Interfacial effects on excited-state potential energy surfaces. Interrelationship between photoreactivity and surface properties

Collins‐Gold, L. C.; Möbius, Dietmar; Whitten, David G.

doi:10.1021/la00068a014

Cited by 22 publications

(10 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The increase in absorbance of the cis ‐isomer at 450 nm upon irradiation at 510 nm is expressed by the ratio A 450 (photostationary state)/A 450 (dark) and is plotted as a function of x d , as shown in Figure 6. These results indicate that trans–cis photoisomerization is significantly suppressed going from a dilute isotropic solution to a more concentrated anisotropic solution, which is consistent with previous studies of 6,6′‐dialkoxythioindigo photoisomerization in other organized multilayer assemblies 28…”

Section: Introductionsupporting

confidence: 92%

Photoswitching of ferroelectric liquid crystals using chiral thioindigo dopants: The development of a photochemical switch hitter

Lemieux¹

2004

The Chemical Record

View full text Add to dashboard Cite

By virtue of its spontaneous polarization (PS), a ferroelectric SmC* liquid crystal can be switched between two states corresponding to opposite molecular tilt orientations using an electric field, thus producing an ON-OFF light shutter between crossed polarizers. Considerable efforts have been made over the past decade to develop photonic FLC light shutters because of their potential uses in dynamic holography and optical data storage. The ON-OFF switching of a FLC light shutter can be triggered by light via a photoinversion of PS using a photochromic dopant. The spontaneous polarization is a chiral bulk property that can be left-handed (negative) or right-handed (positive), depending on the absolute configuration of the chiral component of the SmC* phase. In the approach described herein, the magnitude of PS is modulated via the photoisomerization of a chiral thioindigo dopant that undergoes a large increase in transverse dipole moment upon trans-cis photoisomerization. The sign of PS is photoinverted using an "ambidextrous" thioindigo dopant containing a chiral 2-octyloxy side chain that is coupled to the thioindigo core and induces a positive PS, and a chiral 2,3-difluorooctyloxy side chain that is decoupled from the core and induces a negative PS. In the trans form, the 2,3-difluorooctyloxy side chain predominates and the net PS induced by the dopant is negative. However, upon trans-cis-photoisomerization, the increase in transverse dipole moment of the 2-octyloxy/thioindigo unit raises its induced PS over that of the decoupled 2,3-difluorooctyloxy side chain, and thus inverts the net sign of PS induced by the dopant from negative to positive.

show abstract

Section: Introductionsupporting

confidence: 92%

Photoswitching of ferroelectric liquid crystals using chiral thioindigo dopants: The development of a photochemical switch hitter

Lemieux¹

2004

The Chemical Record

View full text Add to dashboard Cite

show abstract

“…11,12 Additionally, thioindigo is a photochromic compound, undergoing photoinduced trans−cis isomerization. The photoinduced isomerization has been studied in solution, 13−15 monolayers, 16 and thin films 17,18 and on solid support. 19 The application of the trans− cis isomerization in liquid crystals 20,21 and ion transport 22 has also been investigated.…”

Section: ■ Introductionmentioning

confidence: 99%

Synthesis and Photophysics of Thioindigo Diimines and Related Compounds

et al. 2014

View full text Add to dashboard Cite

We report the synthesis and comprehensive characterization of diamine and diimine derivatives of the fluorescent compound thioindigo. Diamines 1 were obtained by metal-mediated amine condensation reaction with thioindigo. Oxidation of the products of the coupling reaction provided the diimines 2. X-ray crystal structures, cyclic voltammetry, and spectral and photophysical data of the compounds are presented. X-ray crystal structures demonstrate a planar structure for the diimine derivatives and a twisted conformation for the diamines. The diamine compounds 1 absorb in the UV (λmax 324-328 nm), significantly blue-shifted from the absorption spectrum of thioindigo. Diamines 1 exhibit moderate fluorescence (ΦF = 0.25, 0.045). A transient triplet state is observed in laser flash photolysis (LFP) experiments of 1, with lifetimes 1 order of magnitude longer than those of thioindigo. The diimine compounds 2 absorb at longer wavelengths (λmax 495-510 nm) than the diamines but are still slightly blue-shifted from thioindigo, with molar extinction coefficients 17-70% higher compared to thioindigo. The diimine compounds are not emissive, and LFP studies indicate transient species with microsecond lifetimes. Quenching experiments and transient absorption spectra are consistent with trans-cis isomerization.

show abstract

“…The most prominent photochemical process of these chromophores is the trans − cis isomerization reaction. Isomerization from trans to cis in condensed monolayers was, however, reported to be strongly inhibited since the process requires a large area expansion of the chromophores − (Figure a). Only a few reports have succeeded to demonstrate highly efficient isomerization in a fluid monolayer , or in systems which have some free volume in the chromophore region. , We report herein a novel design of a photochromic amphiphile with an unexpected isomerization behavior in a condensed monolayer and photochemically-induced reversible phase transition and morphological change at the air−water interface.…”

mentioning

confidence: 99%