Molecular Properties Research Articles

Natural Distribution, Structures, Synthesis, and Bioactivity of Hasubanan Alkaloids.

Hasubanan alkaloids represent a distinct class of alkaloids bearing a structural resemblance to morphine, predominantly found in herbals of the Stephania genus. Their intriguing molecular architecture and potential analgesic properties have captured the interest of medicinal chemists worldwide. This review meticulously examines the natural distribution, structural characteristics, biosynthetic pathways, synthetic methodologies, and biological activities of hasubanans.

Abstract PO1-15-11: Molecular and clinical disparities in breast cancer among East Asian populations

Abstract Background Breast Cancer (BC) is a complex disease with profound genomic aberrations. However, the underlying molecular disparity influenced by age and ethnicity remains elusive. Method We aimed to investigate the molecular properties of 843 primary and metastatic BC patients enrolled in the K-MASTER program. We explored the unique molecular profiles of breast cancer patients by categorizing them into two distinct age subgroups. The first subgroup comprised young breast cancer (YBC) patients, defined as women under the age of 40, while the second subgroup consisted of older breast cancer (OBC) patients. Our study aimed to characterize the molecular differences between these age-defined groups, providing insights into the underlying mechanisms of breast cancer in different age cohorts. Additionally, we leveraged large-scale genomic data from the TCGA and MSK-IMPACT studies to examine the ethnic-driven molecular and clinical disparities. Results The K-MASTER patients were mainly comprised of triple-negative breast cancer (TNBC) and HER2-positive tumors, while the TCGA and MSK-IMPACT cohorts exhibited a predominance of hormone receptor-positive (HR+) subtype. We observed a high prevalence of PI3KCA mutations in K-MASTER HER2+ tumors, particularly in older patients. Moreover, we identified increased mutation rates in DNA damage response molecules, including ARID1A, MSH6, and MLH1. Importantly, GATA3 mutations were less frequently observed in East Asian patients, which correlated with poor clinical outcomes. Our analysis also revealed specific associations between genomic aberrations, organotropisms, and metastatic breast cancer. In addition to characterizing the molecular disparities, we developed a gradient-boosting multivariable model to identify a new molecular signature that could predict the therapeutic response to platinum-based chemotherapy. Conclusion Our findings collectively provide unprecedented insights into the significance of age and ethnicity on the molecular and clinical characteristics of BC patients. Figure 1. Genomic landscape of KM BRCA. (A) Overall characteristic of KM BRCA sample and clinical data. Clinical features of KM BRCA sample. (B) Genomic landscape of somatic mutations and copy number alterations of BRCA by age group. Figure 2. Genomic landscape of KM BRCA: Significantly mutated genes by age group in KM BRCA. Figure 3. Survival Curve Utilizing a curated Gene Set Developed by a Gradient-Boosting Multivariable Model (A) OS of platinum-based therapy treated KM with curated Gene set. (B) OS of platinum-based therapy treated MSK with curated Gene set. Citation Format: Kim Ju Won, LEE JIWON, Kyong Hwa Park, Seung Pil Jung, Jason Sa, SHIN SANG WON, An Jung Seok. Molecular and clinical disparities in breast cancer among East Asian populations [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-15-11.

Online headspace monitoring of volatile organic compounds using proton transfer reaction-mass spectrometry: Application to the multiphase atmospheric fate of 2,4-hexadienedial

