Here, we show that
charge-transfer interactions determine whether
donor and acceptor ditopic ligands will associate in a complementary
or self-complementary fashion upon metal-ion clipping. Anthracene-based
(
9,10
L
D
and
1,5
L
D
) and anthraquinone-based (
1,5
L
A
) ditopic ligands containing two
imidazole side arms as zinc coordination sites were designed. The
9,10
L
D
and
1,5
L
A
systems
associated in a complementary fashion (L
A
/L
D
/L
A
) upon clipping by two zinc ions (Zn2
+) to form an alternating donor–acceptor assembly
[(
9,10
L
D
)(
1,5
L
A
)2–(Zn2
+)2]. However,
once the charge-transfer interactions were perturbed by subtle modifications
of the imidazole side arms (
9,10
L
D
′
(
S
)
and
1,5
L
A
′
(
S
)
), self-complementary
association (L
D
′/L
D
′/L
D
′/L
D
′ and L
A
′/L
A
′/L
A
′/L
A
′) between the donor (
9,10
L
D
′
(
S
)
) and acceptor
(
1,5
L
A
′
(
S
)
) ligands predominantly occurred to form homoassemblies [(
9,10
L
D
′
(
S
)
)4–(Zn2
+)2 and (
1,5
L
A
′
(
S
)
)4–(Zn2
+)2]. As in the case of a homochiral pair (
9,10
L
D
′
(
S
)
and
1,5
L
A
′
(
S
)
), self-complementary association (narcissistic self-sorting)
occurred in the Zn2
+ assembly with heterochiral
combinations of the donor and acceptor ligands (
9,10
L
D
′
(
S
)
/
1,5
L
A
′
(
R
)
and
9,10
L
D
′
(
S
)
/
1,5
L
A
′
(
R
)
/
1,5
L
A
′
(
R
)
). Narcissistic
self-sorting also took place between the positional isomer of the
donor ligands (
9,10
L
D
and
1,5
L
D
) to form individual homoligand assemblies [(
9,10
L
D
)4–(Zn2
+)2 and (
1,5
L
D
)4–(Zn2
+)2]. Conversely,
statistical association took place in the Zn2L4 assembly process of an isomorphous pair of the donor and acceptor
ligands (
1,5
L
D
and
1,5
L
A
).