Asymmetric BF2-Curcuminoid-Based AIE Photosensitizers Enable Singlet Oxygen Generation for Specific Bacterial Eradication.

Aggregation-induced emission (AIE) photosensitizer-based photodynamic therapy (PDT) offers a promising precision strategy against bacterial infections, yet most AIE photosensitizers suffer from low molar extinction coefficients, short excitation wavelengths, and poor intersystem crossing (ISC). Herein, we rationally designed and synthesized two asymmetric BF2-curcuminoid AIE photosensitizers (TBT and TBCT) featuring a D1-π-A-π-D2 architecture, employing thiophene and methoxy-substituted tetraphenylethene (MTPE) as dual donors/AIE units, difluoroboron β-diketonate (BF2bdk) as the acceptor, and styrene/ethylene as π-bridges. This asymmetric design effectively separates Frontier molecular orbitals, reduces the singlet-triplet energy gap (ΔEST), and enhances ISC efficiency. Both photosensitizers exhibit solvent-dependent photophysical properties, high molar extinction coefficients, and excellent AIE performance. Notably, TBCT displays a smaller ΔEST (0.223 eV) than TBT (0.393 eV), leading to efficient singlet oxygen (1O2) generation, outstanding photostability, and nearly 100% photodynamic eradication of Escherichia coli (E. coli). Collectively, this asymmetric molecular engineering provides a reliable paradigm for high-performance AIE photosensitizers with strong light absorption, efficient 1O2 generation, and bacterial sterilization, showing promise for further exploration in antibacterial applications.