Chemistry Reference
In-Depth Information
Scheme 15 5,11-Diethynyl IF diones 65a-f [
53
]
Fig. 4 Solid state packing of 65a (
left
), 65d,
middle
, and 65f (
right
)[
53
]
ordering, as three separate packing motifs were observed (Fig.
4
). TMS-capped
acetylene 65a possessed herringbone packing, while the larger TPS-capped
acetylene 65f displayed one-dimensional columns without
interactions. In
accordance with Anthony's observations with 6,13-bis(triisopropylsilylethynyl)
pentacene [
54
], TIPS-capped 65d exhibited columnar stacking in two dimensions,
also known as brick-and-mortar stacking, a packing motif often favorable for
charge-transport in materials because it increases the likelihood of significant
intermolecular orbital overlap. This was clearly illustrated by comparison of the
carbon-carbon close-contact distances of 65a, 65d, and 65f, which were 3.50, 3.40,
and 3.77
˚
, respectively.
Despite its highly insoluble nature, 2,8-dibromodione 61c has proven to be a
useful precursor for a variety of 2,8-diarylated derivatives, as such species can
further provide access to a larger variance of electron-donating/accepting
substituents (Scheme
16
)[
37
,
55
]. Suzuki or Stille cross-coupling of 61c with
aryls 66a-e furnished diaryl diones 67a-e in 43-81% yield.
Marks installed long alkyl groups onto the IF dione core as another
method to combat insolubility (Scheme
17
)
37
]. Kumada cross-coupling
of 1,4-dichlorobenzene (68) with didodecylmagnesium bromide gave 1,4-
didodecylbenzene (69). Bromination of 69 yielded 2,5-dibromo-1,4-
didodecylbenzene (70), which was reacted with boronic acid 71 under Suzuki
cross-coupling conditions to afford terphenyl 72. Cyclization as before with
concentrated sulfuric acid at elevated temperatures gave didodecyl dione 73
in 93% yield. Unlike parent 22, 73 could be directly brominated on the 2- and
8-positions to generate 74 cleanly, which upon further cross-coupling with
2-tributylstannylthiophene (75) under standard Stille conditions afforded 76.
p
-
p
