Steric Parameters Research Articles

Influence of Pnictogen and Ligand Framework on the Lewis Acidity and Steric Environment in Pnictogen Pincer Complexes.

Pnictogen pincer complexes are a fascinating class of compounds due to their dynamic molecular and electronic structures, and valuable stoichiometric or catalytic reactivity. As recognition of their unique chemistry has grown, so too has the library of pincer ligands employed and pnictogen centres engaged to prepare them. Here we computationally study how the choice of pincer ligand framework and pnictogen influence the electronic and steric outcomes within the complexes obtained. The most relevant electronic parameter is the pnictogen-centred electrophilicity, which has been quantified by fluoride ion affinities and LUMO energies, while the most relevant steric parameter is the crowding around the central pnictogen, which has been quantified by the %Vbur values and visualized using steric maps. The resulting trends are analyzed with reference to binding pocket size, acceptor orbital type, electronic delocalization, π-donor strengths, and heteroatom incorporation. Thus, considering 16 ligand frameworks and 4 heavy pnictogen centres, this study provides a broad-spectrum view of stereo-electronic variation in pnictogen pincer complexes, which, together with a recent study on geometric variation in the same family, provides a substantial dataset to guide future molecular design and reactivity studies.

Experimental and advanced equilibrium studies on the enhanced adsorption of phosphate, cadmium, and safranin dye pollutants using methoxy exfoliated glauconite.

Natural glauconite, as a mixed-layered clay mineral, was subjected to exfoliation processes, producing silicate monolayers or individual sheets that were further modified with methanol into methoxy exfoliated glauconite (Mth/EXG). The structure was assessed as an enhanced adsorbent for three types of common water contaminants, including phosphate (PO4 3-), safranin-O dye (SFR), and cadmium metal ions (Cd2+). The Mth/EXG structure achieved promising adsorption capacities at the saturation points equal to 269.9mg/g for PO4 3-, 312mg/g for SFR, and 234.5mg/g for Cd2+ which are significantly better than the reported values for several studied adsorbents of higher costs and complex production procedures. The adsorption processes and the predicted regulated mechanisms in terms of the adsorbate/adsorbent interface were illustrated based on the steric and energetic findings that correspond to the applied monolayer equilibrium model of one energy site. The structure displays active site densities of 82.5mg/g (PO4 3-), 136.3mg/g (SFR), and 83.4mg/g (Cd2+), which illustrate the high uptake performance of SFR. Also, the steric parameters reflected the suitability of each existing site to be filled with 4 ions of PO4 3-, SFR, and Cd2+. The adsorption energy (less than 40kJ/mol) in conjunction with free adsorption energy from D-R model (8-16kJ/mol) and steric parameters validate the dominant impact of the multi-ionic physical mechanisms (hydrogen bonding and van der Waals forces), in addition to the assistant impact of some weak chemical processes that might be assigned to the formed inner-sphere complex. Also, these reactions all occurred spontaneously with exothermic behaviors according to the thermodynamic functions. Additionally, the structure exhibit significant affinity for the studied pollutants even in the existing of completive chemical including anions, cations and organic molecules.

Chemoselective Intramolecular Rauhut‐Currier Reaction on a Labile Framework of Enone and Acrylamide: Tricyclohexylphosphine as a Stable and Economical Catalyst

AbstractIntramolecular Rauhut‐Currier (IRC) reaction is an atom‐economical way of making carbocyclic and heterocyclic rings. However, its sensitivity towards electronic and steric parameters limits the reaction and stems the need for further development. Acrylamides have been one such left out of their sensitivity. Herein we report an IRC reaction, using acrylamide as a source of initial enolate. The cyclization has been achieved on a labile and challenging framework, prone to decomposition. Different control experiments have addressed the instability of the precursor. Protocol was further extendable to annulation for benzo analogs. We also report tricyclohexylphosphine (PCy3) as a stable, commercial, and easy‐to‐use nucleophilic catalyst in the field of IRC reactions as compared to earlier well‐established trimethyl and tributyl phosphines. Me3P and Bu3P although useful, are sensitive, prone to oxidation, and need careful handling. The protocol leads to the synthesis of piperidone and dihydroquinolone frameworks. A quick study to test the feasibility of catalyzing the Morita‐Baylis‐Hillman (MBH) reaction by PCy3 was also done successfully, although in moderate yields.

Dynamics of paramagnetic permanent chains and self-assembled clusters under a rapidly rotating magnetic field.

