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Yong-Min Kho, Eun Ju Shin
Spiropyran derivatives have been studied as light-regulated chemosensors for a variety of metal cations and anions, but there is little research on chemosensors that simultaneously detect multiple metal cations. In this study, a spiropyran derivative with isoquinoline, SP-IQ, was prepared and it functions investigated as a light-regulated sensor for both Co(2+) and In(3+) cations. A colorless nonfluorescent SP-IQ converts to a pink-colored fluorescent MC-IQ by UV irradiation or standing in the dark, and MC-IQ returns to SP-IQ with visible light...
September 19, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Sabrina Heng, Xiaozhou Zhang, Jinxin Pei, Andrew D Abell
γ-Glutamyl-cysteinyl-glycine (GSH) plays a critical role in maintaining redox homeostasis in biological systems and a decrease in its cellular levels is associated with diseases. Existing fluorescence-based chemosensors for GSH acts as irreversible reaction-based probes that exhibit a maximum fluorescence ('turn-on') once the reaction is complete, regardless of the actual concentration of GSH. A reversible, reaction-based 'turn-off' probe ( 1 ) is reported here to sense the decreasing levels of GSH, a situation known to occur at the onset of various diseases...
September 6, 2017: Biosensors
Alexis Perry, Christina J Kousseff
Spiropyrans bearing an N-alkylcarboxylate tether are a common structure in dynamic, photoactive materials and serve as colourimetric/fluorimetric cation receptors. In this study, we describe an efficient synthesis of spiropyrans with 2-12 carbon atom alkylcarboxylate substituents, and a systematic analysis of their interactions with metal cations using (1)H NMR and UV-visible spectroscopy. All N-alkylcarboxyspiropyrans in this study displayed a strong preference for binding divalent metal cations and a modest increase in M(2+) binding affinity correlated with increased alkycarboxylate tether length...
2017: Beilstein Journal of Organic Chemistry
Mingsong Wang, Gregory Hartmann, Zilong Wu, Leonardo Scarabelli, Bharath Bangalore Rajeeva, Jeremy W Jarrett, Evan P Perillo, Andrew K Dunn, Luis M Liz-Marzán, Gyeong S Hwang, Yuebing Zheng
By harnessing photoswitchable intersystem crossing (ISC) in spiropyran (SP) molecules, active control of plasmon-enhanced fluorescence in the hybrid systems of SP molecules and plasmonic nanostructures is achieved. Specifically, SP-derived merocyanine (MC) molecules formed by photochemical ring-opening reaction display efficient ISC due to their zwitterionic character. In contrast, ISC in quinoidal MC molecules formed by thermal ring-opening reaction is negligible. The high ISC rate can improve fluorescence quantum yield of the plasmon-modified spontaneous emission, only when the plasmonic electromagnetic field enhancement is sufficiently high...
August 21, 2017: Small
Noorjahan Aibani, Paola Fontoura da Costa, Jodie Masterson, Nino Marino, Françisco M Raymo, John Callan, Bridgeen Callan
The ability to control drug release at a specific physiological target enables the possibility of an enhanced therapeutic effect with reduced off-target toxic side effects. The discipline of controlled drug release has grown to include most areas of medicine with examples in the literature of targeted drug delivery to the majority of organs within the human body. In addition, a variety of external stimuli used to meditate the drug release process have also been investigated. Nonetheless, the concurrent real time monitoring of drug release has not been widely studied...
August 18, 2017: Journal of Controlled Release: Official Journal of the Controlled Release Society
Juhyen Lee, Eun Jung Choi, Inwon Kim, Minhe Lee, Chinnadurai Satheeshkumar, Changsik Song
Tuning the sensing properties of spiropyrans (SPs), which are one of the photochromic molecules useful for colorimetric sensing, is important for efficient analysis, but their synthetic modification is not always simple. Herein, we introduce an alkyne-functionalized SP, the modification of which would be easily achieved via Cu-catalyzed azide-alkyne cycloaddition ("click reaction"). The alkyne-SP was conjugated with a bis(triethylene glycol)-benzyl group (EG-BtSP) or a simple benzyl group (BtSP), forming a triazole linkage from the click reaction...
