Spiropyran Moiety Research Articles

Design and Synthesis of an o-Hydroxyphenyl-Containing Spiropyran Thermochromic Colorant

An o-hydroxyphenyl-containing spiropyran thermochromic colorant was designed and synthesized. The prepared compound is sensitive to temperature and has a reversible color change with temperature variation. X-ray diffraction analysis and variable-temperature NMR studies suggest that the thermochromism of the compound presumably involved a ring-opening C-O bond cleavage of the spiropyran moiety followed by an intramolecular hydrogen transfer.

Chiroptical Switching Based on Photoinduced Proton Transfer between Homopolymers Bearing Side‐Chain Spiropyran and Azopyridine Moieties

AbstractA novel optically‐active polymeric methacrylate, bearing the (S)‐3‐hydroxy pyrrolidinyl group linked through the nitrogen atom to an azopyridine chromophore, was synthesized and investigated in combination with a polymeric methacrylate incorporating the photoisomerizable spiropyran chromophore in the side‐chain. In the presence of acid, this system can be operated in solution to modulate the protonation of the azopyridine moieties by photoisomerizing the spiropyran component. In addition to UV‐vis spectroscopy, the proton transfer process occurring between the macromolecular components can be also followed by CD spectroscopy, thus behaving as a chiroptical switch.magnified image

Synthesis and photochromic property of nanoparticles with spiropyran moieties via one-step miniemulsion polymerization

Photochromic nanoparticles with spiropyran moieties were prepared by a facile one-step miniemulsion polymerization. The nanoparticle dispersion was obtained by mixing the monomers, spiropyran-containing molecules and hydrophobe, dispersing them into an aqueous solution with surfactant, subjecting the dispersion to ultrasonification and polymerizing the monomers by using a water soluble initiator. The shape and size of the nanoparticles was determined with the atomic force microscope (AFM) and dynamic light scattering (DLS), and the determined average diameter of the nanoparticles ranges from 30 nm to 60 nm. The absorption and fluorescence spectra for the nanoparticles dispersions reveal that the spiropyran molecules were successfully incorporated in the polymer nanoparticles. Moreover, the nanoparticle dispersions were found to exhibit enhanced photo-reversibility, photo-stability and relatively fast photo-responsive property compare to the same species in aqueous solution.

A Core–Shell Nanoparticle Approach to Photoreversible Fluorescence Modulation of a Hydrophobic Dye in Aqueous Media

Amphiphilic core-shell nanoparticles containing spiropyran moieties have been prepared in aqueous media. The nanoparticles consist of hydrophilic and biocompatible poly(ethyleneimine) (PEI) chain segments, which serve as the shell, and a hydrophobic copolymer of methyl methacrylate (MMA), a spiropyran-linked methacrylate, and a cross-linker, which forms the core of the nanoparticles. A hydrophobic fluorescent dye based on the nitrobenzoxadiazolyl (NBD) group was introduced into the nanoparticles to form NBD-nanoparticle complexes in water. The nanoparticles not only greatly enhance the fluorescence emission of the hydrophobic dye NBD in aqueous media, probably by accommodating the dye molecules in the interface between the hydrophilic shells and the hydrophobic cores, but also modulate the fluorescence of the dye through intraparticle energy transfer. This biocompatible and photoresponsive nanoparticle complex may find applications in biological areas such as biological diagnosis, imaging, and detection. In addition, this nanoparticle approach will open up possibilities for the fluorescence modulation of other hydrophobic fluorophores in aqueous media.

Phosphate-Mediated Molecular Memory Driven by Two Different Protein Kinases as Information Input Elements

There is increasing interest in studying molecular-based devices that perform Boolean logic operations whose output state (0 or 1) depends on the input conditions (0/0, 1/0, 0/1, or 1/1). So far, great efforts have been devoted to establish molecular-scaled logic gates activated by chemical, physical, and biological inputs. We herein describe the design and synthesis of a tandem protein kinase substrate peptide acting as a phosphate-mediated molecular memory. The molecular-based memory system is comprised of two different phosphorylatable substrate regions joined in series and a spiropyran derivative at the N-terminus. We also demonstrated three basic "AND", "OR", and "NOR" logic operations on the basis of alterations in the spiropyran-to-merocyanine (SP-to-MC) thermocoloration properties of the spiropyran moiety in the peptide upon kinase-catalyzed phosphorylation. The three logic functions were successfully performed by adding ionic polymers as programming elements with preset thresholds of a signal intensity in a microplate format. Throughout this study, information was recorded on the substrate peptide by protein kinase-catalyzed phosphorylation, stored stably as phosphoesters, read according to the extent of the SP-to-MC thermocoloration, and erased by phosphatase-catalyzed dephosphorylation, resulting in the peptide returning to the initial recordable state. Thus, the proof-of-concept experiments described herein could be used to provide clues for developing practical molecular-based processing and computing.

