Towards Building Blocks for Supramolecular Architectures Based on Azacryptates

Abstract

In this work, we report the synthesis of a new bis(tris(2-aminoethyl)amine) azacryptand L with triphenyl spacers. The binding properties of its dicopper complex for aromatic dicarboxylate anions (as TBA salts) were investigated, with the aim to obtain potential building blocks for supramolecular structures like rotaxanes and pseudo-rotaxanes. As expected, UV-Vis and emission studies of [Cu2L]4+ in water/acetonitrile mixture (pH = 7) showed a high affinity for biphenyl-4,4′-dicarboxylate (dfc2−), with a binding constant of 5.46 log units, due to the best match of the anion bite with the Cu(II)-Cu(II) distance in the cage’s cavity. Compared to other similar bistren cages, the difference of the affinity of [Cu2L]4+ for the tested anions was not so pronounced: conformational changes of L seem to promote a good interaction with both long (e.g., dfc2−) and short anions (e.g., terephthalate). The good affinity of [Cu2L]4+ for these dicarboxylates, together with hydrophobic interactions within the cage’s cavity, may promote the self-assembly of a stable 1:1 complex in water mixture. These results represent a good starting point for the application of these molecular systems as building units for the design of new supramolecular architectures based on non-covalent interactions, which could be of interest in all fields related to supramolecular devices.

PEEK–WC-Based Mixed Matrix Membranes Containing Polyimine Cages for Gas Separation

“…Acetonitrile, diethyl ether, tris(2-ethylamino) amine 96%, 2,5-furandicarbaldehyde 97%, isophthalaldehyde 97%, terephthalaldehyde reagentPlus 99% and deuterated solvents used for NMR analysis (CDCl 3 ) were purchased from Sigma-Aldrich, Merck Italia (Milano, Italy). Diphenyl-4,4′-dicarboxyaldehyde was synthesized based on a procedure already described by our group [ 51 ]. PEEK-WC was supplied by the Institute of Applied Chemistry, Changchun, China.…”

Recent applications of organic cages in sensing and separation processes in solution

“…the − O⋯O − distance in − OOC–(CH 2 ) n –COO − ) and the separation between the metal centres in the cage cavity. 54 For instance, the separation between Cu( ii ) ions in [Cu 2 ( 4 )] 4+ (Fig. 3) makes this host suitable for the recognition of terephthalate 55 in aqueous solution at neutral pH.…”

Sensing and Liquid–Liquid Extraction of Dicarboxylates Using Dicopper Cryptates

“…As expected, the binding of 5-FAM to the azacryptate cavity is accompanied by the quenching of the fluorophore emission. 22 The experimental profiles could be fitted for a single equilibrium, leading to the formation of the 1:1 complex [Cu 2 ( L1 )(5-FAM)] + with an association constant of 7.20(2) log units.…”

“…This approach, which is well known in the literature, has previously been applied by our group in the determination of polycarboxylates in competing media. 22 …”

“…In this work, by applying the indicator displacement approach to the [Cu 2 ( L1 )] 4+ complex, we obtained an assay for the detection of fum 2– in neutral water. This approach, which is well known in the literature, has previously been applied by our group in the determination of polycarboxylates in competing media …”