A gas electron diffraction study of the molecular structure of trans-azobenzene

Trætteberg, M.; Hillmo, I.; Hagen, Kolbjørn

doi:10.1016/0022-2860(77)85093-x

Cited by 96 publications

(35 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, we find the NN and CN bond lengths to be 1.27 Å and 1.42 Å for trans and 1.25 Å and 1.43 Å for cis. All these values agree well with previous DFT 37 and experimental 38,39 calculations and indicate that our functional provides accurate molecular geometries. After binding to graphene, the trans dihedral CNNC and CCNN angles change only slightly to 179.3 • and 1.4 • , respectively.…”

Section: A Azobenzene Absorption On Graphenesupporting

confidence: 90%

First-principles study of multicontrol graphene doping using light-switching molecules

Trinastic

Cheng

2014

Phys. Rev. B

View full text Add to dashboard Cite

The high carrier mobility in graphene promises its utility in electronics applications. Azobenzene is a widely studied organic molecule for switchable optoelectronic devices that can be synthesized with a wide variety of ligands and deposited on graphene. Using first-principles calculations, we investigate graphene doping by physisorbed azobenzene molecules with various electron-donating and −accepting ligands. We confirm previous experimental results that demonstrate greater pdoping of graphene for the trans compared to cis configuration when using a SO3 electron-accepting ligand, however we find that NO2 ligands maximize the p-doping difference between isomers. We also examine how these doping effects change when the graphene monolayer is supported on a silica substrate. We then extend these findings by examining the doping effects of an applied electrical bias and mechanical strain to the graphene, which lead to changes in doping for both the trans and cis isomers. These results demonstrate a new type of multi-control device combining light, electric field, and strain to change carrier concentration in graphene.

show abstract

Section: A Azobenzene Absorption On Graphenesupporting

confidence: 90%

First-principles study of multicontrol graphene doping using light-switching molecules

Trinastic

Cheng

2014

Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…Experimentally, early GED experiments suggested a non-planar minimum energy structure (with either C 2 or C i symmetry), with the phenyl groups rotated out of the CNNC plane. 100 However, a more recent GED study of E-AB yielded a C 2h planar structure for the compound, in agreement with the most recent theoretical results. 95 The absence of experimental reports on the microwave spectra of azobenzene should be related to the fact that the total molecular dipole moment of E-AB is equal to zero (for both the C i and C 2h symmetries).…”

Section: Vibrational Spectrasupporting

confidence: 84%

“…Then, vibrational spectroscopy experiments on this molecule appear as a valuable experimental tool for probing its molecular geometry. Also note that in the previously reported experimental studies on crystalline AB and for the compound in solution, [100][101][102][103][104][105] the molecular geometry may suffer significant distortions resulting from the effects of the environment. On the other hand, in the matrix isolation technique the effects of environment are minimized.…”

Section: Vibrational Spectramentioning

confidence: 99%

Structural and spectroscopic characterization of E- and Z-isomers of azobenzene

Duarte

Fausto

Reva

2014

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

Monomers of azobenzene were isolated in argon matrices at 15 K and characterized by infrared spectroscopy and theoretical calculations. When the equilibrium vapors existing over the azobenzene crystals at room temperature were trapped in the matrix, only the thermodynamically most stable E-azobenzene was detected. In an attempt to convert E-azobenzene into the Z isomer, the matrix-isolated E-monomers were irradiated either by broad-band or narrow-band UV-visible light of different wavelengths, in the 600-200 nm range. However, no E-to-Z transformation was observed under these conditions. In an alternative experiment, E-azobenzene was irradiated by UV-visible broad-band light in the gas phase prior to trapping in a matrix. In this case, the E-to-Z photoisomerization occurred, and both E- and Z-azobenzene monomers were detected in the matrix sample. Subsequent irradiation of the matrix with narrow-band tunable visible or UV light (λ < 550 nm) resulted in back conversion of Z-azobenzene into the E-form. The observed photoinduced E-to-Z isomerizations allowed for the reliable vibrational characterization of both azobenzene isomers. The two-dimensional potential energy surfaces of Z- and E-azobenzene were explored as functions of the torsional movement of the two phenyl rings. They exhibit large flat areas around the minima, for both isomers, allowing for large-amplitude zero-point torsional vibrations. For the Z-form, these vibrations were found to be responsible for significant changes in the equilibrium NN bond length (up to 0.3 pm). This also allowed to explain the experimentally observed frequency smearing of the N=N stretching vibration in this isomer.

show abstract

“…Since transmission mode FTIR spectroscopy measures the dipole moment projected on to the substrate, this behavior corresponded to the shift of the aromatic plane toward the substrate by isomerization. Various molecular orbital calculations and experimental evidence , have determined the flip angle, α, shown in Figure to be <60°. As a result, the pentyl functional group is likely far below the film–air interface after isomerization to the cis -form.…”

Section: Resultsmentioning

confidence: 99%

Marangoni Instability Driven Surface Relief Grating in an Azobenzene-Containing Polymer Film

Kim

Wistrom

et al. 2016

Macromolecules

View full text Add to dashboard Cite

The Marangoni effect describes fluid flow near an interface in response to a surface tension gradient. Here, we demonstrate that the Marangoni effect is the underlying mechanism for flow driven feature formation in an azobenzene-containing polymer film; features formed in azobenzene-containing polymers are often referred to as surface relief gratings or SRGs. An amorphous poly(4-(acryloyloxyhexyloxy)-4′pentylazobenzene) was synthesized and studied as a model polymer.To isolate the surface tension driven flow from the surface tension pattern inscription step, the surface tension gradient was preprogrammed via photoisomerization of azobenzene in a glassy polymer film without forming topographical features. Subsequently, the latent image was developed in the absence of light by annealing above the glass transition temperature where the polymer is a liquid. The polymer flow direction was controlled with precision by inducing different surface tension changes in the exposed regions, in accordance with expectation based on the Marangoni effect. Finally, the height of the formed features decreased upon extensive thermal annealing due to capillary leveling with two distinct rates. A scaling analysis revealed that those rates originated from dissimilar capillary velocities associated with different azobenzene isomers.

show abstract

A gas electron diffraction study of the molecular structure of trans-azobenzene

Cited by 96 publications

References 14 publications

First-principles study of multicontrol graphene doping using light-switching molecules

First-principles study of multicontrol graphene doping using light-switching molecules

Structural and spectroscopic characterization of E- and Z-isomers of azobenzene

Marangoni Instability Driven Surface Relief Grating in an Azobenzene-Containing Polymer Film

Contact Info

Product

Resources

About