Synthesis and properties of resorcinarene based quadrupoles and dimeric electrostatic capsules
In the present study, the rescorcinarenes decorated with an alternating arrangement of pyridinium and sulfonate moieties were synthesized to establish a molecular quadrupole. These rescorcinarenes are capable of undergoing conformational changes from a ‘collapsed’ to ‘open’ state. The stability of the two state are controlled by the polarity of the solvent environment. The electrostatic interactions between pyridinium and sulfonates enforced a ‘quadrupolar collapse’ in solvents such as chloroform. While these interactions are disrupted in dimethylsulfoxide.
A major synthetic challenge was functionalizing the resorcinarene in a positive/negative/positve/negative pattern was successfully addressed. Comparison to dipolar resorcinarene were undertaken to establish a quantitative measurement of the quadrupolar forces and to address the question of cooperatively provided addition attraction beyond two dipoles.
A,C-functionalized-bis sulfonate resorcinarenes and A,C function bis-pyridinium resocinarenes were synthesized independently. Combining these dicationic and dianionic moieties provided an interdigitating dimeric unit with overall quadrupolar charge distribution.
Disruption of the quadrupolar salt bridges in CDCl[subscript]3 was accomplished through the addition of DMSO or through dilution. DeltaG[superscript]o, DeltaH[superscript]o, and DeltaS[superscript]o have been determined for the dimer formation. Addition of pyridinium salts led to a disruption of the dimeric capsule.
Host-guest binding studies established attractive binding to CS[superscript]2. Larger guests such as toluene, diiodobenzene, dicynanobenzene could not be encapsulated.
School:Kansas State University
School Location:USA - Kansas
Source Type:Master's Thesis
Keywords:cavitands electrostatics quadrupoles capsule chemistry organic 0490
Date of Publication:01/01/2009