Chemically Fueled Transient Geometry Changes in Diphenic Acids.

Area of Science:

• Biochemistry
• Organic Chemistry
• Chemical Kinetics

Background:

• Transient molecular geometry changes are crucial for biochemical system function.
• Diphenic acids are versatile organic molecules with a biaryl bond.

Purpose of the Study:

• To investigate the out-of-equilibrium geometric changes in diphenic acids upon reaction with a carbodiimide chemical fuel.
• To characterize the reaction mechanism, kinetics, and tolerance to steric hindrance.

Main Methods:

• Reaction of functionalized diphenic acids with N-(3-(dimethylamino)propyl)-N"-ethylcarbodiimide hydrochloride (EDC).
• Analysis of changes in dihedral angle about the biaryl bond using structural and kinetic methods.
• Assessment of reaction outcomes under varying steric conditions.

Main Results:

• Diphenic acids form corresponding diphenic anhydrides with a reduction of ~45° in the biaryl bond's torsional angle.
• The reaction mechanism is well-defined in the absence of steric hindrance, allowing derivation of kinetic parameters.
• The reaction tolerates ortho-steric hindrance, though transient byproduct formation can complicate analysis.

Conclusions:

• Carbodiimide-mediated anhydride formation drives significant, out-of-equilibrium molecular geometry changes in diphenic acids.
• The kinetic parameters of this reaction offer valuable insights into system properties like yields and lifetimes.
• Understanding these reactions is key to designing and controlling biochemical systems reliant on dynamic molecular structures.