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.