CXCR4 antagonist 3 (compound 12a) is a potent antagonist of CXCR4 with an IC 50 of 11 nM. CXCR4 antagonist 3 is a congener of TIQ15. CXCR4 antagonist 3 demonstrates the best overall properties including CXCR4 antagonism, CYP 2D6 inhibition, metabolic stability, and permeability. CXCR4 antagonist 3 has the potential for the research of human immunodeficiency virus.