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The rising antimicrobial resistance crisis has diminished the effectiveness of traditional antibiotics against pathogenic bacteria. This study addresses this urgent challenge by exploring the antibacterial potential of novel quinolone derivatives (1–33). Using computational in silico modeling to simulate biological interactions, we aimed to identify candidates with potent antibacterial activity. A total of 33 quinolone derivatives were assessed for their physicochemical properties and effectiveness against a range of clinically relevant pathogens, including methicillin‐resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae, Streptococcus pneumoniae, and Enterococcus faecalis. Molecular docking studies identified compounds 28, 29, 32, and 33 as having notable binding affinities, particularly against MRSA. Further molecular dynamics simulations of compound 29 confirmed its favorable stability and potential for disrupting MRSA, reinforcing the docking results and showing strong alignment with in vitro findings. These findings position compound 29 as a promising lead for developing alternative MRSA therapies and underscore the need for further in vivo studies to evaluate its therapeutic potential. [ABSTRACT FROM AUTHOR]

Diluting a system with metal complexes can sometimes cause free metal ions to increase in concentration. This paper describes "metal ion anti-buffering", a situation in which free metal ion concentrations rapidly increase as system dilution drives dissociation. It only occurs under excess free ligand conditions when a solution is dominated by higher stoichiometry complexes. The Law of Mass Action is used to provide a mathematical justification for the phenomenon. A Cu[superscript 2+]- ethylenediamine mixture exhibits this phenomenon when excess free ethylenediamine (en) is present. For example, it occurs when diluting a solution containing a 4-fold excess of en over Cu[superscript 2+]. As this mixture is diluted by a factor of 5600, the modeled free Cu[superscript 2+] concentration shows a 470-fold increase. Taken together, this is 2.5 million times higher than dilution of the system would yield in other circumstances. Included are experimental data confirming anti-buffering in the Cu[superscript 2+]-en system. Many other metal-ligand systems can display this behavior. Four additional examples are illustrated, including an amino acid under physiological pH. Anti-buffering TOPOS, a free downloadable Excel workbook, allows readers to simulate this behavior for many metal-ligand systems. A PowerPoint lecture and teaching materials are also provided, suitable for inclusion in upper division and graduate courses in analytical chemistry, biochemistry, and geochemistry.

"Complexation TOPOS" is a free software package to generate 3-D topographic surfaces ("topos") for metal-ligand complexometric titrations in aqueous media. It constructs surfaces by plotting computed equilibrium parameters above a composition grid with "volume of ligand added" as the x-axis and overall system dilution as the y-axis. The sample systems in this paper are restricted to EDTA as a ligand. Other chelating ligands that form exclusively 1:1 complexes could also be modeled with this software. The surfaces show the quality of the equivalence point break under various conditions. More importantly, they develop the phenomenon of metal ion buffering. They clearly distinguish the difference between "pseudo-buffering" and "true buffering." They introduce terminology for two different forms of metal ion buffering: (1) mass action metal ion buffering under excess ligand conditions and (2) precipitate metal ion buffering when hydroxide precipitates are present under excess metal ion conditions. Systems modeled are EDTA titrations of Cu[superscript 2]+ and Mg[superscript 2+]. Supporting Information for this paper includes the "Complexation TOPOS" software, an Excel workbook that generates topos in under 20 seconds. Required inputs are the following: (1) a stability constant for the metal-ligand complex, (2) acid dissociation constants for the ligand, (3) stability constants for hydroxy complexes of the metal, and (4) a K[subscript sp] value and stoichiometry for hydroxide precipitates. Many constants are tabulated in a workbook tab. Also included are a PowerPoint lecture and teaching materials (for lecture, homework, and prelaboratory activities) that are suitable in general chemistry courses or third-year and graduate courses in analytical chemistry, biochemistry, and geochemistry.

Species TOPOS is a free software package for generating three-dimensional (3-D) topographic surfaces ("topos") for acid-base equilibrium studies. This upgrade adds 3-D species distribution topos to earlier surfaces that showed pH and buffer capacity behavior during titration and dilution procedures. It constructs topos by plotting computed a values above a composition grid with volume of NaOH added as the "x" axis and overall system dilution as the "y" axis. The systematic shift from protonated to deprotonated forms is clearly visualized on a linear "z" axis. Because pH and buffer capacity surfaces accompany the species topos, it is easy to see their interrelationships. On the basis of their graphical appearance, features on species topos have been named corner buttes, corner pits, curving ridge crests, and dilution plains. Ramps connecting surface features are linear when tied to additions of NaOH and logarithmic when associated with the logarithmic dilution axis. The amphiprotic behavior of water is demonstrated by dilution procedures. Systems examined include acetic acid, CH[subscript 3]COOH (a weak monoprotic acid); carbonic acid, H[subscript 2]CO[subscript 3] (a weak diprotic acid), and phosphoric acid, H[subscript 3]PO[subscript 4] (a weak triprotic acid). For comparative purposes, species topos are depicted for a set of three acids with hypothetical pK[subscript a] values of 4.000, 7.000, and 10.000. The Supporting Information includes the Species TOPOS software, macro-enabled spreadsheets that quickly generate pH, buffer capacity, and a surfaces for any mono-, di-, or triprotic acid desired. Only acid dissociation constant (K[subscript a]) values need be changed. Also included are a set of PowerPoint lecture slides and a document entitled "Suggestions on Using Species TOPOS for Teaching" with sections for lecture, worksheet applications, and laboratory activities in first-year college courses and third-year or graduate analytical chemistry courses.

