## Dissertations from ProQuest

#### Title

Noncovalent forces in molecular recognition: Modes of interaction and self-assembling properties of novel molecular receptors

1993

Article

#### Degree Name

Doctor of Philosophy (Ph.D.)

Chemistry

#### First Committee Member

George W. Gokel, Committee Chair

#### Abstract

In the present work, we have designed and prepared a variety of novel molecular models capable of interacting by means of non-covalent forces. The main goal of the project was to examine their modes of interaction, complexation properties and potential for self-assembly as means to better understand biorelevant processes.The first part of the work dealt with lariat ethers incorporating nucleotide base derivatives. The compounds were synthesized and characterized using conventional synthetic and characterization protocols. We confirmed the self-assembling properties of these model molecules, and proved that this property could be enhanced by complexation of a suitable molecular guest. We explored the energetics involved in the association of two of the monomers, A-O-A and T-O-T, and estimated a free energy value of 4 kcal$\cdot$mol$\sp{-1}$ in CDCl$\sb3$ solution. In addition, we uncovered a dynamic equilibrium between discretely associated species, and present evidence suggesting plausible recognition modes involved in biorelevant processes. Finally, using a second generation of simple molecular models, we have established the relevance of cooperative interplays between hydrogen bonding and stacking interactions, a cooperativity that is often encountered in biological recognition processes.The second part of this work addressed the self-assembly and cation complexation properties of Ni(II)salicylaldimine derivatives. We obtained full characterization data for these complexes and conclusive evidence for a distinctive mechanism for self-assembly. The complexes displayed spectral features that clearly indicated a trans-square planar geometry for these Ni(II) derivatives. In addition, we found that the derivatives were able to complex both alkali-metal cations and transition metal ions, such as nickel, as well, as evidenced from solid state structural analysis. The cation binding profile was undoubtedly coulombic in its origin and not crown-ether-like, as previously suggested by other authors. A plausible mechanism for cation complexation was suggested based on the solid state structures, spectral data and information found by other authors in related systems.

#### Keywords

Chemistry, Biochemistry; Chemistry, Organic