Drug intermediates:
1. Used for synthesizing antibacterial drugs (such as piperazine ring fragments of quinolone antibiotics, such as ciprofloxacin derivatives).
2. Construct antidepressants or antipsychotics (such as rigid structures in 5-HT receptor modulators).
3. Participate in the preparation of anticancer drugs (such as carboxylic acid modifying groups of kinase inhibitors or HDAC inhibitors).

Organic synthesis:
1. Multi functional reactivity: Carboxyl groups can be esterified and amidated, while piperazine ring nitrogen atoms can be alkylated or acylated, expanding molecular diversity.
2. As chiral synthons (such as ligands or adjuvants in asymmetric catalysis).

Research and Materials:
Coordination chemistry: Forming complexes with metal ions such as copper and platinum, used in catalysis or anti-cancer research.