TY - JOUR
T1 - Synthesis, structural characterization and complexation properties of the first "crowned" dipyrrolylquinoxalines
AU - Kirkovits, Gregory J.
AU - Zimmerman, Rebecca S.
AU - Huggins, Michael T.
AU - Lynch, Vincent M.
AU - Sessler, Jonathan L.
PY - 2002/11
Y1 - 2002/11
N2 - The synthesis of four crown-substituted dipyrrolylquinoxalines 1-4 is reported. The key step in the synthesis is reaction of a 1,2-diaminobenzocrown with 1,2-bis(1H-pyrrol-2-yl)ethanedione (20). A single crystal X-ray diffraction analysis of the 18-crown-6-dipyrrolylquinoxaline 1 revealed that this molecule forms a tetramer centered around a single molecule of water, with no fewer than 10 hydrogen bonds holding the supramolecular structure together. In the case of the 15crown-5-dipyrrolylquinoxaline 2, however, X-ray diffraction analysis revealed that this species exists as a dimeric pair in the solid state, with the NH protons of one pyrrole lying within hydrogen-bonding distance of two oxygen atoms on an adjacent crown ether. A second single crystal structure of 2 was solved; it demonstrated that this system is able to coordinate a potassium cation, thereby forming an intermolecular sandwich complex, at least in the solid state. In [D6]acetone solution receptor 2 and congeners 1, 3 and 4 were also found to complex sodium and potassium cations within the crown diethyl ether binding sites, in a 1:1 manner as judged by 1H NMR spectroscopic analyses. Although systems 1-4 appear to bind fluoride anion as well as cations, the inability to obtain quantitative binding affinities of 1-4 with fluoride anion rendered the evaluation of the systems for cooperative binding impossible.
AB - The synthesis of four crown-substituted dipyrrolylquinoxalines 1-4 is reported. The key step in the synthesis is reaction of a 1,2-diaminobenzocrown with 1,2-bis(1H-pyrrol-2-yl)ethanedione (20). A single crystal X-ray diffraction analysis of the 18-crown-6-dipyrrolylquinoxaline 1 revealed that this molecule forms a tetramer centered around a single molecule of water, with no fewer than 10 hydrogen bonds holding the supramolecular structure together. In the case of the 15crown-5-dipyrrolylquinoxaline 2, however, X-ray diffraction analysis revealed that this species exists as a dimeric pair in the solid state, with the NH protons of one pyrrole lying within hydrogen-bonding distance of two oxygen atoms on an adjacent crown ether. A second single crystal structure of 2 was solved; it demonstrated that this system is able to coordinate a potassium cation, thereby forming an intermolecular sandwich complex, at least in the solid state. In [D6]acetone solution receptor 2 and congeners 1, 3 and 4 were also found to complex sodium and potassium cations within the crown diethyl ether binding sites, in a 1:1 manner as judged by 1H NMR spectroscopic analyses. Although systems 1-4 appear to bind fluoride anion as well as cations, the inability to obtain quantitative binding affinities of 1-4 with fluoride anion rendered the evaluation of the systems for cooperative binding impossible.
KW - Crown compounds
KW - Host-guest chemistry
KW - Hydrogen bonds
KW - Supramolecular chemistry
UR - http://www.scopus.com/inward/record.url?scp=0036859323&partnerID=8YFLogxK
U2 - 10.1002/1099-0690(200211)2002:22<3768::AID-EJOC3768>3.0.CO;2-R
DO - 10.1002/1099-0690(200211)2002:22<3768::AID-EJOC3768>3.0.CO;2-R
M3 - Article
AN - SCOPUS:0036859323
SN - 1434-193X
SP - 3768
EP - 3778
JO - European Journal of Organic Chemistry
JF - European Journal of Organic Chemistry
IS - 22
ER -