Bistable photoswitching in poly(N-isopropylacrylamide) with spironaphthoxazine hydrogel for optical data storage

A bistable switching photochromic poly(N-isopropylacrylamide) with spironaphthoxazine hydrogel copolymer (PNIPA-SPO-BIS) has been designed and synthesized by radical polymerization. The PNIPA-SPO-BIS copolymer is identified by ¹H NMR spectroscopy, FIT-IR spectroscopy and gel permeation chromatography (GPC). The morphology of the internal microstructures of the PNIPA-SPO-BIS hydrogels was observed by scanning electron microscopy (SEM). The PNIPA-SPO-BIS copolymer showed excellent photochromic behavior in water solution and in gel state. In addition, erasable and rewritable (EARW) photoimaging on the PNIPA-SPO-BIS hydrogel was successfully demonstrated. A novel optical data storage materials based on photochromic hydrogel was developed. These developments are crucial for fundamental studies and eventual technical application for all-photo mode high-density optical data storage.     

Synthesis and characterization of glucosamine-bound near-infrared probes for optical imaging

[structure: see text] Two novel near-infrared (NIR) fluorescent probes have been synthesized by linking a carbocyanine fluorophore and glucosamine through different linkers. These probes demonstrated a high quantum yield, low cytotoxicity, reversible pH-dependent fluorescence in the physiological pH range, and a decreased aggregation tendency in aqueous solutions. In vitro NIR optical imaging studies revealed cellular uptake and strong intracellular NIR fluorescence of these two probes in four breast epithelial cell lines.     

基于光化学探针的分子键盘锁研究进展

分子键盘锁作为一类新型的分子逻辑器件,其信号输出依赖于特定顺序的信号输入组合,可以在分子水平上保护信息。光化学探针分子以其选择性好、灵敏度高、易于实现在线分析以及可通过目视比色识别和原位检测等特点成为目前研究的热点。本文介绍了基于光化学分子探针发展起来的分子键盘锁,根据信号输入类型主要有阳离子输入、阴离子输入和阳离子/阴离子混合输入等类型。最后,展望了分子键盘锁的发展趋势。     

Synthesis and characterization of ultraviolet light-curable resin for optical fiber coating

UV-curable polydimethylsiloxane epoxy acrylate (PSEA) and polyethylene glycol urethane acrylate (PGUA) were synthesized and characterized by ¹H-NMR and FTIR spectra. PGUA, PSEA and trimethylolpropane triacrylate (TMPTA) were mixed in different proportions to modify the properties of blends to prepare optical fiber coating. Formulation was optimized by the orthogonal table. When the proportion was PGUA:PSEA:TMPTA=10:4:3, it was used for a single coating (OFC-6). However, the proportion PGUA:PSEA:TMPTA=8:3:2 was used for a primary buffer coating. The rheological behavior and the selection of photoinitiators for OFC-6 were also discussed. The photopolymerization of OFC-6 was inspected by the FTIR spectrum. Results show OFC-6 film is completely cured after irradiated 5 s. The thermal behaviors of the cured film were also investigated by TGA, DMA, etc.     

A fluorescent molecular switch for room temperature operation based on oligonucleotide hybridization without labeling of probes or targets

A molecular switch was prepared by self-assembly. Neutravidin served as a template that allowed for a biotinylated probe oligonucleotide to be placed adjacent to a biotinylated long-chain linker that was terminated with thiazole orange (TO). Hybridization of probe oligonucleotide with target to form double-stranded DNA resulted in intercalation of the adjacent TO probe. This was a reversible process that could be tracked by fluorescence intensity changes. Formamide was used as a denaturant for double-stranded DNA, and could be used to depress thermal denaturation temperatures. In this work formamide had a dual function, providing for control of hybridization selectivity at room temperature, while concurrently ameliorating non-specific adsorption to improve signal-to-noise when using thiazole orange as a fluorescence signalling agent to determine oligonucleotide hybridization. Room temperature single nucleotide polymorphism (SNP) discrimination for oligonucleotide targets was achieved both in solution and for molecular switches that were immobilized onto optical fibers. In solution, a concentration of 18.5% formamide provided greater than 40-fold signal difference between single-stranded DNA and double-stranded DNA, in contrast to only a 2-fold difference in the absence of formamide. Selectivity for SNP determination in solution was demonstrated using targets of varying lengths including a 141-base PCR amplicon. The improved signal-to-noise achieved by use of formamide is likely due to preferential displacement of dye molecules that are otherwise electrostatically bound to the polyanionic nucleic acid backbone.     

