The novel use of NMR spectroscopy with in situ laser irradiation to study azo photoisomerisation

Tait, Katrina M.; Parkinson, John; Bates, Simon; Ebenezer, Warren J.; Jones, Anita C.

doi:10.1016/s1010-6030(02)00347-7

Cited by 60 publications

(46 citation statements)

References 16 publications

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“…Usually UV/visible spectroscopy is used to determine the fraction of azobenzene in the two states (22). Here we used a novel approach of NMR spectroscopy to distinguish between the two isomers (23). NMR was used to determine the ratio of cis-to trans-MAG-1 conjugated to 2-mercaptoethanol between 340 and 500 nm, at 20 nm increments (Fig.…”

Section: Resultsmentioning

confidence: 99%

Mechanisms of photoswitch conjugation and light activation of an ionotropic glutamate receptor

Gorostiza

Volgraf²,

Numano

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

165

228

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The analysis of cell signaling requires the rapid and selective manipulation of protein function. We have synthesized photoswitches that covalently modify target proteins and reversibly present and withdraw a ligand from its binding site due to photoisomerization of an azobenzene linker. We describe here the properties of a glutamate photoswitch that controls an ion channel in cells. Affinity labeling and geometric constraints ensure that the photoswitch controls only the targeted channel, and enables spatial patterns of light to favor labeling in one location over another. Photoswitching to the activating state places a tethered glutamate at a high (millimolar) effective local concentration near the binding site. The fraction of active channels can be set in an analog manner by altering the photostationary state with different wavelengths. The bistable photoswitch can be turned on with millisecond-long pulses at one wavelength, remain on in the dark for minutes, and turned off with millisecond long pulses at the other wavelength, yielding sustained activation with minimal irradiation. The system provides rapid, reversible remote control of protein function that is selective without orthogonal chemistry.azobenzene ͉ ion channel ͉ photoisomerization ͉ optical switch ͉ remote control M uch progress has been made recently in the real-time noninvasive detection of protein function (1), but the development of approaches for remote protein manipulation within the complex environment of the cell has lagged behind. A major advance has been the development of photolysable cages for soluble ligands (2). The caged ligand is allowed to slowly diffuse into tissue in its inert form, and a powerful light flash cleaves a photolabile protecting group, releasing the active ligand rapidly (within microseconds) (3,4). This provides fast on-rates that are complemented with reasonably fast off-rates, which depend on native binding affinity, diffusion, sequestration, and breakdown. However, because native ligands often act on multiple proteins, this approach has limited selectivity. Introducing foreign receptors that bind nonnative ligands, on the other hand, enables cellular stimulation without the activation of endogenous proteins (5, 6) and can even be used in a photolysable form for rapid release (7).Photoisomerizable moieties have also found use in the remote and selective control of native protein function. In this case, reversible photochemically induced changes in the shape or electronic character of functionally important amino acids have been used to control the function of proteins in response to light (8-10) or to alter the backbone structure of peptides (11), thereby controlling their interaction with other biological macromolecules (12). In an alternative strategy, photoisomerization of a tethered ligand can be used to reversibly present, and withdraw, a ligand from a binding site. To date, several ion channel photoswitches have been reported wherein a ligand is tethered to the channel via a linker containing a photoisom...

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Section: Resultsmentioning

confidence: 99%

Mechanisms of photoswitch conjugation and light activation of an ionotropic glutamate receptor

Gorostiza

Volgraf²,

Numano

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

165

228

View full text Add to dashboard Cite

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“…1 H-NMR-spectroscopy allows to distinguish between the trans-and cis-form of azo-compounds, because their different spatial arrangements result in distinguishable chemical shifts of their protons. [49] Thus, the highest attainable ratio of the cis-to trans-form in the photostationary state for our experimental set-up could be estimated from the integrals of the corresponding protons in the 1 H-NMR-spectra. In spite of the experimental uncertainties arising from the thermal back reaction and the required preparation of the NMR sample in the photostationary state, very similar values for the maximum of the cis to trans ratio in solution of 0.88 AE 0.06 for AZO1 and of 0.89 AE 0.05 for AZO2 have been determined from their 1 H NMR integrals.…”

