Bond Angle Versus Torsional Deformation in an Overcrowded Alkene: 9-(2,2,2-Triphenylethylidene)fluorene

Bell, Thomas W.; Catalano, Vincent J.; Drew, Michael G. B.; Phillips, Daniel J.

doi:10.1002/1521-3765(20021104)8:21<5001::aid-chem5001>3.0.co;2-a

Cited by 11 publications

(10 citation statements)

References 12 publications

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“…The configuration of this intermediate was assigned by X‐ray crystallography; the solid‐state structure of Z ‐9 is displayed in Figure . As observed for other 9‐bromomethylenefluorenes, steric compression by the bromine atom causes the 1 H NMR resonance of the aromatic proton in the 1‐position of the fluorene ring system to shift downfield ( δ =8.43 ppm for Z ‐ 9 ). The remaining 1 H NMR signals of Z ‐ 9 were assigned by 2D‐NMR spectroscopy.…”

Section: Resultsmentioning

confidence: 63%

“…Of particular interest are the bond angles about the photoactive, exocyclic C=C double bond. The previously reported structure of TEF showed an unusual distribution of strain for an overcrowded alkene. No significant twisting of the C=C double bond was observed.…”

Section: Discussionmentioning

confidence: 64%

“…Table gives selected bond angle data for the crystallographically determined structures of three of the key target compounds, the Z nitro compound ( Z ‐NTEF) and both stereoisomers of the iodo analogue ( E ‐ITEF and Z ‐ITEF). Also provided in Table are corresponding data for intermediates Z ‐ 10 , and Z ‐ 11 , as well as for the unsubstituted parent compound TEF (9‐(2,2,2‐triphenylethylidene)fluorene) …”

Section: Discussionmentioning

confidence: 99%

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Synthesis and Photoisomerization of Substituted Dibenzofulvene Molecular Rotors

Everhart

Jayasundara

Kim

et al. 2016

Chemistry A European J

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The synthesis, spectral and structural characterization, and photoisomerization of a family of 2-substituted dibenzofulvene molecular actuators based on (2,2,2-triphenylethylidene)fluorene (TEF) are reported. The 2-substituted species investigated are nitro (NTEF), cyano (CTEF), and iodo (ITEF). X-ray structures of these three compounds and three intermediates were determined to assign alkene configuration and investigate the effects of the 2-substituents on steric gearing. The addition-elimination reaction of Z-9 with trityl anion to form Z-10 proceeded with complete retention of configuration. Rates of photoisomerization were measured at irradiation wavelengths between 266-355 nm in acetonitrile/dioxane solutions at room temperature. Photoisomerization quantum yields (φ) were calculated by means of a mathematical model that accounts for a certain degree of photodecomposition in the cases of CTEF and ITEF. Quantum yields vary significantly with substituent, having maximum values of φ=0.26 for NTEF, 0.39 for CTEF, and 0.50 for ITEF. NTEF is photochemically robust and has a large quantum yield for photoisomerization in the near-UV, making it a particularly promising drive rotor moiety for light-powered molecular devices.

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Section: Resultsmentioning

confidence: 63%

Section: Discussionmentioning

confidence: 64%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Synthesis and Photoisomerization of Substituted Dibenzofulvene Molecular Rotors

Everhart

Jayasundara

Kim

et al. 2016

Chemistry A European J

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“…The use of light stimulation has many advantages in terms of a fast response with light excitation and the possibility of a fine resolution. The overcrowded alkene, which can be driven by light, has been extensively studied as light-driven molecular motors and switches . Several functional moieties have been introduced into the overcrowded alkene systems to realize special functions, such as the alterations of aggregation, magnetic interaction, and even in situ switching of the chiral preference of a catalytic system .…”

Section: Introductionmentioning

confidence: 99%

“…Several functional moieties have been introduced into the overcrowded alkene systems to realize special functions, such as the alterations of aggregation, magnetic interaction, and even in situ switching of the chiral preference of a catalytic system . The overcrowded alkene system has potential to construct versatile molecular machines that can perform specific mechanical motions due to its favorable photostationary state and remarkable structural changes caused by trans – cis isomerizations of the central double bond . In this paper, we report a [3]rotaxane, with two [2]rotaxane arms separated by an overcrowded alkene switch, to perform the clamlike motion and mimic the action of dumbbell exercise.…”

Section: Introductionmentioning

confidence: 99%

Photodriven Clamlike Motion in a [3]Rotaxane with Two [2]Rotaxane Arms Bridged by an Overcrowded Alkene Switch

Zhou

Guo

2012

J. Org. Chem.

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A [3]rotaxane with two [2]rotaxane arms bridged by an overcrowded alkene switch has been constructed to perform the clamlike motion in response to light stimulus. We demonstrated that this [3]rotaxane can undergo reversible conformational changes caused by the trans-cis isomerizations of the central double bond with a favorable photostationary state (up to 90% conversion). It has been shown that the clamlike motion causes remarkable UV-vis and fluorescence spectral changes, allowing it to behave as a reversible optical molecular switch.

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Highly Enantioselective Biphasic Iminium‐Catalyzed Epoxidation of Alkenes. On the Importance of the Counterion and of N(sp²)C(sp³) Rotamers

2009

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Diastereomeric biaryliminium cations made of an (Ra)-5,5 ',6,6',7,7',8,8'-octahydrobinaphthyl core and exocyclic appendages derived from (S)-or (R)-3,3-dimethylbutan-2-amine are effective asymmetric epoxidation catalysts for unfunctionalized alkenes. Herein, we report that the negative counterion of the iminium salts has to be chosen wisely. While the hexafluoroantimonate anion [SbF 6À ] is optimal for reliable results, one has to be careful about other anions and tetraphenylborate [BPh 4 À ] in particular. We also detail that the so far unexplained "lack" of stereochemical control from the chiral exocyclic appendage in this type of catalysts is due to

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Bond Angle Versus Torsional Deformation in an Overcrowded Alkene: 9-(2,2,2-Triphenylethylidene)fluorene

Cited by 11 publications

References 12 publications

Synthesis and Photoisomerization of Substituted Dibenzofulvene Molecular Rotors

Synthesis and Photoisomerization of Substituted Dibenzofulvene Molecular Rotors

Photodriven Clamlike Motion in a [3]Rotaxane with Two [2]Rotaxane Arms Bridged by an Overcrowded Alkene Switch

Highly Enantioselective Biphasic Iminium‐Catalyzed Epoxidation of Alkenes. On the Importance of the Counterion and of N(sp²)C(sp³) Rotamers

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Bond Angle Versus Torsional Deformation in an Overcrowded Alkene: 9-(2,2,2-Triphenylethylidene)fluorene

Cited by 11 publications

References 12 publications

Synthesis and Photoisomerization of Substituted Dibenzofulvene Molecular Rotors

Synthesis and Photoisomerization of Substituted Dibenzofulvene Molecular Rotors

Photodriven Clamlike Motion in a [3]Rotaxane with Two [2]Rotaxane Arms Bridged by an Overcrowded Alkene Switch

Highly Enantioselective Biphasic Iminium‐Catalyzed Epoxidation of Alkenes. On the Importance of the Counterion and of N(sp2)C(sp3) Rotamers

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Highly Enantioselective Biphasic Iminium‐Catalyzed Epoxidation of Alkenes. On the Importance of the Counterion and of N(sp²)C(sp³) Rotamers