Masahiro KAKO (加固 昌寛)

The photoreactions of C₇₀ and mesityl‐substituted disilirane (disilacyclopropane) 1a afforded the corresponding adducts 2a and 3a, the former of which was reported previously. The structures of 2a and 3a are unequivocally established respectively as a 1,4‐adduct at the [d,d'] site and as a 1,2‐adduct at the [a,b] bond, respectively, using single‐crystal X‐ray crystallographic analyses. The latter structure represents the first example of crystallographic study of 1,3‐disilolane (1,3‐disilacyclopentane) derivatives of fullerenes. The electronic properties of these products are characterized based on electrochemical and theoretical studies elucidating the electron‐donating effects of silyl groups.

Abstract

(6,5)‐enriched single‐walled carbon nanotubes (SWCNTs) were reductively arylated using sodium naphthalenide and monosubstituted and disubstituted iodobenzene derivatives to control their photoluminescence (PL) properties. In the reactions with substituted iodobenzenes, the degree of functionalization was influenced by the substituents on the aryl groups depending on their position, which allowed us to realize control of the PL intensity and wavelength. The methyl or methoxy group at the 2‐position and methyl groups at the 3,5‐positions of the phenyl group respectively increased the E₁₁** PL and E₁₁* PL selectivity at ~1230 and ~1100 nm. Methyl groups at the 2,6‐positions emerged two new PL peaks. These PL characteristics were prominently observed in the (6,4) SWCNT adducts, which were separated by gel chromatography. Theoretical calculations of model compounds showed that the effect of the substituent at the ortho‐position on the relative stability of the isomers with different binding configurations was greater for the diarylated SWCNTs than for the hydroarylated SWCNTs. Experimental and theoretical calculation results revealed that the choice of substituents on the benzene ring was effectively used to modulate the PL wavelength, and these substituents had a considerable effect on the favorable binding configuration of the SWCNT adduct and relative stability and PL wavelength of the conformational isomers.

Offer Organization: Japan Society for the Promotion of Science, System Name: Grants-in-Aid for Scientific Research, Category: Grant-in-Aid for Scientific Research (C), Fund Type: -, Overall Grant Amount: - (direct: 3400000, indirect: 1020000)
次世代を切り拓く革新的な電子・光・磁気機能を有する物質の創出を図るため、分子エレクトロニクス素子や単一分子デバイスをはじめ、磁気的、光学的機能材料としてのナノカーボンが注目され、その基礎および応用研究が精力的に展開されている。本研究では、最も特異な構造と電子的特性を有するナノカーボンの一つである金属内包フラーレンに着目し、元素化学に基づく選択的分子変換による新しい構造や電子的特性を有する分子の創出を図った。これまで金属内包フラーレンの生成量が少なく分離精製が困難であったことから、限られた研究しか行われていなかったが、申請者らが開発した大量分離法がブレークスルーとなり、困難とされていた金属内包フラーレンの化学修飾に関する研究を行える環境が整ったので金属内包フラーレンの分子変換法の開拓の一環として、金属内包フラーレンの光電変換材料としての有用性を発現させるために溶解性の向上とその電子的特性の制御を目的とした。これらの化学は他に例のない全く独創的な研究であり、フラーレン化学の単なる一分野の開拓のみならず、金属内包フラーレンを新しいナノカーボン材料科学へと導くものであり、本研究がもたらす新しい領域への貢献及び波及効果は大きいと信じる。本研究では、金属内包フラーレンの電子的特性や反応性の解明を行うと共に元素化学に基づく分子変換による種々の誘導体合成を遂行した。