Source : Webster's Revised Unabridged Dictionary (1913)

Intramolecular \In`tra*mo*lec"u*lar\, a. (Chem. & Physics)
   Between molecules; situated, or acting, between the molecules
   of bodies.

Source : WordNet®

intramolecular
     adj : within the molecule; occurring by a reaction between
           different parts of the same molecule