Chemical processes in clouds have been suggested to contribute significantly to the mass of organic aerosol particles in the atmosphere. Experimental and theoretical evidence suggest that organic mass production in clouds can be substantial and depends on the concentration of organic precursor compounds available in the gas phase. The present study aims at studying the aqueous phase reactivity of one of these overlooked precursors, i.e. 2,4-hexadienedial, an important and toxic intermediate in the atmospheric oxidation of aromatic species. Cautious synthesis and purification of 2,4-hexadienedial was performed. Its effective Henry's law constant was measured using a new simple and fast method based on online flow-injection analysis. The reactivity of 2,4-hexadienedial in the aqueous phase relevant to atmospheric conditions was studied, including hydrate formation, photolysis, ∙OH- and SO4∙--oxidation as well as reaction with NH3. The results revealed a low hydration constant compared to other dicarbonyls (Khyd1 = 7 × 10−2) and no dihydrate formation, indicating in an intermediate solubility (KH = 1.0 × 104 M atm−1) and high absorption cross sections (σ278nm > 10−16 cm2 molecule−1). Compared to its gas phase photolysis, its aqueous phase photolysis showed low quantum yields (Φ290–380nm = 0.9 %), and a significant red shift of the absorbance maximum, leading to a fast aqueous photolysis kinetics (Jaq,atm = 8.7 × 10−5 s−1) under atmospheric solar radiation, but no triplet state formation was detected. Radical oxidation experiments revealed extremely rapid oxidation kinetics (k∙OH = 1.10 × 1010 M−1 s−1 and kSO4∙- = 1.4 × 109 M−1 s−1) driven by fast addition of the radicals to the unsaturated bonds. In contrast, the reaction with aqueous NH3 (kNH3 = 2.6 × 10−3 M−1 s−1) was found slower than glyoxal and 2-butenedial, likely due to the hyperconjugation of 2,4-hexadienedial. Using these new data complemented with assumed aqueous phase kinetics (for NO3, 3C* and 1O2 reactions) and previous gas-phase kinetic ones, the multiphase atmospheric fate of 2,4-hexadienedial was established under atmospheric conditions reported from previous field measurements and models. The results revealed a short day lifetime (∼1 h) and a long night lifetime (>12 h). It was shown that daytime atmospheric chemistry of 2,4-hexadienedial can be influenced by aqueous-phase reactivity during cloud events, up to ∼50 % under thick cloud conditions (Liquid Water Content >2000 g/m3), indicating that even a compound of intermediate solubility can be strongly affected by condensed-phase reactivity. Besides its fast aqueous phase reactivity towards ∙OH and photolysis, its daytime condensed-phase reactivity may be driven by reactions with dissolved triplet states (3C*), up to 35 %, highlighting the need to study further the kinetics, the nature and concentrations of dissolved 3C* under various atmospheric conditions. In addition, the molecular properties and atmospheric behavior of 2,4-hexadienedial were found different from those of glyoxal and 2-butenedial, highlighting the need for detailed atmospheric reactivity studies of polyfunctional compounds, in particular unsaturated compounds.

Hydrogen-bond stabilized π-π stacking in the solvent-induced dimerization of 4-nitro-1-naphthol: A spectroscopic and computational investigation

π-π Stacking is crucial for stabilizing molecular structures and facilitating interactions in biological systems and chemical processes. The presence of electron-withdrawing and electron-donating substituents, particularly the hydroxyl group, significantly influences the energetics and energetically favorable configurations of π-stacked complexes. In this study, we utilized UV–Vis absorption and resonance Raman spectroscopies, alongside density functional theory (DFT) calculations, to investigate the competition between dissociation and self-aggregation of 4-nitro-1-naphthol (NNH) in various polar solvents. Our results demonstrate the self-aggregation of NNH in polar solvents and identify the most likely dimer configuration, which is antiparallel π-stacked and stabilized by hydrogen bonds between hydroxyl and nitro groups. Given its broad applications in mass spectrometry, environmental remediation, and aerosol tracking, a comprehensive understanding of the molecular interactions and structural properties of NNH is essential for its effective use in various scientific fields.

Lignin-based carbon fibres: Effect of bio-polyamide on oxidative thermal stabilisation of lignin

