reSeArCH Letter
Extended Data Fig. 7 | Formation of armchair-type GNR 8.
a–d, MALDI–TOF mass spectra (reflection mode) of armchair-type GNR
8 (Mn = 8.3 × 103 Da, Đ = 1.31) with 7,7,8,8-tetracyanoquinodimethane
as the matrix and AgOCOCF 3 as an additive. e, Summary of observed
and calculated molecular ion peaks. The formation of GNR 8 with
Mn = 2.4 × 104 Da (Đ = 1.32) was confirmed by MALDI–TOF mass
spectroscopy analysis, where 11 distinct mass peaks, each with gaps of
m/z = 378 (DP(n) = 21–31), were observed. Around the [M+Ag]+ peaks
with n = 25 and 27, mass peaks derived from two additional hydrogen
atoms ([M+Ag+2H]+) were clearly observed, which indicates partial
completion of the Scholl reaction. f, Efficiency of the transformation
reaction to the armchair-type GNR 810. According to the literature^10 , we
also estimated the efficiency of cyclodehydrogenation at each observed
mass peak by using the theoretical number of lost hydrogen atoms during
cyclodehydrogenation (NH(T.)) and the number of lost hydrogen atoms
derived from MALDI–TOF mass measurements (NH(R.)) As a result,
96%–100% efficiencies (NH(T.)/NH(R.)) were confirmed at each m/z
peak. The highest peak was found at m/z = 10,121.3213 (DP(n) = 26,
[M+^107 Ag]+), which is higher than the PS-based Mn, but the top peak DP
(DPtop) and the dispersity pattern were almost identical to those of the
starting fjord-type GNR 2. No peak corresponding to shorter oligomers
or fragments was observed in the full-scale MALDI–TOF mass spectrum
(Supplementary Fig. 19). The detection of larger GNRs with a molecular
weight of over 20,000 Da appeared to be difficult owing to limitations
in the measurement of the highly aggregating flat armchair GNR in the
MALDI–TOF mass instrument.