Triplet excited states, ubiquitous in organic chromophores, can be accessed through various pathways. The feasibility of each pathway is determined by the molecular and electronic structures of the organic chromophores.

A series of extended π-conjugated benzophenone analogs was synthesized through a facile Lewis-acid catalyzed Friedel–Crafts reaction in order to exploit the integral triplet state properties of benzophenone.

The self‐assembly of chiral organic chromophores is gaining huge significance due to the abundance of supramolecular chirality found in natural systems. We report an interdigitated molecular assembly involving axially chiral octabrominated perylenediimide (OBPDI) which transfers chiral information to achiral aromatic moieties. The crystalline two‐component assemblies of OBPDI and electron‐rich aromatic units were facilitated through π‐hole⋅⋅⋅π donor–acceptor interactions, and the charge‐transfer characteristics in the ground and excited states of the OBPDI cocrystals were established through spectroscopic and theoretical techniques. The OBPDI cocrystals entail a remarkable homochiral segregation of P and M enantiomers of both molecular entities in the same crystal system, leading to twisted double‐racemic arrangements. Synergistically engendered cavities with the stored chiral information of the twisted OBPDI stabilize higher‐energy P/M enantiomers of trans‐azobenzene through non‐covalent interactions.

Singlet oxygen (1O2), one of the most sought-after species in oxidative chemical reactions and photodynamic cancer therapy, is activated and neutralized in the atmosphere and living cells. It is essential to see "when" and "where" 1O2 is produced and delivered to understand and utilize it. There is an increasing demand for molecular sensor tools to capture, store, and supply 1O2, controlled by light and engineered singlet and triplet states, indicating the 1O2-capturing-releasing state. Here, we demonstrate the outstanding potential of an aminocoumarin-methylanthracene-based electron donor–acceptor molecule (1). Spectroscopic measurements confirm the formation of an endoperoxide (1-O2) which is not strongly fluorescent and remarkably different from previously reported 1O2 sensor molecules. Moreover, the photoexcitation on the dye in 1-O2 triggers fluorescence enhancement by the oxidative rearrangement and a competing 1O2 release. The unique ability of 1 will pave the way for the spatially and temporally controlled utilization of 1O2 in various areas such as chemical reactions and phototherapies.

Singlet oxygen (1 O 2), the lowest excited-state of molecular oxygen receives great attention in basic research and clinical and industrial settings. Despite several spectroscopic methods available for 1 O 2 sensing, fluorescence sensing receives great attention, for which many fluorogenic sensors based on substituted anthracene are reported. Nonetheless, the roles of substituents on the sensing efficiency, in terms of detection time, remain largely unknown. In this work, we examine the 1 O 2 sensing efficiency of a fluorescence sensor based on a coumarin-anthracene conjugate, which is an electron donor-acceptor dyad, and compare the efficiency with that of 9-methylanthracene. Here, 1 O 2 is generated using the standard photosensitizer Rose Bengal, which is followed by estimation of the rate of reaction of 1 O 2 to the sensor and 9-methylanthracene. The second order reaction rate of the sensor is an order of magnitude less than that of 9-methylanthracene. The lower reactivity of the sensor to 1 O 2 suggests that the roles of substituents, such as electronic interactions, steric interactions and the reactivity of precursor complexes, on sensing efficiency should be carefully considered during construction of fluorogenic molecular sensors.