BufCap TOPOS is free software that generates 3-D topographical surfaces ("topos") for acid-base equilibrium studies. It portrays pH and buffer capacity behavior during titration and dilution procedures. Topo surfaces are created by plotting computed pH and buffer capacity values above a composition grid with volume of NaOH as the x axis and overall system dilution as the y axis. What emerge are surface features that correspond to pH and buffer behaviors in aqueous solutions. Topo surfaces are created for pH, log buffer capacity, and linear buffer capacity. Equivalence point breaks become pH cliffs and logarithmic buffer capacity canyons that grow shallower with dilution. Areas of high buffer capacity become rounded ridges. Dilution alone generates 45° ramps. Example systems include hydrochloric acid, HCl (a strong acid); acetic acid, CH[subscript 3]COOH (a weak monoprotic acid); oxalic acid, HOOCCOOH (a weak diprotic acid); and L-glutamic acid hydrochloride, C[subscript 5]H[subscript 9]NO[subscript 4]·HCl (a weak triprotic acid). The Supporting Information includes a copy of the interactive BufCap TOPOS program, macro-enabled spreadsheets that quickly generate surfaces for any mono-, di-, or triprotic acid. Only acid dissociation constants, K[subscript a] values, need be changed. Other materials include teaching slides for lectures, plus worksheets and laboratory activities for first-year college courses and third-year or graduate analytical chemistry courses.

3-D topographic surfaces ("topos") can be generated to visualize how pH behaves during titration and dilution procedures. The surfaces are constructed by plotting computed pH values above a composition grid with volume of base added in one direction and overall system dilution on the other. What emerge are surface features that correspond to behavior in aqueous solutions. Equivalence point breaks become cliffs that pinch out with dilution. Buffer effects become plateaus. Dilution alone generates 45° ramps. Limitations of the Henderson-Hasselbalch equation can be seen by noting the conditions over which a plateau remains relatively flat. Because dissociation is driven by dilution, the surfaces demonstrate when the solution of a weak acid becomes indistinguishable from that of a strong acid. Surfaces are presented for hydrochloric acid, HCl (a strong acid); acetic acid, CH [subscript 3]COOH (a weak monoprotic acid); oxalic acid, HOOCCOOH (a weak diprotic acid) and l-histidine dihydrochloride, C[subscript 6]H[subscript 9]N[subscript 3]O[subscript 2]·2HCl (a weak triprotic acid). Supplementary materials include suggested use of topos in lecture, as worksheets and in support of laboratory activities for first-year college courses and third-year analytical chemistry courses. Also provided is pH TOPOS, the macro-enabled spreadsheets that quickly generate surfaces for any mono-, di-, or triprotic acid desired. Only a change of acid dissociation constants, K[subscript a] values, is required.

Two characteristics of batteries, their delivery of nearly constant voltage and their rapid failure, are explained through a visual examination of the Nernst equation. Two Galvanic cells are described in detail: (1) a wet cell involving iron and copper salts and (2) a mercury oxide dry cell. A complete description of the wet cell requires a three-dimensional Nernst surface because the potential is a function of two variables: the activities of both the oxidized and reduced forms in each redox couple. Dry cell potentials, which utilize solid or pure liquid species, are functions of only one variable and can be described by a pair of traces in a traditional plot. Plots of the Nernst potential are relatively flat for most activities, but they exhibit cliffs under extreme conditions. The flat spots are responsible for the fairly constant voltage that batteries deliver; the cliffs explain why batteries fail so quickly. (Contains 7 figures.)

Introduction: Alzheimer's disease, akin to coronary artery disease of the heart, is a progressive brain disorder driven by nerve cell damage., Method: This study utilized computational methods to explore 14 anti-acetylcholinesterase (AChE) derivatives (1 ̶ 14) as potential treatments. By scrutinizing their interactions with 11 essential target proteins (AChE, Aβ, BChE, GSK-3β, MAO B, PDE-9, Prion, PSEN-1, sEH, Tau, and TDP-43) and comparing them with established drugs such as donepezil, galantamine, memantine, and rivastigmine, ligand 14 emerged as notable. During molecular dynamics simulations, the protein boasting the strongest bond with the critical 1QTI protein and exceeding drug-likeness criteria also exhibited remarkable stability within the enzyme's pocket across diverse temperatures (300 ̶ 320 K). In addition, we utilized density functional theory (DFT) to compute dipole moments and molecular orbital properties, including assessing the thermodynamic stability of AChE derivatives., Result: This finding suggests a welldefined, potentially therapeutic interaction further supported by theoretical and future in vitro and in vivo investigations., Conclusion: Ligand 14 thus emerges as a promising candidate in the fight against Alzheimer's disease., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)