Diverse Parahydrogen-Induced Hyperpolarization Effects in Chemistry: Expanding Beyond Classical Approaches

Parahydrogen-induced hyperpolarization (PHIP) is a powerful tool for enhancing nuclear magnetic resonance (NMR) signals, with diverse effects beyond the classical PASADENA, ALTADENA, hydrogenative PHIP (hPHIP), and signal amplification by reversible exchange (SABRE) approaches. This review examines less common PHIP phenomena, including photo-PHIP, partially negative line (PNL) effects, oneH-PHIP, metal-free PHIP, and chemically relayed polarization transfer, which provide valuable insights into reaction mechanisms and enable new analytical applications.