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

Abstract 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.