A new class of intramolecularly hydrogen-bonded dendrons based on a 2-methoxyisophthalamide repeat unit.
The synthesis and conformational properties of folded dendrons based on a 2-methoxyisophthalamide (2-OMe-IPA) repeat unit are described. The hydrodynamic properties of dendrons preorganized via the syn-syn conformational preference of 2-methoxyisophthalamide are compared with 2,6-pyridinedicarboxamide (2,6-pydic) analogues. The effect of subtle differences in the nature of the conformational equilibria that exist within the 2-OMe-IPA and 2,6-pydic repeat units on the global structural properties of the corresponding dendrons was explored computationally, by (1)H-DOSY NMR spectroscopy and time-resolved fluorescence anisotropy (TRFA) measurements. Whereas the syn-syn preference of the 2-OMe-IPA branched repeat unit is stabilized entirely by intramolecular hydrogen-bonding interactions, this preference in the 2,6-pydic system is a consequence of both intramolecular hydrogen-bonding and dipole minimization effects. However, nonspecific solvophobic compression is more important in determining hydrodynamic properties than solvent-dependent shifts in the conformational equilibria of the repeat unit for both dendron series.
Gabriel
Christopher J
CJ
Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA.
Dematteo
Matthew P
MP
Paul
Noel M
NM
Takaya
Tomohisa
T
Gustafson
Terry L
TL
Hadad
Christopher M
CM
Parquette
Jon R
JR
D000577:Amides / Q000737:chemistry*; D018360:Crystallography, X-Ray; D050091:Dendrimers / Q000737:chemistry*; D005454:Fluorescence Polarization; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D010795:Phthalic Acids / Q000737:chemistry*
C516982:2-methoxyisophthalamide; D000577:Amides; D050091:Dendrimers; D010795:Phthalic Acids