reduction potential (E Red 1 = À0.49 V vs. Ag/AgCl) remains similar to that of [60]fullerene. [14] The presence of fifteen fluorine atoms in trannulene 3 results in a blue shift of the absorption spectrum (l max = 612 and 658 nm) and a dramatic increase in electron affinity, resulting in an anodic shift of the first reduction potential (E Red 1 = À0.05 V vs. SCE). [9,11,15,16] Although limited physicochemical data has been reported for chlorotrannulene 4, the presence of thirty chlorine atoms in close proximity to the trannulene ring would most probably cause an even greater increase in electron affinity relative to that of 3 and 5.…”

“…Top: X-ray crystal structure of trannulene 5, which is prepared by the reaction of C 60 6À with diethyl 2-bromo-2-methylmalonate. [14] The [18]trannulene ring is depicted in red and the triphenylene substructure in green. Bottom: Schlegel diagram of 4.…”