Orthogonally Incorporating Dual‐Fluorescence Control into Gated Photochromism for Multifunctional Molecular Switching

Abstract

Gated photochromism is of interest for the operation and control of modern high‐tech optofunctional materials. For further advancing this topic towards the achievement of multifunctional molecular switching, however, it remains a great challenge to incorporate multiple fluorescence regulation into gated photochromism in one unimolecular system. Herein, it is reported that a dithienylethene derivative DTEN with a Schiff base connection can be facilely synthesized by one‐step coupling, and it enabled distinct color and spectral changes upon different stimuli, including ultraviolet, visible light, Ni2+, and Al3+. Relying on hydrazine and hydroxy units in this molecule, compound DTEN exhibited novel Ni2+‐locked photochromic characteristics originating from complexation of the compound with Ni2+ in a 2:1 stoichiometry. On the other hand, a 1:1 complexation between compound DTEN and Al3+ could allow both of the initial and photostationary states of DTEN to display fluorescent enhancement and a redshift, realizing a dual‐fluorescence “turn‐on” sensing of Al3+ by light. On this basis, it is argued that the switching of the coordination mode between DTEN and Ni2+ or Al3+ brings up the possibility of tunable photoswitching by multiple stimuli, which offers a novel way for future development of multifunctional switching materials with different input and output signals, as exemplified by the construction of a delicate molecular circuit.

A monomolecular platform with varying gated photochromism

“…Due to the paramagnetic effect of Cu 2+ , we could not utilize 1 H NMR titration experiments to verify the binding mode of compound DTEP with Cu 2+ , however, based on our reports, [13][14][15][16] we assume that N atom within imide group and O atom within amide group take part in forming complex together as displayed in Scheme 1. As shown in Fig.…”

“…Previous studies on the gated photoreactivity have rationalized that the interaction between DTEP and Cu 2+ completely impedes the electrocyclization reaction among two activated carbon atoms assigned to thiophene moieties. 14,16 In order to further investigate the effect of different amounts of Cu 2+ on the gated photoreactivity of compound DTEP, the dependence of absorbance at 525 nm with irradiation time is plotted in Fig. 4A.…”

“…[5][6][7][8][9][10][11] In recent years, diarylethene derivatives with gated photochromic properties have gradually become a hot topic in the eld of photoelectric materials. [12][13][14][15][16] These gated photochromic properties endow diarylethene derivatives with non-destructive readout, which can efficiently inhibit the proportional photons absorbed by molecules within normal photochromic reactions, further gaining a nonlinear response that can be applied in optoelectronic devices, for instance, optical data storages, chemical sensors and photoresponsive self-assemblies. 9,[17][18][19][20][21] So far, several strategies have been adopted to achieve the gated photochemical reactions of diarylethene derivatives, such as xing two aryl rings in a parallel conformation, 22 altering the structure of ethylene bridge based on chemical reaction, [23][24][25] embellishing substituent groups of the aryl rings, 26,27 inhibiting ring-opening reaction by decreasing temperature, 28 multiphoton-gated photochemical reaction, 29 quenching of photoreactive excited state, 30 modifying reactive surface within selfassembled monolayer or polymer lm, 31 and forming intermolecular hydrogen bonds to control the conformation.…”

“…7 In another hand, compared with chemical reactions and heating, the photoreactivity gated by coordination or complexation is superior, on account of the simple and reversible operation modes between molecules and economical complexation agents by the coordination and dissociation processes. [13][14][15][16] Herein, we designed and synthesized a Schiff base DTEP (see Scheme 1) featured with a diarylethene core and 2-pyridine formhydrazide subunit to respond to Cu 2+ and Ni 2+ with high selectivity. Compound DTEP exhibited the typical photoisomerization reaction upon alternative irradiation with UV and visible light.…”

Protonenvermittelter Ringschluss eines negativ photochromen, Azulen‐basierten Diarylethens

“…Unter ihnen sind photochrome Moleküle aufgrund ihrer Fähigkeit zur Umwandlung zwischen (mindestens) zwei Zuständen durch nicht‐invasive und schnelle optische Stimuli bei gleichzeitig potentiell hoher räumlicher und zeitlicher Auflösung besonders attraktiv . Darüber hinaus wurden photochrome Moleküle entwickelt, die zusätzlich zu Licht auf einen sekundären Stimulus reagieren, beispielsweise auf die Anwesenheit von Ionen, Oxidations‐/Reduktionsmitteln, oder Säuren/Basen . Während einerseits der zweite Stimulus die Photochromie beeinflussen kann, wodurch potenzielle Anwendungen z.…”