Shouzhi Pu

Multi-addressable molecular switches based on a new diarylethene salicylal Schiff base derivative

A novel photochromic diarylethene with a salicylidene Schiff base substituent has been synthesized and characterized. The diarylethene could be used as a multi-addressable fluorescence switch when triggered by light, protons and metal ions. As a result, two logic circuits were constructed with the unimolecular platform by using the fluorescence intensity at different wavelengths as outputs and appropriate combinational stimuli of UV/Vis light, TEA/TFA, and Al(III)/EDTA as inputs. Moreover, the diarylethene derivative was found to be highly selective towards Al(III) with significant color and fluorescence changes for potential applications as colorimetric fluorescent chemosensors.

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.

Photochromism of Asymmetrical Diarylethenes with a Pyrrole Unit: Effects of Aromatic Stabilization Energies of Aryl Rings

Four novel asymmetrical diarylethenes with a pyrrole and a variable aryl unit have been synthesized. Their crystal structures and photochromic performance were systematically studied to elucidate the effects of the aromatic stabilization energy (ASE) of aryl units. Experimental results showed that their thermal stability as well as cyclization quantum yield, photoconversion ratio, fluorescence modulation efficiency, and fatigue resistance exhibited a strong correlation with ASE.

Synthesis of 2-(Polyfluoroaryl)benzofurans via a Copper(I)-Catalyzed Reaction of 2-(2,2-Dibromovinyl)phenol with Polyfluoroarene

A novel and efficient route for the synthesis of 2-(polyfluoroaryl)benzofurans via a copper(I)-catalyzed tandem reaction of 2-(2,2-dibromovinyl)phenol with polyfluoroarene is reported. The corresponding products are generated in good yields. During the reaction process, a copper-catalyzed intramolecular C-O bond formation and a C-H activation are involved.

A highly selective fluorescence sensor for Zn2+ and Cu2+ based on diarylethene with a piperazine-linked amidoquinoline unit

A novel asymmetrical diarylethene compound with a piperazine-linked amidoquinoline unit was synthesized and its multi-controllable switching behaviors induced by light and chemical stimuli were investigated in detail. The diarylethene compound was highly selective towards Zn2+ and Cu2+ with different fluorescence signals and binding modes. When triggered by Zn2+, its fluorescence intensity was enhanced evidently and its emission peak was red-shifted from 417 nm to 502 nm with a concomitant color change from light blue to bright green. In contrast, its fluorescence intensity notably decreased accompanied with a color change from light blue to dark when stimulated by Cu2+. The binding affinity of the diarylethene compound to Cu2+ (irreversible) was much higher than to Zn2+ (reversible) with a binding stoichiometry of 1 : 1 to both ions. In addition, its light and metal-responsive fluorescence behavior was applied to the construction of a molecular logic circuit with four inputs and one output.

Recent advances in diarylethene-based multi-responsive molecular switches

In the past decade, extensive functionalization of diarylethene backbones has enabled these molecules to respond not only to light but also to other external stimuli and extended their applications to biological and materials sciences. In this review, the recent progress on diarylethene-based multi-responsive molecular switches is summarized with emphasis on the modulation of their photophysical properties by multiple external stimuli, their structure–property–function relationship, and their underlying operating principles.

Enhancement of cyclization quantum yields of perfluorodiarylethenes via weak intramolecular interactions

The weak intramolecular F∙∙∙N and S∙∙∙N interactions in the novel pyridine-containing perfluorodiarylethenes achieved high cyclization quantum yields in solutions. While the F∙∙∙N interactions stabilize the photoreactive conformation, the S∙∙∙N contacts contribute from the energetic aspect.

Highly sensitive and selective fluorescent sensor for zinc ion based on a new diarylethene with a thiocarbamide unit.

A new photochromic diarylethene has been synthesized by using thiocarbamide as a functional group and perfluordiarylethene as photoswitching trigger via a salicylidene Schiff base linkage. The diarylethene could be used as a multicontrollable fluorescence switch when triggered by base/acid, light, and metal ions. The results showed that the absorption and fluorescence characteristics of the diarylethene exhibited sequence-dependent responses through efficient interaction of specific salicylidene Schiff base-linked thiocarbamide unit with tetrabutylammonium hydroxide/trifluoroacetic acid and photoirradiation. Moreover, the diarylethene was highly selective toward Zn(2+) ion with obvious fluorescence change from light blue to bright yellow in acetonitrile. The deprotonated form of the diarylethene had typical photochromism, but it showed an irreversible photocyclization reaction after binding with Zn(2+). Finally, two logic circuits were constructed by using the fluorescence intensity as the output signal with the inputs of the combinational stimuli of light and chemical species.

Photochromic Diarylethene for Two-Photon 3D Optical Storage

The photochromic diarylethene, 1, 2-bis(2-methyl-5-(3-trifluorophenyl)-3-thienyl)perfluorocyclopentene (BMTTP), was synthesized. This compound undergoes a photochromic reaction either in solution, PMMA amorphous film or in the single crystalline phase. Using this compound as recording medium, two-photon optical bit pattern storage was performed successfully by a femtosecond laser and a reflection confocal scanning-fluorescence microscope.

Polarization multiplexing holographic optical recording of a new photochromic diarylethene

A new unsymmetrical photochromic diarylethene 1a is synthesized, and the photochromic properties of it are also investigated. The compound exhibits good photochromism with UV/ visible light irradiation. Compound 1a in polymethyl methacrylate ( PMMA ) film changes color upon 313- nm light irradiation from colorless to blue, in which the absorption maximum is observed at 587 nm. Photon- mode polarization multiplexing holographic optical recording is performed successfully using this compound as a recording medium. In the diarylethene 1b/ PMMA film, polarization multiplexing hologram recording and retrieval, and a combination with the angular multiplexing scheme, are demonstrated systematically. The results indicate that recording capacity can be significantly improved with the combined method of polarization and angular multiplexing holographic recording