August 7, 2017: Sensors
Kimio Sumaru, Toshiyuki Takagi, Taku Satoh, Toshiyuki Kanamori
The photo- and thermoresponse of poly(N-isopropylacrylamide) (pNIPAAm) functionalized with spiropyran chromophore is examined with respect to the influence of molecular recognition by cyclodextrin (CD). Characterization in aqueous solutions of spiropyran-functionalized poly(N,N-dimethylacrylamide) under coexistence of α-, β-, or γ-CD reveals that β-CD selectively includes the ring-closing isomer of the chromophore, which is dominant under light irradiation, while no inclusion is observed for the protonated ring-opening isomer, which is dominant in the dark before irradiation...
July 26, 2017: Macromolecular Rapid Communications
Zhixiong Li, Yuqiong Zhou, Liuqi Peng, Dongpeng Yan, Min Wei
A bifunctional ultrathin film (UTF) electrode was fabricated based on layered double hydroxides (LDHs) and spiropyran (SP), which exhibited electrochromism and electrochemiluminescence (ECL) sensing behavior toward temperature and Zn(2+) ions.
July 24, 2017: Chemical Communications: Chem Comm
Mohammad Hossain Sharifian, Ali Reza Mahdavian, Hamid Salehi-Mobarakeh
Chemical bonding between photochromic compounds and polymer matrices will induce several consitions such as photostability, photoreversibility, elimination of dye aggregation, and undesirable negative photochromism. In such polymeric systems, the switching rate and photoisomerization are closely dependent on several parameters like chain flexibility, steric restrictions, polarity, and even proticity of the surrounding medium. Here, copolymerization of a synthesized spiropyran-based monomer with butyl acrylate (BA) and methyl methacrylate (MMA) comonomers was carried out with various compositions of MMA and BA through emulsion polymerization, and the corresponding photoisomerization kinetics were studied...
August 1, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Tobias Garling, Yujin Tong, Tamim A Darwish, Martin Wolf, R Kramer Campen
Surfaces whose macroscopic properties can be switched by light are potentially useful in a wide variety of applications. One such promising application is electrochemical sensors that can be gated by optically switching the electrode on or off. One way to make such a switchable electrode is by depositing a self-assembled monolayer (SAM) of bistable, optically switchable molecules onto an electrode surface. Quantitative application of any such sensor requires understanding how changes in interfacial field affect the composition of photostationary states, i...
July 20, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Chris Ritchie, George Vamvounis, Hamid Soleimaninejad, Trevor A Smith, Evan J Bieske, Viktoras Dryza
The spectroscopic properties of poly(methyl methacrylate) polymer films doped with two kinds of photochromic molecular switches are investigated. A green-fluorescent sulfonyl diarylethene (P1) is combined with either a non-fluorescent diarylethene (P2) or red-fluorescent spiropyran (P3). Photoswitching between the colorless and colored isomers (P1: o-BTFO4 ↔ c-BTFO4, P2: o-DTE ↔ c-DTE, P3: SP ↔ MC) enables the P1 + P2 and P1 + P3 films to be cycled through three distinct states. From the initial state (o-BTFO4 + o-DTE/SP), irradiation with UV light generates the second state (c-BTFO4 + c-DTE/MC), where c-BTFO4 → c-DTE/MC energy transfer is established...
July 19, 2017: Physical Chemistry Chemical Physics: PCCP
Maja Feierabend, Ermin Malic, Andreas Knorr, Gunnar Berghäuser
Atomically thin transition metal dichalcogenides (TMDs) hold promising potential for applications in optoelectronics. Due to their direct band gap and the extraordinarily strong Coulomb interaction, TMDs exhibit efficient light-matter coupling and tightly bound excitons. Moreover, large spin orbit coupling in combination with circular dichroism allows for spin and valley selective optical excitation. As atomically thin materials, they are very sensitive to changes in the surrounding environment. This motivates a functionalization approach, where external molecules are adsorbed to the materials surface to tailor its optical properties...
September 27, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Thomas Halbritter, Christoph Kaiser, Josef Wachtveitl, Alexander Heckel
A highly versatile water-soluble pyridine-spiropyran photoswitch is reported which functions as photoacid in a wide pH range. Under neutral conditions, the open-ring merocyanine (MC(-)) exists to 48% and closes quantitatively by irradiation with visible light, while the reverse reaction occurs rapidly in the dark or by irradiation at 340 nm. The different pKa of the pyridine nitrogen in the closed spiropyran (4.8) and open merocyanine form (6.8) leads to a reversible proton release in a pH range of 3-7. Only negligible hydrolytic decomposition was observed in the pH range from 1 to 12...
