Molecular Keypad Lock Research Articles

Sequential-dependent synthesis of gold-chromium nanocomposites for multimode colorimetric sensing, advanced logic computing, and tri-layer information protection

Binary materials combine the properties and advantages of their components, but their fabrication paradigm needs updating to fully exploit their characteristics and broaden their application. Here, multifunctional bimetallic gold-chromium nanocomposites (Au–Cr NCs) were synthesized facilely in a sequential-dependent manner, and applied from multi-channel sensing to molecular informatization (including advanced logic computing and tri-layer information protection). By sequentially mixing Cr6+, Au3+, and NaBH4 (reducing agent), Au–Cr NCs with Au nanoparticles attached to Cr nanobelts can be prepared easily and quickly. The resulting Au–Cr NCs exhibited multi-signal sensing capability for hypochlorite, with significantly improved selectivity (about 5 times) and sensitivity (about 1650 times) when analyzing multiple signals. The synthesis process can be used to implement parallel molecular logic gates and customizable keypad lock operations. Moreover, by digitizing logical relationships and multimodal selective responses based on Au–Cr NCs, specific information (wise sayings and literary works sentence) can be encoded, encrypted and hidden to realize nano-cryptography and steganography. When combined with molecular keypad lock, a tri-layer information protection system can be constructed to enhance anti-cracking ability. This study promotes controllable preparation and multi-purpose applications of advanced multifunctional nanocomposites, but also opens up a new direction for nano-based sensing and digitization in multi-dimension.

Design and development of an azo dye‐based ultra‐sensitive chemosensor for the ubiquitous organic anion in aqueous solutions

AbstractOxalate plays a crucial role in various biological and industrial applications. Its involvement in diseases, drug‐ and toxin‐induced disorders, and disruption of industrial processes makes it a high‐priority chemical for the development of more precise, selective, and straightforward analytical methods. Herein, an innovative and efficient strategy for sequentially measuring Cu2+ and oxalate ions is reported. During an indicator displacement process, where Cu2+ and azo dye, ArsenazoIII (AAIII), are used as receiver and indicator, respectively, oxalate (C2O42−) is measured by a colorimetric method. Proof of concept results from UV–visible spectroscopy, naked eye, and signal reset of the indicator revealed a more robust interaction of the Cu2+ receptor with C2O42− than the AAIII indicator with high selectivity, good sensitivity, and lower detection limit(4.01 × 10−8 and 3.04 × 10−9mol L−1, for Cu2+ and C2O42−, respectively). The results of measuring C2O42− in actual samples (urine, mushrooms, and spinach) showed the applicability of the existing method. Most importantly, the colorimetric system based on molecular exchange in the indicator dislocation proceeding can serve as a colorimetric INHIBIT logic‐gate. It works like a molecular keypad lock system that can be controlled by two users with two different sets of chemical passwords (inputs) that can be identified through optical paths.

Enhancing Control Over Nitric Oxide Photorelease via a Molecular Keypad Lock.

Based on Boolean logic, molecular keypad locks secure molecular information, typically with an optical output. Here we investigate a rare example of a molecular keypad lock with a chemical output. To this end, the light-activated release of biologically important nitric oxide from a ruthenium complex is studied, using proton concentration and photon flux as inputs. In a pH-dependent equilibrium, a nitritoruthenium(II) complex is turned into a nitrosylruthenium(II) complex, which releases nitric oxide under irradiation with visible light. The precise prediction of the output nitric oxide concentration as function of the pH and photon flux is achieved with an artificial intelligence approach, namely the adaptive neuro-fuzzy inference system. In this manner an exceptionally high level of control over the output concentration is obtained. Moreover, the provided concept to lock a chemical output as well as the output prediction may be applied to other (photo)release schemes.

Photocleavable DNA Nanotube-Based Dual-Amplified Resonance Rayleigh Scattering System for MicroRNA Detection Incorporating Molecular Computing-Cascaded Keypad Lock Functionality.