Carbon fibres have been produced from hydroxypropyl-modified lignin (TcC)/bio-based polyamide 1010 (PA1010) blended filaments. Two grades of PA1010, with different molecular weights and rheological properties, were used for blending with TcC. An oxidative thermal stabilisation step was used prior to carbonisation in an inert atmosphere to prevent the fusion of the filaments during the latter step. Thermal stabilisation was not possible using a one-step stabilisation process reported in the literature for lignin and other lignin/synthetic polymer blends. As a consequence, a cyclic process involving an additional isothermal phase at a lower temperature than the precursor filaments’ melting point, was introduced to increase the cross-linking reactions between the lignin and polyamide. Thermally stabilised filaments were characterised by DSC, TGA, TGA-FTIR, ATR, and SEM techniques. Polymer rheology and heating rate used during thermal stabilisation influenced the thermal stabilisation process and mechanical properties of the derived filaments. Thermally stabilised filaments using optimised conditions (heating in the air atmosphere at 0.25°C/min to 180°C; isothermal for 1h, cooling back down to ambient at 5°C/min; heating to 250°C at 0.25°C/min, isothermal for 2 h) could be successfully carbonised. Carbon fibres produced had void-free morphologies and mechanical properties comparable to similarly thermally stabilised and carbonised polyacrylonitrile (PAN) filaments.

Development and validation of a generic methyltransferase enzymatic assay based on an SAH riboswitch

Methylation of proteins and nucleic acids plays a fundamental role in epigenetic regulation, and discovery of methyltransferase (MT) inhibitors is an area of intense activity. Because of the diversity of MTs and their products, assay methods that detect S-adenosylhomocysteine (SAH) – the invariant product of S-adenosylmethionine (SAM)-dependent methylation reactions - offer some advantages over methods that detect specific methylation events. However, direct, homogenous detection of SAH requires a reagent capable of discriminating between SAH and SAM, which differ by a single methyl group. Moreover, MTs are slow enzymes and many have submicromolar affinities for SAM; these properties translate to a need for detection of SAH at low nanomolar concentrations in the presence of excess SAH. To meet these needs, we leveraged the exquisite molecular recognition properties of a naturally occurring SAH-sensing RNA aptamer, or riboswitch. By splitting the riboswitch into two fragments, such that SAH binding induces assembly of a trimeric complex, we engineered sensors that transduce binding of SAH into positive fluorescence polarization (FP) and time resolved Förster resonance energy transfer (TR-FRET) signals. The split riboswitch configuration, called the AptaFluor™ SAH Methyltransferase Assay, allows robust detection of SAH (Z’ > 0.7) at concentrations below 10 nM, with overnight signal stability in the presence of typical MT assay components. The AptaFluor assay tolerates diverse MT substrates, including histones, nucleosomes, DNA and RNA, and we demonstrated its utility as a robust, enzymatic assay method for several methyltransferases with SAM Km values < 1µM. The assay was validated for HTS by performing a pilot screen of 1,280 compounds against the SARS-CoV-2 RNA capping enzyme, nsp14. By enabling direct, homogenous detection of SAH at low nanomolar concentrations, the AptaFluor assay provides a universal platform for screening and profiling MTs at physiologically relevant SAM concentrations.

Theoretical study on the regulation of molecular stacking and charge transport properties of Nitrogen-heteroacene derivatives containing benzocyclobutadiene

The precise control of molecular packing patterns in solid-state materials is crucial for determining their charge transport properties. This study systematically investigates the molecular packing patterns and charge transport properties of triisopropylsilylacetylene (TIPS)-benzobenzene molecules functionalized with different molecular lengths using benzocyclobutadiene (BCBD) as a linker to connect polycyclic aromatic hydrocarbons. In the solid state, these molecules exhibited both herringbone stacking and 1D/2D π-stacking. We discovered an intrinsic relationship between the stacking motifs and the position of the TIPS in the investigated systems. Depending on the ratio (R) of skeleton lengths at both ends of the main chain with TIPS as the split point in the different ranges of ∼2.0, 2.0–3.0, and 3.0∼, these crystals exhibited different packing patterns. Meanwhile, the R value is closely related to the anisotropy of mobility of these organic semiconductors. Multi-scale calculations, including density functional theory (DFT) and molecular dynamics (MD) simulations, were employed to examine the impact of incorporating the BCBD structural moiety on charge transport properties. The results demonstrate that BCBD effectively extends the LUMO orbitals and maintains a balance between hole and electron transport properties. This work aims to elucidate the experimental phenomena and establish a theoretical foundation for the development of high-mobility semiconductor materials.

