Hemicryptophanehost as efficient primary alkylammonium ion receptor

Abstract

Hemicryptophane 3 was found to be an efficient and selective primary alkylammonium receptor. Binding constants are 1000-fold higher than those previously reported for hemicryptophane hosts. Efficient complexation of dopamine emphasizes the use of this host for neurotransmitter complexation. Density functional theory calculations were performed and highlight host-guest complementarities.

Chiral Discrimination of Ammonium Neurotransmitters by C3‐Symmetric Enantiopure Hemicryptophane Hosts

“…This is consistent with the encapsulation of the guest inside the molecular cavity, the protons of the encaged neurotransmitters being located in the shielding region of the aromatic cavity. This is in agreement with our previous results observed in the complexation of achiral dopamine by a racemic mixture of a hemicryptophane receptor …”

“…For instance, ammoniums, or the ammonium part of zwitterionic guests, are oriented toward the CTV unit of hemicryptophane 1 , allowing favorable cation‐π interactions . On the other hand, with hemicryptophane 2 , NMR data and DFT calculations highlighted that the encapsulation of the ammonium part of the dopamine neurotransmitter occurred through hydrogen bonding with the tren unit . Host 3 contains aromatic CTV cap and tren unit, two sites capable of interacting with an ammonium moiety.…”

“…They are particularly well adapted for the recognition of alkyl‐ammonium guests and hemicryptophane 1 was found to complex tetramethylammonium in CDCl 3 with a binding constant of 380 M –1 . Hemicryptophane 2 , which combines the rigid CTV scaffold and a C 3 ‐symmetric tris‐(2‐aminoethyl)amine (tren) unit, presents high affinity for primary alkylammonium cations, such as dopamine, with association constants of three orders of magnitude higher (up to 10 5 M ‐1 in CDCl 3 /CD 3 OD mixture) than those previously reported for other hemicryptophanes …”

Selective Oxidation of Alcohols Catalyzed by a Hemicryptophane-Ruthenium Complex

“…Therefore, discoveries of new classes of synthetic transition metal complexes containing well-defined cavities that are analogous to the active sites of metalloenzymes have been of great interest for improving the reactivity and selectivity of bulk phase reactions [4][5][6][7][8][9][10][11][12][13][14]. Hemicryptophanes are covalent molecular capsules constructed from a cyclotriveratrylene (CTV) host unit and they are responsible for dissymmetry at the molecular cavity level [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. We recently synthesized hemicryptophane 1 (Figure 1), which contains a tris(2-aminoethyl)amine (tren) ligand and three rigid phenyl spacers [30][31][32][33].…”

Novel Nucleobase-Decorated Tripodands: Synthesis and Supramolecular Properties

“…10 Tripodands with C 3 symmetry decorated with terminal groups exhibiting H-bonding ability show, in many cases, a favorable arrangement of the pendant arms for H-bonds interactions with various large guest molecules. The resulted supramolecular architectures facilitate the recognition of carbohydrates, 11 organoammonium cations, 12,13 and ion pairs. 14,15 In this context we have developed an efficient method for the preparation of tripodands I with a C 3 -symmetric central unit that bears terminal groups with H-bonding properties ( Figure 1) starting from an alkyne-terminated podand synthesized in our group 16 or commercially available tripropargylamine as a flexible core on one side, and azide-functionalized nucleobases on the other side.…”