Cascade molecular events in complex systems are of vital importance for enhancing molecular diagnosis and information processing. However, the conversion of a cascaded biosensing system into a multilayer encrypted molecular keypad lock remains a significant challenge in the development of molecular logic devices. In this study, we present a photocleavable DNA nanotube-based dual-amplified resonance Rayleigh scattering (RRS) system for detecting microRNA-126 (miR-126). The cascading dual-amplification biosensing system provides a multilayer-encrypted prototype with the functionality of a molecular computing cascade keypad lock. RRS signals were greatly amplified by using photocleavable DNA nanotubes and enzyme-assisted strand displacement amplification (SDA). In the presence of miR-126, enzyme-assisted SDA produced numerous identical nucleotide fragments as the target, which were then specifically attached to magnetic beads through the DNA nanotube by using a Y-shaped DNA scaffold. Upon ultraviolet irradiation, the DNA nanotube was released into the solution, resulting in an increase in the intensity of the RRS signal. This strategy demonstrated a low limit of detection (0.16 fM) and a wide dynamic range (1 fM to 1 nM) for miR-126. Impressively, the enzyme-assisted SDA offers a molecular computing model for generating the target pool, which serves as the input element for unlocking the system. By cascading the molecular computing process, we successfully constructed a molecular keypad lock with a multilevel authentication technique. The proposed system holds great potential for applications in molecular diagnosis and information security, indicating significant value in integrating molecular circuits for intelligent sensing.

Dual Fluorimetric Sensor for Tandem Detection of Cadmium and Cysteine: An Approach for Designing a Molecular Keypad Lock System.

A fluorimetric sensor for dual and sensitive detection of Cd2+ ion and Cysteine (based on 2-picolylamine platform) was developed.The sensor was designed and synthesized by simple condensation method and characterized by using common spectroscopic methods. The observations made from the kinetics of absorption and emission profile shows that probe Pdac behaves as ''ON-OFF'' fluorescent quenching sensor for cadmium ions. The probe exhibit selectivity in fluorescence quenching behaviour over other competitive metal ions, and also the Pdac-Cd2+ ensemble behave as an efficient ''OFF-ON'' type sensor for an essential amino acid Cysteine. Moreover, this dual sensing nature of the sensor makes it successfully applied for the designing of a molecular keypad lock system.

A Chromo-fluorogenic Probe for Selective Detection of Picric Acid Alongside Its Recovery by Aliphatic Amines and Construction of Molecular Logic Gates.

Nitroaromatic compounds are illicit explosive chemicals. For environmental security and homeland safety, selective and sensitive identification of these secondary-class explosives has been a reason for the exhaustive research arena of chemists for about a decade. We introduced a sensitive optical sensor with desalted neutral red (NR) dye. After ingressing picric acid (PA) in acetonitrile, the probe becomes non-fluorescent, displaying a colorimetric changefrom yellow to pink. The quenched phenomena and the changed color were re-established with aliphatic amine, trimethylamine (TEA). The reversibility is produced cyclically, both in fluorimetrically and spectrophotometrically. The detection limit for PA with our probe comes out as 0.639µM; this value is significantly lower than many chemosensors available in the literature. Also, NR-stained filter paper strips-based test kit analysis has been deployed as a displayable photonic device for in-situ detection of PA. Furthermore, the whole system was conceptualized to produce single input, single output, and double input single output logic gates, which can be applied to digital devices. The chronological input manner as NTP (NR- TEA-PA) pushed us to configure a molecular keypad lock system, the basis of digital locking devices. The repeatable & reversible detection system exhibits "Write read- Erase-read Write-read' type memory devices.

