ABSTRACT
Triangular 30- and 27-membered hexaiminomacrocycles 4 and 5 of D(3) and C(3) symmetry, respectively, are readily obtained by unprecedented [3 + 3] cyclocondensation of (R,R)-1, 2-diaminocyclohexane with, accordingly, terephthalaldehyde and isophthalaldehyde. The course of the reaction, leading to macrocyclization, is governed by conformational constraints imposed on the structural components of the intermediate products, as shown by molecular modeling. X-ray analysis of cocrystal 4.AcOEt revealed that the macrocycle symmetry significantly departs from ideal D(3) symmetry due to crystal environment. Cyclic hexaamines 6 and 7 were prepared by sodium borohydride reduction of 4 and 5, respectively.
ABSTRACT
It is demonstrated that chirality of molecules composed of 1,2,4, 5-benzenetetracarboxydiimide (pyromellitic diimide) or 1,4,5, 8-naphthalenetetracarboxydiimide units is reflected by their exciton Cotton effects. The analysis is based on the calculated (ZINDO/S) excited states of the model diimide chromophores 1a and 2a. Rotation of the diimide chromophores around the C-N bond in diimides 3-5 is evaluated from the dynamic (1)H NMR data. A comparison of chiroptical properties of bis-diimides 3-5 with the CD spectra of bis-imides 6-8 is also presented. Copyright 2000 Wiley-Liss, Inc.
