Helimeric porphyrinoids: Stereostructure and chiral resolution of meso -tetraarylmorpholinochlorins

Bru?ckner, Christian; Go?tz, Daniel C. G.; Fox, Simon P.; Ryppa, Claudia; McCarthy, Jason R.; Bruhn, Torsten; Akhigbe, Joshua; Banerjee, Subhadeep; Daddario, Pedro; Daniell, Heather W.; Zeller, Matthias; Boyle, Ross W.; Bringmann, Gerhard

Abstract

The synthesis and chiral resolution of free-base and Ni(II) complexes of a number of derivatives of meso-tetraphenylmorpholinochlorins, with and without direct β-carbon-to-o-phenyl linkages to the flanking phenyl groups, is described. The morpholinochlorins, a class of stable chlorin analogues, were synthesized in two to three steps from meso-tetraphenylporphyrin. The conformations and the relative stereostructures of a variety of free-base and Ni(II) complexes of these morpholinochlorins were elucidated by X-ray diffractometry. Steric and stereoelectronic arguments explain the relative stereoarray of the morpholino-substituents, which differ in the free-base and Ni(II) complexes, and in the monoalkoxy, β-carbon-to-o-phenyl linked morpholinochlorins, and the dialkoxy derivatives. The Ni(II) complexes were all found to be severely ruffled whereas the free-base chromophores are more planar. As a result of the helimeric distortion of their porphyrinoid chromophores, the ruffled macrocycles possess a stable inherent element of chirality. Most significantly, resolution of the racemic mixtures was achieved, both by classical methods via diastereomers and by HPLC on a chiral phase. Full CD spectra were recorded and modeled using quantum-chemical computational methods, permitting, for the first time, an assignment of the absolute configurations of the chromophores. The report expands the range of known pyrrole-modified porphyrins. Beyond this, it introduces large chiral porphyrinoid π-systems that exist in the form of two enantiomeric, stereochemically stable helimers that can be resolved. This forms the basis for possible future applications, for example, in molecular-recognition systems or in materials with chiroptic properties. © 2011 American Chemical Society.

Citation

Brückner, C., Götz, D. C. G., Fox, S. P., Ryppa, C., McCarthy, J. R., Bruhn, T., Akhigbe, J., Banerjee, S., Daddario, P., Daniell, H. W., Zeller, M., Boyle, R. W., & Bringmann, G. (2011). Helimeric porphyrinoids: Stereostructure and chiral resolution of meso -tetraarylmorpholinochlorins. Journal of the American Chemical Society, 133(22), 8740-8752. https://doi.org/10.1021/ja202451t

• Acceptance Date: Feb 1, 2011
• Online Publication Date: May 2, 2011
• Publication Date: Jun 8, 2011
• Deposit Date: Nov 13, 2014
• Publicly Available Date: Feb 23, 2018
• Journal: Journal Of The American Chemical Society
• Print ISSN: 0002-7863
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 133
• Issue: 22
• Pages: 8740-8752
• DOI: https://doi.org/10.1021/ja202451t
• Keywords: Colloid and Surface Chemistry; Biochemistry; General Chemistry; Catalysis
• Public URL: https://hull-repository.worktribe.com/output/463238
• Contract Date: Nov 13, 2014