Heavy Atom Engineering‐Mediated Conformational Diversification to Construct Aggregation‐Induced NIR‐II Emission Luminogens for Cancer Phototheranostics

Chromophores with emission in the second near-infrared (NIR-II) window have captivated much interest by taking advantage of the reduced light scattering and bio-autofluorescence in this region. However, those conventional construction approaches to NIR-II chromophores inevitably suffer from some unpractically limitations, as well as from undiversified molecular skeletons and stereotyped design philosophy. A concise strategy is reported for developing an NIR-II chromophore, PSeD, through heavy chalcogen atom engineering-induced conformational diversification. Compared with the quasi-axis conformer, the emission peak of the quasi-equatorial counterpart is significantly redshifted to the NIR-II region, and the NIR-II emission behaviour is also contributed by the long-range ordered J-aggregates resulting from heavy atom selenium-driven intermolecular interactions. Moreover, the presence of selenium atoms enables PSeD to possess high photothermal conversion efficiency, eventually endowing it with unprecedented performance on NIR-II fluorescence imaging-guided phototherapy.