Crystal Structure and Crystalline State Multiphotochromism Properties of a Fused Diarylethene Dimer

The crystal structure of fused photochromic diarylethene dimer, 1,4-bis-[4-(4-{2-(5-phenyl)-2-methyl-thiophen-3-yl]-3,3,4,4,5,5-hexafluoro-cyclopent-1-enyl}-5-methyl-thiophen-2-yl) buta-1,3-diyne(1 oo, C46 H23 F12 S4) was determined by single-crystal X-ray diffraction analysis. This crystal belongs to the triclinic system, space group P1 with a = 7.546(3), b = 8.869(3), c = 16.196(5), α = 98.000(4)°, β = 100.803(4)°, γ = 98.449(4)°, Z = 2, V = 1037.6(6) ?~3, Dc = 1.496 mg/m^3, μ = 0.317, F(000) = 474, the final R = 0.0428 and wR = 0.1199 for 4115 observed reflections(I > 2σ(I)). Further study demonstrated this compound underwent reversible photochromism with color-switching between colorlessness and green in crystalline state. Upon 365 nm irradiation, the diarylethene shows one step photochromism to form isomer 1 oc. When irradiated with 312 nm, the stepwise photocyclization reactions occurred in diarylethene dimer through the line of 1 oo to 1 oc to 1 cc.

Synthesis,Structure and Photochromism of a New Diarylethene and Its Ag(Ⅰ) Complex

A new symmetric diarylethene containing cyano group was synthesized and structurally characterized by elemental analysis,IR,1 H NMR and X-ray single-crystal diffraction.It belongs to the monoclinic system,space group C2/c with a = 18.848（6）,b = 8.561（2）,c = 16.875（5） ？,β = 100.398（6）o,V = 1344.6（11） ？~3,Z = 4,μ = 0.262 mm^（-1）,Dc = 1.415 g/cm^3,Mr = 570.56,F（000） = 1160,the final R = 0.0808 and wR = 0.2107 with I 〉 2σ（I）.The two thienyls adopt reactive anti-parallel conformation and the carbon distance of photocyclization is 3.57 ？.The neighboring molecules are stacked closely with C-H…F hydrogen bonding.In addition,the photochromism of the new compound was investigated in solvents with different polarity and PMMA film.The alternative photo-irradiation of 254 nm light and ≥550 visible light can induce the reversible photo-cyclization and photo-reversion with the color interconversion between colorlessness and blue.In THF solution,the λ（max） of diarylethene in PSS in visible band is 585 nm.The diarylethene further reacted with AgBF4 in benzene to give rise to complex 1,which was structurally characterized by elemental analysis,IR,ESI-MS and TG.1 demonstrated reversible photochromism in both solution and PMMA film.The complexation of metal ions with diarylethene leads to a minor red-shift of the λ（max） of 1 in THF in PSS to 590 nm.

Synthesis, Photochromic Property and Application for Optical Recording of a New Asymmetrical Diarylethene

The reversible molecule switching of an assymmetrical photochromic diarylethene 1-[2-methy1-5-(3-chlorophenyl)-3-thienyl]-2-(1,2-dimethy1-3-indol) perfluorocyelopentene (1a) has been prepared for the examination of photo-switching, fluorescence switching. This compound exhibited reversible photochromism, changing from colorless to blue after irradiation with UV light both in solution and in poly-methyl methacrylate (PMMA) amorphous film. Also, it exhibited remarkable fluorescence switching in the solid state. Using diarylethene 1b/PMMA film as recording medium, polarization optical recording was performed perfectly by a He-Ne laser with 633 nm wavelength. The results demonstrated that it can be potentially used as polarization optical recording medium.

