Breast cancer remains the most common and leading cause of cancer deaths among women worldwide. The efficacy of conventional therapies is often hampered by off-target effects and multidrug resistance. Phototherapy, encompassing photodynamic therapy (PDT) and photothermal therapy (PTT), has gained significant attention due to its non-invasiveness, high spatiotemporal selectivity, and minimal side effects. However, its application is hindered by several obstacles, including the tumor hypoxic microenvironment, insufficient light penetration depth, and acquired heat resistance. Metal–organic frameworks (MOFs) have adjustable structures, enormous specific surfaces, and facile functionalization, providing an ideal platform to overcome these limitations. This review summarizes the latest research progress in the application of MOFs for precision phototherapy in breast cancer treatment. It emphasizes their role as a direct photosensitizer (PS), photothermal agent (PTA), or multifunctional nanocarrier for PDT, PTT, and synergistic phototherapy (including PDT/PTT, chemo/phototherapy, and immunotherapy/phototherapy). The design strategy and therapeutic effect of MOFs for phototherapy of breast cancer are critically discussed. In addition, the current bottlenecks and future perspectives are outlined to facilitate the clinical translation of MOF-based breast cancer treatment platforms.

Water-soluble alanine-functionalized perylene diimide derivatives (PDI-Ala) were synthesized by introducing alanine units at the imide positions of the PDI framework. Their photoluminescence properties and supramolecular aggregation behavior were investigated in solvents of varying polarity. Chiral L-PDI-Ala displayed distinct solvent-dependent emission colors and intensities, whereas the achiral PDI-Ala showed negligible emission under the same conditions. Poor solvents such as acetone and ethyl acetate promoted relatively efficient emission with hypsochromically shifted bands, while good solvents such as N, N-dimethylformamide and dimethyl sulfoxide induced bathochromically shifted emission with much lower quantum yields. The results indicate that strong face-to-face π-π stacking in the solid-state leads to aggregation-caused quenching (ACQ), whereas ordered aggregates formed by intermolecular forces such as hydrogen bonds or stacking in solution can recover luminescence. On the basis of the spectroscopic and structural results, a solvent-regulated emission mechanism involving excimer/exciplex formation together with H-type and J-type aggregation is proposed. This work provides useful insight into the aggregation-controlled optical behavior of chiral amino-acid-modified PDI materials and offers guidance for the design of chiroptical and self-assembled luminescent systems.