A New and All-Solid-State Potentiometric Aluminium Ion Sensor for Water Analysis.

An all-solid-state potentiometric electrode system for aluminium ion determination was developed with a new aluminium ion sensor as the working electrode based on a new ionophore for aluminium ion, 1,1'-[(methylazanediyl)bis(ethane-2,1-diyl)]bis[3-(naphthalen-1-yl)thiourea] (ACH). The reference electrode was a potassium ion sensor, which acts as a pseudo-reference. Both electrodes were made from Ag/AgCl screen-print electrodes fabricated from a non-plasticized and photocurable poly(n-butyl acrylate) membrane that contained various other membrane components. The pseudo-reference potential based on the potassium ion sensor was fixed in 0.050 M KNO3, and such concentration of K+ ion did not interfere with the measurement of the Al3+ ion using the aluminium sensor. With such a pseudo-reference and in the presence of 0.050 M KNO3 as a background medium, the aluminium sensor measured changes of aluminium ion concentrations linearly from 10-6 to 10-2 M Al3+ ion with a Nernstian response of 17.70 ± 0.13 mV/decade. A low detection limit of 2.45 × 10-7 M was achieved with this all-solid-state potentiometric system. The aluminium sensor was insensitive to pH effects from 2.0 to 8.0 with a response time of less than 50 s. Under optimum conditions, a lifetime of 49 days was achieved with good sensor selectivity, reversibility, repeatability, and reproducibility. The all-solid-state electrode system was applied to analyze the Al3+ ion content of water samples from a water treatment plant. Compared with the conventional potentiometric detection system for aluminium ions, the new all-solid-state aluminium ion sensor incorporating a pseudo-reference from the potassium sensor demonstrated similar analytical performance. It thus provided a convenient means of aluminium content analysis in water treatment plants.

A Highly Sensitive Impedimetric DNA Biosensor Based on Hollow Silica Microspheres for Label-Free Determination of E. coli.

A novel label-free electrochemical DNA biosensor was constructed for the determination of Escherichia coli bacteria in environmental water samples. The aminated DNA probe was immobilized onto hollow silica microspheres (HSMs) functionalized with 3-aminopropyltriethoxysilane and deposited onto a screen-printed electrode (SPE) carbon paste with supported gold nanoparticles (AuNPs). The biosensor was optimized for higher specificity and sensitivity. The label-free E. coli DNA biosensor exhibited a dynamic linear response range of 1 × 10-10 µM to 1 × 10-5 µM (R2 = 0.982), with a limit of detection at 1.95 × 10-15 µM, without a redox mediator. The sensitivity of the developed DNA biosensor was comparable to the non-complementary and single-base mismatched DNA. The DNA biosensor demonstrated a stable response up to 21 days of storage at 4 ℃ and pH 7. The DNA biosensor response was regenerable over three successive regeneration and rehybridization cycles.

An Electrochemical DNA Biosensor for Carcinogenicity of Anticancer Compounds Based on Competition between Methylene Blue and Oligonucleotides.

A toxicity electrochemical DNA biosensor has been constructed for the detection of carcinogens using 24 base guanine DNA rich single stranded DNA, and methylene blue (MB) as the electroactive indicator. This amine terminated ssDNA was immobilized onto silica nanospheres and deposited on gold nanoparticle modified carbon-paste screen printed electrodes (SPEs). The modified SPE was initially exposed to a carcinogen, followed by immersion in methylene blue for an optimized duration. The biosensor response was measured using differential pulse voltammetry. The performance of the biosensor was identified on several anti-cancer compounds. The toxicity DNA biosensor demonstrated a linear response range to the cadmium chloride from 0.0005 ppm to 0.01 ppm (R2 = 0.928) with a limit of detection at 0.0004 ppm. The biosensor also exhibited its versatility to screen the carcinogenicity of potential anti-cancer compounds.

2,4-Di-chloro-N-[eth-yl(2-hy-droxy-eth-yl)carbamo-thio-yl]benzamide.