New cyclen-cored dendrimers functionalized with pyrene: Synthesis characterization,optical and photophysical properties

New cyclen (1,4,7,10-teraazacyclododecane) cored dendrimers up to the second generation, functionalized with 4, 8 and 16 pyrene units, respectively, were synthesized following a convergent procedure. All new compounds were characterized by NMR spectroscopies and ESI or MALDI TOF mass spectrometry. The optical and photophysical properties of the new dendrimers were studied in THF solution. Absorption spectra showed the typical absorption bands of pyrene moieties. In the fluorescence spectra, monomer as well as excimer emission were observed for all compounds. An increased proportion of excimer emission was observed in the dendrimer of the highest generation.     

Synthesis and characterization of fluorescent magneto polymeric nanoparticles (FMPNs) for bimodal imaging probes

Novel bifunctional fluorescent magneto polymeric nanoprobes (FMPNs) were synthesized to provide simultaneous diagnostic information via magnetic resonance imaging (MRI) and optical imaging. FMPNs consist of ultra-sensitive magnetic nanocrystals that function as MR probes combined with Nile Red, which functions as a fluorescent probe. FMPNs were encapsulated by a nano-emulsion method in polyvinyl alcohol (PVA, 87–89% hydrolyzed) through a matrix of polymethyl methacrylate (PMMA). FMPNs exhibited excellent colloidal stability and monodispersity. The production of MR and optical images demonstrated that FMPNs have potential as dual-mode imaging agents.     

Synthesis and spectroscopic characterization of gold nanoparticles

Photoluminescent nanoparticles of gold with size 3, 4, 6, and 9nm are prepared by borohydride/citrate reduction in presence of polyethylene glycol (PEG)/tannic acid. The prepared nanomaterials are characterized by UV-vis spectroscopy and dynamic light scattering (DLS) technique. Intense photoluminescence (PL) is observed in nanoparticles prepared by fast reduction with borohydride in presence of PEG. A red shift of PL emission from 408 to 456nm is observed for the change of size from 4 to 6nm. Increase in PL intensity is observed for all the nanoparticles on the addition of KCl. Citrate reduced gold colloid which consists of large particles of size approximately 35nm with anisotropic shapes showing two plasmon peaks is also prepared. The anisotropy is confirmed by TEM measurement. SERS activity of this colloid is tested using glutamic acid as an adsorbate probe. Assignment of the observed bands is given.     

Synthesis and characterization of photolabeling probes of miltefosine

Miltefosine is an ether-phospholipid analogue showing remarkable anti-cancer and anti-leishmanial activity thanks to its cell membrane-targeting properties. In order to study the mechanisms responsible for the biological effects of miltefosine using a photolabeling approach, we designed, synthesized and characterized photolabeling probes for studying the effects of miltefosine. In these probes, the photoactivatable tetrafluorophenylazido group is incorporated either at the polar head or in the alkyl chain of miltefosine. The probes showed fast, clear-cut photochemical reactions, which suggests that they are promising tools for use in photolabeling studies.     

