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1.
JACS Au ; 3(8): 2257-2268, 2023 Aug 28.
Article in English | MEDLINE | ID: mdl-37654579

ABSTRACT

A recurring dream of molecular recognition is to create receptors that distinguish between closely related targets with sufficient accuracy, especially in water. The more useful the targets, the more valuable the dream becomes. We now present multianionic trimeric cyclophane receptors with a remarkable ability to bind the iconic (bipyridine)3Ru(II) (with its huge range of applications) while rejecting the nearly equally iconic (phenanthroline)3Ru(II). These receptors not only selectively capture (bipyridine)3Ru(II) but also can be redox-switched to release the guest. 1D- and 2D(ROESY)-NMR spectroscopy, luminescence spectroscopy, and molecular modeling enabled this discovery. This outcome allows the control of these applications, e.g., as a photocatalyst or as a luminescent sensor, by selectively hiding or exposing (bipyridine)3Ru(II). Overall, a 3D nanometric object is selected, picked-up, and dropped-off by a discrete molecular host. The multianionic receptors protect excited states of these metal complexes from phenolate quenchers so that the initial step in photocatalytic phenolate oxidation is retarded by nearly 2 orders of magnitude. This work opens the way for (bipyridine)3Ru(II) to be manipulated in the presence of other functional nano-objects so that many of its applications can be commanded and controlled. We have a cyclophane-based toolkit that can emulate some aspects of proteins that selectively participate in cell signaling and metabolic pathways by changing shape upon environmental commands being received at a location remote from the active site.

2.
Chempluschem ; 88(4): e202200362, 2023 Apr.
Article in English | MEDLINE | ID: mdl-36456470

ABSTRACT

The general tool of fluorescent PET (photoinduced electron transfer) sensors/switches - a molecular design principle with engineering features - is outlined, with the aid of frontier orbital energy diagrams. Fluorophores such as anthracene, 1,3-diaryl-Δ2 -pyrazolines and 4-amino-1,8-naphthalimides are employed within this system, alongside receptors such as amines, carboxylates, crown ethers and amino acids. This tool appealed to a multinational corporation for building a medical analyzer for electrolytes such as Na+ , K+ , Ca2+ and gases like CO2 , which became a commercially successful application. Finally, the tool was a springboard for chemistry to cross into computer science. The field of molecular logic can elucidate how molecules inside us handle information. Molecular examples of the simplest logic gates such as YES, NOT, OR, AND are described. A case of a human-level computation - visual edge detection - is also included.

3.
Chem Sci ; 13(36): 10856-10867, 2022 Sep 21.
Article in English | MEDLINE | ID: mdl-36320709

ABSTRACT

Shape-switchable cyclophane hosts allow the controlled capture and release of reactive polypyridineRu(ii) complexes in water. This gives rise to a network of host-guest binding, acid-base reactions in ground and excited states, and chemical redox interconversions. In the case of (2-(2'-pyridyl)imidazole)Ru(ii) complexes, several molecular logic gate arrays of varying complexity emerge as a result. Cyclophane-induced 'off-on' switching of luminescence in neutral solution is found to originate from two features of these aromatic hosts: enhancement of radiative decay by the polarizable host and the suppression of nonradiative decay involving deprotonation by reducing the water content within the deep host cavity. These are examples of nanometric coordination chemistry/physics being controlled by inclusion in an open box. The aromatic units of the macrocycle are also responsible for the shape-switching mechanism of wall collapse/erection.

4.
J Am Chem Soc ; 144(11): 4977-4988, 2022 03 23.
Article in English | MEDLINE | ID: mdl-35274938

ABSTRACT

Electron/proton transfers in water proceeding from ground/excited states are the elementary reactions of chemistry. These reactions of an iconic class of molecules─polypyridineRu(II)─are now controlled by capturing or releasing three of them with hosts that are shape-switchable. Reversible erection or collapse of the host walls allows such switchability. Some reaction rates are suppressed by factors of up to 120 by inclusive binding of the metal complexes. This puts nanometric coordination chemistry in a box that can be open or shut as necessary. Such second-sphere complexation can allow considerable control to be exerted on photocatalysis, electrocatalysis, and luminescent sensing involving polypyridineRu(II) compounds. The capturing states of hosts are symmetry-matched to guests for selective binding and display submicromolar affinities. A perching complex, which is an intermediate state between capturing and releasing states, is also demonstrated.


