Published papers

A Monocationic biscyclometalated Ir(III) complex with triarylborane‐bound 2,2′‐bipyridine was designed and synthesized, and its photophysical properties were investigated. The triarylborane–Ir(III) complex exhibited significantly enhanced absorption in the 300–400 nm region compared to pristine biscyclometalated Ir(III) complexes, attributed to contributions from π(aryl)–p(B) charge transfer (CT) and metal‐to‐ligand charge transfer (MLCT) transitions. Moreover, IrPhB retained sub‐microsecond‐scale excited‐state lifetimes comparable to the reference complexes without triarylborane moiety. These features—strong absorption in a broad visible‐light region and long‐lived excited states—highlight the high potential of IrPhB for applications in photochemical systems.

A metastable narcissistic self-sorted state was generated from structurally similar tritopic ligands depending on the pathway and the leaving-ligand, which cannot be realized under thermodynamic control.

A reversible ligand exchange reaction occurred between two different symmetric Pt acetylide complexes to give an asymmetric Pt complex, which gave Pt–Cu assemblies showing photoluminescence in the crystalline state.

The anions of the Ir complex salts control the thermodynamic stability and photoluminescence properties of the host–guest complex.

Abstract Supramolecular assemblies of a concaved aromatic host as an electron donor (D) and a cationic heterocyclic guest as an electron acceptor (A) are reported. These molecular units were noncovalently bound to afford charge‐transfer (CT) complexes in solution and a CT cocrystal, displaying drastic color change from colorless to orange. The binding motif of the assemblies in the solution state was analyzed by NMR spectroscopic analysis and visualized by X‐ray crystallographic analysis. Theoretical calculations for the assemblies revealed electronic communication between the D and A fragments, proving their CT characteristics. The CT complexes were stabilized by not only CT and cation‐π interactions, but also Coulomb interaction between the cationic acceptor unit and its anion supported by a hydrogen bond with a hydroxy group in the aromatic host, resulted in enhancement of orbital overlapping of the D‐A fragments. Owing to the strong D‐A interaction in the assemblies, the CT complexes undergo ultrafast charge recombination on a femtosecond timescale after photoexcitation of the CT transition, as confirmed by transient absorption spectroscopy. These results demonstrate that understanding of assembly motif and its noncovalent interactions can lead to create optical materials manipulating electron transition dynamics.