In the title compound, C12H14Cl2N2O2S, the mol-ecule adopts a cis conformation with respect to the di-chloro-benzoyl group against the thiono group about the C-N bond. However, the di-chloro-benzene group and the thio-urea moiety are twisted by 75.41 (8)°. An intra-molecular N-H⋯O hydrogen bond occurs between the amido H atom and hydroxyl O atom. In the crystal, O-H⋯S and O-H⋯O hydrogen bonds link the molecules, forming chains along the b-axis direction.

1-(4-Chloro-butano-yl)-3-(3-chloro-phen-yl)thio-urea.

The two independent mol-ecules in the asymmetric unit of the title compound, C11H12Cl2N2OS, exhibit different conformations, with the benzene ring and the N2CS thio-urea group forming dihedral angles of 87.40 (18) and 69.42 (15)°. An intra-molecular N-H⋯O hydrogen bond is present in each mol-ecule. Two further N-H⋯O hydrogen bonds link the independent mol-ecules into a dimer. In the crystal, the dimers are linked by N-H⋯S and C-H⋯S hydrogen bonds, forming chains parallel to the c axis.

1-(4-Bromo-phen-yl)-3-(3-chloro-propan-oyl)thio-urea.

The title compound, C10H10BrClN2OS, adopts a trans-cis conformation with respect to the position of the 3-chloro-propanoyl and 4-bromo-phenyl groups, respectively, against the thiono C=S bond across their C-N bonds. The benzene ring makes a dihedral angle of 9.55 (16)° with the N2CS thio-urea moiety. Intra-molecular N-H⋯O and C-H⋯S hydrogen bonds occur. In the crystal, mol-ecules are linked into chains along the c-axis direction by N-H⋯S, C-H⋯S and C-H⋯O hydrogen bonds.

Crystal structure of 4-fluoro-N-[2-(4-fluoro-benzo-yl)hydra-zine-1-carbono-thio-yl]benzamide.

In the title compound, C15H11F2N3O2S, the dihedral angle between the fluoro-benzene rings is 88.43 (10)° and that between the central semithiocarbazide grouping is 47.00 (11)°. The dihedral angle between the amide group and attached fluoro-benzene ring is 50.52 (11)°; the equivalent angle between the carbonyl-thio-amide group and its attached ring is 12.98 (10)°. The major twists in the mol-ecule occur about the C-N-N-C bonds [torsion angle = -138.7 (2)°] and the Car-Car-C-N (ar = aromatic) bonds [-132.0 (2)°]. An intra-molecular N-H⋯O hydrogen bond occurs, which generates an S(6) ring. In the crystal, the mol-ecules are linked by N-H⋯O and N-H⋯S hydrogen bonds, generating (001) sheets. Weak C-H⋯O and C-H⋯F inter-actions are also observed.

N-[Eth-yl(2-hy-droxy-eth-yl)carbamo-thio-yl]-3-fluoro-benzamide.

In the title compound, C12H15FN2O2S, the mol-ecule adopts a cis configuration of the fluoro-benzoyl group with respect to the thiono group about their C-N bond. The dihedral angle between the fluoro-benzoyl group and the thio-urea N2CS fragment is 69.60 (11)°. An intra-molecular N-H⋯O hydrogen bond occurs. In the crystal, mol-ecules form chains along the b-axis direction via O-H⋯S and C-H⋯O hydrogen bonds.

N-[Eth-yl(2-hy-droxy-eth-yl)carbamo-thio-yl]-2-methyl-benzamide.

The title compound, C13H18N2O2S, adopts a cis conformation between the methyl-benzoyl and thiono groups across their thio-urea C-N bond. However, the methyl-benzoyl group and N2CS thio-urea moiety are twisted by 15.03 (3)°. In the molecule there is an N-H⋯O hydrogen bond. In the crystal, mol-ecules are linked by O-H⋯O inter-actions, generating chains extending along the c-axis direction.

Adsorption of metal porphyrins using chitosan/zeolite-X composite as an efficient demetallization agent for crude oil: Isotherm, kinetic, and thermodynamic studies.

