Tetra Schiff base macrocycles

For 20- [11] and 40-membered [12] macrocyclic di- and tetra-Schiff bases being derivatives of (R)-BTNOL, the chemical shift differences (AS) measured for diastereotopic methylene protons of BINOL unit in CDCI3 have suggested the presence of the partial rotation around the Ar—O—CH2 bond.27 The splitting of some 1H signals in acetone-d6 was explained as a result of a dynamic interconversion process on the NMR time-scale. 

Martell, 1989). The authors suggested that the macrocycle was formed through the cyclic tetra Schiff base or through aminal formation. 

Dioxygen binding in a dinuclear copper(I)-complex, based on a macrocyclic tetra Schiff base ligand 11, was reported by Martell and co-workers (scheme 5). 

Bis(ethylenediamine)gold(III) chloride reacts with a variety of -diketonates in aqueous base, via Schiff base condensation, to form 14-membered tetraaza 12jt macrocyclic species [78[. The parent member of the series [AuL ]" being 22 (where H2L = 5,7,12,14-tetramethy]-l,4,8,ll-tetraazacydotetradeca-4,6,ll,13-tetra-ene) (Figure 2.15). The X-ray structure shows the cation to be nearly planar. 

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