13 metastable states arising from a simple multifunctional unimolecular system

Sanguinet, Lionel; Berthet, Jérôme; Szalóki, György; Alévêque, Olivier; Pozzo, Jean‐Luc; Delbaere, Stéphanie

doi:10.1016/j.dyepig.2016.10.027

Cited by 5 publications

(8 citation statements)

References 21 publications

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“…Therefore, a system combining n different two-state molecular switches exhibits theoretically 2 n different forms, each one possessing its own properties. An illustration is given by the system built from the following three different units: a BOX, a diarylethene, and an alkene linker (which can exhibit two isomers: cis and trans ), leading to an octa-state molecular switch. − However, in that case, the different reactions of switching can be in competition and may lead to difficulties in controlling one or more forms of the molecular switch, especially if the photoisomerization reactions are achieved in similar conditions. This is particularly true when the different molecular switches are chemically close to each other.…”

Section: Introductionmentioning

confidence: 99%

Combining Benzazolo-Oxazolidine Twins toward Multi-state Nonlinear Optical Switches

et al. 2021

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Molecular switches are chemical compounds exhibiting the possibility of reversible transformations between their different forms accompanied by a modification in their properties. Among these, switching of multi-addressable Benzazolo-OXazolidines (BOXs) from a closed form to an open form results in drastic modifications in their linear and nonlinear optical properties. Here, we target molecules containing two identical BOX units (DiBOX) connected by different π-conjugated linkers, and we combine synthesis, UV/visible absorption, and hyper-Rayleigh scattering (HRS) measurements, together with density functional theory (DFT) calculations. Three derivatives have been considered, which differ by the linker: (i) a bithiophene moiety (Bt), (ii) two 3,4-ethylenedioxythiopene (EDOT) units, and (iii) a triad composed of an EDOT−thiophene−EDOT sequence (TtO). As a matter of fact, these systems can adopt three states (CF−CF, POF−POF, and CF−POF) depending on the closed form (CF) or the protonated open form (POF) of each BOX unit. Despite chemical equivalence, stepwise switching of such systems under the addition of a chemical acid or an oxidant has been experimentally evidenced for two of them (DiBOX-Bt and DiBOX-TtO). Then, DFT calculations show that the first BOX opening leads to the formation of a push−pull π-conjugated segment, exhibiting a huge increase in the first hyperpolarizability (β) and a bathochromic shift with respect to the fully closed form. On the contrary, the second BOX opening induces not only a slight bathochromic shift but also a reduction in their β values conferring the great and uncommon abilities to modulate their linear and nonlinear properties over three discrete levels. Among these results, those on DiBOX-Bt agree with the experimental data obtained by HRS measurements and further shed light on their structure−property relationship.

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Section: Introductionmentioning

confidence: 99%

Combining Benzazolo-Oxazolidine Twins toward Multi-state Nonlinear Optical Switches

et al. 2021

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“…This complex molecular system did not allow addressing selectively each BOX unit under acidic stimulation whatever the open/closed status of the DAE. 41 These results were explained by the almost orthogonality of the BOX units with regard to their olefinic substituent which leads to consider no interaction through bonds between them. 41 Scheme 1.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

BT-2-BOX: An Assembly toward Multimodal and Multilevel Molecular System Simple as a Breeze