Fluorocitrate inhibition of astrocytes reduces nicotine self-administration and alters extracellular levels of glutamate and dopamine within the nucleus accumbens in male wistar rats

Emerging evidence suggests an important role of astrocytes in mediating behavioral and molecular effects of commonly misused drugs. Passive exposure to nicotine alters molecular, morphological, and functional properties of astrocytes. However, a potential involvement of astrocytes in nicotine reinforcement remains largely unexplored. The overall hypothesis tested in the current study is that astrocytes play a critical role in nicotine reinforcement. Protein levels of the astrocyte marker glial fibrillary acidic protein (GFAP) were examined in key mesocorticolimbic regions following chronic nicotine intravenous self-administration. Fluorocitrate, a metabolic inhibitor of astrocytes, was tested for its effects on behaviors related to nicotine reinforcement and relapse. Effects of fluorocitrate on extracellular neurotransmitter levels, including glutamate, GABA, and dopamine, were determined with microdialysis. Chronic nicotine intravenous self-administration increased GFAP expression in the nucleus accumbens core (NACcr), but not other key mesocorticolimbic regions, compared to saline intravenous self-administration. Both intra-ventricular and intra-NACcr microinjection of fluorocitrate decreased nicotine self-administration. Intra-NACcr fluorocitrate microinjection also inhibited cue-induced reinstatement of nicotine seeking. Local perfusion of fluorocitrate decreased extracellular glutamate levels, elevated extracellular dopamine levels, but did not alter extracellular GABA levels in the NACcr. Fluorocitrate did not alter basal locomotor activity. These results indicate that nicotine reinforcement upregulates the astrocyte marker GFAP expression in the NACcr, metabolic inhibition of astrocytes attenuates nicotine reinforcement and relapse, and metabolic inhibition of astrocytes disrupts extracellular dopamine and glutamate transmission. Overall, these findings suggest that astrocytes play an important role in nicotine reinforcement and relapse, potentially through regulation of extracellular glutamate and dopamine neurotransmission.

Synthesis and mechanism of quaternary ammonium salts based on porphyrin as high-performance copper levelers

The molecular structure and energy distribution of organic compounds have a great influence on their adsorption capacity on the metal surface. However, there are still insufficient researches on the influence of energy distribution on adsorption properties of organic molecules. Herein, a family of porphyrin derivatives (TPyP-Et, TPyP-Oct, TPyP-Bn and TPyP-Al) bearing quaternary ammonium groups were synthesized for the first time as promising levelers for through-hole copper electrodeposition. Electrochemical tests revealed that all four TPyP derivatives displayed enhanced electrochemical properties. Theoretical calculations and molecular dynamics simulations were carried out to investigate the physisorption capacity and chemical reaction activity of the TPyP molecules, as well as the adsorption capacity on the surface of the copper layer. Through optical and scanning electron microscopy as well as X-ray diffractometry, it was demonstrated that TPyP molecules are effective electroplating levelers. TPyP-Oct, with its longer carbon chain substituent, exhibited superior hole-filling performance in practical PCB experiments among the four compounds. This study expandes the application range of porphyrin compounds, analyzes the influence of organic molecular adsorption properties in copper electrodeposition, and provides theoretical guidance for the future study of organic compounds adsorbed on metal surfaces.

Characterization and drug solubilization of arginine-based ionic liquids – Impact of counterions and stoichiometry

Ionic liquids (ILs) exhibit very diverse physicochemical properties, such as non-volatility, stability, and miscibility, which render them excellent candidate excipients for multi-purpose use. Six novel arginine (Arg)-based ILs were obtained using a one-step ultrasound method. Salt formation was confirmed by Fourier-transform infrared (FTIR), Raman, and nuclear magnetic resonance (NMR) spectroscopies. Moreover, the effects of anions and molar ratio on the molecular states and thermal properties of Arg-ILs were investigated. In addition, the solubilization of drugs with different pKa and LogP values was attempted using Arg-ILs consisting of asparagine, proline, octanoic acid, and malic acid, respectively, and a comparative study was performed. Furthermore, the interaction mode between the drugs and ILs was determined by FTIR and Raman spectroscopy. Presumably, partial interaction between the component of ILs and drugs such as ofloxacin and valsartan occurred, whereas flurbiprofen and isosorbide mononitrate were dispersed in the viscous IL. The development of strategies for the application of ILs as solubilizers or carriers of active pharmaceutical ingredients is an extremely promising and wide avenue of research

Challenges for exploiting nanomagnet properties on surfaces.