We study experimentally and theoretically the dynamics of permanent paramagnetic chains and mixed clusters formed by permanent paramagnetic chains and paramagnetic particles under the influence of a time-varying magnetic field. First, we examine the dynamics of permanent chains at high frequencies (∼50 to 1000Hz). These permanent chains exhibit continuous rotational motion with a frequency several orders of magnitude lower than that of the magnetic field. We develop a theoretical model that accurately describes the dependence of the rotational dynamics of chains on their length, as well as the amplitude and frequency of the external magnetic field in this high frequency regime. Next, we examine how cluster dynamics are affected by the presence of permanent chains. We show that the rotation of clusters composed of a high proportion of permanent chains is slowed down but remains qualitatively well described by the theoretical model we developed for homogeneous clusters of isotropic particles. We propose that the decrease in angular velocity for mixed clusters is due to the hardening of the cluster's 2D elastic modulus caused by the increase of the steric interaction parameter stemming from the presence of chemical links between particles in the chains.

Physicochemical, steric, and energetic characterization of kaolinite based silicate nano-sheets as potential adsorbents for safranin basic dye: effect of exfoliation reagent and techniques.

Kaolinite was subjected to advanced exfoliation processes to form separated nano-silicate sheets (EXK) with enhanced physicochemical properties as adsorbents. This involved the incorporation of different exfoliating agents, urea (U/EXK), KNO3 (N/EXK), and CTAB (C/EXK), highlighting their impacts on their textural and surficial properties as adsorbents for safranin dye. The applied characterization techniques confirmed the higher exfoliating degree of C/EXK, followed by N/EXK and U/EXK. This appeared significantly in the determined surface area (55.7m2/g (C/EXK), 36.7m2/g (U/EXK), and 47.1m2/g (N/EXK)) and adsorption performances. The C/EXK structure displayed a better safranin uptake capacity (273.2mg/g) than N/EXK (231mg/g) and U/EXK (178.4mg/g). Beside the remarkable differences in textural properties, the advanced mathematical modeling and the corresponding steric and energetic parameters illustrate the mentioned uptake properties. The interface of C/EXK is highly saturated by active uptake sites (Nm = 158.8mg/g) as compared to N/EXK (109.3mg/g) and U/EXK (93.4mg/g), which is in agreement with the characterization findings and the expected higher exposure of siloxane groups. Each of these sites can be filled with four dye molecules using C/EXK and N/EXK, which implies the vertical orientation of these adsorbed ions and the effective operation of multi-molecular mechanisms. The energetic (ΔE < 40kJ/mol) and thermodynamic investigations indicate the spontaneous, physical, and exothermic uptake of safranin molecules by EXK particulates. These mechanisms might involve dipole bonding (2-29kJ/mol), electrostatic attraction (2-50kJ/mol), van der Waals forces (4-10kJ/mol), and hydrogen bonding (<30kJ/mol).

Controlling (E/Z)-Stereoselectivity of -NHC=O Chlorination: Mechanism Principles for Wide Scope Applications.

Organic halogen compounds are cornerstones of applied chemical sciences. Halogen substitution is a smart molecular design strategy adopted to influence reactivity, membrane permeability and receptor interaction. Chiral bioreceptors may restrict the stereochemical requirements in the halo-ligand design. Straightforward (but expensive) catalyzed stereospecific halogenation has been reported. Historically, PCl5 served access to uncatalyzed stereoselective chlorination although the stereochemical outcomes were influenced by steric parameters. Nonetheless, stereochemical investigation of PCl5 reaction mechanism with carbamoyl (RCONHX) compounds has never been addressed. Herein, we provide the first comprehensive stereochemical mechanistic explanation outlining halogenation of carbamoyl compounds with PCl5; the key regioselectivity-limiting nitrilimine intermediate (8-Z.HCl); how substitution pattern influences regioselectivity; why oxadiazole byproduct (P1) is encountered; stereo-electronic factors influencing the hydrazonoyl chloride (P2) production; and discovery of two stereoselectivity-limiting parallel mechanisms (stepwise and concerted) of elimination of HCl and POCl3. DFT calculations, synthetic methodology optimization, X-ray evidence and experimental reaction kinetics study evidence all supported the suggested mechanism proposal (Scheme 2). Finally, we provide mechanism-inspired future recommendations for directing the reaction stereoselectivity toward elusive and stereochemically inaccessible (E)-bis-hydrazonoyl chlorides along with potentially pivotal applications of both (E/Z)-stereoisomers especially in medicinal chemistry and protein modification.

Domino Sequence of Ketimization and Electrophilic Amination for an Inverse Aza Intramolecular Morita-Baylis-Hillman Adduct.