Engineering a Two-in-one Ni(II)-azophenine switch: Intelligent Lab-on a-box device for decentralized recognition event

A new Ni2+ complex of an azophenine-based sensory receptor, CN-1•Ni2+ is judiciously designed for selective aqueous phase fluoride recognition based on specific hydrogen bonding interaction with sharp chromogenic variation from brownish orange to purple. The mechanistic pathway of interaction has been thoroughly investigated via ESI-MS, FT-IR, differential pulse voltammetry (DPV) studies with theoretical DFT support and Loewdin spin population analysis. The detection limit was acquired to be 148 ppb, which is lower than the WHO permissible limit. The real-time sensitivity of the probe has been displayed by TLC strip-based solid-state sensing assay. The probe is also responsive towards recognition of fluoride from various real field water specimens with promising recoveries (95–119%). One step ahead, the chemically obtained outcomes have been extensively synchronized with electronic circuitry to fabricate lab-on a-box based Layman’s prototype for on-spot, decentralized detection of fluoride, which would be beneficial for the end users, particularly in the fluoride endemic areas. Moreover, based on the reversible spectroscopic outcome, herein AND-NOT-OR-NOR gate-based complex logic circuitry and sequence-dependent molecular keypad lock has been fabricated. In addition, silica gel supported composite material, CN-1•Ni2+@SG has been prepared for effectual remediation of aqueous fluoride below safe limit. Thus, the present work relies on recognition as well as proficient remediation of aqueous fluoride based on selective tuning of acidity, validating the ‘Two-in-one’ approach.

Sequential-Stimuli Induced Stepwise-Response of Pyridylpyrenes.

Stimuli-responsive materials, especially multi-stimuli-responsive materials, can sense external stimuli such as light, heat, and force, have shown great potential in drug delivery, data storage, encryption, energy-harvesting, and artificial intelligence. Conventional multi-stimuli-responsive materials are sensitive to each independent stimulus, causing losses in the diversity and accuracy of the identification for practical application. Herein, a unique phenomenon of sequential-stimuli induced stepwise-response generated from elaborately designed single-component organic materials is reported, which shows large bathochromic shifts up to 5800cm-1 under sequential stimuli of force and light. In contrast to multi-stimuli-responsive materials, the response of these materials strictly relies on the sequence of stimuli, allowing logicality, rigidity, and accuracy to be integrated into one single-component material. The molecular keypad lock is built based on these materials, pointing promising to a future for this logical response in significant practical applications. This breakthrough gives a new drive to classical stimuli-responsiveness and provides a fundamental design strategy for new generations of high-performance stimuli-responsive materials.

Intramolecular dual hydrogen bonded fluorescent “turn-on” probe for Al3+ and HSO4- ions: Applications in real water samples and molecular keypad lock

Dual hydrogen bonded Schiff base containing unsymmetrical double proton transfer sites, one with imine bond (CN) and hydroxyl group (OH), and the other with benzimidazole and hydroxyl groups has been successfully synthesized. Probe 1 displayed intramolecular charge transfer and acts as a potential sensor for Al3+ and HSO4- ions. Probe 1 displayed two absorption peaks at 325 nm and 340 nm and an emission band at 435 nm upon excitation at 340 nm. Probe 1 behaves as a fluorescence “turn-on” chemosensor for both Al3+ and HSO4- ions in H2O-CH3OH solvent system. The proposed method allows the determination of Al3+ and HSO4- ions up to 39 nM and 23 nM at emission wavelength 385 nm and 390 nm, respectively. The binding behavior of probe 1 towards these ions is determined by the Job’s plot method and 1H NMR titrations. Probe 1 is used to construct a molecular keypad lock where the absorbance channel can be opened only in the presence of the correct sequence. Further, it is used for the quantitative determination of HSO4- ion in different real-field water samples.

Sequential-Dependent Synthesis of Bimetallic Silver-Chromium Nanoparticles for Multichannel Sensing, Logic Computing, and 3 in 1 Information Protection.

