Host-guest interactions of coumarin-based 1,2-pyrazole using analytical and computational methods: Paper strip-based detection, live cell imaging, logic gates and keypad lock applications.

A novel Coumarin-based 1,2-pyrazole, HCPyTSC is synthesised and characterized. The chemosensor has been shown to have efficient colourimetric and fluorescence sensing capabilities for the quick and selective detection of fluoride and copper ions. At 376 and 430 nm, the HCPyTSC exhibits selective sensing for Cu2+ and F- ions. By examining the natural bond orbital (NBO) analysis and the potential energy curve (PES) of the ground state for the function of the C-H bond, it has been determined from the theoretical study at hand that the deprotonation was taken from the 'CH' proton of the pyrazole ring. For F- and Cu2+, the HCPyTSC detection limits were 4.62 nM and 15.36 nM, respectively. Similarly, the binding constants (Kb) for F- and Cu2+ ions in acetonitrile medium were found to be 2.06 × 105 M-1 and 1.88 × 105 M-1. Chemosensor HCPyTSC with and without F- and Cu2+ ions have an emission and absorption response that can imitate a variety of logic gates, including the AND, XOR, and OR gates. Additionally, a paper-based sensor strip with the HCPyTSC was created for use in practical, flexible F- sensing applications. The paper-based sensor was more effective in detecting F- than other anions. The effectiveness of HCPyTSC for the selective detection of F- in living cells as well as its cell permeability were examined using live-cell imaging in T24 cells.

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.

TD-DFT investigation on anion recognition mechanism of anthraldehyde-based fluorescent thiosemicarbazone derivatives.

The mechanism of host-guest interaction of receptors towards fluoride ion has been investigated using computational methods. To distinguish the effect of aromaticity in host-guest interaction, we investigated unsubstituted (ATSC) and phenyl-substituted (APTSC) anthracene thiosemicarbazones towards different ions. In the ground state of receptor-fluoride complex, the added fluoride ion made hydrogen bond through N - H…F…H - N, whereas the intramolecular hydrogen bonding was through F - H…N in the excited state of receptor-fluoride complex. Experimental absorption and emission spectra were well reproduced by the calculated vertical excitation energies. The transition state (TS) calculations were performed to understand the thermodynamic features and mechanism of host-guest interaction. The natural bond orbital analyses show that the second perturbation energy for donor-acceptor interaction of F- with hydrogen is more than 300 kcal/mol-1 at the excited state of receptor-fluoride complex, which indicates the strong single bond between fluoride and hydrogen atom. The PES scan confirms that deprotonation took place at the excited state of receptor-fluoride complex. The results indicate the excited-state proton transfer (ESPT) process from N-H group nearby the anthracene moiety. The APTSC is a better chemosensor than ATSC. This infers that the aromaticity will increase the efficiency of fluorescence receptor towards fluoride ion. A schematic representation of sensing mode of anthracene-based thiosemicarbazones toward fluoride ion. The fluoride ion first makes a hydrogen bond with NH proton nearby anthracene moiety. The excited state proton transfer mechanism was confirmed by PES and NBO studies.

Analytical and computational investigation on host-guest interaction of cyclohexyl based thiosemicarbazones: Construction of molecular logic gates using multi-ion detection.

Two novel cyclohexyl based thiosemicarbazones, H2L1 and H3L2, are synthesized and characterized. The anion and cation sensing properties of the two receptors has been unveiled as an effective ratiometric and colorimetric sensor for selective and rapid detection of fluoride, copper and cobalt ions. The H2L1 shows selective sensing towards F- and Cu2+ at 429 and 393 nm, whereas, H3L2 can detect F-, Cu2+ and Co2+ at 350, 393 and 408 nm respectively. The fluoride-sensing mechanism of the receptors has been investigated by means of the DFT and TD-DFT methods. The experimental UV-vis and fluorescence spectra are well reproduced by the calculated vertical excitation energies in the ground state and the first singlet excited state. The present theoretical study indicates that the deportation was taken from the 'NH' proton which is closer to the imine group, which has been confirmed by natural bond orbital (NBO) analysis and the potential energy curve (PES) of ground state for the function of NH bond. The absorption and emission response for receptors with and without F-, Co2+ and Cu2+ ions can mimic multiple logic gate such as NOR, XNOR, OR and TRANSFER gates.

Highly selective inhibition of α-glucosidase by green synthesised ZnO nanoparticles - In-vitro screening and in-silico docking studies.