Morita-Baylis-Hillman (MBH) reaction, typically catalyzed by a Lewis base, is a popular and useful method for C-C bond formation. Unfortunately, it is limited by a slow reaction rate and has sensitivity toward steric and electronic parameters. Despite tremendous efforts, the versatility of the reaction keeps the quest open for new mechanistic and catalytic pathways. Here, we have reported a Bro̷nsted acid-catalyzed, electrophilic amination (Umpolung of imine) as a method for an inverse Aza Intramolecular MBH adduct in the form of 2-acylindole. Umpolung of imine with nitrogen acting as an electrophilic center has been achieved. Interestingly, the reaction was also shown to occur under catalyst-free conditions also. The expected products of ketimine formation, 6π electrocyclization, or quinoline formation were least/not observed. A large number of examples have demonstrated the reaction strength. β-aryl-substituted acrylate and acrylamide (cinnamates and cinnamides), which are extremely sluggish in conventional MBH chemistry, are the highlights of the developed methodology. The annulated product exhibited keto-enol tautomerism, which was proven by 1H NMR integrals. As an application, another tandem reaction in the form of Michael addition on a highly complex amine was carried out to provide spiro-annulated indole.

Achieving Linear α-Macro-olefins in Ethylene Polymerization through Precisely Tuned Bis(imino)pyridylcobalt Precatalysts with Steric and Electronic Parameters

Achieving Linear α-Macro-olefins in Ethylene Polymerization through Precisely Tuned Bis(imino)pyridylcobalt Precatalysts with Steric and Electronic Parameters

Density-based quantification of steric effects: validation by Taft steric parameters from acid-catalyzed hydrolysis of esters.

The steric effect is one of the most widely used concepts for chemical understanding in publications and textbooks, yet a well-accepted formulation of this effect is still elusive. Experimentally, this concept was quantified by the acid-catalyzed hydrolysis of esters, yielding the so-called Taft steric parameter. Theoretically, we recently proposed a density-based scheme to quantify the effect from density functional theory. In this work, we directly compare these two schemes, one from theory and the other from experiment. To this end, we first establish the ester hydrolysis mechanism with multiple water molecules explicitly considered and then apply the energetic span model to represent the hydrolysis barrier height between the two schemes. Our results show that the barrier height of the reaction series is strongly correlated with both Taft steric parameters from experiment and steric quantification from theory. We also obtained strong correlations with steric potential, steric force, and steric charge from our theoretical scheme. Strong correlations with a few information-theoretic quantities are additionally unveiled. To the best of our knowledge, this is the first time in the literature that such a direct comparison between theoretical and experimental results is made. These results also suggest that our proposed two-water three-step mechanism for ester hydrolysis is effective, and our theoretical quantification of the steric effect is valid, robust, and experimentally comparable. In our view, this work should have satisfactorily addressed the issue of how the steric effect can be formulated and quantified, and thus it lays the groundwork for future applications.

Synergetic studies on the thermochemical activation and polyaniline integration on the adsorption properties of natural coal for chlorpyrifos pesticide: steric and energetic studies

Three types of synthetic coal-derived adsorbents were characterized as potential enhanced structurers during the removal of chlorpyrifos pesticide. The raw coal (CA) was activated into porous graphitic carbon (AC), and both CA and AC were blended with polyaniline polymers (PANI/CA and PANI/AC) forming two advanced composites. The adsorption performances of the modified structures in comparison with CA were evaluated based on both the steric and energetic parameters of the applied advanced isotherm model (the monolayer model of one energy). The uptake performances reflected higher capacities for the PANI hybridized form (235.8 mg/g (PANI/CA) and 309.75 mg/g (PANI/AC) as compared to AC (156.9 mg/g) and raw coal (135.8 mg/g). This signifies the impact of activation step and PANI blending on the surface and textural properties of coal. The steric investigation determined the saturation of the coal surface with extra active sites after the activation step (Nm(AC) = 62.05 mg/g) and the PANI integration (Nm(PANI/CA) = 113.5 mg/g and Nm(PANI/AC) = 169.7 mg/g) as compared to raw coal (Nm(CA) = 39.6 mg/g). This illustrated the reported uptake efficiencies of the modified samples, which can be attributed to the enhancement in the surface area and the incorporation of additional chemical groups. The results also reflect that each site can be loaded with 3–4 molecules of chlorpyrifos, which are arranged vertically and adsorbed by multi-molecular mechanisms. The energetic studies (< 40 kJ/mol) suggested the physical uptake of pesticide molecules by dipole bonding and hydrogen bonding processes. The thermodynamic functions donate the exothermic properties of 47reactions that occur spontaneously.

