Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Unusual Blue-Shifted Acid-Responsive Photoluminescence Behavior in 6-Amino-8-cyanobenzo[1,2-b]indolizines.

ABSTRACT: 6-Amino-8-cyanobenzo[1, 2-b]indolizines, a new class of photoluminescent materials, exhibit reversible pH-dependent optical properties characterized by an uncommon and dramatic blue shift in fluorescence emission when protonated. Acid titration and NMR spectroscopy experiments reveal that, rather than the anticipated N-protonation, C-protonation and loss of aromaticity is responsible for the observed photophysical changes. Efficient synthesis from indole-2-carboxaldehydes makes variously substituted versions of this nucleus readily available to tune optical and pH effects.

SUBMITTER: Outlaw VK

PROVIDER: S-EPMC5450917 | biostudies-other | 2016 Jul

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Publications

Unusual Blue-Shifted Acid-Responsive Photoluminescence Behavior in 6-Amino-8-cyanobenzo[1,2-<i>b</i>]indolizines.

Outlaw Victor K VK Zhou Jiawang J Bragg Arthur E AE Townsend Craig A CA

RSC advances 20160603 66

6-Amino-8-cyanobenzo[1, 2-<i>b</i>]indolizines, a new class of photoluminescent materials, exhibit reversible pH-dependent optical properties characterized by an uncommon and dramatic blue shift in fluorescence emission when protonated. Acid titration and NMR spectroscopy experiments reveal that, rather than the anticipated N-protonation, C-protonation and loss of aromaticity is responsible for the observed photophysical changes. Efficient synthesis from indole-2-carboxaldehydes makes variously ...[more]

PMID: 28580137

Similar Datasets

Interconvertible multiple photoluminescence color of a gold(i) isocyanide complex in the solid state: solvent-induced blue-shifted and mechano-responsive red-shifted photoluminescence.

Project description:In this study, we report the interconvertible tetracolored solid state photoluminescence of gold(i) isocyanide complex 2 upon various external stimuli through solid state structural changes. Soaking complex 2 in acetone yields blue emission as a result of the formation of 2B. The subsequent removal of acetone yields 2G through a crystal-to-crystal phase transition, which exhibits green emission. This green-emitting solid 2G exhibits stepwise emission color changes to yellow and then to orange upon mechanical stimulation by ball-milling, which corresponds to the formation of 2Y and 2O, respectively. 2B could be recovered upon the addition of acetone to 2G, 2Y, and 2O. Thus, these four emitting solid states of 2 can be switched between repeatedly by means of acetone soaking and the application of mechanical stimulation. Importantly, single crystal and powder X-ray diffraction (PXRD) studies fully show the detailed molecular arrangements of 2B, 2G, and 2Y. This is the first mechanochromic compound to show interconvertible four color emission in the solid state. We also present the first example of using PXRD measurements and the Rietveld refinement technique for the structural analysis of a ground powder in a luminescence mechanochromism study. We obtained complete molecular-level structural information of the crystalline states of 2B, 2G, 2Y, and 2O. In comparison with a more solvophobic analogue 1, we suggest that the weak interaction of 2 with acetone in the solid state would allow a solvent inclusion/release mode, which is an important structural factor for the unprecedented multicolor mechanochromic luminescence.

| S-EPMC5644376 | biostudies-literature

Blue fluorescent amino acid for biological spectroscopy and microscopy.

Project description:Many fluorescent proteins are currently available for biological spectroscopy and imaging measurements, allowing a wide range of biochemical and biophysical processes and interactions to be studied at various length scales. However, in applications where a small fluorescence reporter is required or desirable, the choice of fluorophores is rather limited. As such, continued effort has been devoted to the development of amino acid-based fluorophores that do not require a specific environment and additional time to mature and have a large fluorescence quantum yield, long fluorescence lifetime, good photostability, and an emission spectrum in the visible region. Herein, we show that a tryptophan analog, 4-cyanotryptophan, which differs from tryptophan by only two atoms, is the smallest fluorescent amino acid that meets these requirements and has great potential to enable in vitro and in vivo spectroscopic and microscopic measurements of proteins.

| S-EPMC5468623 | biostudies-literature

Probing the Aggregation and Signaling Behavior of Some Twisted 9,9'-Bianthryl Derivatives: Observation of Aggregation-Induced Blue-Shifted Emission.

