Crystal Structure of an L-Carnitine Complex with Pyrogallol[4]arene

Effect of the formation of capsules of tetra(propyl) pyrogallol[4]arene on the host-guest interaction with neurotransmitters

“…5 mmol (0.660 g) of pyrogallol was dissolved in 20 mL of ethanol and cooled for one hour in a bath of ice, 0.4 mL of hydrochloric acid (37%) and 0.5 mL (5 mmol) of respective aldehyde was added dropwise to that solution. The reaction mixture was stirred and heated to 80ᵒC for 12 h, and the solid precipitate was filtered and washed with a mixture of water/ethanol (1:1), producing a white solid with 60% yield, which was characterized by IR, 1 H-NMR, 13 C-NMR, and ESI-MS. [4]…”

“…These derivatives were characterized using spectral techniques, including FT-IR, 1 H-NMR, 13 C-NMR, and mass spectrometry (see the experimental section). The first precipitate was obtained as white crystal.…”

“…As an example, the use of macrocyclic ligands such as crown ethers 1 calixarenes 2,3 or resorcinarenes 4 for different analytical applications can be mentioned. In this field, the use of pyrogallol [4]arenes as macrocyclic molecules for molecular recognition has made a significant contribution to the development of new applications, including receptors for ammonium salts [5][6][7][8][9] , choline 10 , dopamine 11 , carnitine 12,13 , phosphocholine 14 , betaine 15 and pipecolinic acid among others 16,17 .…”

Metal Organic Nanocapsules as Two-Dimensional Network Building Blocks

“…Recently, the Atwood group reported that coordination polymers can be formed using pyrogallol[4]­arene-based metal organic nanocapsules (MONCs) as secondary building units. Pyrogallol[4]­arenes (PgCs) are calixarene-like macrocyclic molecules that are used primarily as supramolecular building blocks in materials constructed through noncovalent means. − However, with an upper rim consisting of 12 phenolic hydroxyl groups, these macrocycles can also function as coordinative building blocks in the construction of more complex superstructures. Common structural motifs of PgC-based entities include the hexameric (PgC) 6 M 24 and dimeric (PgC) 2 M 8 MONCs formed with transition metal cations − and the infinite-layered networks formed with alkali cations, , among others. , The cage-like coordination complexes formed from transition metal cations are very similar in size and shape to their noncovalently seamed complementary supramolecules , and feature two distinct coordination patterns: eight distinct trimetal clusters in the hexamer and an “octametal belt” in the dimer. ,− , The coordination number of the metal cations is also different in the two motifs, with tetra- or hexacoordinate sites seen in the hexamer and pentacoordinate sites typically seen in the dimer.…”

Glycine Betaine Recognition through Cation−π Interactions in Crystal Structures of Glycine Betaine Complexes with C-Ethyl-pyrogallol[4]arene and C-Ethyl-resorcin[4]arene as Receptors

“…In many kinds of protein architectures recognizing molecules with trimethylammonium groups, the cation−π interactions play important roles for recognition and binding [21,22]. In the Cambridge Structural Database (CSD), just one betaine structure among about one hundred fifteen reported betaine structures seems to form the cation−π interaction, though it is not clear whether the cation−π interaction is critical for the structure formation, because many other hydrogen bonds are formed simultaneously.…”