July 19, 2017: Journal of Organic Chemistry
Bijnaneswar Mondal, Aloke Kumar Ghosh, Partha Sarathi Mukherjee
A spiropyran-decorated covalent organic cage (PC2) has been designed, employing dynamic imine chemistry followed by imine bond reduction. The molecule is capable of altering its color upon exposure to external stimuli such as heat and light. Construction of a 3D organic cage introduces a new piece to the system by swapping the closed form with the open form in the solid state with diverse color change. Moreover, this material has high chemical stability and is capable of reversible stimuli-responsive color change without any degradation for an extended period...
July 14, 2017: Journal of Organic Chemistry
Doory Kim, Zhengyang Zhang, Ke Xu
By recording both the images and emission spectra of thousands of single fluorescent molecules stochastically generated from the ring-opening reaction of a spiropyran, we provide mechanistic insights into its multipath reaction pathways. Through statistics of the measured single-molecule spectra, we identify two spectrally distinct isomers, presumably TTC and TTT cis-trans isomers, for the open-ring merocyanine product, and discover a strong solvent polarity-dependence for the relative population of the two isomers...
July 3, 2017: Journal of the American Chemical Society
Masayuki Suda, Naoto Takashina, Supawadee Namuangruk, Nawee Kungwan, Hidehiro Sakurai, Hiroshi M Yamamoto
The presence of interface dipoles in self-assembled monolayers (SAMs) gives rise to electric-field effects at the device interfaces. SAMs of spiropyran derivatives can be used as photoactive interface dipole layer in field-effect transistors because the photochromism of spiropyrans involves a large dipole moment switching. Recently, light-induced p-type superconductivity in an organic Mott insulator, κ-(BEDT-TTF)2 Cu[N(CN)2 ]Br (κ-Br: BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene) has been realized, thanks to the hole carriers induced by significant interface dipole variation in the spiropyran-SAM...
September 2017: Advanced Materials
Chaoqun Liu, Yan Zhang, Min Liu, Zhaowei Chen, Youhui Lin, Wei Li, Fangfang Cao, Zhen Liu, Jinsong Ren, Xiaogang Qu
Most chemotherapeutic drugs commonly suffer from several shortcomings, including the lack of aqueous solubility, limited stability and adverse side effects. Although caging strategy has recently been employed as an effective approach to conceal and stabilize these drugs to achieve light-activated cancer therapy, it is plagued by the sophisticated drug modification process and deleterious solvent usage. In addition, using UV or Visible light to remove photocaged group is restricted to its limited tissue penetration ability in and phototoxicity...
September 2017: Biomaterials
Stephan Stremlau, Friedrich Maass, Petra Tegeder
Spiropyrans are prototype molecular switches, which undergo a reversible photoinduced ring-opening/-closure reaction between the closed three-dimensional spiropyran (SP) and the open, planar merocyanine (MC) form. In solution the SP isomer is the thermodynamically stable form. Using high resolution electron energy loss spectroscopy, we resolve a thermally-activated irreversible ring-opening reaction of nitrospiropyran resulting in the MC form for coverages above one monolayer. Thus, the situation found in solution is reversed for the adsorbed molecules, since the MC form is more stable due to the modified energetics by the presence of the substrate...
August 9, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Colm Delaney, Peter McCluskey, Simon Coleman, Jeffrey Whyte, Nigel Kent, Dermot Diamond
A novel approach that allows control of flow in microfluidic channels with unsurpassed performance using light is described. Valve structures have been created using photoresponsive hydrogels based on spiropyran-functionalised pNIPAAm hydrogels photopolymerised around pillar structures within the channels. Valve actuation is controlled from outside the fluidic system using externally located LEDs. Highly precise and accurate flow rates can be selected by passing real-time flow rate measurements into a PID algorithm...
May 31, 2017: Lab on a Chip
Dushanthi S Dissanayake, Gregory T McCandless, Mihaela C Stefan, Michael C Biewer
Spiropyrans are notable among different classes of photochromic compounds due to their large structural and electronic transformation upon isomerization. In order to parlay the electronic differences associated with the two isomeric forms into a materials based switch, the spiropyran ultimately requires a covalent attachment through a conjugated pathway. In this work a synthetic method was developed to incorporate spiropyran (SP) into thiophene based materials. A series of compounds with a systematic variation of substituents were synthesized (SP-T, SP-T-Br, SP-T-T, SP-T-T-T and SP-T-T-T-T-SP) and their photochromism in both polar (methanol) and non-polar (toluene) solvents were studied...
July 1, 2017: Photochemical & Photobiological Sciences
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