Synthesis, chiroptical properties and photoinduced linear birefringence of the homopolymer of (R)-3-methacryloyloxy-1-(4′-cyano-4-azobenzene)pyrrolidine and of the copolymers with the enantiomeric monomer

We have investigated a new optically active photochromic homopolymer poly[(R)-3-methacryloyloxy-1-(4′-cyano-4-azobenzene)pyrrolidine] containing in the side-chain a chiral group of one prevailing configuration linked to a trans-azoaromatic system. As expected it exhibits in solution homogeneous conformations with a prevailing chirality induced by dipole-dipole interactions between side-chain chromophores. Copolymers with the enantiomeric monomer (S)-3-methacryloyloxy-1-(4′-cyano-4-azobenzene)pyrrolidine have also been prepared in order to evaluate the effect on the photoinduced optical properties of side-chain chiral groups of opposite configuration in various ratios. The possibility of producing reversible photomodulation of linear birefringence without any significant degradation of these materials seems to be promising for their use in optical data storage.     

对羟基苯氧基蒽醌的合成与表征

合成了两种新的光致变色化合物1-羟基-4-苯氧基-9,10-蒽醌及1-羟基-4-对氯苯氧基-9,10-蒽醌,并通过核磁共振谱、红外光谱、质谱和元素分析确定了其结构。通过紫外-可见光谱表征了其光致变色性,并讨论了结构对光致变色性的影响。     

Synthesis and characterization of coumarin and dimedone-derived diazabicycles

A series of diazabicyclic derivatives were prepared in three to four steps from p-anisidine and p-nitrobenzaldehyde. The key step of the synthesis involved the acid-catalyzed coupling of 4-aminocoumarin or dimedone derivatives with amino alcohols 3 or 7 to give the ring-opened forms 4, 10, 12 and the ring-closed diazabicycles 5, 6, 9, 11. When 4-alkylaminocoumarins were used as the coupling reagents, the major cyclized product was N-dealkylated diazabicycle 5, rather than the corresponding N-alkylated products. Alternatively, compound 4 was cyclized by DDQ oxidation to produce quinone imine 13. The molecular structures of the synthesized compounds were characterized by X-ray crystallography.     

Design and characterization of a Li-selective optical sensor

An optical ion-sensing system based on a PVC membrane containing a Li⁺ ionophore in combination with a H⁺ selective chromoionophore (ETH 5294) is presented. It exhibits an absorbance response to Li⁺ concentration in pH buffered solutions. The dynamic range and Li⁺/Na⁺ selectivity of this new optode system are discussed.     

Synthesis and characterization of fluorophore-absorber pairs for sensing of ammonia based on fluorescence

A new and simple preparation procedure for fluorophore absorber pairs which enable optical sensing of ammonia is reported. In ion pairs formed between organoruthenium complexes (fluorophore) and triphenylmethane dyes (absorber), a deprotonation of the absorber leads to an absorbance band which overlaps the emission of the fluorophore whereby both the fluorescence intensity and the fluorescence lifetime of the fluorophore are altered. Dissolving these ion pairs in polymer materials such as poly (vinyl chloride) or porous glass obtained by the sol–gel process results in membranes which respond to ammonia. Plasticized PVC membranes containing the fluorophore-absorber pair and coated with a PTFE layer allow a continuous assay of dissolved ammonia in the range of 0.01 to 25 mg l⁻¹. Membranes composed of the ion pair dissolved in a sol–gel-based glass and coated with PTFE respond to ammonia with a similar sensitive range and a limit of detection of 0.01 mg l⁻¹.     