Diabetic control through the inhibition of carbohydrate hydrolysing enzymes is established as an effective strategy. Many of the inorganic materials have already been investigated as enzyme inhibitors. Present study investigates the in-vitro antidiabetic activity of ZnO nanoparticles assessing their inhibition efficiency on α-glucosidase and α-amylase. The nanoparticles obtained with average dimeson of 11, 32 and 49 nm via green strategy were subjected to in-vitro antidiabetic assays. The samples were particularly selective for α-glucosidase while very mild inhibitors for α-amylase. ZnO sample with particle dimension of 32 nm was found to be the most potent inhibitor capable of preventing 97.86% enzymatic action. The IC50, and CC50 values of the sample were determined as 1.24 µg/mL and 88.89 µg/mL respectively. The selectivity index (SI) value obtained is 71.68 which indicates good selectivity towards enzymes inhibition rather than the host body. Molecular docking models were generated for ZnO association with α-glucosidase and possible binding sites were recognized.

Colorimetric and fluorimetric response of salicylaldehyde dithiosemicarbazone towards fluoride, cyanide and copper ions: Spectroscopic and TD-DFT studies.

The sensing mechanism of salicylaldehyde phenyldithiosemicarbazone (SDTSC) chemosensor has been investigated by spectroscopic and TD-DFT methods. The SDTSC shows colourimetric and spectral changes towards fluoride, cyanide and copper ions. The interaction between SDTSC with fluoride, cyanide and copper ions was examined through their absorption and fluorescence behaviour, and found that SDTSC has more sensing ability towards Cu2+ ion than CN- and F- ions. The 1H NMR titration with SDTSC and F- gives the structural changes in the sensing process. The reversibility of SDTSC was also evaluated and thus it is confirmed as a reusable chemosensor which can be clarified by the "Read-Erase-Read-Write" logic system. The DFT and TD-DFT calculations give the detailed sensing mechanism of SDTSC towards fluoride ion. The potential energy surface (PES) analysis confirms the excited state electron transfer mechanism.

Multi-ion detection and molecular switching behaviour of reversible dual fluorescent sensor.

The selective chemosensing behaviour of imidazole bisthiocarbohydrazone (IBTC) towards F- and Cu2+ are studied via colorimetric, UV-Visible, fluorescence spectra studies, and binding constants were calculated. The 1H NMR titration study strongly support that the deprotonation of IBTC followed by the hydrogen bond formation via N1H1 and N2H2 protons with fluoride ion. The fluorescence inactive IBTC-Cu complex became fluorescence active in the presence of perchlorate (ClO4-) ion. The selective detection of perchlorate ion was also explained. The F- sensing mechanism of IBTC has been investigated by Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TDDFT) methods. The theoretical outcomes well reproduce the experimental results. And it concluded the NH protons, nearby the imine group was first captured by the added F- ion and then deprotonation happened followed by the formation of hydrogen bond. The IBTC found good reversibility character with the alternative addition of Ca2+ and F-. The multi-ion detection of IBTC was used to construct the NOR, OR and INHIBITION molecular logic gates.

Spectroscopic and TDDFT investigation on highly selective fluorogenic chemosensor and construction of molecular logic gates.

1,5-Bis(2-fluorene)thiocarbohydrazone (FBTC) was designed and synthesized for selective sensing of fluoride and copper ions. The binding constants of FBTC towards fluoride and copper ions have been calculated using the Benesi-Hildebrand equation, and FBTC has more binding affinity towards copper ion than fluoride ion. The 1H NMR and 13C NMR titration studies strongly support the deprotonation was taken from the N-H protons followed by the formation of hydrogen bond via N-H…F. To understand the fluoride ion sensing mechanism, theoretical investigation had been carried out using the density functional theory and time-dependent density functional theory. The theoretical data well reproduced the experimental results. The deprotonation process has a moderate transition barrier (481.55kcal/mol). The calculated ΔE and ΔG values (-253.92 and -192.41kcal/mol respectively) suggest the feasibility of sensing process. The potential energy curves give the optimized structures of FBTC-F complex in the ground state and excited state, which states the proton transition occurs at the excited state. The excited state proton transition mechanism was further confirmed with natural bond orbital analysis. The reversibility of the sensor was monitored by the alternate addition of F- and Cu2+ ions, which was explained with "Read-Erase-Write-Read" behaviour. The multi-ion detection of sensor used to construct the molecular logic gate, such as AND, OR, NOR and INHIBITION logic gates.