This review paper specifically focuses on the fabrication and application of helical metallic structures with a size ranging from the micro- to nanoscale.

A series of organic–inorganic hybrid complexes based on different types of polyoxomolybdates and transition metal complexes, namely, [Zn₂(TPMA)₂(H₂P₂Mo₅O₂₃)]·11H₂O (1), [Zn₂(TPMA)₂(Mo₈O₂₆)] (2), [Co₂(TPMA)₂(Mo₈O₂₆)] (3), [Ni₂(TPMA)₂(Mo₈O₂₆)(H₂O)₂] (4), [Ni₂(TPMA)₂(2-PA)(H₂O)](PMo₁₂O₄₀) (5) [Cu₂(TPMA)₂(Mo₈O₂₆)] (6), 2[Cu(TPMA)(CrMo₆(OH)₆O₁₈)]·H[Cu₂(TPMA)₂(CrMo₆(OH)₆O₁₈)]·4H₂O (7) (TPMA = Tris[(2-pyridyl)methyl]amine, 2-PA = 2-picolinic acid), have been successfully synthesized under hydrothermal conditions. All complexes were characterized by single-crystal X-ray structural analysis, powder X-ray diffraction, IR spectroscopy and TG analysis. All the complexes showed polyoxomolybdate-based zero-dimensional (0D) structures, and could be further extended into three-dimensional (3D) supramolecular frameworks through hydrogen bonding interactions. In addition, the electrochemical properties of complexes 1–7 have been investigated. Interestingly, some complexes have efficient photocatalytic activities to degradate pararosaniline hydrochloride dye molecules.