Energy Barrier of the cis-trans Isomerization of Difluorodiazine

Binenboym, J.; Burcat, Alexander; Lifshitz, Assa; Shamir, Jacob

doi:10.1021/ja00973a058

Cited by 44 publications

(13 citation statements)

References 3 publications

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“…For the process, two different extreme mechanisms have been proposed ( Fig. 6 ); one involving a simple rotation around the N–N bond [ 45 – 46 ], and another implying an inversion, in-plane lateral shift, through a linear transition state [ 47 – 49 ]. However, recent advances in both gas phase and in solution point out that some mixed mechanisms, such as the concerted inversion or the inversion-assisted rotation, can also be possible pathways for the trans -to- cis photoisomerisation of azobenzenes [ 50 – 52 ].…”

Section: Reviewmentioning

confidence: 99%

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Recent advances towards azobenzene-based light-driven real-time information-transmitting materials

García-Amorós¹,

Velasco²

2012

Beilstein J. Org. Chem.

273

227

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SummaryPhotochromic switches that are able to transmit information in a quick fashion have attracted a growing interest within materials science during the last few decades. Although very fast photochromic switching materials working within hundreds of nanoseconds based on other chromophores, such as spiropyranes, have been successfully achieved, reaching such fast relaxation times for azobenzene-based photochromic molecular switches is still a challenge. This review focuses on the most recent achievements on azobenzene-based light-driven real-time information-transmitting systems. Besides, the main relationships between the structural features of the azo-chromophore and the thermal cis-to-trans isomerisation, the kinetics and mechanism are also discussed as a key point for reaching azoderivatives endowed with fast thermal back-isomerisation kinetics.

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Section: Reviewmentioning

confidence: 99%

“…In this way, the rotation around the N–N bond facilitates the recovery of the more stable trans isomer ( Fig. 14 ) [ 46 , 59 – 61 ].…”

Section: Reviewmentioning

confidence: 99%

Recent advances towards azobenzene-based light-driven real-time information-transmitting materials

García-Amorós¹,

Velasco²

2012

Beilstein J. Org. Chem.

273

227

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“…The mechanism of the thermal cis-trans-isomerization of azobenzenes is still the subject of considerable debate in spite of several investigations carried out on the influence of substi tuen ts , I * * temperature; pre~sure,~ and solven t. 5,6 Two basic mechanisms have been proposed, (a) rotation about the N=N bond through a n-bond rupture and (b) the inversion of one of the nitrogens through an sp-hybridized linear transition state as postulated for imines ' 9 ~3 (Figure 1). The most frequently cited argument in favour of the latter mechanism is probably the fact that activation energies for azobenzene isomerizations are in the order of 85 kJ mol-I or less, while stilbenes, where inversion is not possible, require CQ.…”

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confidence: 99%

Solvent and substituent effects on thermal cis–trans-isomerization of some 4-diethylaminoazobenzenes

Marcandalli¹,

Liddo²,

Fede³

et al. 1984

J. Chem. Soc., Perkin Trans. 2

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Thermal cis-trans-isomerization of some 4'-substituted 4-diethylaminoazobenzenes has been studied. Substitution in the 4'-position leads invariably to an acceleration of the reaction regardless of the nature of the substituent. Logarithms of kinetic constants in various solvents were found to be satisfactorily correlated by the x* scale of solvent polarities both for 4'-nitro-4-diethylaminoazobenzene (I) and for 4'-methoxy-4-diet hylaminoazo benzene (11), excluding amphi protic solvents. Activation parameters (AH* and ASs) were also measured in NN-dimethylformamide. The results support an inversion mechanism rather than a rotational one; in the case of (I), the highlydipolar nature of the transition state can be justified by its stabilization through coplanar resonance structures (impossible in pure rotation).

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“…Nevertheless, this interesting phenomenon could be an argument for a preferably performed thermal cis ‐to‐ trans relaxation mechanism in polar solvents that is discussed in literature. It is reported that the thermal cis ‐to‐ trans relaxation of azobenzene and its derivatives can occur in different ways, for example, by a simple rotation around the N–N bond (Binenboym et al ., ) or by an inversion, in‐plane lateral shift, through a linear transition state (Schulte‐Frohlinde, ). Both mechanisms are extremely solvent dependent, and the inversion mechanism is preferably performed in nonpolar solvents, whereas the rotation mechanism is favored and achieved in very polar solvents (Nishimura et al ., ; Dokic et al ., ).…”

Section: Resultsmentioning

confidence: 99%

The cis‐state of an azobenzene photoswitch is stabilized through specific interactions with a protein surface

Korbus

Backé

Meyer‐Almes

2015

J of Molecular Recognition

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The photocontrol of protein function like enzyme activity has been the subject of many investigations to enable reversible and spatiotemporally defined cascading biochemical reactions without the need for separation in miniaturized and parallelized assay setups for academic and industrial applications. A photoswitchable amidohydrolase variant from Bordetella/Alcaligenes with the longest reported half-life (approximately 30 h) for the cis-state of the attached azobenzene group was chosen as a model system to dissect the underlying mechanism and molecular interactions that caused the enormous deceleration of the thermal cis-to-trans relaxation of the azobenzene photoswitch. A systematic site-directed mutagenesis study on the basis of molecular dynamics simulation data was employed to investigate enzyme and thermal cis-to-trans relaxation kinetics in dependence on selected amino acid substitution, which revealed a prominent histidine and a hydrophobic cluster as molecular determinants for the stabilization of the cis-isomer of the attached azobenzene moiety on the protein surface. The nature of the involved interactions consists of polar, hydrophobic, and possibly aromatic Π-Π contributions. The elucidated principles behind the stabilization of the cis-state of azobenzene derivatives on a protein surface can be exploited to design improved biologically inspired photoswitches. Moreover, the findings open the door to highly long-lived cis-states of azobenzene groups yielding improved bistable photoswitches that can be controlled by single light-pulses rather than continuous irradiation with UV light that causes potential photodamage to the employed biomolecules.

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Energy Barrier of the cis-trans Isomerization of Difluorodiazine

Cited by 44 publications

References 3 publications

Recent advances towards azobenzene-based light-driven real-time information-transmitting materials

Recent advances towards azobenzene-based light-driven real-time information-transmitting materials

Solvent and substituent effects on thermal cis–trans-isomerization of some 4-diethylaminoazobenzenes

The cis‐state of an azobenzene photoswitch is stabilized through specific interactions with a protein surface

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