Subject(s)
Coordination Complexes , Heterocyclic Compounds , Ruthenium , 2,2'-Dipyridyl/chemistry , Coordination Complexes/chemistry , Ruthenium/chemistry , Water
5.
Chemistry ; 27(52): 13268-13274, 2021 Sep 15.
Article in English | MEDLINE | ID: mdl-34233035

ABSTRACT

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.


Subject(s)
Logic , Protons , Electron Transport , Fluorescent Dyes , Temperature
6.
Angew Chem Int Ed Engl ; 60(25): 13819-13823, 2021 06 14.
Article in English | MEDLINE | ID: mdl-33723888

ABSTRACT

A colorimetric indicator displacement assay (IDA) amenable to high-throughput experimentation was developed to determine the percentage of cis and trans alkenes. Using 96-well plates two steps are performed: a reaction plate for dihydroxylation of the alkenes followed by an IDA screening plate consisting of an indicator and a boronic acid. The dihydroxylation generates either erythro or threo vicinal diols from cis or trans alkenes, depending upon their syn- or anti-addition mechanisms. Threo diols preferentially associate with the boronic acid due to the creation of more stable boronate esters, thus displacing the indicator to a greater extent. The generality of the protocol was demonstrated using seven sets of cis and trans alkenes. Blind mixtures of cis and trans alkenes were made, resulting in an average error of ±2 % in the percentage of cis or trans alkenes, and implementing E2 and Wittig reactions gave errors of ±3 %. Furthermore, we developed variants of the IDA for which the color may be tuned to optimize the response for the human eye.


Subject(s)
Alkenes/chemistry , Colorimetry , Molecular Structure , Stereoisomerism
7.
Chem Commun (Camb) ; 56(50): 6838-6841, 2020 Jun 23.
Article in English | MEDLINE | ID: mdl-32432237

ABSTRACT

Molecular AND logic gates 1, 3, 5 and 7, which are designed according to principles of photoinduced electron transfer (PET) switching, respond to co-existing Candida antarctica lipase B and H+ (and Na+).


Subject(s)
Fungal Proteins/chemistry , Lipase/chemistry , Logic , Electron Transport , Fluorescence , Hydrogen/chemistry , Sodium/chemistry
8.
Polymers (Basel) ; 11(8)2019 Aug 14.
Article in English | MEDLINE | ID: mdl-31416199

ABSTRACT

Our experiences concerning fluorescent molecular sensing and logic devices and their intersections with polymer science are the foci of this brief review. Proton-, metal ion- and polarity-responsive cases of these devices are placed in polymeric micro- or nano-environments, some of which involve phase separation. This leads to mapping of chemical species on the nanoscale. These devices also take advantage of thermal properties of some polymers in water in order to reincarnate themselves as thermometers. When the phase separation leads to particles, the latter can be labelled with identification tags based on molecular logic. Such particles also give rise to reusable sensors, although molecular-scale resolution is sacrificed in the process. Polymeric nano-environments also help to organize rather complex molecular logic systems from their simple components. Overall, our little experiences suggest that researchers in sensing and logic would benefit if they assimilate polymer concepts.

9.
Chemistry ; 25(36): 8522-8527, 2019 Jun 26.
Article in English | MEDLINE | ID: mdl-30947361

ABSTRACT

One of the challenges for fluorescent sensors is to reduce their target environment size from a micrometer scale, such as biological cells, to a nanometer scale. Proton maps near membranes are of importance in bioenergetics and are the first goal in nanometer-scale analysis with fluorescent sensors. Thirty-three fluorescent photoinduced-electron-transfer pH sensors bearing an environment-sensitive benzofurazan fluorophore and having different hydrophobicity/hydrophilicity and hydrogen-bonding abilities were prepared. These sensors were scattered in nanospaces associated with anionic and cationic micelles as model membranes to indicate proton availability and polarity in local spaces. Gathering the data from the sensors allowed the successful drawing of proton maps near anionic and cationic micelles, in which electrostatic attraction/repulsion of protons by the charged head groups of micelles and dielectric suppression of protons were clearly observed.


