Tonglei Li, Ph.D. Department of Industrial and Physical Pharmacy, Purdue University 575 Stadium Mall Drive, West Lafayette, Indiana 47907 tonglei@purdue.edu Abstract. Self-assembling of molecules in crystallization is collectively driven by intermolecular interactions among the solute and solvent. Better understanding of nucleation mechanism may be perceived in light of the locality, strength, and hierarchy of intermolecular interactions. Primary interactions such as hydrogen bonding decide pre-nucleation dynamics and the secondary such as aromatic stacking and close contacts may effect complementing and competing functions while primary assemblies develop. Additionally, molecular conformation and local preference of a particular interaction can mutually influence the kinetics and structure of self-associates. To demonstrate these principles, several of our recent studies focus on solution chemistry and the interplay between conformation and intermolecular interaction of a series of structurally similar diarylamine compounds.