Shiqiang Cui

Multi-addressable molecular switches based on photochromic diarylethenes bearing a rhodamine unit

Two novel diarylethene derivatives bearing a rhodamine unit have been successfully synthesized. Their unique multi-addressable switching characteristics as induced by chemical and optical dual inputs stimulation were observed using UV and FL measurements. The two diarylethenes showed excellent photochormism with alternating UV/vis light irradiation. Addition of trifluoroacetic acid (TFA) protonated the diarylethenes, which resulted in good photochromism and notable fluorescence change via the FRET mechanism. Subsequent addition of triethanolamine base would neutralize and return both their protonated open-ring and closed-ring isomers to their original forms. It was found that the diarylethene bearing a rhodamine unit linked by a benzhydrazide bridge group was more sensitive, efficient and reacted faster to protonation by TFA when compared to the benzamide bridged derivative. Furthermore, the benzhydrazide bridged diarylethene derivative was found to be selective towards Cr(III), Al(III), or Ca(II) with significant color and fluorescence changes.

Multi-responsive photochromism of a new diarylethene with a salicylaldehyde group

A new photochromic diarylethene with a salicylaldehyde group was synthesized and fully characterized. With the stimulation of acid/base and light, the diarylethene showed multi-responsive photochromism. The deprotonated derivative of the diarylethene with salicylaldehyde group, due to the addition of triethylamine into its solution, also showed excellent photochromism with distinguishable color change. And the deprotonated example could recover its original state with trifluoroacetic acid. Furthermore, the processes of photochromism and acidichromism could be effectively modulated with light and chemicals. Cyclic voltammetry tests suggested that triethylamine could significantly decrease band-gaps of both open-ring and closed-ring isomers of the diarylethene.

The effect of the formyl group position upon asymmetric isomeric diarylethenes bearing a naphthalene moiety

Summary Three new isomeric asymmetric diarylethenes with a naphthyl moiety and a formyl group at the para, meta or ortho position of the terminal benzene ring were synthesized. Their photochromism, fluorescent-switch, and electrochemical properties were investigated. Among these diarylethenes, the one with a formyl group at the ortho position of benzene displayed the largest molar absorption coefficients and fluorescence quantum yield. The cyclization quantum yields of these compounds increased in the order of para < ortho < meta, whereas their cycloreversion quantum yields decreased in the order of meta > para > ortho. Additionally, all of these diarylethenes functioned as effective fluorescent switches in both solution and PMMA films. Cyclic voltammograms proved that the formyl group and its position could effectively modulate the electrochemical behaviors of these diarylethene derivatives.

A multi-addressable diarylethene for the selective detection of Al3+ and the construction of a logic circuit

A novel photochromic diarylethene with a naphthalofuran group was designed and synthesized, and its structure was determined by single-crystal X-ray diffraction analysis. Its multi-addressable properties were investigated using light stimulation and chemical agents. The diarylethene was highly sensitive to Al3+ with obvious emission intensity and fluorescent color changes, indicating that it could act as a naked-eye fluorescent sensor for Al3+. Furthermore, a combinational logic circuit was constructed with the unimolecular platform using four input signals (In1: UV light; In2: visible light; In3: Al3+; In4: DETA) and one output signal (fluorescence intensity at 536 nm).

Synthesis, crystal structure and photochromic properties of a new unsymmetrical diarylethene

A new unsymmetrical diarylethene bearing a pyridine group, 1-(2-methyl-5-phenyl-3-thienyl)-2-[2-methyl-5-(2-pyri-dyl)-3-thienyl]perfluorocyclopentene (3o), was synthesised and its structure determined by single-crystal X-ray diffraction analysis. This diarylethene exhibits excellent photochromic properties by alternate irradiation with UV and with visible light. Diarylethene 3o dissolved in hexane or embedded in a poly(methyl methacrylate) (PMMA) amorphous film showed good fluorescence switching properties. In the photostationary state, the fluorescence intensity can be quenched to 20% in hexane and to 29% in PMMA.

Synthesis of a new Diarylethene for Optical Recording

A novel photochromic diarylethene bearing five and six-membered aryl units 1-[(2-methyl-5-(3-pyridinyl)-4-thienyl)]-2-[(2-methoxylphenyl)]perfluorocyclopentene was synthesized and its photochromic, fluorescent electrochemical propertieswere investigated in detail. using diarylethene (1a) as recording medium, polarization holographic optical recording was carried out successfully.

Synthesis and Fluorescence Switching of a New Photochromic Diarylethene

A new photochromic diarylethene compound, 1-[2-methyl-5-(4-pyridine) -3-thienyl]-2-[2-methyl-5-(4-methoxylphenyl)-3-thienyl]perfluorocyclopentene(1a) was synthesized. its photochromism was investigated. It showed good photochromism both in solution and PMMA amorphous film upon photoirradiation. Its fluorescence properties in the solution also were reaearched.

Synthesis a New Photochromic Diarylethene for Electrochemical Switching and Holographic Optical Recording

A novel unsymmetrical photochromic diarylethene, 1-[2-methyl-5-(4-methylphenyl)-3-thienyl]-2-[2-methyl-5-(4-formylphenyl)-3-thienyl] perfluoroyclopentene(1a), was synthesized, its photochromic properties and electrochemical properties were examined, the result indicated that the colorless open-ring isomers were assigned to the exclusive oxidation process, but the closed-ring isomers of these compounds were assigned to two redoxation processes and the peaks shift are obvious. Using diarylethene 1b/PMMA film as recording medium and a He-Ne laser (633 nm) for recording and readout, four types of holographic optical recording were performed perfectly. the results demonstrated that the orthogonal circular polarization recording is the best method for polarization holographic optical recording when this compound was used as recording material.

A highly selective fluorescence “turn-on” sensor for Ca2+ based on diarylethene with a triazozoyl hydrazine unit

A new photochromic diarylethene derivative with a triazozoyl hydrazine unit has been designed and synthesized. Its photochromism and photoswitchable fluorescence behaviors were studied systematically by the stimuli of lights and chemical substances in acetonitrile solution. With the addition of Ca2+, the emission intensity enhanced 6.7 fold, accompanied by an obvious fluorescent color change from dark to light blue. The complexation between the derivative and Ca2+ is reversible with the 1 : 1 stoichiometry, which was verified by Jobs plot and MS. The limit of detection (LOD) for Ca2+ was determined to be 2.49 × 10−8 mol L−1. Based on this unimolecular platform, a logic circuit was designed with fluorescence intensity at 482 nm as the output and the combined stimuli of UV/vis and Ca2+/EDTA as four inputs.

A highly selective fluorescent sensor for Al3+ based on a new diarylethene with a 3-hydroxy-2-naphthohydrazide unit

A novel diarylethene derivative with a 3-hydroxy-2-naphthohydrazide unit was successfully synthesized. It displayed favorable photochromism upon irradiation with UV/vis lights. The deprotonated derivative of the diarylethene, due to the addition of triethylamine into its solution, also showed excellent photochromism with a distinguishable color change. The deprotonated example could recover its original state using trifluoroacetic acid. Furthermore, the diarylethene was highly selective toward Al3+ with an obvious fluorescent color change from dark to green in acetonitrile. Finally, two logic circuits were constructed on the basis of the unimolecular platform with multi-responsive photochromism and fluorescent switching properties.