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., …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
• Electronic ISSN: 1520-5126
• 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