Spiro-conjugated indenodiarylethenes: enabling steric-induced electronic tuning of photochromic and photoluminescent properties by spiro-conjugation

Light-operated excited-state photochemical reactions and the resulting photochromic materials have gained significant attention for their promising technological applications in molecular electronic and photonic devices.To obtain photochromic materials(e.g.,diarylethenes)with desired properties,the way to tune energy processes of the excited state is essentially important,from both fundamental and practical viewpoints.The modified diarylethenes mostly focused on structural improvements to achieve efficient photochromism.We report here two new spiro-conjugated indenodiarylethenes(named,SFI-Th and SFI-Sul)with an orthogonally arranged spiroπ-scaffold.The spiro fluorene sterically constrains the free volume of photoactive side aromatic rings,while the spiro-conjugation points toward modulation of the decaying channels of excited-state energy,thus allowing for tuning photochromic performances.These spirodiarylethenes SFI-Th and SFI-Sul are readily accessible with low cost and show distinct photochromic and photoluminescent properties.On one hand,the SFI-Th bearing bisthienyl side rings,is an excellent photochromic switch showing high thermal stability and high fatigue resistance in both solution and amorphous state,likely benefited from steric-induced excited-state energy transfer into reversible photochemical reactions,owing to higherπ-orbital spiro-conjugation between the two molecular halves.On the other hand,the SFI-Sul with bissulfonyl side rings,most notably,displays quantitative photocyclization to yield SFI-Sulc upon excitation.However,the ring-closed SFI-Sulc has an extremely slow photocycloreversion,and meanwhile immediately switches on emissive state with a strong fluorescence(Φf=0.57 in amorphous powder state).We study the modulated roles of spiroπ-scaffold in both cases computationally and experimentally,and attribute the facilitated photochemical reaction to the positively electronic effects of spiro-conjugation,and the photo-responsive radiative transition to the negatively electronic effects of spiro-conjugation,respectively.In all,this work demonstrates that the spiro-conjugation is a new and efficient strategy to deliver excitation energy transfer(EET)for featured photochromic properties,due to its advantage in steric-induced electronic modulation.

Photoswitchable Photon Upconversion from Turn-on Mode Fluorescent Diarylethenes

Photon upconversion(UC)is one kind of anti-Stokes shift process,which generally requires a combination of two or more low-energy photons to produce one high-energy photon.However,another interesting anti-Stokes process,namely,single-photon-absorption-based upconversion(SPA-UC),can take place by exciting thermally excited vibrational-rotational energy levels of ground state to the first level of excited state.This phenomenon is less involved in organic systems due to the limitation of appropriate materials.Herein,for the first time,we have demonstrated a series of turn-on mode fluorescent diarylethenes,including Thiophene-and p-alkoxybromo-substituted phenyl-substituted derivatives(DAES and DAEC4),which exhibited SPA-UC phenomenon in the closed-ring state.An anti-Stokes shift of 0.36 eV was observed in these molecules,which was the highest value accessible in such UC systems.A relatively high quantum efficiency(13.5%)was evaluated through a relative method by using methylene blue as a standard.Phonon-assisted or hot band absorption was in charge of the achievement of SPA-UC.Besides,the upconverted emission could be switched on/off by cyclization and cycloreversion reaction,regulated by UV–visible light.Thus,this unique finding of the SPA-UC phenomena in photoswitchable diarylethenes might enrich the development of new molecular engineering strategies for designing photofunctional materials.

Effects of Aromatic Stabilization Energies on Photochromism of New Asymmetrical Azaindole-Containing Diarylethenes

Three new asymmetrical diarylethenes containing an azaindole moiety and a variable heteroaryl ring have been synthesized. Their properties, such as photochromism, fatigue resistance, thermal stability, acidichromism, and fluorescence, were systematically investigated to elucidate the effects of aromatic stabilization energies （ASE） of the heteroaryl moieties. The results indicated that thermal stability decreased with the increment of the aromatic stabilization energies of the variable heteroaryl rings in the order of thiazyl〈thienyl〈pyrrolyl. Moreover, the dual switching behaviors of these azaindole-containing diarylethenes were also studied by the stimulation of acid/base and light. Addition of trifluoroacetie acid to the solutions of these diarylethenes resulted in obvious hypochromie shifts, and their N-protonated forms also exhibited favorable photochromism.

