A Panchromatic Cyclometalated Iridium Dye Based on 2-Thienyl-Perimidine

Abstract

Though 2-arylperimidines have never been used in iridium(III) chemistry, the present study on structural, electronic and optical properties of N-unsubstituted and N-methylated 2-(2-thienyl)perimidines, supported by DFT/TDDFT calculations, has shown that these ligands are promising candidates for construction of light-harvesting iridium(III) complexes. In contrast to N-H perimidine, the N-methylated ligand gave the expected cyclometalated μ-chloro-bridged iridium(III) dimer which was readily converted to a cationic heteroleptic complex with 4,4′-dicarboxy-2,2′-bipyridine. The resulting iridium(III) dye exhibited panchromatic absorption up to 1000 nm and was tested in a dye-sensitized solar cell.

Tailoring the π-system of benzimidazole ligands towards stable light-harvesting cyclometalated iridium(iii) complexes

“…This indicates that the lowest T 1 emissive state of the complexes is dominated by the 3 MLCT state, that is in line with results for similar benzimidazole-diketonate iridium( iii ) complexes. 24,50…”

“…This indicates that the lowest T 1 emissive state of the complexes is dominated by the 3 MLCT state, that is in line with results for similar benzimidazole-diketonate iridium(III) complexes. 24,50 Complexes 1-5 demonstrate one reversible anodic wave related to the Ir(C^N) 2 2+ ⇌ Ir(C^N) 2 + process as evidenced by cyclic voltammetry in acetonitrile at 25 °C (Fig. S59 †).…”

“…44,45 In turn, octahedral d 6 metal complexes with ligands having the extended conjugated π-system tend to possess enhanced visible light absorption preserving the favorable charge transfer direction. [46][47][48][49][50] Among other N-heterocyclic systems suitable for cyclometalation, 2-arylbenzimidazoles have been recognized as a versatile platform for creating various cyclometalated iridium(III) entities because all aromatic units in these ligands (2-aryl, N-aryl, benzimidazolyl) can be easily and independently decorated with various π-extended systems by conventional chemical reactions. Thus, several series of iridium (III) complexes with cyclometalated π-extended benzimidazoles and a diverse set of ancillary ligands were reported (Fig.…”

Rational design of efficient photosensitizers based on cyclometalated iridium(iii) complexes with 2-arylbenzimidazole and aromatic 1,3-diketone ligands

“…15,[23][24][25][26][27] However, excessive bulkiness of such ligands might lead to large steric encumbrance in the coordination sphere of the iridium ion, causing loss in absorptivity and even increase of lability. 28,29 Meanwhile, the use of rigid compact heterocyclic scaffolds such as perimidine 30 or bis(arylimino)acenaphthene 31 gives access to panchromatic but irreversibly oxidizing iridium complexes. A good photosensitizer should not only demonstrate substantial absorption in the visible region but also have an efficient way to transfer excited electrons into the conduction band of a semiconductor followed by the fast reduction to its initial state.…”

Tunable Optical Properties and Self-Assemblies of a Water-Soluble Perimidinium Imide Dye

“…15 The tremendous demand from such diverse areas as materials chemistry, medicinal chemistry, life science, and coordination chemistry, has led to the generation of a wide variety of derivatives with adjustable properties, reactivities, and electronic characters. 16 In most of the perimidines, there is substantial polarization of the π-electron cloud through the expulsion of a formally excessive π-electron from the six-membered N-containing ring to the naphthalene fragments. However, the situation can be altered by appropriate changes.…”