Project description:With an aim to understand the photophysical behavior of twisted organic fluorescent molecules in their aggregated state, two twisted biaryl molecules, namely, 9,9'-bianthryl and 10,10'-dicyano-9,9'-bianthryl, have been synthesized and characterized by conventional spectroscopic methods. To understand the role of C-C bond twisting on the photophysical response of biaryl aggregates, monoaryl counterparts (anthracene and 9-anthracenecarbonitrile) of the biaryl systems are also investigated. Photophysical behaviors of these systems along with their monoaryl counterpart are investigated in both solution and aggregated state. Investigations reveal that fluorescence spectra of the biaryl compounds show blue-shifted emission upon aggregation. Interestingly, no blue shift of the emission has been observed for monoaryl aggregates. Photophysical data of biaryl systems compared to monoaryl unit reveal that change in geometry, during self-assembly process, disfavors the formation of charge-transfer state, which eventually causes blue shift in the emission upon aggregation. In addition to this, potential of these systems toward signaling of nitroaromatic explosive has also been explored. Among all of the nitroaromatics, the highest fluorescence quenching is observed for nitrophenols (say picric acid (PA)). The investigation also reveals that compared to monoaryl systems, biaryl systems are more responsive to fluorescence quenching by nitroaromatics. Perrin's model of quenching sphere action has been attributed to nitrophenol (PA) selective signaling behavior of biaryl systems.

| S-EPMC6644316 | biostudies-literature

Beetle luciferases with naturally red- and blue-shifted emission.

Project description:The different colors of light emitted by bioluminescent beetles that use an identical substrate and chemiexcitation reaction sequence to generate light remain a challenging and controversial mechanistic conundrum. The crystal structures of two beetle luciferases with red- and blue-shifted light relative to the green yellow light of the common firefly species provide direct insight into the molecular origin of the bioluminescence color. The structure of a blue-shifted green-emitting luciferase from the firefly Amydetes vivianii is monomeric with a structural fold similar to the previously reported firefly luciferases. The only known naturally red-emitting luciferase from the glow-worm Phrixothrix hirtus exists as tetramers and octamers. Structural and computational analyses reveal varying aperture between the two domains enclosing the active site. Mutagenesis analysis identified two conserved loops that contribute to the color of the emitted light. These results are expected to advance comparative computational studies into the conformational landscape of the luciferase reaction sequence.

| S-EPMC6238593 | biostudies-literature

Stimuli-Responsive Nucleotide-Amino Acid Hybrid Supramolecular Hydrogels.

Project description:The ability to assemble chemically different gelator molecules into complex supramolecular hydrogels provides excellent opportunities to construct functional soft materials. Herein, we demonstrate the formation of hybrid nucleotide-amino acid supramolecular hydrogels. These are generated by the silver ion (Ag+)-triggered formation of silver-guanosine monophosphate (GMP) dimers, which undergo self-assembly through non-covalent interactions to produce nanofilaments. This process results in a concomitant pH reduction due to the abstraction of a proton from the guanine residue, which triggers the in situ gelation of a pH-sensitive amino acid, N-fluorenylmethyloxycarbonyl tyrosine (FY), to form nucleotide-amino acid hybrid hydrogels. Alterations in the supramolecular structures due to changes in the assembly process are observed, with the molar ratio of Ag:GMP:FY affecting the assembly kinetics, and the resulting supramolecular organisation and mechanical properties of the hydrogels. Higher Ag:GMP stoichiometries result in almost instantaneous gelation with non-orthogonal assembly of the gelators, while at lower molar ratios, orthogonal assembly is observed. Significantly, by increasing the pH as an external stimulus, nanofilaments comprising FY can be selectively disassembled from the hybrid hydrogels. Our results demonstrate a simple approach for the construction of multicomponent stimuli-responsive supramolecular hydrogels with adaptable network and mechanical properties.

| S-EPMC8482081 | biostudies-literature

A blue-shifted light-driven proton pump for neural silencing.

Project description:Ion-transporting rhodopsins are widely utilized as optogenetic tools both for light-induced neural activation and silencing. The most studied representative is Bacteriorhodopsin (BR), which absorbs green/red light (?570 nm) and functions as a proton pump. Upon photoexcitation, BR induces a hyperpolarization across the membrane, which, if incorporated into a nerve cell, results in its neural silencing. In this study, we show that several residues around the retinal chromophore, which are completely conserved among BR homologs from the archaea, are involved in the spectral tuning in a BR homolog (HwBR) and that the combination mutation causes a large spectral blue shift (?max = 498 nm) while preserving the robust pumping activity. Quantum mechanics/molecular mechanics calculations revealed that, compared with the wild type, the ?-ionone ring of the chromophore in the mutant is rotated ?130° because of the lack of steric hindrance between the methyl groups of the retinal and the mutated residues, resulting in the breakage of the ? conjugation system on the polyene chain of the retinal. By the same mutations, similar spectral blue shifts are also observed in another BR homolog, archearhodopsin-3 (also called Arch). The color variant of archearhodopsin-3 could be successfully expressed in the neural cells of Caenorhabditis elegans, and illumination with blue light (500 nm) led to the effective locomotory paralysis of the worms. Thus, we successfully produced a blue-shifted proton pump for neural silencing.

| S-EPMC3711326 | biostudies-literature

Atomistic design of microbial opsin-based blue-shifted optogenetics tools.

