Photophysical and electrochemical properties of new ortho-metalated complexes of rhodium(iii) containing 2,2′-dipyridylketone and 2,2′-dipyridylamine. An experimental and theoretical study

Aggregation-induced emission of cyclometalated rhodium(III) and iridium(III) phenylpyridine complexes with ancillary 1,3-diketones

A joint structural and spectroscopic study of simple bis-cyclometataled rhodium(III) and iridium(III) complexes with 2-phenylpyridine and aromatic β-diketones (dibenzoylmethane, benzoylacetone, benzoyltrifluoroacetone, and 2-thenoyltrifluoroacetone) reveals an interplay between the solid-state emission efficiency and crystal packing peculiarities of the complexes. Although the prepared rhodium(III) cyclometalates are isostructural with iridium(III) analogues, different types of π-π interactions are responsible for the aggregation-induced emission (AIE) of the complexes depending on the metal ion. For iridium(III) complexes, pyridyl-pyridyl contacts are essential for AIE because they lower the energy of the emissive metal-to-ligand charge transfer state below that of the non-emissive state located at the ancillary ligand. Enabled by phenyl-pyridyl interactions partially blocking the population of non-emissive d-d states, solid-state phosphorescence enhancement is successfully achieved in a rhodium(III) complex with ancillary benzoyltrifluoroacetone, which is the first example of a rhodium complex exhibiting AIE.

Rational Design of Mono- and Bi-Nuclear Cyclometalated Ir(III) Complexes Containing Di-Pyridylamine Motifs: Synthesis, Structure, and Luminescent Properties

Heteroleptic cyclometalated iridium (III) complexes (1–3) containing di-pyridylamine motifs were prepared in a stepwise fashion. The presence of the di-pyridylamine ligands tunes their electronic and optical properties, generating blue phosphorescent emitters at room temperature. Herein we describe the synthesis of the mononuclear iridium complexes [Ir(ppy)₂(DPA)][OTf] (1), (ppy = phenylpyridine; DPA = Dipyridylamine) and [Ir(ppy)₂(DPA-PhI)][OTf] (2), (DPA-PhI = Dipyridylamino-phenyliodide). Moreover, the dinuclear iridium complex [Ir(ppy)₂(L)Ir(ppy)₂][OTf]₂ (3) containing a rigid angular ligand “L = 3,5-bis[4-(2,2′-dipyridylamino)phenylacetylenyl]toluene” and displaying two di-pyridylamino groups was also prepared. For comparison purposes, the related dinuclear rhodium complex [Rh (ppy)₂(L)Rh(ppy)₂][OTf]₂ (4) was also synthesized. The x-ray molecular structure of complex 2 was reported and confirmed the formation of the target molecule. The rhodium complex 4 was found to be emissive only at low temperature; in contrast, all iridium complexes 1–3 were found to be phosphorescent in solution at 77 K and room temperature, displaying blue emissions in the range of 478–481 nm.

2,2'-Dipyridylamines: more than just sister members of the bipyridine family. Applications and achievements in homogeneous catalysis and photoluminescent materials

2,2'-Dipyridylamines (dpa) and related compounds belong to the family of polydentate nitrogen ligands. More than a century has passed since their first report but new complexes and applications have been emerging in recent years owing to the versatility of dpa-based architectures. This review aims to present and highlight the main achievements attained with dpa-containing metal complexes in the domains of homogeneous catalysis and luminescent materials.

An experimental and quantum chemical study on the non-covalent interactions of a cyclometallated Rh(iii) complex with DNA and BSA

The interaction of a new cyclometallated Rh(iii) complex with DNA and BSA was investigated. The three-layer ONIOM method was employed to calculate the interaction energy between DNA and the complex.

Theoretical studies of molecular structure, electronic structure, spectroscopic properties and the ancillary ligand effect: a comparison of tris-chelate ML3-type and ML2X-type species for gallium(III) complexes with N,O-donor phenolic ligand, 2-(2-hydroxyphenyl)benzothiazole

Two Ga(III) complexes with main ligand, 2-(2-hydroxyphenyl)benzothiazole (HL'), namely mixed-ligand ML2X-type [GaL'2X'] (1) (HX'=acetic acid, as ancillary ligand) and the meridianal tris-chelate [GaL'3] (2) have been investigated by the density functional theory (DFT/TDDFT) level calculations. Both 1 and 2 can be presented as a similar "mixed-ligand ML2X-type" species. The molecular geometries, electronic structures, metal-ligand bonding property of Ga-O (N) (main ligand), Ga-O (N) (ancillary ligand) interactions, and the ancillary ligand effect on their HOMO-LUMO gap, their absorption/emission property, and their absorption/emission wavelengths/colors for them have been discussed in detail based on the orbital interactions, the partial density of states (PDOS), and so on. The current investigation also indicates that it is quite probable that by introduction of different ancillary ligands, a series of new mixed-ligand ML2X-type complexes for group 13 metals can be designed with their absorption/emission property and the absorption/emission wavelengths and colors being tuned.