Chitosan/zeolite-X (CHS/ZX) was synthesized to serve as an effective adsorbent for metal porphyrins through adsorption processes as an alternative to traditional separation methods from crude oil. The adsorption-desorption mechanisms of vanadyl and nickel tetraphenyl porphyrin (VO-TPP and Ni-TPP) were conducted on the model solution. Compared to individual components CHS and ZX, the CHS/ZX composite exhibited a doubled capacity for metal porphyrin removal. The synthesized composite was systematically characterized using FESEM, BET, XRD, FTIR, TGA, XPS, and CHN analyses. The study investigated the impact of many factors, including temperature, initial metal-porphyrin concentration, CHS/ZX dose, and contact time, on the adsorption efficiency of metal-porphyrin using CHS/ZX adsorbents. The adsorption processes of VO-TPP and Ni-TPP on CHS/ZX were effectively assessed through various equilibrium models, such as Langmuir, Freundlich, and Dubinin-Radushkevich (D-R). The pseudo-second-order model accurately depicted the adsorption processes of both VO-TPP and Ni-TPP. Determining the point of zero charge (pHPZC) highlighted the composite's surface charge distribution. Furthermore, considering the ΔG° and ΔH° values, the adsorption processes at different temperatures are exothermic, and VO-TPP exhibits a greater adsorption capacity than Ni-TPP under similar conditions. Notably, 73.7 % of VO-TPP and 83.8 % of Ni-TPP that were adsorbed were successfully recovered.

Exploring diverse frontiers: Advancements of bioactive 4-aminoquinoline-based molecular hybrids in targeted therapeutics and beyond.

Amongst heterocyclic compounds, quinoline and its derivatives are advantaged scaffolds that appear as a significant assembly motif for developing new drug entities. Aminoquinoline moiety has gained significant attention among researchers in the 21stcentury. Considering the biological and pharmaceutical importance of aminoquinoline derivatives, herein, we review the recent developments (since 2019) in various biological activities of the 4-aminoquinoline scaffold hybridized with diverse heterocyclic moieties such as quinoline, pyridine, pyrimidine, triazine, dioxine, piperazine, pyrazoline, piperidine, imidazole, indole, oxadiazole, carbazole, dioxole, thiazole, benzothiazole, pyrazole, phthalimide, adamantane, benzochromene, and pyridinone. Moreover, by gaining knowledge about SARs, structural insights, and molecular targets, this review may help medicinal chemists design cost-effective, selective, safe, and more potent 4-aminoquinoline hybrids for diverse biological activities.

Design and synthesis of pyrano[2,3-c]pyrazole-4-aminoquinoline hybrids as effective antimalarial compounds.

In this work, a series of nineteen novel pyrano[2,3-c]pyrazole-4-aminoquinoline hybrids were synthesized as potent antimalarial agents by covalently linking the scaffolds of 4-aminoquinoline and pyrano[2,3-c]pyrazoles via an ethyl linker and characterized using Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). Molecular docking was used to test each hybrid's and standard chloroquine's ability to bind to Plasmodium falciparum lactate dehydrogenase enzyme (PfLDH), an important enzyme in the parasite's glycolytic pathway. The hybrid compounds had a stronger binding affinity than the standard chloroquine (CQ). The schizontical antimalarial test of pyrano[2,3-c]pyrazole-4-aminoquinoline hybrid compound shows that all nineteen hybrid compounds were potent with the IC50 values ranging from 0.0151 to 0.301 µM against the CQ-sensitive 3D7 P. falciparum strain, and were active against the CQ-resistant K1 P. falciparum strain with the IC50 values ranging from 0.01895 to 2.746 µM. All the tested hybrid compounds were less potent than the standard drug chloroquine dipaspate (CQDP) against the CQ-sensitive 3D7 strain. In contrast, nine of the nineteen hybrids (16d, 16g, 16h, 16i, 16l, 16n, 16o, 16r, and 16s) displayed superior antimalarial activity than the CQDP against the CQ-resistant K1 P. falciparum strain. Among all the tested hybrids, 16c against the 3D7 strain and 16h against the K1 strain were the most promising antimalarial agents with 0.0151 and 0.01895 µM of IC50 values, respectively. In addition, the compounds were selective, showing moderate to low cytotoxic activity against a human normal liver WRL68 cell line. The synthesis of pyrano[2,3-c]pyrazole-4-aminoquinoline hybrids introduces new chemical entities that have the potential to exhibit potent antimalarial activity. It could address the ongoing challenge of drug resistance in malaria treatment.