Molecular complexes with single-molecule magnet (SMM) or qubit properties, commonly called molecular nanomagnets, are great candidates for information storage or quantum information processing technologies. However, the implementation of molecular nanomagnets in devices for the above-mentioned applications requires controlled surface deposition and addressing the nanomagnets' properties on the surface. This Perspectives paper gives a brief overview of molecular properties on a surface relevant for magnetic molecules and how they are affected when the molecules interact with a surface; then, we focus on systems of increasing complexity, where the relevant SMMs and qubit properties have been observed for the molecules deposited on surfaces; finally, future perspectives, including possible ways of overcoming the problems encountered so far are discussed.

Scaling factor of dispersion force interaction between dyes and corn cobs in water

Obtaining the interaction between two substances in liquid through their molecular structures can promote the design and preparation of new functional materials. When multiple types of intermolecular forces coexist, whether the contribution terms generated by each type of intermolecular force have the same scaling factor is a key consideration. In this paper, an empirical equation for calculating the total intermolecular interaction is proposed. The required molecular property parameters for calculation can be obtained through quantum–chemical calculation. For the experiments of removing eight ionic dyes in water by using corn cobs as adsorbents, linear correlation was found between the removal percentage and the total interaction calculated from the proposed equation. When the scaling factors of polar and hydrogen bond interaction terms are 1, the scaling factor of dispersion force interaction term in the equation is greater than 2.5.

Machine learning framework to predict pharmacokinetic profile of small molecule drugs based on chemical structure.

Accurate prediction of a new compound's pharmacokinetic (PK) profile is pivotal for the success of drug discovery programs. An initial assessment of PK in preclinical species and humans is typically performed through allometric scaling and mathematical modeling. These methods use parameters estimated from invitro or invivo experiments, which although helpful for an initial estimation, require extensive animal experiments. Furthermore, mathematical models are limited by the mechanistic underpinning of the drugs' absorption, distribution, metabolism, and elimination (ADME) which are largely unknown in the early stages of drug discovery. In this work, we propose a novel methodology in which concentration versus time profile of small molecules in rats is directly predicted by machine learning (ML) using structure-driven molecular properties as input and thus mitigating the need for animal experimentation. The proposed framework initially predicts ADME properties based on molecular structure and then uses them as input to a ML model to predict the PK profile. For the compounds tested, our results demonstrate that PK profiles can be adequately predicted using the proposed algorithm, especially for compounds with Tanimoto score greater than 0.5, the average mean absolute percentage error between predicted PK profile and observed PK profile data was found to be less than 150%. The suggested framework aims to facilitate PK predictions and thus support molecular screening and design earlier in the drug discovery process.

An in silico study of the effects of chemical compounds in Petiveria alliacea leaf extract on inflammatory mediators

Background: Petiveria alliacea (P. alliacea) is a botanical species renowned for its bioactive compounds and is utilised for medicinal purposes worldwide. In Southwestern Nigeria, P. alliacea finds common application in herbal medicine to address diverse ailments, including diabetes due to chronic inflammation. Objective: This study investigates the drug-like molecular properties of chemical compounds in P. alliacea, targeting the interleukin one receptor (IL1R) and Tumor Necrosis Factor-alpha receptor (TNFAR). Method: The target binding of the P. alliacea chemical compounds was evaluated through drug-likeness tests on the SCFBIO server. All compounds found in P. alliacea adhere to Lipinski’s Rule of Five, classifying them as drug-like molecules. Employing molecular docking simulations on PyRx v9.9.0, the interaction dynamics between P. alliacea ligands and IL1R and TNFAR were simulated. Result: Among the compounds found in P. alliacea, namely astilbin and isoarborinol, emerge as potential candidates for IL1R and TNFAR protein inhibitors due to their notably elevated negative binding affinity values and involve Van der Waals, hydrogen and alkyl bond interactions. Then, a response was elicited that was marked by diminished oxidative stress and anti-inflammatory activity. Conclusion: P. alliacea has the potential to inhibit proinflammatory proteins, such as IL1R and TNFAR, due to its content, namely astilbin and isoarborinol.

