All‐Optical Integrated Logic Operations Based on Chemical Communication between Molecular Switches

Abstract

Molecular logic gates process physical or chemical "inputs" to generate "outputs" based on a set of logical operators. We report the design and operation of a chemical ensemble in solution that behaves as integrated AND, OR, and XNOR gates with optical input and output signals. The ensemble is composed of a reversible merocyanine-type photoacid and a ruthenium polypyridine complex that functions as a pH-controlled three-state luminescent switch. The light-triggered release of protons from the photoacid is used to control the state of the transition-metal complex. Therefore, the two molecular switching devices communicate with one another through the exchange of ionic signals. By means of such a double (optical-chemical-optical) signal-transduction mechanism, inputs of violet light modulate a luminescence output in the red/far-red region of the visible spectrum. Nondestructive reading is guaranteed because the green light used for excitation in the photoluminescence experiments does not affect the state of the gate. The reset is thermally driven and, thus, does not involve the addition of chemicals and accumulation of byproducts. Owing to its reversibility and stability, this molecular device can afford many cycles of digital operation.

Building pH Sensors into Paper-Based Small-Molecular Logic Systems for Very Simple Detection of Edges of Objects

“…Figure 2b shows that 1 is largely preserved during irradiation, whereas 2 is significantly decomposed (into 3 and H + ). 46 It is worth reiterating that the irradiated areas are understood to show XOR logic using light dose inputs [40][41][42] and fluorescence output. On the other hand, no logic assignment can be made in a similar manner to the visualized edges themselves or to the unirradiated areas since the light dose is not supplied directly to those places.…”

Molecular Switches as Platforms for Information Processing

“…This inhomogeneity of the signals impedes direct gatetogate communica tion. In order to overcome this problem several strategies were published as proof ofprinciple, among them communication via EnT [17] or through the generation of chemical species such as protons [18] or sin glet oxygen [19] as output signals.…”

Molecular Implementation of Sequential and Reversible Logic Through Photochromic Energy Transfer Switching

“…Effectively, a chemical (sensing) input and a remote-addressing photonic input are combined in a "hybrid approach" (neither all-chemical nor all-photonic). This can be used to devise comprehensive logic operations, [52][53][54][55][56][57] beyond the bistable photoswitching of spiropyrans (SP!ME and vice versa). It should be noted here that other classical photochromes, such as dithienylethenes or fulgimides, have only two differentiated states (closed and open form).…”