Chemistry Reference
In-Depth Information
O
O
NH
O
-
OH
[Ga
4
L
6
]
12-
HNR
3
+
-
OH
NR
3
+
H
2
O
strong
encapsulation
+
HNR
3
HN
O
O
O
Fig. 17 The equilibrium between free amine NR
3
and protonated ammonium cation HNR
3
+
as
promoted by encapsulation within the M
4
L
6
assembly. Strong binding by the M
4
L
6
assembly
drives formation of the ammonium cation
Fig. 18 Catalysis of the hydrolysis of orthoformates as promoted by encapsulation within the
M
4
L
6
assembly. Binding of the protonated intermediate allows catalytic turnover even in basic
aqueous solution, which would normally preclude the formation of acidic intermediates
assembly, the ammonium species is tightly bound and the equilibrium is shifted in
favor of the protonated species. The M
4
L
6
host is highly negatively charged and
has a strong affinity for monocationic guests, tightly binding the protonated amine.
This strongly perturbs the equilibrium in favor of the bound cation, increasing the
basicity of these amines by up to 4.5 orders of magnitude!
Recognizing that this principle could be applied not only to perturbing the
equilibrium of unreactive species such as ammonium ions, the M
4
L
6
assembly