Subject(s)
Fluorescent Dyes/chemistry , Micelles , Bis-Trimethylammonium Compounds/chemistry , Electron Transport , Hydrogen-Ion Concentration , Protons , Sodium Dodecyl Sulfate/chemistry , Spectrometry, Fluorescence
10.
Chem Sci ; 10(8): 2272-2279, 2019 Feb 28.
Article in English | MEDLINE | ID: mdl-30881652

ABSTRACT

The first population analysis is presented for submillimetric polymer beads which are tagged with five multi-valued logic gates, YES, 2YES + PASS 1, YES + PASS 1, YES + 2PASS 1 and PASS 1 with H+ input, 700 nm near-infrared fluorescence output and 615 nm red excitation light as the power supply. The gates carry an azaBODIPY fluorophore and an aliphatic tertiary amine as the H+ receptor where necessary. Each logic tag has essentially identical emission characteristics except for the H+-induced fluorescence enhancement factors which consistently map onto the theoretical predictions, after allowing for bead-to-bead statistical variability for the first time. These enhancement factors are signatures which identify a given bead type within a mixed population when examined with a 'wash and watch' protocol under a fluorescence microscope. This delineates the scope of molecular computational identification (MCID) for encoding objects which are too small for radiofrequency identification (RFID) tagging.

11.
Nat Commun ; 10(1): 49, 2019 01 21.
Article in English | MEDLINE | ID: mdl-30664631

ABSTRACT

Molecular-logic based computation (MLBC) has grown by accumulating many examples of combinational logic gates and a few sequential variants. In spite of many inspirations being available in biology, there are virtually no examples of MLBC in chemistry where sequential and combinational operations are integrated. Here we report a simple alcohol-ketone redox interconversion which switches a macrocycle between a large or small cavity, with erect aromatic walls which create a deep hydrophobic space or with collapsed walls respectively. Small aromatic guests can be captured or released in an all or none manner upon chemical command. During capture, the fluorescence of the alcohol macrocycle is quenched via fluorescent photoinduced electron transfer switching, meaning that its occupancy state is self-indicated. This represents a chemically-driven RS Flip-Flop, one of whose outputs is fed into an INHIBIT gate. Processing of outputs from memory stores is seen in the injection of packaged neurotransmitters into synaptic clefts for onward neural signalling. Overall, capture-release phenomena from discrete supermolecules now have a Boolean basis.


Subject(s)
Computers, Molecular , Models, Molecular , Alcohols/chemistry , Crystallography, X-Ray , Fluorescence , Ketones/chemistry , Logic , Magnetic Resonance Spectroscopy , Oxidation-Reduction
12.
Chem Commun (Camb) ; 54(11): 1319-1322, 2018 Feb 01.
Article in English | MEDLINE | ID: mdl-29210385

ABSTRACT

The fluorescence of sensors 1 and 6, which are designed in terms of photoinduced electron transfer (PET), is switched 'on' by factors of 15 and 6 with avidin in a rather selective manner. Sensors 3 and 7, simpler derivatives of 1, are switched 'on' by factors of 16 and 7.5 with bovine serum albumin, though at 30-fold higher concentrations.


