Synthesis and Crystal Structure of 1-(2-Methyl-5-formyl-3-thienyl)-2-(2-methoxylphenyl)perfluorocyclopentene

A new family of photochromic diarylethene compounds, 1-（2-methyl-5-formyl-3- thienyl）-2-（2-methoxylphenyl）perfluorocyclopentene （1o） having an unsymmetrically substituted hexafluorocyclopentene unit, was synthesized and its structure was determined. The crystal belongs to the monoclinic system, space group P21/c with a = 15.4866（5）, b = 9.0744（9）, c = 12.6906（3）, β = 90.1480（10）°, Z = 4, V = 1783.4（3）3, Dc = 1.513 mg/m3, μ = 0.25, F（000） = 824, the final R = 0.0579 and wR = 0.1566 for 2584 observed reflections （I 2σ（I））. Interestingly, a colorless compound 1o undergoes photocyclization upon irradiation of UV light to give the blue isomer diarylethene. Upon irradiation with visible light with wavelength greater than 510 nm, the blue compound can return to its initial colorless state.

Spectral Properties and Photochromic Characteristics of Spiropyran Dyes

A bis-benzospiropyran（BBSP） and nitro-substituted indoline spirobenzopyrans（SBP） were prepared by following a simple procedure. The reaction mechanism of synthesizing bis-benzospiropyran is discussed. A comparative analysis of the spectral and photochromic properties between SBP and BBSP was carried out with the aid of a PMMA film. The results indicate that chemical structures and UV irradiation played an important role in the spectral and photochromic properties of SBP and BBSP, which would readily affect λmax of the colored forms and the reversibility. The IR spectra and ^1H NMR spectra of these compounds are used to interpret the photochromic phenomena under different UV irradiation and determine the configurations of SBP and BBSP.

DNA Modification with Photochromic Spiro Compounds

The photochromic spiropyrans and spirooxazine having a succinimidyl ester or isothiocyanate pendant group can form covalent products with transaminated DNA. The absorption spectra and solid reflection spectra of modified DNA with these photochromic spiro compounds were investigated.

Preparation and Photochromic Behavior of Novel Hybrid Inorganic-Organic Thin Film

A novel photochromic complex comprising of Keggin type tungstophosphate acid (PW12) and polyacrylamide (PAM) was prepared. FT-IR results showed that the Keggin geometry of PW12 was still preserved inside the composite, and a charge-transfer bridge was built between PW12 and PAM via hydrogen bond. AFM images indicated that surface topography of polymer matrix changed after adding PW12. Under UV irradiation, the film was reduced photochemically to yield a blue species, which was reversible in the present of oxygen in polymeric network.

Effect of TiO_2 Nanoparticles on Photochromism of WO_3 Colloids

WO2 and TiO2 colMds were synthesized by the hydrolysis technique and part of the TiO2 colloid was treated by means of the hydrothermal method. The photochromic performances of the resulting materials obtained via combining the WO3 colloid with the treated TiO2 colloid and the non-treated TiO2 colloid, respectively, are very different. The TiO2 colloid without hydrothermal treatment can effectively improve the photochromic performance of the WO3colloid. The TiO2 nanoparticles were investigated in detail by XRD, TEM, surface photovohage spectra（SPS） and field-induced surface photovoltage spectrometry（FISPS）. The photochromism mechanism of WO3 colloid is discussed.

Interfacial Behaviors of Azocalixarene Derivatives at the Air/Water Interface and Photochromism in the Langmuir-Blodgett Films

The interfacial behaviors of the non-typical amphiphilic compound p-methylphenylazocalix[4]arene 1 and p-chlorophenylazocalix[4]arene 2 at the air/water interface and photochromism in the Langmuir-Blodgett films were studied by surface pressure-area isotherm and UV-Vis spectra. The results indicate that they can form stable monolayers at the air / water interface although they have no hydrophobic alkyl chains, and their LB film underwent reversible trans-cis photoisomerization on UV and daylight illumination.