Project description:Microbial opsins with a bound chromophore function as photosensitive ion transporters and have been employed in optogenetics for the optical control of neuronal activity. Molecular engineering has been utilized to create colour variants for the functional augmentation of optogenetics tools, but was limited by the complexity of the protein-chromophore interactions. Here we report the development of blue-shifted colour variants by rational design at atomic resolution, achieved through accurate hybrid molecular simulations, electrophysiology and X-ray crystallography. The molecular simulation models and the crystal structure reveal the precisely designed conformational changes of the chromophore induced by combinatory mutations that shrink its π-conjugated system which, together with electrostatic tuning, produce large blue shifts of the absorption spectra by maximally 100 nm, while maintaining photosensitive ion transport activities. The design principle we elaborate is applicable to other microbial opsins, and clarifies the underlying molecular mechanism of the blue-shifted action spectra of microbial opsins recently isolated from natural sources.

| S-EPMC4479019 | biostudies-literature

Laser-induced greenish-blue photoluminescence of mesoporous silicon nanowires.

Project description:Solid silicon nanowires and their luminescent properties have been widely studied, but lesser is known about the optical properties of mesoporous silicon nanowires (mp-SiNWs). In this work, we present a facile method to generate greenish-blue photoluminescence (GB-PL) by fast scanning a focused green laser beam (wavelength of 532?nm) on a close-packed array of mp-SiNWs to carry out photo-induced chemical modification. The threshold of laser power is 5?mW to excite the GB-PL, whose intensity increases with laser power in the range of 5-105?mW. The quenching of GB-PL comes to occur beyond 105?mW. The in-vacuum annealing effectively excites the GB-PL in the pristine mp-SiNWs and enhances the GB-PL of the laser-modified mp-SiNWs. A complex model of the laser-induced surface modification is proposed to account for the laser-power and post-annealing effect. Moreover, the fast scanning of focused laser beam enables us to locally tailor mp-SiNWs en route to a wide variety of micropatterns with different optical functionality, and we demonstrate the feasibility in the application of creating hidden images.

| S-EPMC4018655 | biostudies-literature

Molecular-Fluorescence Enhancement via Blue-Shifted Plasmon-Induced Resonance Energy Transfer.

Project description:We report molecular-fluorescence enhancement via the blue-shifted plasmon-induced resonance energy transfer (PIRET) from single Au nanorods (AuNRs) to merocyanine (MC) dye molecules. The blue-shifted PIRET occurs when there is a proper spectral overlap between the scattering of AuNRs and the absorption of MC molecules. Along with the quenching of scattering from AuNRs, the blue-shifted PIRET enhances the fluorescence of nearby molecules. On the basis of the fluorescence enhancement, we conclude that AuNRs can be used as donors with clear advantages to excite the fluorescence of molecules as acceptors in AuNR-molecule hybrids. On the one hand, compared to conventional molecular donors in Förster resonance energy transfer (FRET), AuNRs have much larger absorption cross sections at the plasmon resonance frequencies. On the other hand, energy-transfer efficiency of PIRET decreases at a lower rate than that of FRET when the donor-acceptor distance is increased. Besides, the blue-shifted PIRET allows excitation with incident light of lower energy than the acceptor's absorption, which is difficult to achieve in FRET because of the Stokes shift. With the capability of enhancing molecular fluorescence with excitation light of low intensity and long wavelength, the blue-shifted PIRET will expand the applications of nanoparticle- molecule hybrids in biosensing and bioimaging by increasing signal-to-noise ratio and by reducing photodamage to biological cells and organelles at the targeted areas.

| S-EPMC5863757 | biostudies-literature

Efficient sky-blue perovskite light-emitting diodes via photoluminescence enhancement.

Project description:The efficiencies of green and red perovskite light-emitting diodes (PeLEDs) have been increased close to their theoretical upper limit, while the efficiency of blue PeLEDs is lagging far behind. Here we report enhancing the efficiency of sky-blue PeLEDs by overcoming a major hurdle of low photoluminescence quantum efficiency in wide-bandgap perovskites. Blending phenylethylammonium chloride into cesium lead halide perovskites yields a mixture of two-dimensional and three-dimensional perovskites, which enhances photoluminescence quantum efficiency from 1.1% to 19.8%. Adding yttrium (III) chloride into the mixture further enhances photoluminescence quantum efficiency to 49.7%. Yttrium is found to incorporate into the three-dimensional perovskite grain, while it is still rich at grain boundaries and surfaces. The yttrium on grain surface increases the bandgap of grain shell, which confines the charge carriers inside grains for efficient radiative recombination. Record efficiencies of 11.0% and 4.8% were obtained in sky-blue and blue PeLEDs, respectively.

| S-EPMC6904584 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data