Synthesis, characterization and coordination chemistry of aminophenylbenzothiazole substituted 1,4,7-triazacyclononane macrocycles

The synthesis and spectroscopic characterization of four new 2-(4-aminophenyl)benzothiazole substituted 1,4,7-triazacyclononane derivatives with and without appended pyridyl groups on the macrocycle is reported: 1-(2-(4-aminophenyl)benzothiazolyl)-2-oxoethyl)-1,4,7-triazacyclononane (L1), 1-(2-(4-aminophenyl)benzothiazolyl)-2-oxoethyl)-4-(2-pyridylmethyl)-1,4,7-triazacyclononane (L2), 1-(2-(4-N-methylaminophenyl)benzothiazolyl)-2-oxoethyl)-4-(2-pyridylmethyl)-1,4,7-triazacyclononane (L3), 1,4-bis(2-pyridylmethyl)-7-(2-(4-aminophenyl)benzothiazolyl)-2-oxoethyl)-1,4,7-triazacyclononane (L4). The ligands have been applied in the synthesis of a series of copper (II) complexes, [Cu(L1)(OH2)](ClO4)2·0.5ACN (C1), [Cu(L3)](ClO4)2·ACN (C2) and [Cu(L4)(OH2)](ClO4)2·0.5THF (C4) whose structures have been determined by X-ray crystallography. As commonly observed for Cu(II) complexes of 1,4,7-triazacyclononane derivatives, the geometry of the metal centre ranges from distorted square pyramidal to pseudo-octahedral. Notably, the amide carbonyl coordinates to the copper(II) centre in C1 and C2 but not in C4 where the presence of an additional pyridyl group results in an N5 coordination sphere.

Graphical abstractThe synthesis and characterization of four new 2-(4-aminophenyl)benzothiazole substituted 1,4,7-triazacyclononane derivatives with and without appended pyridyl groups on the macrocycle is reported together with a series of copper(II) complexes. As commonly observed for Cu(II) complexes of 1,4,7-triazacyclononane derivatives, the geometry of the metal centre ranges from distorted square pyramidal to pseudo-octahedral.Figure optionsDownload full-size imageDownload as PowerPoint slide