Bimetallic nanomaterials (BNMs) have been used in sensing, biomedicine, and environmental remediation, but their multipurpose and comprehensive applications in molecular logic computing and information security protection have received little attention. Herein, This synthesis method is achieved by sequentially adding reactants under ice bath conditions. Interestingly, Ag-Cr NPs can dynamically selectively sense anions and reductants in multiple channels. Especially, ClO- can be quantitatively detected by oxidizing Ag-Cr NPs with detection limits of 98.37nM (at 270nm) and 31.83nM (at 394nm). Based on sequential-dependent synthesis process of Ag-Cr NPs, Boolean logic gates and customizable molecular keypad locks are constructed by setting the reactants as the inputs, the states of the resulting solutions as the outputs. Furthermore, dynamically selective response patterns of the Ag-Cr NPs can be converted into binary strings to exploit molecular crypto-steganography to encode, store, and hide information. By integrating the three dimensions of authorization, encryption, and steganography, 3 in 1 advanced information protection based on Ag-Cr nanosensing system can be achieved, which can enhance the anti-cracking ability of information. This research will promote the development and application of nanocomposites in the field of information security and deepen the connection between molecular sensing and the information world.

Pilot Study on the Visualization of Latent Fingerprints and Naked Eye Detection of Hg2+ and Zn2+ Ions in Aqueous Media Using Ninhydrin-Based Thiosemicarbazone.

Here, we described a cheap and effective chemosensor (NHPyTSC) that can distinguish Hg2+ and Zn2+ ions from other metal ions and evaluated this phenomenon using several spectroscopy techniques. With the addition of mercury and zinc ions, the proposed chemosensor in particular showed noticeable changes in color and absorption spectra. Additionally, by including EDTA in the NHPyTSC-Hg2+ and NHPyTSC-Zn2+ solutions, colorimetry readings can be reversed. We developed a molecular-scale sequential information processing circuit and presented the "writing-reading-erasing-reading" and "multiwrite" behaviors in the form of binary logic based on the great reversibility of this process. Moreover, by sequentially adding Hg2+, Zn2+, and EDTA, NHPyTSC imitates a molecular keypad lock and molecular logic gates. Density functional theory (DFT) investigations provided more evidence of the Hg2+ and Zn2+ ions' ability to attach to NHPyTSC. The most interesting part of this work is that a study on the latent fingerprint detection of the powder compound revealed that NHPyTSC exhibits good adherence and finger ridge features without background stains. When compared to black and white fingerprint powders, it is discovered that the NHPyTSC powder produces results that are remarkably clear on the majority of surfaces. This demonstrated their potential for real-world use, particularly in the area of criminal investigations.

A simple fluorescent sensor for the meticulous recognition of Cu2+ ion and its functioning in logic gate and keypad lock

A highly selective and perceptive “off–on” mode fluorescent receptor (E)-1-(5-methylfuran-2-yl)-N-(2-(phenylthio)phenyl)methanimine (R) has been constructed for the expeditious recognition of Cu2+ ions in the semi-aqueous medium. The strong fluorescence was observed at 468 nm for Cu2+ ions over other tested metal ions by R, which could be attributed to the constraint of the CHN isomerization mechanism and provoked chelation enhanced fluorescence effect (CHEF) upon interaction with copper ions. According to Job’s plot, the binding proportion between R and copper ion is 2:1 and further validated by mass analysis and quantum chemical studies. Based on the emission titration, the limits of detection (LOD) were determined to be 0.194 μM. The obtained results designate that the receptor R serves as a significant nominee for an expeditious recognition of Cu2+ ions. Further, R was fruitfully useful in molecular keypad locks, and molecular logic gate circuits and it could be applied to find out the trace quantity of Cu2+ ions in water samples.

Facile Label-Free Three-Input Molecular Keypad Lock

Featured with molecule-level data encryption, molecular keypad locks show attractive merits in information security. Most of the previous multiple-input locks use fluorescence as output but are impeded by inefficient/labile prequenching or highly synthetic complexity/difficulty of the fluorophore-containing processor molecules. We herein propose a facile three-input molecular keypad lock, which is simple in synthesis and label free but capable of in situ generation of a fluorescent moiety (dityrosine) for background-free fluorescence readout. A nonfluorescent ("Locked") tyrosine derivate zYpc was easily synthesized as the processor. The correct "password" (i.e., UV → ALP → TYR, ABC) stepwise converted zYpc to a dityrosine-containing product, exhibiting a bright blue fluorescence output ("Open"). In contrast, wrongly permutated inputs failed to open this lock. This device shows potential to be extended as a more advanced keypad lock with better security.

