Premium
On the Transfer of Chirality, Thermodynamic Stability, and Folding Characteristics of Stereoisomeric Gated Baskets
Author(s) -
Hu Lei,
Polen Shane,
Hardin Alex M.,
Pratumyot Yaowalak,
Hadad Christopher M.,
Badjić Jovica D.
Publication year - 2015
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201501071
Subject(s) - chemistry , intramolecular force , hydrogen bond , chirality (physics) , folding (dsp implementation) , crystallography , monomer , ring (chemistry) , solvent , thermal stability , polar , hydrogen , stereochemistry , polymer , molecule , organic chemistry , chiral symmetry breaking , physics , engineering , quantum mechanics , astronomy , nambu–jona lasinio model , electrical engineering , quark
We have prepared and characterized chiral and gated baskets ( P / M )‐ 2 , each containing a twisted P or M platform and three amidopyridine gates at the rim. Racemic ( P / M )‐ 2 was found ( 1 H NMR and IR spectroscopy) to stay monomeric in CDCl 3 at 298.0 K with the gates forming a seam of intramolecular N–H ··· N hydrogen bonds. In particular, the amidopyridine gates assume a unidirectional orientation, as directed by the twisted platform, that is, the P ‐shaped cup sets the amidopyridine gates in a counterclockwise (–) orientation of intramolecular N–H ··· N hydrogen bonds (VT 1 H/ 13 C NMR and M06‐2X/6‐31G*). The folded form of spacious (355 Å 3 ) and chiral ( P / M )‐ 2 undergoes an unfolding process in the presence of the polar [D 6 ]DMSO solvent; specifically, with around 25 vol.‐% of [D 6 ]DMSO, the N–H ··· N hydrogen bonds at the rim are broken, thereby allowing a stochastic rotation of the amidopyridine gates about the rim. Interestingly, the thermal stability of folded ( P / M )‐ 2 is good with only a small fraction of unfolded state(s) forming at 104 °C in o ‐xylene.