A Simple Doublet Lens Design for Mid-Infrared Imaging.

Wide-field mid-infrared (MIR) hyperspectral imaging offers a promising approach for studying heterogeneous chemical systems due to its ability to independently characterize the molecular properties of different regions of a sample. However, applications of wide-field MIR microscopy are limited to spatial resolutions no better than ∼1 μm. While methods exist to overcome the classical diffraction limit of ∼λ/2, chromatic aberration from transmissive imaging reduces the achievable resolution. Here we describe the design and implementation of a simple MIR achromatic lens combination that we believe will aid in the development of resolution-enhanced wide-field MIR hyperspectral optical and chemical absorption imaging. We also examine the use of this doublet lens to image through polystyrene microspheres, an emerging and simple means for enhancing spatial resolution.

The analysis of growth performance and expression of growth-related genes in natural gynogenic blunt snout bream muscle derived from the blunt snout bream (Megalobrama amblycephala, ♀) × Chinese perch (Siniperca chuatsi, ♂)

Gynogenesis is an advanced breeding technique that can quickly establish pure lines, increase progenies genetic variation, cultivate strains with higher dominant traits. As a good model for cross order species hybridization, there are few reports on the study of natural gynogenetic blunt snout bream (GBSB), even on the differences in growth between gynogenesis progenies and their parent fish (blunt snout bream♀ and Chinese perch♂). In this research we compared the growth characteristics of the natural GBSB with its parents. It was found that GBSB had a faster growth rate and higher meat content than its female parent, and the diameter and density of muscle fibers were between those of paternal and maternal fish. We performed transcriptome sequencing of muscle tissues from GBSB and BSB, it identified 1353 significant DEGS in the muscle of the GBSB compared to the BSB, with 820 up- and 533 down-regulated genes. And the relative expression of myosins was notable rise in GBSB. In addition, the MRFs of gene structure, motifs, and phylogenetic relations were characterized in BSB and CP. It showed that MRFs and mstn central domain was highly conserved, but the number of conservative motifs in MRFs of CP is generally higher than that of BSB. Further, the relative expression of myosin complex, myogenic regulatory factors (MRFs), growth hormone/insulin-like growth factor (GH/IGF)-axis and most hypothalamic-pituitary-gonadal (HPG)-axis genes in GBSB were higher than that of the female fish and some were closer to that of the paternal fish. Through the distant hybridization between BSB and CP, a gynogenetic progeny with enhanced growth rate compared to the maternal fish was successfully generated. The research has contributed significant insights into the genes and molecular properties associated with muscle development, as well as their potential functional correlations in response to different functional requirements during the growth process of hybrid progeny formed by cross breeding.

Solvent Acidity and Basicity Scales: Analysis of Catalan’s SB and SA Scales and Gutmann’s Acceptor Number and Comparison with Kamlet and Taft’s β and α Solvent Scales, Gutmann’s Donor Number and Abraham’s B and A Solute Scales

The use of experimental parameters to quantify solvent properties, for example in linear free energy relationships, is well established and several scales of solvent acidity, basicity and polarity/polarizability have been developed. The success of this approach raises questions of which molecular properties contribute to particular solvent parameters and whether these contributions are found in all parameters representing a particular solvent property. In the present study, Catalan’s hydrogen bond basicity and acidity parameters, SB and SA, and Gutmann’s acceptor number, AN, a measure of a solvent’s Lewis acidity, are correlated with molecular properties derived from computational chemistry. The results are compared with the results of similar correlations with Kamlet and Taft’s β and α Solvent Scales, Gutmann’s donor number DN) and Abraham’s B and A solute scales. The results show that measures of solvent basicity, SB, β and DN all correlate strongly with the partial charge on the most negative atom in the solvent molecule and the energy of the donor orbital and, in all cases, the parameter values for hydrogen-bonded solvents are anomalous. Abraham’s B, a measure of solute hydrogen basicity, depends only on the partial charge on the most negative atom and there is no anomaly in the values for solutes that, in the pure state, form hydrogen-bonded liquids. Similarly, all measures of solvent acidity, SA, α and AN, and Abraham’s A, a measure of solute hydrogen bond acidity, depend on the partial charge on the most positive hydrogen on the molecule.