Section: Photochemical Characterizationmentioning

confidence: 99%

Single Component Self‐Assembled Monolayers of Aromatic Azo‐Biphenyl: Influence of the Packing Tightness on the SAM Structure and Light‐Induced Molecular Movements

Elbing

Błaszczyk

Hänisch³

et al. 2008

Adv Funct Materials

106

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Aiming at modulating the packing density within functional self‐assembled monolayers (SAMs), two azo‐biphenyl derivatives AZO1 and AZO2 comprising a terminal sulfur anchor group have been designed and synthesized. While AZO1 allows for a coplanar arrangement of both biphenyl subunits, additional steric repulsion due to two methyl side groups attached to the footing biphenyl of AZO2 results in an increased intermolecular distance within the SAM, providing additional free volume. SAMs of both derivatives on gold and platinum substrates have been formed and thoroughly investigated by photoelectron (XPS) and near‐edge absorption fine structure (NEXAFS) spectroscopy as well as cyclic voltammetry and scanning tunneling microscopy. These measurements confirmed the formation of tightly packed SAMs for AZO1, while AZO2 formed SAMs consisting of less organized and more loosely packed molecules. Optical investigations of both azo derivatives in solution as well as their SAMs displayed efficient photoisomerization in solution and in SAMs. Comparable maximal cis/trans ratios of ca. 0.9 have been observed in all cases upon irradiation at λ = 370 and 360 nm for AZO1 and AZO2, respectively. The thermally induced cis → trans back reaction on AZO1 was found to be slower by a factor of 3 in SAMs as compared to solution, while AZO2 displayed comparable rates of the back reaction in both environments. This behavior can be explained by the different nature of molecular isomerization in the two SAM systems: whereas the isomerization in AZO1 SAMs takes place in a highly coordinated, collective way and involves many adjacent molecules, AZO2 species behave rather individually even packed in SAMs, such that their isomerization process is similar in SAMs and in solutions.

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“…13 Azobenzene derivatives are the molecules of choice since their cis/trans isomerisation is controlled by light and this class of photochromic compound has been thoroughly investigated. [30][31][32] The thermodynamically stable trans-isomer can be switched by irradiation with UV light (λ = 365 nm) to the cis-isomer. The back switching can be achieved by irradiation with visible light (λ = 455 nm) or thermally.…”

Section: Introductionmentioning

confidence: 99%

Introducing a photo-switchable azo-functionality inside Cr-MIL-101-NH2 by covalent post-synthetic modification

et al. 2012

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For the first time an azo functionality was covalently introduced into a MOF by post-synthetic modification. The reaction of Cr-MIL-101-NH 2 with p-phenylazobenzoylchloride (1) and 4-( phenylazo)-phenylisocyanate (2) as the reactants led to the compounds Cr-MIL-101_amide and Cr-MIL-101_urea, with the azo groups protruding into the mesoporous cages. XRPD and N 2 sorption measurements confirm the intactness of the framework and the successful covalent modification was proven by IR-and NMRspectroscopy. Furthermore, cis/trans isomerisation upon irradiation with light was demonstrated by UV/ Vis spectroscopy. More distinct changes in the UV/Vis spectra were observed for Cr-MIL-101_amide compared to Cr-MIL-101_urea, while the degree of functionalization, i.e. the number of reacted NH 2 -groups, seems to have a less pronounced effect. The variation of the sorption properties due to the cis/trans isomerisation was proven by methane adsorption measurements.

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The novel use of NMR spectroscopy with in situ laser irradiation to study azo photoisomerisation

Cited by 60 publications

References 16 publications

Mechanisms of photoswitch conjugation and light activation of an ionotropic glutamate receptor

Mechanisms of photoswitch conjugation and light activation of an ionotropic glutamate receptor

Single Component Self‐Assembled Monolayers of Aromatic Azo‐Biphenyl: Influence of the Packing Tightness on the SAM Structure and Light‐Induced Molecular Movements

Introducing a photo-switchable azo-functionality inside Cr-MIL-101-NH2 by covalent post-synthetic modification

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