Synthesis, Structure and Properties of Two Photochromic Compounds Containing A Pyrazolone-ring

Two photochromic compounds with the pyrazolonering as the photochromic functional structure, 2(1phenyl3methyl4benzoformylpyrazolone5)thiosemicarbazone(PMBPTSC) and 2(1phenyl3methyl4benzoformylpyrazolone5)smethylthiosemicarbazone(PMBPMTSC), were synthesized and characterized by elemental analysis, MS, IR spectra, NMR spectra. The crystal structure of the photocolored product of PMBPTSC was determined by single crystal XRD analysis. The results show that the photochromic phenomenon is due to the photoisomerization from enol form to keto form. Their photochromic properties were studied by powderUV reflectance spectra under the irradiation of 200—380 nm light. The firstorder rate constants of the photocoloring reaction were found to be 780×10 -3 s -1 for compound 1A and 103×10 -3 s -1 for compound 2A.

Synthesis,Photochromism and Crystal Structure of 1-(2-Cyano-1,5-dimethyl-4-pyrryl)-2-[2-methyl-5-(3-pyridyl)-3-thienyl]perfluorocyclopentene

A new family of photochromic diarylethene compounds, 1-（2-cyano-l,5-dimethyl- 4-pyrryl）-2-[2-methyl-5-（3-pyridyl）-3-thienyl]perfluorocyclopentene （lo） having an unsymmetrical pyrryl and thienyl substituted hexafluorocyclopentene unit, was synthesized and its structure was determined by X-ray analysis. The crystal belongs to triclinic system, space group PI with a = 8.897（7）, b = 10.139（8）, c = 12.361（9） A, α = 85.222（7）, ρ = 75.439（7）, γ = 78.736（8）°, Z = 2, V= 1057.8（14） A3, D,.= 1.468 mg/m3, p = 0.220 mm-1, F（000） = 476, the final R = 0.0608 and wR = 0.1754 for 3199 observed reflections （1 〉20（/））. Interestingly, compound 1 exhibits good photochromic properties with alternate irradiation of UV light and visible light （〉 510 nm） to form two photoisomers in hexane solution and crystal phase.

Preparation of Photochromic Waterborne Polyurethane Films:Effect of Spiropyran Concentration on Photochromic Properties

Incorporation of photochromic compounds to the polymer through chemical bonding will result in an enhancement of photoactivity and stabilization of optical properties.Here,spiropyran(SP)was introduced into polyurethane(PU)through semi-continuous emulsion copolymerization to get waterborne polyurethane dispersion(SPU).Studies on photochromic properties by UV-vis technique demonstrated the absorption intensity increased with the increasing of SP concentration and the colorless film turned to purple under UV irradiation.The kinetics for ring-opening and ring-closing reaction against SP were both first order,but the rate constants decreased with the increasing of SP concentration.The prepared SPU films showed reasonable photostability and photoreversibility according to the convenient test methods under UV-vis irradiation.Temperature dependence studies demonstrated that the photobleaching rate increased at higher temperatures with the same SP concentration.The chemical combination between SP and isocyanate(NCO)end group of polyurethane was confirmed through swelling experiments.Morphology studies were conducted by scanning electron microscope(SEM)micrographs and showed good compatibility between SP and PU.

Synthesis,Structure and Properties of a Novel Copolymer with Photochromic and Photoluminescence Functions

Photochromic and photoluminescence materials show bright colors under different excitation conditions,and thus,these functional materials have been applied in many fields.Based on the photochromic and photoluminescence theories,a block copolymer,which could be directly processed into nanofibers by electrospinning,was successfully prepared through atom transfer radical polymerization(ATRP).To synthesize the block copolymer,a vinyl monomer containing a spiropyran unit was employed to prepare the photochromic chain segment,and a polymethyl methacrylate(PMMA)chain segment was introduced to improve the processability of the block copolymer.Acting as the photoluminescence unit,the rare earth complex was linked to the side chain through coordination bonding between the rare earth ions and the ester groups of PMMA.When the photochromic and photoluminescence block copolymer was exposed to different wavelengths of ultraviolet(UV)light and visible(Vis)light,it could show white,red,green,yellow,and blue-purple.These results provide the potential of the as-prepared photochromic and photoluminescence block copolymer for application in fibers and fabrics.

