TY - JOUR
T1 - Multifunctional macrocyclic receptors as templates for aromatic amino acids
T2 - A rare example of a highly selective multi-input multi-output chemo-"Logic Gate"
AU - Fraschetti, Caterina
AU - Filippi, Antonello
AU - Crestoni, Maria Elisa
AU - Ema, Tadashi
AU - Speranza, Maurizio
PY - 2013/9
Y1 - 2013/9
N2 - Proton-bound [M×H×G]+ diastereomeric complexes between some chiral aromatic amino acids or dipeptides(G) and a chiral multifunctional macrocyclic receptor (M=Chirabite-A) undergo, in the gas phase, highly selective substitution and addition reactions by amines, such as 2-aminobutane and piperidine. All the [M×H×G]+ complexes follow time-dependent monoexponential decays. In some cases, the kinetic curves exhibit a plateau revealing the presence of unreactive [M×H×G] + structures. In them, the amino acid is accommodated in the macrocycle cavity in the zwitterionic form by sharing its acidic hydrogen atoms with the pyridine nitrogen atoms of the host. The same interactions are structurally inaccessible to G=dipeptides or monofunctional amines, which then can be readily released from [M×H×G]+. When the amino acid interacts with the amidocarbonyl oxygen atoms pointing outside the macrocycle cavity, it saves the canonical structure and can be readily displaced by the amine. The Chirabite-A may act as an efficient template for aromatic amino acids by releasing them or not depending upon the amino acid configuration and the basicity of the amine. These unique properties confer to the gas-phase diastereomeric [M×H×G]+ complexes the features of multi-input multi-output chemo-"logic gates".
AB - Proton-bound [M×H×G]+ diastereomeric complexes between some chiral aromatic amino acids or dipeptides(G) and a chiral multifunctional macrocyclic receptor (M=Chirabite-A) undergo, in the gas phase, highly selective substitution and addition reactions by amines, such as 2-aminobutane and piperidine. All the [M×H×G]+ complexes follow time-dependent monoexponential decays. In some cases, the kinetic curves exhibit a plateau revealing the presence of unreactive [M×H×G] + structures. In them, the amino acid is accommodated in the macrocycle cavity in the zwitterionic form by sharing its acidic hydrogen atoms with the pyridine nitrogen atoms of the host. The same interactions are structurally inaccessible to G=dipeptides or monofunctional amines, which then can be readily released from [M×H×G]+. When the amino acid interacts with the amidocarbonyl oxygen atoms pointing outside the macrocycle cavity, it saves the canonical structure and can be readily displaced by the amine. The Chirabite-A may act as an efficient template for aromatic amino acids by releasing them or not depending upon the amino acid configuration and the basicity of the amine. These unique properties confer to the gas-phase diastereomeric [M×H×G]+ complexes the features of multi-input multi-output chemo-"logic gates".
KW - amino acids
KW - chirality
KW - logic gates
KW - macrocycles
KW - noncovalent complexes
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U2 - 10.1002/cplu.201300086
DO - 10.1002/cplu.201300086
M3 - Article
AN - SCOPUS:84883860901
VL - 78
SP - 979
EP - 987
JO - ChemPlusChem
JF - ChemPlusChem
SN - 2192-6506
IS - 9
ER -