Photoinduced Formation of Microscopic Ordering and Macroscopic Pattern in Spiropyran-Containing Polyacrylate−Tetraoctylammonium Bromide Films

In this study, photoisomerizable polyacrylate containing spiropyran moieties was synthesized. By taking advantage of the photoinduced structural transformations of the spiropyran moieties, photoinduced microscopic ordering and eventually macroscopic patterns were formed in the polymer films consisting of spiropyran-containing polyacrylate (SPPA) and tetraoctylammonium bromide (TOAB). The patterns thus obtained are composed of concentric rings, which alternatively consist of macroscopic convex ridges and concave valleys, with the former being amphormous phases and the latter being ordered mesomorphous ones. It was found that the open-ring protonated merocyanine (MC) form of the spiropyran moieties, which is triggered by UV illumination, was crucial to the formation of mesomorphous structure and macroscopic patterns for this polymer−surfactant system. It is possible that the interaction between the MC form and TOAB leads to the formation of the microscopic ordering and macroscopic pattern in the polymer−TOA...

Photon Gated Transport at the Glass Nanopore Electrode

The interior surface of the glass nanopore electrode was modified with spiropyran moieties to impart photochemical control of molecular transport through the pore orifice (15-90 nm radius). In low ionic strength acetonitrile solutions, diffusion of a positively charged species (Fe(bpy)(3)(2+)) is electrostatically blocked with approximately 100% efficiency by UV light-induced conversion of the neutral surface-bound spiropyran to its protonated merocyanine form (MEH+). Transport through the pore orifice is restored by either irradiation of the electrode with visible light to convert MEH+ back to spiropyran or addition of a sufficient quantity of supporting electrolyte to screen the electrostatic field associated with MEH+. The transport of neutral redox species through spiropyran-modified glass nanopores is not affected by light, allowing photoselective transport of redox molecules to the electrode surface based on charge discrimination. The glass nanopore electrode can also be employed as a photochemical trap, by UV light conversion of surface-bound spiropyran to MEH+, preventing Fe(bpy)(3)(2+) initially in the pore from diffusing through the orifice.

Effect of complexation with lanthanide metal ions on the photochromism of (1,3,3‐trimethyl‐5′‐hydroxy‐6′‐formyl‐ indoline‐spiro2,2′‐[2h]chromene) in different media

Complexation of lanthanide ions {Ln(III) ions [Tb(III), Eu(III), or Sm(III)]} with the spiropyran‐derived merocyanine obtained in dark and under steady irradiation of indoline spiropyran (1,3,3‐trimethyl‐5′‐hydroxy‐6′‐formyl‐indoline‐spiro‐2,2′‐[2H]chromene) induces a noticeable hypsochromic shift of about 10–110 nm of its visible absorption band concomitant with hypochromic effect and influences its thermal bleaching in the dark. The effect of lanthanide ions and medium on photochromic, spectral‐and‐kinetic, and luminescence properties of the spiropyran and its complexes in solution and polymer matrix of polymethylmethacrylate (PMMA) is studied. Efficient energy transfer from the spiropyran moiety results in efficient typical luminescence from the Ln(III) ion that becomes more pronounced in polar nonalcoholic solvents and PMMA solid matrix. Moreover, luminescence mappings for pattern recognition analysis have been obtained from which the nature of the solvent and/or the ligand is clearly identified.

Photoregulated Transmembrane Charge Separation by Linked Spiropyran−Anthraquinone Molecules

Amide-linked spiropyran-anthraquinone (SP-AQ) conjugates were shown to mediate ZnTPPS(4-)-photosensitized transmembrane reduction of occluded Co(bpy)3(3+) within unilamellar phosphatidylcholine vesicles by external EDTA. Overall quantum yields for these reactions were dependent upon the isomeric state of the dye; specifically, 30-35% photoconversion of the closed-ring spiropyran (SP) moiety to the open-ring merocyanine (MC) form caused the quantum yield to decrease by 6-fold in the simple conjugate and 3-fold for an analogue containing a lipophilic 4-dodecylphenoxy substituent on the anthraquinone moiety. Transient spectroscopic and fluorescence quenching measurements revealed that two factors contributed to these photoisomerization-induced changes in quantum yields: increased efficiencies of fluorescence quenching of 1ZnTPPS4- by the merocyanine group and lowered transmembrane diffusion rates of the merocyanine-containing redox carriers. Transient spectrophotometry also revealed the sequential formation and decay of two reaction intermediates, identified as 3ZnTPPS4- and a species with the optical properties of a semiquinone radical. Kinetic profiles for Co(bpy)3(3+) reduction under continuous photolysis in the presence and absence of added ionophores indicated that transmembrane redox mediated by SP-AQ was electroneutral, but reaction by the other quinone-containing mediators was electrogenic. The minimal reaction mechanism suggested from the combined studies is oxidative quenching of vesicle-bound 3ZnTPPS4- by the anthraquinone unit, followed by either H+/e- cotransport by transmembrane diffusion of SP-AQH* or, for the other redox mediators, semiquinone anion-quinone electron exchange leading to net transmembrane electron transfer, with subsequent one-electron reduction of the internal Co(bpy)3(3+). Thermal one-electron reduction of Co(bpy)3(3+) by EDTA is energetically unfavorable; the photosensitized reaction therefore occurs with partial conversion of photonic energy to chemical and transmembrane electrochemical potentials.