Crystal Structure and Photochromic Properties of [1-(2-Methyl-5-(4-cyanophenyl)-3-thienyl)]-2-(2-methyl-5-phenyl-3-thienyl)perfluorocyclopentene

A new photochromic diarylethene, [1-（2-methyl-5-（4-cyanophenyl）-3-thienyl-2- （2-methyl-5-phenyl-3-thienyl）]perfluorocyclopentene （lo, C28H17F6NS2）, was synthesized and its structure was determined by single-crystal X-ray diffraction analysis. Its crystal belongs to the monoclinic system, space group P21/c with a = 24.1381（5）, b = 9.3834（6）, c = 11.1073（8）, fl = 94.477（4）°, Z = 4, V= 2508.1（3） A3, Dc = 1.445 mg/m3, μ = 0.275, F（000） = 1112, the final R = 0.0482 and wR = 0.1429 for 5834 observed reflections （I 〉 2σ（I））. Further study demonstrated the diarylethene underwent reversible photochromism, changing between colorless and blue in hexane solution, crystalline phase and PMMA films, respectively.

Crystal Structure and Photoreactive Properties of 1-(2,5-Dimethyl-3-thienyl)-2-[2-methyl-5-(N-(quinolin-8-yl)-2-carboxamide)-3-thienyl)]perfluorocyclopentene

The photochromic title compound,C_（26）H_（18）F_6N_2OS_2,contains a 2,5-dimethylthiophene ring and a N-formyl aminoquinolinyl thiophene ring on the C=C double bond of the cyclopentene ring.The dihedral angles between the cyclopentene and attached N-formyl aminoquinolinyl thiophene ring and 2,5-dimethylthiophene ring are 63.0° and 137.1°,respectively.The dihedral angle between the thiophene ring and the adjacent aminoquinoline ring is 5.7°.The molecule adopts an antiparallel conformation,with a distance between the two photoreactive C atoms of 3.763 ？.In addition,the absorption and fluorescence spectral changes were measured in acetonitile and solid at room temperature,and the result showed that the title compound could undergo photochromic reaction in both states.

Transparent Photochromic Wood Composites Incorporating AgBr Nanoparticles for UV-shielding Applications

Transparent wood(TW)is a wood-based biomaterial with several advantages,such as high optical transmittance,low thermal conductivity,and tunable haze.TW is functionalized according to its transparency to broaden its applications in different fields.Several studies have examined wood functionalization in recent years;however,few studies have reported photochromic TW(PTW)for ultraviolet(UV)-shielding window applications.Herein,PTW was obtained by infiltrating the delignified wood template with photochromic silver bromide(AgBr)nanoparticles and a pre-polymerized methyl methacrylate(MMA)mixture solution.The obtained PTW can adjust the luminous flux on change in the color in the visible light region.The photochromic properties were examined,and the optical properties of the composites were characterized using UV-Vis spectrophotometry.Light transmittance of PTW was up to 86.5%at 800 nm before UV irradiation,and it decreased to 70.1%at 800 nm after UV irradiation,as the wood color changed from colorless to dark purple under UV irradiation.Thus,this work not only achieves high-value utilization of wood,but also produces a new material that can be used in varied fields,such as UV-shielding,energy saving,and smart building.

