Redox-controlled hydrogen bonding: turning a superbase into a strong hydrogen-bond donor.
Herein the synthesis, structures and properties of hydrogen-bonded aggregates involving redox-active guanidine superbases are reported. Reversible hydrogen bonding is switched on by oxidation of the hydrogen-donor unit, and leads to formation of aggregates in which the hydrogen-bond donor unit is sandwiched by two hydrogen-bond acceptor units. Further oxidation (of the acceptor units) leads again to deaggregation. Aggregate formation is associated with a distinct color change, and the electronic situation could be described as a frozen stage on the way to hydrogen transfer. A further increase in the basicity of the hydrogen-bond acceptor leads to deprotonation reactions.
Anorganisch-Chemisches Institut, Ruprecht-Karls Universität Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg (Germany).
Ute
U
Wild
Christiane
C
Neuhäuser
Sven
S
Wiesner
Elisabeth
E
Kaifer
Hubert
H
Wadepohl
Hans-Jörg
HJ
Himmel
D004396:Coloring Agents / Q000138:chemical synthesis / Q000737:chemistry; D019791:Guanidine / Q000138:chemical synthesis / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D010084:Oxidation-Reduction
D004396:Coloring Agents; D006859:Hydrogen; D019791:Guanidine
aggregation; guanidine; hydrogen bonds; oxidation; self-assembly