Biogenic fluorescent carbon dots modulated fabrication of concatenate logic library and pattern-mediated molecular keypad lock for chemical sensing application

In recent years, molecular logic gates (MLGs) have gained much attention among researchers to replace conventional silicon-based electronic computers. MLGs are employed for various applications, including biological–chemical sensors, heavy metal ion detection, illness diagnosis, and therapy. In this work, we developed two different chemically functionalized forms of biogenic Carbon (C)-dots synthesized using F. religiose and applied as MLGs for multi-stimulus responsive computing. To mimic the operation of Boolean logic gates, we combined as-synthesized three different C-dot platforms (including bulk C-dots, thiol-functionalized (TC)-dots, and acid-functionalized (AC)-dots) with other analytes such as Fe3+, Hg2+, ascorbic acid (AA), glucose (Glu), dichlorvos (DV), and H2O2 and integrated to build a logic library that represents 15 fundamental logic gates (IMP, INH, NOT, NOR, YES, PASS0, and PASS1) and their combinational operations (IMP-OR, IMP-INH, INH-OR). Furthermore, we have developed a parity checker that distinguishes 0 to 9 natural integers as even or odd by using dual-source responsive C-dots and AC-dots platforms. Further, because of the lack of studies using C-dots in “On-Off-On” and “Off-On-Off” sensing to generate logic computation, we have developed a swiping pattern-mediated molecular keypad lock to promise the confidentiality, integrity, and availability of discrete information. A novel design idea for an advanced molecular keypad lock has been proposed based on the dynamic switching of C-dots photoluminescence emission (PLE) with 9 input keys and 6 input key combinations. The keypad lock can be potentially used in different fields, such as electronic gadgets, security systems, sensors, and therapeutics. This is an approach to replacing conventional silicon-based electronic systems with PLE-based nanoforms.

A multi-cation responsive Ni(II)-supramolecular metallogel mimics a molecular keypad lock via reversible fluorescence switching.

Synthesis of a bidentate N,O-donor Schiff base fluorescent ligand 5-(diethylamino-2-((4-(diethylamino-2-((4-(diethylamino)phenylimino)ethyl)phenol) (HL) adopting a new preparation procedure and its complexes with Ni(II) (1) and Zn(II) (2) has been illustrated. Structures of HL and 1 have been elucidated using X-ray single crystal analysis. Moreover, HL leads to the formation of a mechanically stable Ni(II)-gel (MG) upon treatment with Ni(NO3)2·6H2O in the presence of triethylamine (TEA) using THF/MeOH (1 : 1) solvents at rt. The gelator HL, complexes 1-2 and MG have been characterized by different spectroscopic and microscopic techniques including NMR (1H & 13C), FT-IR, ESI-MS, SEM, powder-XRD, rheology, UV/vis and fluorescence analysis. Rheological studies suggested good mechanical and thermal stability, whereas SEM analysis reveals a porous earth crust-like morphology of MG. Notably, 1 : 1 complexation between HL and Ni(II) forms a stable gel (MG), whereas 2 : 1 (HL : Ni2+) complexation leads to partial gelation. Formation of the Ni(II)-MG leads to slight "Turn-OFF" fluorescence relative to HL with a limit of detection (LOD) of 7.76 × 10-9 M; however, MG is considered as the "ON" state due to moderate emission. Remarkably, Ni(II)-MG further displayed reversible "ON-OFF-ON" fluorescence switching behavior through detection of Zn2+, Cu2+ and Hg2+. The emission intensity of MG is quenched with Cu2+/Hg2+ but enhances with Zn2+ in 1 : 1 (MG : M2+) stoichiometry. Therefore, MG mimics a sequence dependent molecular keypad lock for Cu2+ (C), Hg2+ (H) and Zn2+ (Z) to give the maximum output. Association and quenching constants were calculated by the Benesi-Hildebrand method, and from the Stern-Volmer plot the LOD was determined to be 4.2 × 10-6 M, 5.8 × 10-6 M and 7.8 × 10-6 M for MG with Zn(II), Cu(II) and Hg(II), respectively. To date, Ni(II) based MGs have been explored only toward electrochemical, thermal and conduction studies; however, the present work demonstrates the fluorescent reversible cation detection behavior of Ni(II)-MG to act as a molecular keypad lock for development of password protection devices.