Subject(s)
Avidin/chemistry , Fluorescent Dyes/chemistry , Serum Albumin, Bovine/chemistry , Animals , Anthracenes/chemistry , Biotin/analogs & derivatives , Biotin/chemistry , Cattle , Fluorescence , Hydrophobic and Hydrophilic Interactions , Ligands
13.
Chemphyschem ; 18(13): 1760-1766, 2017 Jul 05.
Article in English | MEDLINE | ID: mdl-28349591

ABSTRACT

Proton-driven YES and PASS 1 molecular logic tags based on anthracene and 4-aminonaphthalimide fluorophores, emitting blue and green, respectively, are employed on amino-terminated polyethylene glycol-polystyrene and aminopropyl silica particles. The (YES+PASS 1) logic combination is also a distinguishable tag in both colours. The scope of such tags is delineated.

14.
Angew Chem Int Ed Engl ; 55(2): 768-71, 2016 Jan 11.
Article in English | MEDLINE | ID: mdl-26503173

ABSTRACT

The Na(+) concentration near membranes controls our nerve signals aside from several other crucial bioprocesses. Fluorescent photoinduced electron transfer (PET) sensor molecules target Na(+) ions in nanospaces near micellar membranes with excellent selectivity against H(+). The Na(+) concentration near anionic micelles was found to be higher than that in bulk water by factors of up to 160. Sensor molecules that are not held tightly to the micelle surface only detected a Na(+) amplification factor of 8. These results were strengthened by the employment of control compounds whose PET processes are permanently "on" or "off".


Subject(s)
Micelles , Sodium/analysis , Electron Transport , Fluorescence , Spectrometry, Fluorescence , Surface Properties
15.
Faraday Discuss ; 185: 337-46, 2015.
Article in English | MEDLINE | ID: mdl-26395473

ABSTRACT

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.

17.
J Am Chem Soc ; 137(11): 3763-6, 2015 Mar 25.
Article in English | MEDLINE | ID: mdl-25751676

ABSTRACT

Genetically engineered bacteria and reactive DNA networks detect edges of objects, as done in our retinas and as also found within computer vision. We now demonstrate that simple molecular logic systems (a combination of a pH sensor, a photo acid generator, and a pH buffer spread on paper) without any organization can achieve this relatively complex computational goal with good fidelity. This causes a jump in the complexity achievable by molecular logic-based computation and extends its applicability. The molecular species involved in light dose-driven "off-on-off" fluorescence is diverted in the "on" state by proton diffusion from irradiated to unirradiated regions where it escapes a strong quencher, thus visualizing the edge of a mask.

18.
Chem Commun (Camb) ; 51(40): 8403-9, 2015 May 18.
Article in English | MEDLINE | ID: mdl-25752825

ABSTRACT

Molecular logic-based computation is a broad umbrella covering molecular sensors at its simplest level and logic gate arrays involving steadily increasing levels of parallel and serial integration. The fluorescent PET (photoinduced electron transfer) switching principle remains a loyal servant of this entire field. Applications arise from the convenient operation of molecular information processors in very small spaces.

19.
Chem Soc Rev ; 44(13): 4203-11, 2015 Jul 07.
Article in English | MEDLINE | ID: mdl-25695939

ABSTRACT

Following a brief introduction to the principle of fluorescent PET (photoinduced electron transfer) sensors and switches, the outputs of laboratories in various countries from the past year or two are categorized and critically discussed. Emphasis is placed on the molecular design and the experimental outcomes in terms of target-induced fluorescence enhancements and input/output wavelengths. The handling of single targets takes up a major fraction of the review, but the extension to multiple targets is also illustrated. Conceptually new channels of investigation are opened up by the latter approach, e.g.'lab-on-a-molecule' systems and molecular keypad locks. The growing trends of theoretically-fortified design and intracellular application are pointed out.

20.
Beilstein J Org Chem ; 11: 2774-84, 2015.
Article in English | MEDLINE | ID: mdl-26877799

ABSTRACT

The circumstances in Colombo, Sri Lanka, and in Belfast, Northern Ireland, which led to a) the generalization of luminescent PET (photoinduced electron transfer) sensing/switching as a design tool, b) the construction of a market-leading blood electrolyte analyzer and c) the invention of molecular logic-based computation as an experimental field, are delineated. Efforts to extend the philosophy of these approaches into issues of small object identification, nanometric mapping, animal visual perception and visual art are also outlined.

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