Synthesis,Structure and Photophysical Property of the Schiff Base on N,N-Ethylene-bis(3,5-dichlorosalicylideneimine) and Its Salen-Co(Ⅱ) Complex

The ligand ethylenediamine-3,5-dichloro salicylaldehyde（HS） and its crystal Co（Ⅱ） complex（MS） were yielded.The compounds have been characterized on the basis of elemental analysis,IR and 1H NMR spectral studies.X-ray single-crystal diffraction of crystal MS1 showed a classical Salen-N2O2 tetrahedral coordination model,space group P1 with a = 25.73（2）,b = 9.899（9）,c = 6.753（6） A,β = 103.467（10）o,V = 1673（3） A^3,Z = 4,C16H10Cl4 Co N2O2,Mr = 462.99,Dc = 1.838 g/cm^3,F（000） = 924,μ（Mo Kα） = 1.678 mm^-1（λ = 0.71073 A）,R = 0.0275 and w R = 0.0567 for 1247 observed reflections with I 〉 2σ（I）.Furthermore,luminescent properties were evaluated by UV-Visible absorption and FL spectra.Meanwhile,the thermal stability of compound HS was investigated.TG-DTG showed that the decomposition temperature（Td） of the molecules is up to 256 ℃ and the compound has fine performance in thermal stability.The results also indicated that the target compound HS exhibited certain chemiluminescence properties under the conditions of different time of 365 nm UV light and different temperature.In general,this kind of multi-functional compounds has potential applications in the fields of information storage and nonlinear optical materials.

Processes underlying the laser photochromic effect in colloidal plasmonic nanoparticle aggregates

We have studied the dynamic and static processes occurring in disordered multiparticle colloidal Ag aggregates with natural structure and affecting their plasmonic absorption spectra under pico-and nanosecond pulsed laser radiations, as well as the physical origin responsible for these processes. We have shown that depending on the duration of the laser pulse,the mechanisms of laser modification of such aggregates can be associated both with changes in the resonant properties of the particles due to their heating and melting(picosecond irradiation mode) and with the particle shifts in the resonant domains of the aggregates(nanosecond pulses) which depend on the wavelength, intensity, and polarization of the radiation.These mechanisms result in formation of a narrow dip in the plasmonic absorption spectrum of the aggregates near the laser radiation wavelength and affect the shape and position of the dip. The effect of polydispersity of nanoparticle aggregates on laser photochromic reaction has been studied.

PHOTOCHROMIC PROPERTIES OF (E)-DICYCLOPROPYLMETHYLENE-(2,5-DIMETHYL-3-FURYLETHYLIDENE)-SUCCINIC ANHYDRIDE DOPED IN POLYSTYRENE THIN FILMS

Fulgide 1-E doped in polystyrene polymer films was heated at various annealing temperatures.Upon irradiation with UV light(366 nm),fulgide 1-E undergoes a conrotatory ring closure to the pink colored closed form 1-C.The later color was switched back to the original color when the films were irradiated with white light.The kinetics of photocoloration and photobleaching processes were followed spectrophotometrically by monitoring the absorbance of the ring closed product 1-C at itsλ_(max) of 525 nm.The first-...

Synthesis and Characterization of Two New Photochromic Inorganic-organic Hybrid Materials Based on Keggin-type Polyoxometalates

Two new photochromic inorganic-organic hybrid materials formed from Keggin-type polyoxometalates（POMs） and metronidazole （C6H9N3O3, MNZ）, formulated as H3PMo12OaO-3MNZ·3H2O （1） and H3PW12O40.3MNZ·3H2O（2）, were synthesized and characterized by elemental analysis, IR spectra, electronic spectra, electron spin resonance （ESR） spectra and thermogravi-metry-differential thermal analysis （TG-DTA）. Reflectance spectra show the presence of weak intermolecular charge transfer between the organic and inorganic moieties in the solid state. The photochromic properties were studied by solid diffuse reflectance spectra and ESR spectra, and the photochromic reactions were found to exhibit first-order kinetics. TG-DTA showed that two hybrid materials have similar thermal behavior.