Building a New Platform for Significantly Improving Performance of Hartree-Fock and CCSD(T) Correlation Energy Based on Two-Point Complete Basis Set Extrapolation Schemes.

The leading cause of high expense in gold standard coupled cluster theory is that calculations of electronic energies converge exceedingly slowly with an increased basis set size. Extrapolation principally allows for achieving higher-quality outcomes at reduced costs. Numerous extrapolation formulas have been developed, with attempts to predict energies up to the complete basis set limit. Unfortunately, since the intricate shape of the function hinges on the molecular properties with the highest angular momentum of the basis set, the accuracy of the extrapolated energies highly depends on the fitted empirical parameters, which rely on the quality of the data sets for fitting. In this work, to overcome the extrapolation deficiency caused by the very limited data sets and smaller basis sets in the early stages, we constructed a new benchmark platform that includes a broader data set of 183 species (containing open-shell, closed-shell, ionic, and neutral species) and a larger basis set up to aug-cc-pV6Z. The newly optimized parameters can significantly improve the energy-predictive abilities of ten published formulas. Notably, all ten formulas perform quite similarly under the new platform with the reoptimized parameters. Finally, we built an online calculator for researchers to use for these extrapolation schemes. Our work would reignite the interest and applications of the underestimated formulas.

Concentration Fluctuation/Microheterogeneity Duality Illustrated with Aqueous 1,4-Dioxane Mixtures.

The structural properties of aqueous 1-4 dioxane mixtures are studied by computer simulations of different water and dioxane force field models, from the perspective of illustrating the link between structural properties at the molecular level and measurable properties such as radiation scattering intensities and Kirkwood-Buff integrals (KBIs). A strategy to consistently correct the KBI obtained from simulations is proposed, which allows us to obtain the genuine KBI corresponding to a given pair of molecular species, in the entire concentration range, and without necessitating excessively large system sizes. The application of this method to the aqueous dioxane mixtures, with an all-atom CHARMM dioxane model and 2 water models, namely, SPC/E and TIP3P, allows one to understand the differences in the structure of the corresponding mixtures at the molecular level, particularly concerning the role of the water aggregates and its model dependence. This study allows us to characterize the dual role played by the concentration fluctuations and the domain segregation, particularly in what concerns the calculated X-ray spectra.

Preparation of Fe(II) − 6-chloro-3-hydroxy-7-methyl-2-(2′-thienyl)-4-oxo-4H-1-benzopyran complex for analytical, biological & computational studies

An easy, rapid, sensitive and selective spectrophotometric method which shows maximum absorbance at 433 nm to detect micro amount of Fe(II) with 6-chloro-3-hydroxy-7-methyl-2-(2′-thienyl)-4-oxo-4H benzopyran(CHMTB) has been developed which form a stable dark brownish complex in an acidic environment which is extractable in dichloromethane (DCM). The complex showed molar absorptivity coefficient and sandell’ssensitivity 2.335 x 104 l mol-1and 0.0023 µg cm−2 respectively.The correlation value and detection limit for this method is 0.9998 and 0.0893 µg ml−1 respectively. Various cations and anions/complexing agents had no effect on the detection of divalent iron.The DFT/B3LYP/6-31G(d,p) method is a commonly used computational approach used for studying molecular properties and to calculate energy gaps for complex and ligand which are foundto be 0.0767 eV and 0.1380 eV respectively. Global reactivity descriptors provide valuable information about the reactivity and stability of molecules. Molecular Electrostatic Potential (MEP) analysis is a useful tool for identifying potential sites for nucleophilic or electrophilic attacks on chemical structures. The complex interaction with anti-cancer, antibacterial, and antifungal agents had been thoroughly studied along with the selectivity of the method by its detection in presense of other metal ions.