Information gathering and processing with fluorescent molecules

A Reconfigurable, Dual-Output INHIBIT and IMPLICATION Molecular Logic Gate

Molecules that respond to input stimulations to produce detectable outputs can be exploited to mimic Boolean logic operators and reproduce basic arithmetic functions. We have designed a two-state fluorescent probe with tunable emission wavelength for the construction of a molecular logic gate with reconfigurable single- or dual-output capability. The system is based on a BODIPY skeleton coupled with 4-(dimethylamino)benzaldehyde. The behavior of the molecular logic gate can be easily investigated in solution with fluorescence spectroscopy, and the optical readout (fluorescence) can be monitored in one (green) or two (green and red) channels. Depending on the solvent of choice, single INHIBIT or dual INHIBIT/IMPLY logic functions can be achieved using chemical inputs (acid and base). Reconfiguration from single- to dual-output is thus made possible by operating the system in acetonitrile (single output) or toluene (dual output), respectively. The logic gate can be switched by manipulating the fluorescence emission via protonation or deprotonation, even when immobilized onto a glass substrate. At the solid state, the resulting output can be stored for extended periods of time. This feature provides two added benefits: (i) memory function and (ii) "set/reset" capability of the logic gate. Our design thus provides a proof-of-concept interface between the molecular and electronic domains.

Recent Progress on the Evolution of Pourbaix Sensors: Molecular Logic Gates for Protons and Oxidants

Recent progress in the area of molecular logic, in particular molecules capable of sensing for acidity and oxidizability, are gathered together in this short review. Originally proposed as AND logic gates that provide a high fluorescence output when simultaneously protonated and oxidized, the concept has been extended from two-input to three-input variants and to include molecules that function as INHIBIT logic gates. Photochemical concepts such as photoinduced electron transfer (PET) and internal charge transfer (ICT) are exploited as favorite design concepts. This review highlights the evolution of Pourbaix sensors with anthracene, pyrazoline, and naphthalimide fluorophores. Future applications abound in various disciplines from corrosion science, material science, geochemistry to cell imaging.

Selenoureas for anion binding as molecular logic gates

The first example of a molecular logic gate based on selenourea/anion host–guest interaction that performs a ternary logic operation using an ¹H-NMR easy to read response output is described here.

A naphthalimide-based ‘Pourbaix sensor’: a redox and pH driven AND logic gate with photoinduced electron transfer and internal charge transfer mechanisms

A molecular logic gate with a ‘receptor–spacer–fluorophore–spacer–redox-unit’ format emits a fluorescent signal on simultaneous oxidation and protonation in aqueous methanol solution.