A Highly Selective Chemosensor for Cu^2＋ Based on a Diarylethene Linking an Aminoquinoline Unit

A new diarylethene derivative containing an aminoquinoline unit was synthesized and its structure was determined by single crystal X-ray diffraction analysis. Its properties such as photochromism, fluorescent switches and detection for metal ions were measured. The results indicated that the closed-ring of the diarylethene was highly selective toward Cu^2＋ with an obvious absorption decrease and color changes from blue to colorless, even in the presence of other metal ions. The binding constant for the closed isomer of this new diarylethene and Cu^2＋ was 2.0× 10^4 L·mol^-1 and the limit of detection for Cu^2＋ was calculated to be lower than that in drink water. Finally, a logic circuit was constructed by using the absorption intensity as the output signal with the inputs of the combina- tional stimuli of light and Cu^2＋.

Acid/Alkali Gated Photochromism of Diarylethenes with Quinoline Derivatives

Three new diarylethenes 1--3 combined with quinoline derivatives have been synthesized. Through controlled chemical condition of deprotonation/protonation, they presented some new irreversible photochromic phenomenons under UV/Vis light irradiation in chloroform solution. It was found that 1--3 had well photoisomerization upon UV/Vis light irradiation in neutral chloroform solution. Addition of acid to the solution of the ring-opening isomers of 1--3 produced 1 oa--3oa, which performed reversible photochromic behavior under UV/Vis light irradiation and reversed back to 1--3 under neutralizing with adding lewis base. However, addtion of base to neutral soluton of the ring-opening isomers of 1--3 produced lob--3ob, which could not change to the deprotonated ring-closing isomers under UV light irradiation.

A novel family of diarylethene-phthalocyanine dyad systems for nondestructive data processing

A novel family of diarylethene (DTE)-phthalocyanine (Pc) dyad systems were designed and synthesized. It was found that the significant change in the extension of the linear π-conjugation of DTE when irradiated by 254 nm UV light directly made the absorption of the Q-band of phthalocyanine decrease. Detecting the absorption changes of the Q-band would not induce the reversible photochromic reaction. Therefore, non-destructive readout was feasible based on the spectral changes of the Q-band when such materials were used as storage media.

Enhancement of Optical Density of Photochromic Diarylethene with Multiphotochromophores

3,4-Diaryl-2,5-dihydropyrrole with multiphotochromophore units la was synthesized and its photochromic properties were investigated. It showed that all photochromophore units underwent reversible ring-opening （1a） and ring-closing （1b） photoisomerization reactions in both solution and polymer film with UV/Vis light irradiation, and photochromic properties of la were similar to those of photochromic diarylethene with monophotochromophore 2a. It was found that the optical density of lb was increased linearly with increase of the photochromophore units by comparison with that of 2b in the same condition. It was also found that no significant changes in absorption band and response time between diarylethenes with multiphotochromophores and monophotochromophore were detected in the same condition.

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.

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.

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.

Crystal Structure and High Contrast Color-/fluorescent-switching Properties of 1-[2-Methyl-5-(4-chlorophenyl)-3-thienyl]-2-(2-methoxylphenyl)hexafluorocyclopentene

A new photochromic diarylethene, [1-（2-methyl-5-（4-chlorophenyl）-3-thienyl-2-（2- methoxylphenyl）]perfluorocyclopentene （1o, C23HIsC1F6OS） was synthesized and its structure was determined by single-crystal X-ray diffraction analysis. The crystal belongs to the triclinic system, space group Pi with a = 9.421（1）, b = 10.4664（1）, c = 11.2988（2）, α= 88.014（1）, β= 76.976（1）,γ= 82.319（1）°, Z= 2, V= 1075.7（2） A3, Dc = 1.509 mg/m3, μ= 0.339 mm-1, F（000） = 496, the final R = 0.0353 and wR = 0.0922 for 3303 observed reflections （I 〉 2σ（I））. Further study demonstrated this compound underwent reversible photochromism with high contrast color-switching between colorless and blue in hexane. Upon UV/Vis irradiation, the fluorescence quenching efficiency can be attached to ca. 98% and recover to the initial state which exhibits high contrast fluorescentswitching between ＂on＂ and ＂off＂ states.