A Coumarin-azo Derived Colorimetric Chemosensor for Hg2+ Detection in Organic and Aqueous Media and its Extended Real-world Applications.

Pollution caused by the release of toxic heavy metals into the environment by industrial and farming processes has been regarded as a major problem worldwide. This has attracted a great deal of attention into restoration and remediation. Mercury is classified as a toxic heavy metal which has posed significant challenges to public and environmental health. To date, conventional methods for mercury detection rely on expensive, destructive, complex, and highly specialized methods. Evidently, there is a need to develop systems capable of easily identifying and quantifying mercury within the environment. In this way, organic-based colorimetric chemosensors are gaining increasing popularity due to their high sensitivity, selectivity, cost-effectiveness, ease of design, naked-eye, and on-site detection ability. The formation of coumarin-azo derivative AD1 was carried out by a conventional diazotization reaction with coumarin-amine 1c and N,N-dimethylaniline. Sensor AD1 displayed remarkable visual colour change upon mercury addition with appreciable selectivity and sensitivity. The detection limit was calculated as 0.24µM. Additionally, the reversible nature of AD1 allowed for the construction of an IMPLICATION type logic gate and Molecular Keypad Lock. Chemosensor AD1 displayed further sensing applications in real-world water samples and towards on-site assay methods. Herein, we describe a coumarin-derived chemosensor bearing an azo (N = N) functionality for the colorimetric and quantitative determination of Hg2+ in organic and aqueous media.

A FRET-based ratiometric fluorescent probe for detecting Hg2+: Its application in cell imaging and molecular keypad lock

A novel FRET-based ratiometric fluorescent probe (Ro1) based on rhodamine and naphthalimide groups was designed and synthesized. The probe displayed high selectivity and sensitivity to Hg2+ and the significant color changed from yellow to pink could enable naked-eye detection of Hg2+. Ro1 also showed rapid respond to Hg2+ within 60 s with the limit of detection was 0.75 μM. The possible mechanism of probe Ro1 for detecting Hg2+ was investigated by using 1H NMR, ESI-MS and HPLC spectra. Further, Ro1 was designed as a molecular keypad lock with different sequences of Hg2+ and Cu2+ chemical input. Moreover, fluorescence imaging experiment of Hg2+ in living Hela cells demonstrated its potential applications in biological systems.

Three and four inputs combinational logic circuits based on a azo-azomethine chemosensor for the detection of Ni2+ and CN−/OAC− ions: Experimental and DFT studies

A novel Schiff base ligand HL2 was synthesized as a colorimetric sensor for Ni2+ and CN−/OAC− ions. The binding constants (Ka) calculated using the Benesi-Hildebrand analysis of the UV–vis titration data for Ni2+ and CN−/OAC− ions were determined to be 2.88 × 1010, 7.03 × 104 and 3.44 × 103 M−1, respectively. The stoichiometry ratio between receptor HL2 and Ni2+ was verified to be 2:1. The experimental results were confirmed by Density Functional Theory (DFT) studies using the B3LYP level and 6-31+g (d) basis set. The absorbance outputs signals were measured at 370 nm (Out1) and 500 nm (Out 2) based on three chemical inputs CN− (Inc), OAC− (InO) and HSO4− (InH) in eight different combinations. The combinatorial circuit was designed by three logic gates (OR, NOT and AND) using different output signals towards CN− (Inc), OAC− (InO) and HSO4− (InH). The absorbance output signals for four chemical inputs, Including Ni2+ (In Ni2+), CN− (Inc), OAC− (InO) and HSO4− (InH) in sixteen different combinations, were successfully recorded at 500 nm (out1) and 425 nm (out2). Furthermore, two chemical inputs (Ni2+ and CN− or Ni2+ and OAC−) and one output (absorbance at 420 nm) can be used to construct a molecular keypad lock.