Synthesis, chiroptical properties and photoinduced birefringence of optically active methacrylic copolymers bearing side-chain bisazoaromatic moieties

Three series of optically active photochromic copolymers, deriving from methyl methacrylate (MMA) and the chiral bisazoaromatic monomers (S)-3-methacryloyloxy-1-[4′-phenylazo-(4-azobenzene)]-pyrrolidine [(S)-MPAAP], (S)-3-methacryloyloxy-1-[4′-cyanophenylazo-(4-azobenzene)]-pyrrolidine [(S)-MPAAP-C] and (S)-3-methacryloyloxy-1-[4′-nitrophenylazo-(4-azobenzene)]-pyrrolidine [(S)-MPAAP-N], have been prepared and characterized in solution and in the solid state with the aim to evaluate the effect on their chiroptical and thermal properties originated by the insertion of inactive MMA groups along the main chain. The optical activity displayed by the bisazo polymers is discussed in terms of extent of chiral conformation assumed by the macromolecules as a consequence of dipole-dipole interactions between the bisazoaromatic chromophores.The photoinduction of birefringence has been assessed on thin films of the investigated copolymers in order to evaluate their behaviour as materials for optical data storage. The results are interpreted in terms of copolymer composition and conformational stiffness of the bisazoaromatic chromophoric co-units, which are responsible for the optical response rates, and are compared to those of the similar derivatives containing only one azo bond. The observed enhanced thermal properties and the temporal stability appear of interest for a potential use of these materials in nano technologies for all-optical data manipulation and in optoelectronics.     

Infrared, optical absorption, and EPR spectroscopic studies on natural gypsum

The natural gypsum has been investigated by infrared, Raman, X-ray diffraction, optical absorption and electron paramagnetic resonance spectroscopy. The fundamental stretching and bending vibrations observed in the infrared region for SO₄²⁻ and H₂O are compared with the near-infrared overtones and combinations of these vibrations. MIR and Raman spectral features are attributed to sulfate fundamentals and lattice vibrations of H₂O, SO₄²⁻. The charge transfer and ligand field transition bands were observed near 490, 630, and 800–900 nm and were compared to those of iron oxides. The optical absorption spectrum indicates the presence of ferric and ferrous ions in the mineral. The site symmetry of Fe(III) in the sample is tetragonally distorted. EPR results indicate the presence of the ferric ion in a tetragonally distorted state.     

Synthesis, optical and electrochemical characterization of lnter-ring bridged tetramers based on thiophene

Tetramers based on thiophene and phenylene residues in which the torsion angles between thiophene rings are locked by a chemical bridge have been synthesised by organosynthetic routes. The effect of locking on photoluminescence and absorption in solution has been studied. An enhanced tendency of doubly locked tetrathiophene to aggregate together with its facile decomposition upon light exposure greatly influence the luminescence properties.     

1,3,4-噁二唑键联二芳基乙烯化合物的合成及性质

将1,3,4-噁二唑基团引入二芳基乙烯分子中, 合成了2种新的二芳基乙烯类光致变色化合物1-氰基-2-(2H-5-苯基-1,3,4-噁二唑)-1,2-二(2,4,5-三甲基-3-噻吩)乙烯(3)和1,4-二{[1-氰基-2-(2H-5-苯基-1,3,4-噁二唑)-1,2-二(2,4,5-三甲基-3-噻吩)乙烯]-1,3,4-噁二唑}苯(4). 通过IR, NMR, MS和元素分析对化合物进行了结构表征, 并研究了其UV-Vis吸收、荧光发射、动力学特性和抗疲劳性质. 实验结果表明, 化合物[STHZ]3[STBZ]和[STHZ]4[STBZ]具有良好的光致变色性质, 光致变色闭环反应为零级反应, 开环反应为一级反应.     

Synthesis, spectroscopic characterization and alignment of novel azobenzene-containing monomers

A series of novel bifunctionalized photochromic monomers were synthesized, focusing on those with polymerizable acrylic/methacrylic groups attached to both ends of an azobenzene core via flexible spacers. The phase behaviour of the monomers was investigated using DSC, polarizing optical microscopy and X-ray diffraction. The change in UV-vis absorbance of the monomers under illumination with non-polarized/polarized UV light was studied for both solutions and thin films; also studied was its relaxation in the dark. On illumination with LPUV light, in-plane reorientation of the molecules normal to the polarization of the exciting UV light, and aggregation of the molecules in the films, were found.