Synthesis and Crystal Structure of cis-1,2-Dicyano-1,2-bis(2-methyl-4-bromo-3-thienyl)ethane

The title compound cis-1,2-dicyano-1,2-bis（2-methyl-4-bromo-3-thienyl）ethane has been synthesized and structurally characterized by X-ray single-crystal diffraction method. Crystal data： triclinic, space group P1^1, Z = 2, C14H8Br2N2S2, Mr = 428.16, a = 6.9410（5）, b = 11.0150（9）, c = 11.1760（8） A, α = 70.3390（10）,β = 76.1860（10）, γ = 79.5490（10）°, V= 776.59（10） A^3, Dc = 1.831 g/cm^3, μ（MoKα） = 5.478 mm^-1, F（000） = 416, R = 0.0487 and wR = 0.1453 for 2456 observed reflections with I 〉 2σ（/）. X-ray analysis reveals that the two thiophene rings are significantly twisted with an average dihedral angle of 57.45°. The molecule adopts a photo-active antiparaUel conformation and the distance between the two reactive C atoms of thiophene rings is 3.465（8）A. These structural elements which exhibit a suitable geometry are extensively explored for photochromic behavior in the crystalline state.

一种快速响应的光致变色SCC-MOF用于光开关和信息加密

由于银硫簇的不稳定性和有限的刺激响应特性,构建新型的具有光开关性质的银-硫簇基金属有机框架(SCC-MOF)面临着重大挑战.基于此,本文设计并合成了一种新型光致变色的SCC-MOF(Ag_(12)-BMPTC),该材料利用二芳基乙烯配体和银硫簇前驱体通过溶剂缓慢挥发而得到.Ag_(12)-BMPTC在365和500 nm光照射下表现出优异的可逆光响应特性.此外,这种光开关性质为其在信息加密和手性开关方面提供了潜在应用.本研究不仅扩大了SCC-MOF的种类,而且为设计和合成新型光致变色材料提供了新的思路和潜在应用.

基于可重构光开关多态荧光聚合物的信息加密工具箱

具有坚固、智能、且易于编程等特性的信息加密材料对于防止信息泄露和打击造假具有重要意义.为此,我们开发了一种信息加密材料工具箱,该工具箱基于一系列新型的自修复光开关双态(P1和P2)和多态(P3)荧光聚合物.这类聚合物含有两种二芳基乙烯光致变色荧光基团(SDTE和BTBA)和四重氢键构筑单元(UPy).在不同波长的光照射下,P1/P2可以在绿-猝灭/红-猝灭两态之间交替,而P3可以在红-绿-猝灭三态之间变化.它们可以作为像素单元用来制备可重构的图案和代码;所得到的图案和代码均显示出良好的机械性能和优异的光学特性,包括快速的光响应性、突出的光可逆性、优异的荧光热稳定性和抗酸碱腐蚀的能力.本文展示了该工具箱在3D代码阵列和二维码信息加密中的应用潜能.

An Optic/Proton Dual-Controlled Fluorescence Switch based on Novel Photochromic Bithienylethene Derivatives

A simple method for the synthesis of new bithienylethenes bearing a functional group on the cyclopentene moi- ety is developed. Three new photochromic compounds （4a, 4b, 4c） have been successfully synthesized through this simple method, and exhibit good photochromic properties with alternate irradiation of ultraviolet and visible light. Furthermore, the fluorescence of compound 4a, which bears a quinoline unit on the cyclopentene, can be modulated via optic and proton dual inputs. Upon excitation by 320 nm light, 4a emits a strong fluorescence at 404 nm. After irradiation with 254 nm light, the emission intensity is reduced due to the fluorescence resonance energy transfers （FRET） from quinoline unit to bithienylethene unit. Moreover, on addition of H~, the fluorescence is quenched completely due to the protonation of the quinoline. In addition, both the FRET and protonation process are reversi- ble, which indicates a potential application in molecular switches and logic gates.