Synthesis, characterization, X-ray structure and biological activities of C-5-bromo-2-hydroxyphenylcalix[4]-2-methyl resorcinarene.

C-5-bromo-2-hydroxyphenylcalix[4]-2-methylresorcinarene (I) was synthesized by cyclocondensation of 5-bromo-2-hydroxybenzaldehyde and 2-methylresorcinol in the presence of concentrated HCl. Compound I was characterized by infrared and nuclear magnetic resonance spectroscopic data. X-ray analysis showed that this compound crystallized in a triclinic system with space group of Pi, a = 15.9592(16)Å, b = 16.9417(17)Å, c = 17.0974(17)Å, α = 68.656(3)°, ß = 85.689(3)°, γ = 81.631(3)°, Z = 2 and V = 4258.6(7)Å3. The molecule adopts a chair (C2h) conformation. The thermal properties and antioxidant activity were also investigated. It was strongly antiviral against HSV-1 and weakly antibacterial against Gram-positive bacteria. Cytotoxicity testing on Vero cells showed that it is non-toxic, with a CC50 of more than 0.4 mg/mL.

3-Chloro-N-[N-(furan-2-carbon-yl)hydrazinocarbo-thio-yl]benzamide.

In the title compound C13H10ClN3O3S, the benzoyl group maintains its trans conformation against the thiono group about the C-N bond and the intra-molecular hydrogen bond between the benzoyl O atom and thio-amide H atom. In the crystal, N-H⋯O and C-H⋯O hydrogen bonds link the mol-ecules, forming chains along the b-axis direction. In addition, C-H⋯π inter-actions occur between a phenyl H atom and the furan ring.

Triazole hybrid compounds: A new frontier in malaria treatment.

Reviewing the advancements in malaria treatment, the emergence of triazole hybrid compounds stands out as a groundbreaking development. Combining the advantages of triazole and other moieties, these hybrid compounds offer a new frontier in the battle against malaria. Their potential as effective antimalarial agents has captured the attention of researchers and holds promise for overcoming the challenges posed by drug-resistant malaria strains. We focused on their broad spectrum of antimalarial activity of diverse hybridized 1,2,3-triazoles and 1,2,4-triazoles, structure-activity relationship (SAR), drug-likeness, bioavailability and pharmacokinetic properties reported since 2018 targeting multiple stages of the Plasmodium life cycle. This versatility makes them highly effective against both drug-sensitive and drug-resistant strains of P. falciparum, making them invaluable tools in regions where resistance is prevalent. The synergistic effects of combining the triazole moiety with other pharmacophores have resulted in even greater antimalarial potency. This approach has the potential to circumvent existing resistance mechanisms and provide a more sustainable solution to malaria treatment. While triazole hybrid compounds show great promise, further research and clinical trials are warranted to fully evaluate their safety, efficacy and long-term effects. As research progresses, these compounds can potentially revolutionize the field and contribute to global efforts to eradicate malaria, ultimately saving countless lives worldwide.

Recent developments in antimalarial activities of 4-aminoquinoline derivatives.

Malaria is the fifth most lethal parasitic infection in the world. Antimalarial medications have played a crucial role in preventing and eradicating malaria. Numerous heterocyclic moieties have been incorporated into the creation of effective antimalarial drugs. The 4-aminoquinoline moiety is favoured in antimalarial drug discovery due to the diverse biological applications of its derivative. Since the 1960s, 4-aminoquinoline has been an important antimalarial drug due to its low toxicity, high tolerability, and rapid absorption after administration. This review focused on the antimalarial efficacy of the 4-aminoquinoline moiety hybridised with various heterocyclic scaffolds developed by scientists since 2018 against diverse Plasmodium clones. It could aid in the future development of more effective antimalarial agents.

Pyrazole and pyrazoline derivatives as antimalarial agents: A key review.

