Azobenzene-functionalized iridium(iii) triscyclometalated complexes

Abstract

Twelve Ir(iii) triscyclometalated compounds containing up to three azobenzene fragments on their structure have been synthesized based on photochromic 2-phenylpyridyl type ligands . These complexes are intended to study the possibility of transferring the photochromicity of the azobenzene fragment to the organometallic compound, and the effect of the substitution pattern, relative distance of the azobenzene to the metal centre, and number of azobenzenes on their properties.

Functionalized Lanthanide(III) Complexes Constructed from Azobenzene Derivative and β-Diketone Ligands: Luminescent, Magnetic, and Reversible Trans-to-Cis Photoisomerization Properties

“…Representative examples are the families of azobenzene-functionalized transition metal complexes that have been studied in detail, such as ferrocene− azobenzene, 10,13 bis-or tris(bipyridine), 14 terpyridine metal complexes with azobenzene conjugation, 15 metalladithiolenes with azobenzene groups, and azobenzene-containing triscyclometalated complexes. 16,17 Most of the studied complexes displayed trans-to-cis photoisomerization upon UV light and the reverse cis-to-trans isomerization by excitation of the n−π* band of azobenzene. 18,19 However, the efficiency of the photoisomerization was quite low, and the quantum yields of the trans-to-cis photoisomerization were much lower than those of the organic azobenzenes.…”

“…A large number of azobenzene derivatives have been studied in solution as well as in polymer matrices. − These compounds are promising for application in a wide variety of areas, from biological research to information technology. − Azobenzene-functionalized transition metal complexes are an alternative to pure organic azobenzene derivatives and can provide more versatile molecular materials. − Combining an azo moiety within coordination compounds can lead to systems capable of exhibiting novel and unusual properties, such as redox, optical, and magnetic properties, of the metal complexes with the photoisomerization reaction. Representative examples are the families of azobenzene-functionalized transition metal complexes that have been studied in detail, such as ferrocene–azobenzene, , bis- or tris­(bipyridine), terpyridine metal complexes with azobenzene conjugation, metalladithiolenes with azobenzene groups, and azobenzene-containing tris-cyclometalated complexes. , Most of the studied complexes displayed trans-to-cis photoisomerization upon UV light and the reverse cis-to-trans isomerization by excitation of the n –π* band of azobenzene. , However, the efficiency of the photoisomerization was quite low, and the quantum yields of the trans-to-cis photoisomerization were much lower than those of the organic azobenzenes . Some of the metal complexes such as Ir­(III) and Ru­(II) complexes even showed decreased quantum yields of photoisomerization. , …”

Azo-Label Heterometal–Organic Rhomboids Exhibiting Photoswitchable NIR Luminescence in Crystalline State

“…5 Recently, the azobenzene-functionalized metal complexes have aroused wide attention, including azobenzen-functional ferrocene derivatives, 6,7 Co III/II , 8 Fe II , 9 Zn II , 10 Ir III complexes, etc. 11 By anchoring an azo moiety with a metal center, the multifunctional properties, including photochromism, redox, magnetism, etc., can be integrated. 12−16 The majority of complexes based on reversible photoisomerization belongs to the monometallic 3d-block transition-metal complexes.…”

“…Due to their photochromic properties, the pure organic azobenzene derivatives have many potential applications in fields, such as information storage, molecular switches, liquid crystal, nonlinear optical, and biological research . Recently, the azobenzene-functionalized metal complexes have aroused wide attention, including azobenzen-functional ferrocene derivatives, , Co III/II , Fe II , Zn II , Ir III complexes, etc . By anchoring an azo moiety with a metal center, the multifunctional properties, including photochromism, redox, magnetism, etc., can be integrated. − The majority of complexes based on reversible photoisomerization belongs to the monometallic 3d-block transition-metal complexes.…”

Triaryl-Boron Functionalized Dinuclear Platinum Complexes Linked by Photoisomerizable Bpe Ligand: Luminescence and Isomerism

“…As a result, low energy irradiation such as visible light is more ideal for triggering such transformations. One way of achieving this is by introducing low lying metal-to-ligand charge transfer (MLCT) states of transition metal complexes, often significantly perturbing the photoisomerization efficiency of such systems. − Notably, most examples displaying visible light induced olefin isomerization are limited to mononuclear transition metal complexes, while di- or multinuclear complexes are less common. − Herein, we report new bpe linked triarylboron-functionalized N^C chelate dinuclear Pt­(II) complexes and their trans – cis isomerism phenomenon, as shown in Chart . The impact of the triarylboron unit on the photophysical properties of the dinuclear Pt­(II) complexes has been examined, and the details are presented herein.…”