Photochromic materials

Maeda, Hiroaki; Nishikawa, Michihiro; Sakamoto, Ryota; Nishihara, Hiroshi

doi:10.1016/b978-0-12-823144-9.00089-3

“…Therefore, we explored the synthesis and photoisomerization properties of structurally diverse heterocycle‐based chelating ligands functionalized with 4‐phenylazopyridine and phenylazo‐3,5‐dimethylpyrazole photoswitches. We have also observed only a few reports on ligand frameworks containing multiple units of photochromes [2a,3b] . Indeed, the presence of multiple photoresponsive units in the ligand framework maximizes the light‐triggered isomerization‐related changes and their properties.…”

Section: Introductionmentioning

confidence: 97%

“…Indeed, the presence of multiple photoresponsive units in the ligand framework maximizes the light‐triggered isomerization‐related changes and their properties. However, the photoisomerization behavior of such systems is complex and susceptible to minor differences in structural features, and photoswitchable units, etc [2a,3b] . This inspired us to design and synthesize structurally diverse photoresponsive ligands, which contain more than one photochrome per unit and study their properties.…”

Section: Introductionmentioning

confidence: 99%

Photoswitchable Azoheteroarene‐Based Chelating Ligands: Light Modulation of Properties, Aqueous Solubility and Catalysis

Gupta,

Gaur,

Kaur

et al. 2023

Chemistry A European J

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We report the design and synthesis of eight photoswitchable phenylazopyridine‐ and phenylazopyrazole‐based molecular systems as light‐controllable chelation‐type ligands. Besides the studies on fundamental photoisomerization behaviour, the ligands were also screened for light‐tuneable properties such as photochromism, phase transition, and solubility especially in the aqueous medium. This investigation demonstrates how the modulation of aqueous solubility can be achieved through photoisomerization and can further be utilized toward controlling the amount of catalytically active Cu(I) species in the homogeneous aqueous conditions. Through this approach, light control over the catalytic activity was achieved for Cu‐catalyzed azide‐alkyne cycloaddition (CuAAC) reactions, along with a partial recovery of the catalytically active species.

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Visible‐Light‐Triggered Photoswitching of Diphosphene Complexes

Taube,

Fidelius,

Schwedtmann

et al. 2023

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Although diphosphene transition metal complexes are known to undergo E to Z isomerization upon irradiation with UV light, their potential for photoswitching has remained poorly explored. In this study, we present diphosphene complexes capable of reversible photoisomerizations through haptotropic rearrangements. The compounds [(2‐κ2P,κ6C)Mo(CO)2][OTf] (3a[OTf]), [(2‐κ2P,κ6C)Fe(CO)][OTf] (3b[OTf]), and [(2‐κ2P)Fe(CO)4][OTf] (4[OTf]) were prepared using the triflate salt [(LC)P=P(Dipp)]OTf (2[OTf) as a precursor (LC = 4,5‐dichloro‐1,3‐bis(2,6‐diisiopropylphenyl)‐imidazolin‐2‐yl; Dipp = 2,6‐diisiopropylphenyl, OTf = triflate). Upon exposure to blue or UV light (λ = 400 nm, 470 nm), the initially red‐colored ƞ2‐diphosphene complexes 3a,b[OTf] readily undergo isomerization to form blue‐colored ƞ1‐complexes [(2‐κ1P,κ6C)M(CO)n][OTf] (5a,b[OTf]; a: M = Mo, n = 2; b: M = Fe, n = 1). This haptotropic rearrangement is reversible, and the (κ2P,κ6C)‐coordination mode gradually reverts back upon dissolution in coordinating solvents or more rapidly upon exposure to yellow or red irradiation (λ = 590 nm, 630 nm). The electronic reasons for the reversible visible‐light‐induced photoswitching observed for 3a,b[OTf] are elucidated by DFT calculations. These calculations indicate that the photochromic isomerization originates from the S1 excited state and proceeds through a conical intersection.

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Visible‐Light‐Triggered Photoswitching of Diphosphene Complexes

Taube,

Fidelius,

Schwedtmann

et al. 2023

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Although diphosphene transition metal complexes are known to undergo E to Z isomerization upon irradiation with UV light, their potential for photoswitching has remained poorly explored. In this study, we present diphosphene complexes capable of reversible photoisomerizations through haptotropic rearrangements. The compounds [(2‐κ2P,κ6C)Mo(CO)2][OTf] (3a[OTf]), [(2‐κ2P,κ6C)Fe(CO)][OTf] (3b[OTf]), and [(2‐κ2P)Fe(CO)4][OTf] (4[OTf]) were prepared using the triflate salt [(LC)P=P(Dipp)]OTf (2[OTf) as a precursor (LC = 4,5‐dichloro‐1,3‐bis(2,6‐diisiopropylphenyl)‐imidazolin‐2‐yl; Dipp = 2,6‐diisiopropylphenyl, OTf = triflate). Upon exposure to blue or UV light (λ = 400 nm, 470 nm), the initially red‐colored ƞ2‐diphosphene complexes 3a,b[OTf] readily undergo isomerization to form blue‐colored ƞ1‐complexes [(2‐κ1P,κ6C)M(CO)n][OTf] (5a,b[OTf]; a: M = Mo, n = 2; b: M = Fe, n = 1). This haptotropic rearrangement is reversible, and the (κ2P,κ6C)‐coordination mode gradually reverts back upon dissolution in coordinating solvents or more rapidly upon exposure to yellow or red irradiation (λ = 590 nm, 630 nm). The electronic reasons for the reversible visible‐light‐induced photoswitching observed for 3a,b[OTf] are elucidated by DFT calculations. These calculations indicate that the photochromic isomerization originates from the S1 excited state and proceeds through a conical intersection.

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Photochromic materials

Cited by 4 publications

References 412 publications

Photoswitchable Azoheteroarene‐Based Chelating Ligands: Light Modulation of Properties, Aqueous Solubility and Catalysis

Photoswitchable Azoheteroarene‐Based Chelating Ligands: Light Modulation of Properties, Aqueous Solubility and Catalysis

Visible‐Light‐Triggered Photoswitching of Diphosphene Complexes

Visible‐Light‐Triggered Photoswitching of Diphosphene Complexes

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