An efficient 2-aminothiazolesalicylaldehyde fluorescent chemosensor for Fe2+ ion detection and a potential inhibitor of NUDT5 signaling hormone for breast cancer cell and molecular keypad lock application

A novel thiazole phenol conjugate, 2-aminothiazolesalicylaldehyde (receptor1) was designed and synthesized for the first time through a single step process via Schiff base condensation reaction. The formation of receptor1 was confirmed by FTIR, 13C NMR, and 1H NMR. The IR spectra confirmed the presence of the aldimine formation. It is further supported by the proton NMR, showing the disappearance of aldehyde peaks and the formation of a new imine peak. This is further corroborated by the 13C NMR. The receptor1 complexing with various metal ions were studied through fluorescence spectroscopy showed its selectivity toward Fe2+ ion following a reverse photoinduced electron transfer (PET) process compared to all other potentially competing ions. The receptor1 was applied as a sensor to sense Fe2+ ion in water samples. The detection limit for Fe2+ ion in drinking water was substantially lower (0.003 µM) than the EPA (environmental protection agency) recommendation (5.37 M). The capability of receptor1 in recovering Fe2+ ion in bore water, tap water, and drinking water was up to 99.5%. The receptor1 was also used as a chelating ligand (receptor1) in molecular docking and it was assessed as a potential inhibitor of NUDT5, a silence hormone signaling for breast cancer. The test compound (PDB: 5NWH) showed good affinity toward the target receptor1 with the binding energy of – 5.23 kcal mol−1. Furthermore, the receptor1 showed excellent reversibility property on adding EDTA solution. Due to the marvelous reversible property, a molecular-scale sequential information processing circuit is designed for the multi-task behavior such as ‘Writing-Reading-Erasing-Reading’ in the form of binary logic gate. The consecutive addition of Fe2+ ion and EDTA solution to receptor1 paves a way for the construction of INHIBIT logic gate. Additionally, the receptor1 showed the mimicking behavior of molecular keypad lock.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11696-022-02373-z.

A benzoxazole-based smart molecule for relay detection of zinc and phosphate ions and its implication towards molecular logic gate constructions

A benzoxazole-based fluorescent chemosensor (OPMP) has been designed, synthesized, and characterized by various analytical techniques. The as-prepared OPMP is employed for the cascade detection of Zn2+ and PO43- ions, respectively, based on the ‘off–on-off’ photoluminescence mechanism in 30% (v/v) water-DMSO mixture. A significant fluorescence enhancement of OPMP at 495 nm is observed due to chelation-enhanced fluorescence upon binding with Zn2+ ions. A visual bluish-green color could be seen under 365 nm UV light irradiation, which is also well supported by the color chromaticity diagram. The fluorescence of the Zn2+chelated OPMP complex is quenched in the presence of PO43- ions. The sensitivity of OPMP and Zn2+chelated OPMP complex towards detection of Zn2+ and PO43- ions can be possible down to 38 nM and 48 nM, respectively. Such as dual ions detection system with outstanding reversibility and reproducibility led us to consider our OPMP as a feasible candidate for the construction of molecular logic circuits, molecular keypad locks, and set-reset memorized molecular devices. Further, an OPMP staining paper strips-based test kit has been fabricated and demonstrated for the sequential detection of Zn2+ and PO43- ions, respectively.