Cinchona alkaloids - acid, anion-driven fluorescent INHIBIT logic gates with a receptor1-fluorophore-spacer-receptor2 format and PET and ICT mechanisms

The fluorescent natural products, quinine, quinidine, cinchonine and cinchonidine are demonstrated as H⁺-enabled, halide-disabled (Cl^-, Br^- or I^-) INHIBIT and INHIBIT-OR combinatorial logic gates in water. More fluorescent natural products with intrinsic logic properties await to be discovered.

Design and Synthesis of a Novel ICT Bichromophoric pH Sensing System Based on 1,8-Naphthalimide Fluorophores as a Two-Input Logic Gate and Its Antibacterial Evaluation

The synthesis, sensor activity, and logic behavior of a novel 4-iminoamido-1,8-naphthalimide bichromophoric system based on a "fluorophore-receptor" architecture with ICT chemosensing properties is reported. The synthesized compound showed good colorimetric and fluorescence signaling properties as a function of pH and proved itself as a promising probe for the rapid detection of pH in an aqueous solution and base vapors in a solid state. The novel dyad is able to work as a two-input logic gate with chemical inputs H⁺ (Input 1) and HO^- (Input 2) executing INHIBIT logic gate. The synthesized bichromophoric system and the corresponding intermediates demonstrated good antibacterial activity toward Gram (+) and Gram (-) bacteria when compared with the Gentamycin standard.

Molecular engineering of fluorescent bichromophore 1,3,5-triaryl-Δ2-pyrazoline and 4-amino-1,8-naphthalimide molecular logic gates

Emissive bichromophoric solvatochromatic molecules are introduced as a new platform for the development of fluorescent molecular logic gates.

Fluorescent Molecular Logic Gates Driven by Temperature and by Protons in Solution and on Solid

Temperature-driven fluorescent NOT logic is demonstrated by exploiting predissociation in a 1,3,5-trisubstituted Δ² -pyrazoline on its own and when grafted onto silica microparticles. Related Δ² -pyrazolines become proton-driven YES and NOT logic gates on the basis of fluorescent photoinduced electron transfer (PET) switches. Additional PASS 1 and YES+PASS 1 logic gates on silica are also demonstrated within the same family. Beside these small-molecule systems, a polymeric molecular thermometer based on a benzofurazan-derivatized N-isopropylacrylamide copolymer is attached to silica to produce temperature-driven fluorescent YES logic.

A fluorescent polymeric INHIBIT logic gate based on the natural product quinidine

The natural product quinidine was polymerised with acrylamide and demonstrated as a H⁺-enabled, Cl⁻-disabled INHIBIT logic gate in water.

Revealing the switching mechanisms of an off–on–off fluorescent logic gate system

We showed that TICT and PET were responsible for the off–on–off switching mechanisms of a fluorescent molecular logic gate.

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.

Synthesis and fluorescence studies of novel bisarylmethylidene derivatives of 2-methoxy-2-methyl-1,3-dioxan-5-one

The first general procedure is described for the synthesis of novel bisarylmethylidenes of 2-methoxy-2-methyl-1,3-dioxan-5-one 1. Thus, several derivatives of 3 are obtained rapidly in high yields by reacting 1 with different aldehydes in the presence of catalytic quantities of pyrrolidine in EtOH at room temperature. Upon completion of the reactions, products are obtained directly by spontaneous precipitation avoiding time consuming and expensive chromatographic separations. All products were characterized by proton and carbon NMR spectroscopy methods, and in one case, the proposed structure was elucidated by X-ray crystallography, confirming the Z stereochemistry for the olefinic C=C bonds. Due to showing different colours in solid and solution states, products were studied for their photophysical properties as well.

A fluorescent combinatorial logic gate with Na+, H+-enabled OR and H+-driven low-medium-high ternary logic functions

A fluorescent combinatorial Na⁺, H⁺ logic gate is demonstrated that could represent a class of probes for investigating antiporters in biological systems.

Fluorescent logic systems for sensing and molecular computation: structure–activity relationships in edge-detection

Molecular logic-based computation continues to throw up new applications in sensing and switching, the newest of which is the edge detection of objects. The scope of this phenomenon is mapped out by the use of structure–activity relationships, where several structures of the molecules and of the objects are examined. The different angles and curvatures of the objects are followed with good fidelity in the visualized edges, even when the objects are in reverse video.

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.