<s>
In	O
some	O
cases	O
,	O
the	O
degree	O
of	O
charge	O
transfer	O
is	O
"	O
complete	O
"	O
,	O
such	O
that	O
the	O
CT	B-Algorithm
complex	I-Algorithm
can	O
be	O
classified	O
as	O
a	O
salt	O
.	O
</s>
<s>
A	O
number	O
of	O
organic	O
compounds	O
form	O
charge-transfer	B-Algorithm
complex	I-Algorithm
,	O
which	O
are	O
often	O
described	O
as	O
electron-donor-acceptor	O
complexes	O
(	O
EDA	O
complexes	O
)	O
.	O
</s>
<s>
1	O
,	O
3	O
,	O
5-Trinitrobenzene	O
and	O
related	O
polynitrated	O
aromatic	O
compounds	O
,	O
being	O
electron-deficient	O
,	O
form	O
charge-transfer	B-Algorithm
complexes	I-Algorithm
with	O
many	O
arenes	O
.	O
</s>
<s>
A	O
well-known	O
example	O
is	O
the	O
complex	O
formed	O
by	O
iodine	O
when	O
combined	O
with	O
starch	B-Application
,	O
which	O
exhibits	O
an	O
intense	O
purple	O
charge-transfer	O
band	O
.	O
</s>
<s>
Unlike	O
most	O
paper	O
,	O
the	O
paper	O
used	O
in	O
US	O
currency	O
is	O
not	O
sized	O
with	O
starch	B-Application
.	O
</s>
<s>
In	O
1954	O
,	O
charge-transfer	B-Algorithm
salts	I-Algorithm
derived	O
from	O
perylene	O
with	O
iodine	O
or	O
bromine	O
were	O
reported	O
with	O
resistivities	O
as	O
low	O
as	O
8	O
ohm·cm	O
.	O
</s>
<s>
In	O
1973	O
,	O
it	O
was	O
discovered	O
that	O
a	O
combination	O
tetracyanoquinodimethane	O
(	O
TCNQ	O
)	O
and	O
tetrathiafulvalene	B-Algorithm
(	O
TTF	B-Algorithm
)	O
form	O
a	O
strong	O
charge-transfer	B-Algorithm
complex	I-Algorithm
,	O
referred	O
to	O
as	O
TTF-TCNQ	B-Algorithm
.	O
</s>
<s>
In	O
a	O
TTF-TCNQ	B-Algorithm
crystal	O
,	O
TTF	B-Algorithm
and	O
TCNQ	O
molecules	O
are	O
arranged	O
independently	O
in	O
separate	O
parallel-aligned	O
stacks	O
,	O
and	O
an	O
electron	O
transfer	O
occurs	O
from	O
donor	O
(	O
TTF	B-Algorithm
)	O
to	O
acceptor	O
(	O
TCNQ	O
)	O
stacks	O
.	O
</s>
<s>
Hence	O
,	O
electrons	O
and	O
electron	O
holes	O
are	O
separated	O
and	O
concentrated	O
in	O
the	O
stacks	O
and	O
can	O
traverse	O
in	O
a	O
one-dimensional	O
direction	O
along	O
the	O
TCNQ	O
and	O
TTF	B-Algorithm
columns	O
,	O
respectively	O
,	O
when	O
an	O
electric	O
potential	O
is	O
applied	O
to	O
the	O
ends	O
of	O
a	O
crystal	O
in	O
the	O
stack	O
direction	O
.	O
</s>
<s>
Superconductivity	O
is	O
exhibited	O
by	O
tetramethyl-tetraselenafulvalene-hexafluorophosphate	O
(	O
TMTSF2PF6	O
)	O
,	O
which	O
is	O
a	O
semi-conductor	O
at	O
ambient	O
conditions	O
,	O
shows	O
superconductivity	O
at	O
low	O
temperature	O
(	O
critical	O
temperature	O
)	O
and	O
high	O
pressure	O
:	O
0.9	O
K	B-Operating_System
and	O
12	O
kbar	O
.	O
</s>
<s>
Many	O
reactions	O
involving	O
nucleophiles	O
attacking	O
electrophiles	O
can	O
be	O
usefully	O
assessed	O
from	O
the	O
perspective	O
of	O
an	O
incipient	O
charge-transfer	B-Algorithm
complex	I-Algorithm
.	O
</s>
