<s>
In	O
organic	O
chemistry	O
,	O
the	O
acenes	B-Algorithm
or	O
polyacenes	B-Algorithm
are	O
a	O
class	O
of	O
organic	O
compounds	O
and	O
polycyclic	O
aromatic	O
hydrocarbons	O
made	O
up	O
of	O
benzene	O
(	O
)	O
rings	O
which	O
have	O
been	O
linearly	O
fused	O
.	O
</s>
<s>
Pentacene	O
has	O
been	O
incorporated	O
into	O
organic	B-Algorithm
field-effect	I-Algorithm
transistors	I-Algorithm
,	O
reaching	O
charge	O
carrier	O
mobilities	O
as	O
high	O
as	O
5cm2/Vs	O
.	O
</s>
<s>
Heptacene	O
(	O
and	O
larger	O
acenes	B-Algorithm
)	O
is	O
very	O
reactive	O
and	O
has	O
only	O
been	O
isolated	O
in	O
a	O
matrix	O
.	O
</s>
<s>
Due	O
to	O
their	O
increased	O
conjugation	O
length	O
the	O
larger	O
acenes	B-Algorithm
are	O
also	O
studied	O
.	O
</s>
<s>
The	O
first	O
reports	O
of	O
stable	O
nonacene	O
derivatives	O
claimed	O
that	O
due	O
to	O
the	O
electronic	O
effects	O
of	O
the	O
thioaryl	O
substituents	O
the	O
compound	O
is	O
not	O
a	O
diradical	O
but	O
a	O
closed-shell	O
compound	O
with	O
the	O
lowest	O
HOMO-LUMO	O
gap	O
reported	O
for	O
any	O
acene	B-Algorithm
,	O
an	O
observation	O
in	O
violation	O
of	O
Kasha	O
's	O
rule	O
.	O
</s>
<s>
The	O
acene	B-Algorithm
series	O
have	O
the	O
consecutive	O
rings	O
linked	O
in	O
a	O
linear	O
chain	O
,	O
but	O
other	O
chain	O
linkages	O
are	O
possible	O
.	O
</s>
