Open Access“Reverse” pyridyl cryptands as hosts for viologens
Author(s) -
Pederson Adam M.P.,
Price Terry L.,
Schoonover Daniel V.,
Slebodnick Carla,
Gibson Harry W.
Publication year - 2018
Publication title -
heteroatom chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.283
H-Index - 42
eISSN - 1098-1071
pISSN - 1042-7163
DOI - 10.1002/hc.21422
Subject(s) - cryptand , chemistry , pyridine , aromaticity , chloride , viologen , medicinal chemistry , polymer chemistry , organic chemistry , molecule , ion
Abstract Two new cryptands, 2 and 4 , were prepared from bis( m ‐phenylene)‐32‐crown‐10 (BMP32) 5,5'‐diacid chloride and dibenzo‐30‐crown‐10 (DB30) 4,4'‐diacid chloride, respectively, by reaction with pyridine‐2,6‐dimethanol. The resultant cryptands 2 and 4 have the ester moieties reversed from the previously reported isomers, 1 and 3 . These “reverse” cryptands display lower association constants with viologen derivatives than the original cryptands; this is rationalized by the conjugation of the ester moieties with the aromatic rings, which reduces their electron‐donating properties and offsets the increased basicity of the pyridyl nitrogen atoms. The crystal structure of the BMP32‐based cryptand 2 indeed confirms the coplanarity of the ester and aromatic moieties and indicates that, as a result, the available cavity is quite small and that the pyridyl nitrogen atom points away from the cavity.