Malaria poses a severe public health risk and a significant economic burden in disease-endemic countries. One of the most severe issues in malaria control is the development of drug resistance in malaria parasites. The standard treatment for malaria is artemisinin-combination therapy (ACT). Nevertheless, the Plasmodium parasite's extensive resistance to prior drugs and reduced ACT efficiency necessitates novel drug discovery. The progress in discovering novel, affordable, and effective antimalarial agents is significant in combating drug resistance, and the hybrid drug concept can be used to covalently link two or more active pharmacophores that may act on multiple targets. Pyrazole and pyrazoline derivatives are considered pharmacologically necessary active heterocyclic scaffolds that possess almost all types of pharmacological activities. This review summarized recent progress in antimalarial activities of synthesized pyrazole and pyrazoline derivatives. The studies published since 2000 are included in this systematic review. This review is anticipated to be beneficial for future study and new ideas in searching for rational development strategies for more effective pyrazole and pyrazoline derivatives as antimalarial drugs.

Highly sensitive pork meat detection using copper(ii) tetraaza complex by electrochemical biosensor.

Three copper(ii) tetraaza complexes [Cu(ii)LBr]Br (1a), [Cu(ii)L(CIO4)](CIO4) (2a) and [Cu(ii)L](CIO4)2 (2b), where L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7,14-diene were prepared and confirmed by FTIR, 1HNMR and 13CNMR. The binding interaction of complex (1a, 2a, 2b) with calf thymus DNA (CT-DNA) was investigated using UV-vis absorption, luminescence titrations, viscosity measurements and molecular docking. The findings suggested that complex 1a, 2a and 2b bind to DNA by electrostatic interaction, and the strengths of the interaction were arranged according to 2b > 1a > 2a. The differences in binding strengths were certainly caused by the complexes' dissimilar charges and counter anions. Complex 2b, with the biggest binding strength towards the DNA, was further applied in developing the porcine sensor. The developed sensor exhibits a broad linear dynamic range, low detection limit, good selectivity, and reproducibility. Analysis of real samples showed that the biosensor had excellent selectivity towards the pork meat compared to chicken and beef meat.

2-Amino-cyclo-hexan-1-aminium thio-cyanate.

The title compound, C(6)H(15)N(2) (+)·NCS(-), was obtained unexpectedly from the reaction mixture of benzoyl chloride, ammonium thio-cyanate and cyclo-hexane-1,2-diamine. The cyclo-hexane ring adopts a chair conformation. In the crystal, N-H⋯S and N-H⋯N inter-actions involving the thio-cyanate anion and both the amine and the aminium N atoms link the mol-ecules, forming two-dimensional networks parallel to (001).

A New Sensing Material Based on Tetraaza/SBA15 for Rapid Detection of Copper(II) Ion in Water.

A novel rapid and sensitive optical sensor for Cu2+ ion detection based on 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7,14-dienium dibromide (TL) immobilized on Santa Barbara Amorphous (SBA-15) has been successfully developed. The inner and outer space of SBA15 allowed a high capacity of TL compound to immobilize onto it. FESEM (Field Emission Scanning Electron Microscopy) analysis was performed to confirm the morphology of TL-SBA15, while FTIR (Fourier Transform Infrared Spectroscopy) was utilized to confirm the interaction of TL−SBA15. A binding study of TL compound towards Cu2+ ion was performed via UV-vis solution study and binding titration. The stoichiometric binding ratio and binding constant value Kb of TL towards Cu2+ ion was 1:1 and 2.33 × 103 M−1, respectively. The optical reflectance sensor based on the TL compound is selective to Cu2+ ion and demonstrated a linear response over a Cu2+ ion concentration range of 1 × 10−7 M to 2 × 10−5 M, with a detection limit (LOD) of 1.02 × 10−7 M (R2 = 0.99) and fast response time of < 1 min. It showed high reproducibility, with a relative standard deviation (RSD) obtained at 0.47%. This optical sensor is reusable up to five consecutive times on Cu2+ ion by using 0.1 M EDTA with a pH of 6 as a regeneration solution, with a reversibility RSD value of 0.79%. The developed optical sensor provides a rapid and sensitive tool for Cu2+ ion detection in teabag samples, and the results align with those obtained by the ICP-MS standard method.