Photochromism of Dihydroindolizines and Related Systems

Dürr, Heinz

doi:10.1007/0-306-46911-1_7

Cited by 11 publications

(15 citation statements)

References 27 publications

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“…The fourth point is of particular interest: the isomerization was detected by IR spectroscopy. The isomerization read out by nondestructive methods is a topic in recent organic photochromisms which may open the way to the development of practical devices,2d and the present results are the first example of organometallic photochromisms in the solid state detectable by IR light.…”

Section: Discussionmentioning

confidence: 69%

“…The experimental results described above revealed that both the thermal (Δ G ⧧ = 23 kcal/mol) and photochemical (Φ = 0.30) haptotropic rearrangement take place with ease in solution. While photochromism in solution has been widely investigated, photochromism in the solid state has lately attracted attention in relation to studies on molecular switches and crystal engineering. 2d, The possibility of thermally reversible photoisomerization of organometallic compounds was shown by Vollhardt and co-workers, who reported that thermal rearrangement from (μ 2 ,η 1 :η 5 -cyclopentadienyl) 2 Ru 2 (CO) 4 to (μ 2 ,η 5 :η 5 -bicyclopentadienyl)Ru 2 (CO) 4 actually takes place in crystals 3b. However, there has been no preceding paper on the solid state of organometallic compounds showing both the photochemical and thermal processes proceeding.…”

Section: Resultsmentioning

confidence: 99%

“…Reversible structural changes of a single molecule induced by photolysis have the potential to develop underlying principles of molecular switches . Organic photochromic molecules are one successful example of this issue, and a number of studies have been undertaken to date . In contrast, there are only a few organometallic compounds that undergo reversible photoisomerization or thermally reversible photoisomerization between their two possible structural isomers …”

Section: Introductionmentioning

confidence: 99%

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Thermally Reversible Photochemical Haptotropic Rearrangement of Diiron Carbonyl Complexes Bearing a Bridging Acenaphthylene or Aceanthrylene Ligand

et al. 2004

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The haptotropic rearrangement of diiron carbonyl species on the conjugate π-ligand in (µ 2 ,η 3 :η 5 -acenaphthylene)Fe 2 (CO) 5 (1) and its analogue (µ 2 ,η 3 :η 5 -aceanthrylene)Fe 2 (CO) 5 ( 2) is investigated in both solution and solid states. The diiron complexes 1 and 2 have two isomers, and each isomer is isolated and characterized. Isomers 1-A and 2-A are thermodynamically more stable than 1-B and 2-B, respectively (∆G°2 96 ) 2.3 kcal/mol for 1; ∆G°2 96 > 2.3 kcal/mol for 2). The thermodynamically less stable isomers can be prepared photochemically. Interconversions between 1-A and 1-B and between 2-A and 2-B occur both thermally and photochemically. Kinetic studies on the thermal isomerizations in solution provide ∆G q 298 ) 23 ( 1 kcal/mol, ∆H q 298 ) 23 ( 1 kcal/mol, and ∆S q 298 ) 1 ( 4 cal/mol‚deg for the reaction of 1-B to 1-A, and ∆G q 298 ) 26 ( 1 kcal/mol, ∆H q 298 ) 26 ( 1 kcal/mol, and ∆S q 298 ) 0 ( 2 cal/mol‚deg for the reaction of 2-B to 2-A. Photochemical interconversion at λ ) 600 nm provides the isomer ratio of 1-A:1-B ) 9:91 at the photostatic state, and 2-A: 2-B ) 66:34. In both of the isomerization reactions, irradiation with light of shorter wavelength tends to give lower ratios of the thermodynamically less stable isomers. The quantum yields of the isomerization reactions are found to be Φ 1-Af1-B ) 0.30(3), Φ 1-Bf1-A ) 0.09(1), Φ 2-Af2-B ) 0.013(2), and Φ 2-Bf2-A ) 0.009(1). From these experimental data the reaction mechanisms of the thermal and photochemical haptotropic rearrangements are discussed with the aid of EHMO calculations. A single crystal of 1-B converts to a single crystal of 1-A upon heating. A photolysis (5 min by a 500 W xenon lamp)/thermal treatment (10 min at 100 °C) cycle of a KBr pellet containing 1-A or 1-B results in reversible interconversion between 1-A and 1-B in the solid state, which can be monitored by the IR absorption at ν ) 1825 cm -1 . The cycle is repeatable for over 10 times without change in the signal intensity. These results are the first to indicate a possible organometallic photochromism in the solid state detectable by the IR light.

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Section: Discussionmentioning

confidence: 69%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Thermally Reversible Photochemical Haptotropic Rearrangement of Diiron Carbonyl Complexes Bearing a Bridging Acenaphthylene or Aceanthrylene Ligand

et al. 2004

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“…The synthesis and structure of 1 have been reported. 8 The triad consists of a tetraarylporphyrin (P) linked to both a substituted dihydropyrene photochrome (DHP) 35 and a photochrome of the dihydroindolizine family 36 based on pyrrolo[1,2-b]pyridazine (DHI). Because each photochrome may exist in two metastable forms, the triad may assume any of four isomeric structures (ignoring chirality).…”

Section: Introductionmentioning

confidence: 99%

A Molecule-Based 1:2 Digital Demultiplexer

et al. 2007

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A trichromophoric molecule consisting of a porphyrin linked to both a dihydropyrene and a dihydroindolizine-type photochrome, in combination with a third harmonic generating crystal, functions as a 1:2 digital demultiplexer with photonic inputs and outputs. Each of the two photochromes may be cycled independently between two metastable forms, leading to four photoisomers, three of which are used in the demultiplexer. These isomers interact photochemically with the porphyrin in order to yield the demultiplexer function. With the address input (1064 nm light) off, one output of the device (porphyrin fluorescence) tracks the state of the data input (532 nm light).

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“…Macrocyclic ligands have found diverse applications in areas such as phase transfer catalysis, mimicry of enzyme systems, and photoresponsive chromophores etc. [3] When the macrocyclic ligands are bound to polymeric supporting materials, the resulting materials can serve as ion sensing materials, exchange resins, metal ion extraction, or sorbents in chromatography. [4,5] Our group has been continuously focusing on studying some conjugated polymers functionalized with transition metal complexes on the polymer main or side chain.…”

Section: Introductionmentioning

confidence: 99%