High Yield Synthesis, Separation and Structural Characterization of New [n+n]-Polyazamacrocycles

Abstract

t-Bu- and isopropyl-substituted aromatic dialdehydes (la-c) and diamines (2a-f) were used to synthesize a series of imine macrocycles (3a-m). The highly selective cyclization reaction resulted either in a [2+2] stoechiometry or in a mixture of different [n+n] cycles, depending on the diamine building block. For some defined macrocycles (3b, 3d, 3e) the structure was elucidated by single crystal X-Ray diffraction that revealed a column-like arrangement of the macrocycles in the solid state. Mixtures of macrocycles were investigated with a combination of MALDI-Tof and analytical GPC which brought significant improvements in the determination of the exact size distribution. Isolated higher homologues of polyimine cycles were made available by preparative GPC for the first time. The possibility to reduce the imine macrocycles quantitatively to their corresponding amine analogues was demonstrated exemplary by the reduction of two pyridine containing cycles (4a-b).