A chromism-based assay (CHROBA) technique for in situ detection of protein kinase activity

A unique chromism-based assay technique (CHROBA) using photochromic spiropyran-containing peptides has been firstly established for detection of protein kinase A-catalyzed phosphorylation. The alternative method has advantages that avoid isolation and/or immobilization of kinase substrates to remove excess reagents including nonreactive isotope-labeled ATP or fluorescently-labeled anti-phosphoamino acid antibodies from the reaction mixture. Such a novel protocol based on thermocoloration of the spiropyran moiety in the peptide can offer not only an efficient screening method of potent kinase substrates but also a versatile analytical tool for monitoring other post-translational modification activities.

A novel fluorescence sensing system using a photochromism-based assay (P-CHROBA) technique for the detection of target proteins

In the post-genomic era a number of biological technologies, including protein-detecting microarrays which can detect molecular interactions based on changes in fluorescence intensity, have been developed to investigate complicated protein functions and networks. However, the ability of such techniques to obtain reproducible and quantitative results can be compromised due to the need for the immobilization of capture agents and the labelling analytes with chromophores. In the present study, first we report the design and synthesis of photochromic spiropyran-containing peptides and then demonstrate a unique fluorescence sensing system comprising a photochromism-based assay (P-CHROBA) technique to distinguish between target proteins. The spiropyran moiety in the peptides exhibited characteristic physicochemical properties in the SP-to-MC isomerization (thermocoloration) and the MC-to-SP photoisomerization (photobleaching) depending upon changes in micro-environments such as the dielectric constants of solvents and steric hindrances generated by molecular interactions. We attempted to detect protein–peptide interactions using reproducible MC-to-SP photoisomerization properties by monitoring the fluorescence decay of the MC form in the peptide. This can reduce background fluorescence signals caused by emission from excess reagents and avoid the laborious introduction of probing molecules to analytes and the immobilization of capture agents onto solid surfaces. The protein fingerprints (PFPs) based on the photoisomerization properties could successfully distinguish between six different model proteins, and the combination of the P-CHROBA and PFP technique would be a powerful tool for profiling target proteins with reproducible and reliable results.

Towards molecular T-junction relays

The synthesis of a ditopic 2,2′:6′,2′′-terpyridine ligand and bis-ruthenium(II) complex is described which incorporates in its molecular backbone a light-activated spiropyran moiety.

Photochromic behavior of new bifunctional copolymer containing spiropyran and chalcone moiety in the side chain

We synthesized two copolymers bearing photochromic spiropyran dye in the side chain for studying the dynamic properties of their photochromism. The dynamic processes of colorization and decolorization under an excitation light were investigated using the two copolymers. One of the copolymers contains methylmethacrylate (MMA) and methacrylate-spiropyran (MA-spiropyran). The other one contains methacrylate-spiropyran (MA-spiropyran) and methacrylate-chalcone (MA-chalcone) as a comonomer. Investigation of the photosensitivity of the newly synthesized copolymers was carried out by using UV–vis absorption spectroscopy. We observed the photodimerization and photochromic behavior under UV irradiation simultaneously. The effect of photocrosslink on the stability of photochromism was considered from this study.

Stability of Photochromism in New Bifunctional Copolymers Containing Spiropyran and Chalcone Moiety in the Side Chain

We synthesized three copolymers bearing photochromic spiropyran dye and chalcone moiety in the side chain for studying the dynamic properties of their photochromism. They contain methacrylate-spiropyran (MAspiropyran) and methacrylate-chalcone (MA-chalcone) with the different concentration. The photosensitivity of the newly synthesized copolymers was investigated by using UV-Vis absorption spectroscopy. We observed photodimerization and photochromic behavior under UV irradiation at the same time. The effect of photocrosslink on the rate and stability of photochromism in three copolymers was considered in this study. This study might be helpful to design photochromic materials for irreversible optical memory by virtue of photocrosslinking reaction.

