Synergistic regulation of nonbinary molecular switches by protonation and light

Abstract

We report a molecular switching ensemble whose states may be regulated in synergistic fashion by both protonation and photoirradiation. This allows hierarchical control in both a kinetic and thermodynamic sense. These pseudorotaxane-based molecular devices exploit the so-called Texas-sized molecular box (cyclo[2]-(2,6-di(1H-imidazol-1-yl)pyridine)[2](1,4-dimethylenebenzene); 14+, studied as its tetrakis-PF6− salt) as the wheel component. Anions of azobenzene-4,4′-dicarboxylic acid (2H+•2) or 4,4′-stilbenedicarboxylic acid (2H+•3) serve as the threading rod elements. The various forms of 2 and 3 (neutral, monoprotonated, and diprotonated) interact differently with 14+, as do the photoinduced cis or trans forms of these classic photoactive guests. The net result is a multimodal molecular switch that can be regulated in synergistic fashion through protonation/deprotonation and photoirradiation. The degree of guest protonation is the dominating control factor, with light acting as a secondary regulatory stimulus. The present dual input strategy provides a complement to more traditional orthogonal stimulus-based approaches to molecular switching and allows for the creation of nonbinary stimulus-responsive functional materials.

Profile of Jonathan L. Sessler

“…In the Inaugural Article ( 3 ), Sessler and Gong describe a Texas box that, in conjunction with dibasic photo-isomerizable acids, can act as a nonbinary molecular switch. Depending on the pH, the guest molecules for the Texas box can be neutral, mononegative, or dinegative, with a correspondingly different degree of binding.…”

“…The Texas box described in the article ( 3 ) can move through multiple switching events under nonequilibrium conditions. “It’s like instead of just turning your light on and off, you can turn your light on, off, and sideways, which, of course, is key to logic devices, such as transistors,” says Sessler.…”

“One-pot” synthesis of oligopyrrolic dialdehydes

“…Heterocycle bridged dialdehydes constitute a family of building blocks that have found diverse applications in materials chemistry and beyond. 1–6 Within this class of compounds, α,α′-linked oligopyrrolic dialdehydes have emerged as useful building blocks for the construction of expanded porphyrins and related macrocycles, as well as molecular cage systems. 7–12 To date, extensive efforts have been dedicated to developing improved and convenient routes to various heterocycle bridged α,α′-linked oligopyrrolic dialdehydes.…”

Tunable cyclic operation of dissipative molecular switches based on anion recognition

“…38 To help better understand the design of this type of dissipative system, we decide to prepare molecular switches based on Texas-sized molecular box, a well-recognized artificial anion receptor. 39,40 Here, we report the design and preparation of dissipative molecular switches based on Texas-sized molecular box and carboxylate guests. 41 Various activated carboxylic acids are used as chemical fuels, which may undergo decarboxylation under basic conditions.…”

“…38 To help better understand the design of this type of dissipative system, we decide to prepare molecular switches based on Texas-sized molecular box, a well-recognized artificial anion receptor. 39,40…”