Photochemical one-way adiabatic isomerization of aromatic olefins

Arai, Tatsuo; Tokumaru, Katsumi

doi:10.1021/cr00017a002

Cited by 266 publications

(181 citation statements)

References 26 publications

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“…[4] Chemical design and synthesis allow access to functional molecules offering great diversity, better structural and dynamic control, as well as feasibility of observation and analysis. Artificial molecular devices have been developed by using mainly organic components which exhibit reversible structural changes driven by external stimuli including light, [5] heat and light, [6] pH control (acid/base control), [7] Abstract: Ruthenium(II)-TPA-diimine complexes,…”

Section: Introductionmentioning

confidence: 99%

Ruthenium(II) Pyridylamine Complexes with Diimine Ligands Showing Reversible Photochemical and Thermal Structural Change

Kojima

Morimoto

Sakamoto

et al. 2008

Chemistry A European J

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Ruthenium(II)-TPA-diimine complexes, [Ru(TPA)(diimine)]2+ (TPA=tris(2-pyridylmethyl)amine; diimine=2,2'-bipyridine (bpy), 2,2'-bipyrimidine (bpm), 1,10-phenanthroline (phen)) were synthesized and characterized by spectroscopic and crystallographic methods. Their crystal structures demonstrate severe steric hindrance between the TPA and diimine ligands. They exhibit drastic structural changes on heating and photoirradiation at their MLCT bands, which involve partial dissociation of the tetradentate TPA ligand to exhibit a facially tridentate mode accompanied by structural change and solvent coordination to give [Ru(TPA)(diimine)(solvent)]2+ (solvent=acetonitrile, pyridine). The incoming solvent molecules are required to have pi-acceptor character, since sigma-donating solvent molecules do not coordinate. The thermal process is irreversible dissociation to give the solvent-bound complexes, which takes place by an interchange associative mechanism with large negative activation entropies. The photochemical process is a reversible reaction reaching a photostationary state, probably by a dissociative mechanism involving a five-coordinate intermediate to afford the same product as obtained in the thermal reaction. Quantum yields of the forward reactions to give dissociated products were lower than those of the backward reactions to recover the starting complexes. In the photochemical process, the conversions of the forward and backward reactions depend on the absorption coefficients of the starting materials and those of the products at certain wavelength, as well as the quantum yields of those reactions. The reversibility of the motions can be regulated by heating and by photoirradiation at certain wavelength for the recovery process. In the bpm system, we could achieve about 90 % recovery in thermal/photochemical structural interconversion.

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Section: Introductionmentioning

confidence: 99%

Ruthenium(II) Pyridylamine Complexes with Diimine Ligands Showing Reversible Photochemical and Thermal Structural Change

Kojima

Morimoto

Sakamoto

et al. 2008

Chemistry A European J

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“…Photoisomerization [22,23] of dihydronaphthalene derivative 3c was therefore investigated as a model reaction with the aim to improve the E/Z ratio. The photoisomerization of the 1-alkoxy-1,3-diene 3c was carried out in dry DMSO using a very dilute sample (1 mM) and focused 280 nm irradiation (l max for cis-3c ¼ 281.5 nm).…”

Section: Photochemistrymentioning

confidence: 99%

Terminal Heck Vinylations of Chelating Vinyl Ethers

et al. 2004

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Terminal chelation-controlled Heck vinylations of electron-rich amino-functionalized vinyl ethers were performed with high regioselectivity furnishing moderate to good isolated yields of the corresponding 1-alkoxy-1,3-butadienes. DFT calculations support an amine-palladium(II) coordination strength reactivity/selectivity rationale, where the dimethylamino group was the preferred metal presenting functionality. Controlled microwave heating effectively accelerated these palladium-catalyzed reactions and full conversion could be achieved within 30 minutes.Subsequent Diels-Alder reactions with dimethyl acetylenedicarboxylate under microwave irradiation resulted exclusively in partly aromatized bi-and tricyclic compounds by elimination of the aminoalkoxy group. Thus, the selected dimethylamino auxiliary both controlled the regiochemistry in the palladiumcatalyzed vinylation and was easily displaced in the aromatization process.

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“…34 This twisted state does not necessarily have the same geometry as that reached on the singlet excited state surface, and in principle could have a different preference for relaxing toward the unstable or the stable form (Scheme 3). 35 The photostationary state that is obtained depends on the efficiency of the excitation and the decay ratio. If there is a large energy difference between the triplet excited state of the stable and the unstable forms, the energy transfer efficiency to both forms will be different.…”

Section: ■ Introductionmentioning

confidence: 99%