et al. 2019

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The design of multistate/multifunctional molecular systems arouses a lot of interest. Such compounds are able to commutate between two metastable states by the application of an external stimulation such as light, heat, protons, or electrons. In this context, we are interested in molecular switches based on indolino-oxazolidine (BOX) which is a relatively less-known sub-class of multimodal addressable units. Their particularity consists of the possibility to induce the opening/closing of the oxazolidine ring by using indifferently light, electrochemical, or acido-basic stimulation. Up to now, most of the reported systems based on BOX have allowed to modulate a molecular property but only between two discrete levels which can only be extended by their association with other classical switchable unit such as a dithienylethene unit. For this reason, we report here our effort to enhance the number of metastable states by simply connecting two identical BOX units by a bithiophene (BT) linker. The resulting system's ability to switch between the three possible metastable states was investigated. Irrespective of the nature of the stimulation, full commutation of the system could be reached, but our work mainly revealed that the opening of both oxazolidine rings occurs in a stepwise manner. If this unreported selectivity upon a unique stimulus with two identical switchable units is observed irrespective of the stimulation, it must be pointed out that its efficiency depends on the nature of the latter. The direct stimulation with acid or light leads to the coexistence of the three different states of the system over a broad stimulation period. On the contrary, the indirect stimulation of BOX via an electromediated process due to the electroactivity of BT enhances the selective addressability between both identical BOX units.

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“…BOX-DTE hybrid switch 21 has two BOX units linked to a DTE core via an ethylenic junction ( Figure 20). [88] Twenty discrete states can be visualized based on the symmetry of 21, and 13 metastable states can be experimentally addressed. When the central DTE is opened, ring opening of the BOX units Other BOX hybrids that have been investigated [89] exhibit complications in their photoswitching processes similar to those found in 20 and 21.…”

Section: Eurjocmentioning

confidence: 99%

“…This protonation-driven change in π-conjugation significantly alters the photoswitching behavior of the DTE unit. [88] membered ring depopulates the orbitals in a manner that resembles the reorganization of electron density occurring during the ring closure of DTE photoswitches. This orbital depopulation promotes the formation of a C-C bond in the cyclohexadiene core and restoration of the aromaticity of the tropylium moiety.…”

Section: Eurjocmentioning

confidence: 99%

“…BOX‐DTE hybrid switch 21 has two BOX units linked to a DTE core via an ethylenic junction (Figure 20). [ 88 ] Twenty discrete states can be visualized based on the symmetry of 21 , and 13 metastable states can be experimentally addressed. When the central DTE is opened, ring opening of the BOX units ( 21 ‐ I ‐ EE → 21 ‐ II ‐ EE ) can be induced by adding TFA (TFA and Et 3 N are universally effective for BOX opening and closing, respectively), irradiation at 254 nm, or electrochemical stimulation.…”

Section: Molecular Switches and Motors Activated By Multiple Orthomentioning

confidence: 99%

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Molecular Switches and Motors Powered by Orthogonal Stimuli

2020

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Synthetic molecular machines are designed to undergo specific nanoscale movements in response to specific physical or chemical stimuli. The “engines” of molecular machines responsible for their motion are usually presented by molecular switches and motors that undergo predetermined shape transformations upon appropriate stimulation. Various types of molecular switches and motors activated by different stimuli, such as light irradiation or chemical input, have been devised and used as the core of mechanically active molecular systems. However, despite extensive research, the structural and functional complexity of state‐of‐the‐art synthetic molecular machines does not rival that of biological or human‐scale counterparts. The most apparent difference is that current molecular machines show only limited modes of translational, rotational, and oscillatory motion that are typically triggered by a single stimulus. A promising strategy for achieving more elaborate movement is to integrate multiple active parts that can be manipulated by orthogonal stimuli. However, this approach is often complicated by mutual interference between the components or between stimuli. In this review, we survey recent notable progress in the development of molecular switches and motors that exhibit distinct modes of movement triggered by orthogonal stimuli. Though this approach is challenging, it may provide insights about the innovation needed to develop next‐generation molecular machines with improved maneuverability and more sophisticated functions.

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13 metastable states arising from a simple multifunctional unimolecular system

Cited by 5 publications

References 21 publications

Combining Benzazolo-Oxazolidine Twins toward Multi-state Nonlinear Optical Switches

Combining Benzazolo-Oxazolidine Twins toward Multi-state Nonlinear Optical Switches

BT-2-BOX: An Assembly toward Multimodal and Multilevel Molecular System Simple as a Breeze

Molecular Switches and Motors Powered by Orthogonal Stimuli

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