Reactions of C₆₀ with Pyridazine and Phthalazine

Abstract

Cage-opened bisfulleroids are one of suitable building blocks for making a large hole on fullerenes. This work focuses on the Diels-Alder reaction of C 60 with azines, among synthetic methods developed thus far, to provide bisfulleroids. Surprisingly, the computational study predicted that the reaction proceeds with normal electron demand in contrast to hitherto considered inverse-electrondemand pathway. The benzoannulation to the pyridazine ring, i. e., phthalazine, resulted in the remarkably shortened reaction time due to the better interaction between the HOMO of phthalazine and the LUMO of C 60 as well as stronger 2,3-diaza-1,3-butadiene character in the phthalazine as confirmed crystallographically. Contrary to expectations, the benzobisfulleroid was converted into corresponding orifice-enlarged derivative via the photooxygenation slightly faster than the fulleroid derived from pyridazine.The construction of openings on fullerene C 60 had received great attention in 1990s for the organic synthesis targeting endohedral fullerenes, i. e., molecular containers [1] as well as for exploring potential performance as electron acceptors in solar cells. [2] Currently, several methods are available for making holes on the fullerene surface, such as photooxygenation of azafulleroids [3] or 1,6-disubstituted derivatives, [4] oxidation of vicinal diol, [5] and sequential pericyclic reactions. [6] The first cage-opened derivative was reported by Wudl and co-workers in 1995. [3] They performed a 1,3-dipolar cycloaddition of C 60 using methoxyethoxymethyl azide, giving an azafulleroid derivative which was further transformed into a compound bearing an 11-membered-ring opening. Using the similar strategy, the research group of Rubin, Houk, Saunders, and Cross demonstrated that a two-fold addition of azide followed by photooxygenation provides a corresponding cage-opened derivative which can encapsulate an He atom and H 2 molecule. [7] Among reported methods, ring-opening reactions of cyclohexadiene-fused C 60 derivatives via sequential [4 + 4] and retro [2 + 2 + 2] rearrangements are one of well-established methods to provide cage-opened bisfulleroids having an eight-mem-

Near‐Infrared‐Absorbing Chiral Open [60]Fullerenes

“…In all cases, N , N ‐dimethylaminomethylidene derivatives 3 b – 3 g were obtained in 5–32 % yields together with 4 b – 4 g . The low yield of 3 f might be due to the steric demand originated from the fused benzene ring closely located near the carbonyl group [33] …”

“…In all cases, N,N-dimethylaminomethylidene derivatives 3 b-3 g were obtained in 5-32 % yields together with 4 b-4 g. The low yield of 3 f might be due to the steric demand originated from the fused benzene ring closely located near the carbonyl group. [33] To get deep insights into the reaction mechanism, we carefully surveyed this unusual carbene-mediated C=C bond scission. We noticed the generation of colorless needle crystals attached on the ceiling of the reaction vessel after cooling it down to room temperature (Figure 3a).…”

Recent advances in versatile pyridazine-cored materials: principles, applications, and challenges

“…This review calls for more efforts to enrich versatile PDs for high-performance materials beyond bioactive pharmaceutical drugs and pesticides. 49,147 For the sake of more and better functional PD-ringbased materials, herein, the general strategy can be explored by combining the previous studies and interesting results with practical synthetic methodologies (Scheme 7), 50,106,[148][149][150][151][152][153][154][155][156] theoretical calculations, 129,[157][158][159][160][161] aza-quantity effect and azaregioisomerism, 159,160 and supramolecular strategies, 29,[162][163][164][165] the serendipitously discovered or well-designed of PD-based materials possess huge application prospects in the fields of optoelectronics, chromism, fluorescence probes, and energy materials. The unceasing breakthroughs in catalysis, 9,45,115,154,166,167 magnetic complexes, 155,168 molecular rotators (Fig.…”