Navigating the Roads to Drug Discovery: Part 1: Design, Synthesis, and Biological Evaluation of a Novel Class of Allosteric Modulators of N-Methyl-D-Aspartate Receptor Function Part 2: Discovery of Novel Tetrahydroisoquinoline (THIQ)-Based CXCR4 Antagonists and Conformational Analysis of Structurally Similar CXCR4 Antagonists