Two‐step Synthesis of a New Twenty‐Membered Macrocycle: Spectroscopic Characterization and Theoretical Calculations

Abstract

A highly symmetrical substituted macrocycle was designed, synthesized and characterized as a novel supramolecular scaffold, whose structure was unequivocally characterized by 1H, 13C, COSY, HMBC, HMQC and DOSY NMR, UV‐Vis, FTIR spectroscopy and mass spectrometry. With its defined and electron‐rich aromatic cavity, this macrocycle could be a potential host for inorganic and organic cations. Preliminary investigations on the coordinating abilities of the studied macrocycle show a noticeable interaction between the obtained product and Pb2+ ions. These interactions have been highlighted by mass spectrometry, UV‐Vis spectroscopy, and supported by DFT and TD‐DFT modelling, making this new macrocycle an interesting candidate for possible heavy metal ions removal or for the design of artificial molecular machines. Good reaction yields, accessibility of reagents and absence of catalysts make this synthetic approach useful for systematic screening and up‐scaling of a large number of compounds.

N-Based Polydentate Ligands and Corresponding Zn(II) Complexes: A Structural and Spectroscopic Study

“…In the case of L2, the high symmetry of the skeleton greatly simplifies the spectrum with respect to the complexity of L1, in which the imine bonds imply the asymmetry of the pyridine rings. These considerations are further confirmed by the 13 C NMR spectra where, in particular, the imine (quaternary carbon signal at 166.5 ppm for L1) and the amine (68.4 ppm signal for L2) signals are clearly recognisable.…”

“…In the 1 H and 13 C NMR spectra of the corresponding Zn(II) complexes, [ZnL1] 2+ and [ZnL2] 2+ , all the signals are shifted compared to those of the employed ligands, providing clear evidence of the complexation that occurred with the Zn(II) ion. [ZnL1] 2+ and [ZnL2] 2+ show a very similar resonance pattern that highlights the asymmetrical nature of the coordinated pyridine rings on the Zn(II) centre (see Figure S1 for the 1 H NMR spectrum of [ZnL1] 2+ and Figure 2 for [ZnL2] 2+ ).…”

“…They have been extensively studied because they integrate the properties of large-sized molecules, such as structural tunability and high selectivity, moderate manufacturing costs, positive pharmaco-kinetic behaviour and availability. Well-documented cases, such as triethylenetetramine, ethylenediaminetetraacetate (EDTA), cyclodextrins, substituted porphyrins and crown ethers, represent useful scaffolds between aromatic Inorganics 2023, 11, 435 2 of 12 ligands and functional structures [12,13]. Over the past few decades, polydentate ligand chemistry has been widely investigated and innovative synthetic approaches have been reported to collect new molecular skeletons with different binding properties, geometries, sizes and solubility [14][15][16][17][18][19].…”

Imidazopyridine Family: Versatile and Promising Heterocyclic Skeletons for Different Applications

“…Krapcho and J.R. Powell employed the same synthetic method as an efficient synthetic approach to collect 1,3-disubstituted imidazo[1,5- a ]pyridines by treating ketimines derived from commercial 2,2′-dipyridylketone or benzophenone [ 9 ]. Interestingly, these ketones have been previously employed to obtain many other ligands with structures different from imidazopyridines [ 157 , 208 , 209 , 210 , 211 ].…”

From π-conjugated macrocycles to heterocycloarenes based on benzo[2,1-b:3,4-b′]dithiophene (BDTh): size- and geometry-dependent host–guest properties

“… 4 They can be roughly divided into single bond linked macrocycles and fully fused cycloarenes according to different structural characteristics. Among them, the single bond linked macrocycles have an inner cavity formed by single bonds and aromatic rings 5 or double 6 /triple 7 bonds, while fully fused cycloarenes 8 have clear internal and external rings constructed by aromatic rings with common edges. Their geometric configurations, optoelectronic properties as well as supramolecular assembly behaviours can be controlled by adjusting the building blocks and conjugation length of π-conjugated systems.…”