Photochromism of Liquid Crystalline Polymers with Spiropyran Derivatives

New liquid crystalline polymers with spiropyran derivative for optical recording applications were prepared by radical polymerization from two different monomers composed of mesogenic unit and spiropyran moiety. The resulting polymers have been characterized by FT-IR, 1H-NMR, DSC and UV/Vis spectroscopy. The weight average molecular weight (M w ) of polymers were in the range of 13,000–30,700 and thermal decomposition initiated in the range of 350-370°C. Good quality films were obtained by spin-coating onto indium tin oxide (ITO) glass plate and some of polymers exhibited smectic and nematic liquid crystalline phase at elevated temperatures. These polymers showed promising photochromic and thermochromic activities for optical recording materials.

Photoswitched singlet energy transfer in a porphyrin-spiropyran dyad.

A photochromic nitrospiropyran moiety (Sp) has been covalently linked to a zinc (PZn) and to a free-base (P(H2)) porphyrin. In the resulting dyads (P(Zn)-Sp(c) and P(H2)-Sp(c)), the porphyrin first excited singlet states are unperturbed by the closed form of the attached spiropyran. Excitation of the spiropyran moiety of either dyad in the near-UV region results in ring opening to a merocyanine form (P-Sp(o)) that absorbs at 600 nm. The open form re-closes thermally in 2-methyltetrahydrofuran with a time constant of 20 s, or following irradiation into the 600 nm band. Excitation of the zinc porphyrin moiety in the merocyanine form of the dyad yields 1PZn-Sp(o). The lifetime of the zinc porphyrin excited state is reduced from its usual value of 1.8 ns to 130 ps by singlet-singlet energy transfer to the merocyanine moiety to give PZn-1Sp(o). The quantum yield of energy transfer is 0.93. Quenching is also observed in the free base dyad, where 1P(H2)-Sp(o) and P(H2)-1Sp(o) exchange singlet excitation energy. This photoswitchable quenching phenomenon provides light-activated control of the porphyrin excited states, and consequently control of any subsequent energy or electron-transfer processes that might be initiated by these excited states in more complex molecular photonic or optoelectronic devices.

Photoregulation of Metal Ion-Adsorbability of Photoresponsive Cellulosic Chelate Polymer.

A cellulosic derivative (Cell-ox-sp) containing both chelating functional 8-hydroxyquinoline (ox) and photoresponsive spiropyran (sp) moieties was synthesized and photoregulation of metal ion-adsorption of Cell-ox-sp was examined. Reaction of powdered cellulose with 5-chloromethyl-8-hydroxyquinoline gave cellulosic derivatives with degree of substitution (DS) by ox up to 1.1, and subsequent reaction of the products with a spiropyran derivative containing carboxyl group did Cell-ox-sp with DS by sp of about 0.5. In the reaction sequence, metal ion- adsorption of the each product increased from cellulose to Cell-ox and considerably decreased from Cell-ox to Cell-ox-sp. Under irradiation with UV light, Cu2+- adsorption of Cell-ox-sp considerably increased and under subsequent irradiation with visible light it decreased as it had been before. These substantial changes in Cu2+- adsorption may suggest that ox moiety and merocyanine type sp moiety yielded with UV light irradiation co-operatively adsorbs Cu2+. Adsorption of Zn2+ showed similar behaviors under irradiations with UV light and with subsequent visible light, but the extent of the change was lower than that for Cu2+. These results show that metal ion-adsorption of Cell-ox-sp may be photoregulated under irradiation with UV light and visible light, possibly selectively in respect to ion species.

スピロピラン修飾界面活性剤の光異性化による有機顔料薄膜と像の作製

スピロピラン修飾界面活性剤の光異性化による有機顔料薄膜と像の作製

Extraction Spectrophotometry of Lithium Ions Based on Cation-and Photo-Induced Isomerization of Crowned Spirobenzopyran

A spirobenzopyran derivative incorporating monoaza-12-crown-4 moiety was applied as a reagent for extraction spectrophotometry of alkali metal ions, taking advantage of the cation-complexation-induced Isomerization of its spiropyran moiety to the corresponding colored merocyanine form. The present spectrophotometry is quite selective for lithium ion against the other alkali metal ions. Photoisomerization of the crowned spirobenzopyran promoted the lithium extraction; especially, it increased the extraction rate remarkably.

Highly calcium-ion-accelerated coloration of bis(spirobenzopyran) bridged by diaza-18-crown-6 moiety at the 8-position

Abstract Complexation of metal ions, especially of polyvalent metal ions, by a spirobenzopyran dimer bridged by a diaza-18-crown-6 moiety at the 8-position induced remarkable isomerization of its spiropyran moiety to the corresponding merocyanine even under dark conditions. Crowned bis(spirobenzopyran) can bind Ca2+ to form stable metal ion complexes of its merocyanine isomer, which in turn brings about the high rate constant of its thermal coloration after visible-light irradiation.