Dimeric self-assembly of pyridyl guanidinium carboxylates in polar solvents.
A series of pyridyl guanidinium-carboxylates has been prepared and the dimeric self-assembly of these studied in H(2)O/DMSO mixtures, principally using dilution isothermal calorimetry. Compounds 5 and 6, incorporating an aromatic ring in the "tethering" region between the guanidinium and carboxylate groups, demonstrate the strongest dimerisation in neat DMSO. X-ray crystal structures of 5 and 6 reveal two different dimerisation architectures in the solid-state, but both involve carboxylate-guanidinium salt bridges as anticipated, and π-π interactions. Compounds 10-16 incorporating peptidic fragments between the guanidinium and carboxylate groups, showed reduced dimerisation strength with increased amino acid content, but also sustained dimerisation under increasingly aqueous conditions, up to 50% H(2)O/DMSO in the case of 14 and 15. The extent of our study in H(2)O/DMSO mixtures was determined by substrate solubility of 10-16, and not the limit of self-assembly.
Ashiq
Muhammad Irfan
MI
School of Chemistry, University of Southampton, Southampton, SO17 1BJ UK.
Tesfatsion
Biniam F
BF
Gaggini
Francesca
F
Dixon
Sally
S
Kilburn
Jeremy D
JD
D002151:Calorimetry; D002264:Carboxylic Acids / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004121:Dimethyl Sulfoxide; D004952:Esters; D019791:Guanidine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D011725:Pyridines / Q000737:chemistry*; D012995:Solubility; D012997:Solvents / Q000737:chemistry*; D013890:Thiourea / Q000138:chemical synthesis / Q000737:chemistry; D014867:Water / Q000737:chemistry
D002264:Carboxylic Acids; D004952:Esters; D011725:Pyridines; D012997:Solvents; D014867:Water; D013890:Thiourea; D019791:Guanidine; D004121:Dimethyl Sulfoxide