Synergetic studies on the nitrogen functionalization and polyaniline hybridization on the uptake performances of acephate pesticides by raw coal: Steric and energetic studies

Three forms of modified coal-based adsorbents were developed and characterized as potential enhanced structurers during the removal of acephate pesticide. The raw coal (CA) was oxidized by nitric acid, forming nitrogen functionalized coal (N.CA), and both CA and N.CA were hybridized with polyaniline polymers (PANI/CA and PANI/N.CA). The adsorption performances of the modified structures in comparison with CA were evaluated based on both the steric and energetic parameters of the applied advanced isotherm model (the monolayer model of one energy). The uptake performances reflected higher capacities for the PANI hybridized form (261.9 mg/g (PANI/CA) and 316.6 mg/g (PANI/N.CA) as compared to N.CA (232.3 mg/g) and raw coal (201.2 mg/g). This signifies the impact of nitrogen functionalization and PANI hybridization on the surface properties of coal. The steric investigation determined the saturation of the coal surface with extra active sites after the nitric acid treatment (Nm (N.CA) = 103.5 mg/g) and the PANI hybridization (Nm (PANI/CA) = 119.07 mg/g and Nm (PANI/N.CA) = 146.4 mg/g) as compared to raw coal (Nm (CA) = 81.9 mg/g). This illustrated the reported uptake efficiencies of the modified samples, which can be attributed to the enhancement in the surface area (5.4 m2/g (CA), 18.3 m2/g (N.CA), 27.7 m2/g (PANI/CA), and 36.2 m2/g (PANI/N.CA)) and the incorporation of additional chemical groups (NO, C-N, and N-H). The results also reflect that each site can be loaded with three molecules of acephate, which are arranged vertically and adsorbed by multi-molecular mechanisms. The energetic studies (<40 kJ/mol) suggested the physical uptake of pesticide molecules by dipole bonding and hydrogen bonding processes. The thermodynamic functions reflect the exothermic properties of reactions that occur spontaneously.

Investigation of propranolol hydrochloride adsorption onto pyrolyzed residues from Bactris guineensis through physics statistics modeling

In this study, PROP adsorption was investigated using activated carbon derived from Bactris Guineensis residues and physical statistical modeling. The characterization results indicate high specific surface areas (624.72 and 1125.43 m2 g−1) and pore diameters (2.703 and 2.321 nm) for the peel and stone-activated carbon, respectively. Adsorption equilibrium was investigated at different temperatures (298 to 328 K), and it was found that the adsorption capacity increased with temperature, reaching maximum values of 168.7 and 112.94 mg g−1 for the peel and stone-activated carbon, respectively. The application of physical statistical modeling indicates that a monolayer model with one energy site is adequate for describing both systems, with an R2 above 0.986 and a low BIC of 20.021. According to the steric parameters, the density of molecules per site tends to increase by 116.9% for the stone and 61.6% for the peel. In addition, the model indicates that the number of molecules decreases with increasing temperature from 1.36 to 0.81 and from 1.03 to 0.82. These results indicate that temperature controls the number of receptor sites and the orientation in which propranolol is adsorbed at the surface. The adsorption energies were similar for both systems (approximately 10 kJ mol−1), which indicates that the adsorption occurred due to physical interactions. Finally, the application of thermodynamic potential functions indicates that the maximum entropy is reached at concentrations of half-saturation (Ce 3.85 and 4.6 mg L−1), which corresponds to 1.60 × 10–18 and 1.86 × 10–18 kJ mol−1 K−1 for the stone and peel, respectively. After this point, the number of available sites tends to decrease, which indicates the stabilization of the system. The Gibbs energy tended to decrease with increasing concentration at equilibrium, reaching minimum values of − 1.73 × 10–19 and − 1.99 × 10–19 kJ mol−1, respectively. Overall, the results obtained here further elucidate how the adsorption of propranolol occurs for different activated carbons from the same source.

Reactivity and Steric Parameters from 2D to 3D Bulky Pyridines: Increasing Steric Demand at Nitrogen with Chiral Azatriptycenes

AbstractSterically hindered pyridines embedded in a three‐dimensional triptycene framework have been synthesized, and their resolution by chiral HPLC enabled access to unprecedented enantiopure pyridines exceeding the known steric limits. The design principles for new axially chiral pyridine derivatives are then described. To rationalize their associations with Lewis acids and transition metals, a comprehensive determination of the steric and electronic parameters for this new class of pyridines was performed. This led to the general parameterization of the steric parameters (percent buried volume %VBur, Tolman cone angle θ, and He8_steric descriptor) for a large set of two‐ and three‐dimensional pyridine derivatives. These parameters are shown to describe quantitatively their interactions with carbon‐ and boron‐centered Lewis acids and were used to predict the ΔG° of association with the prototypical B(C6F5)3 Lewis acid widely used in frustrated Lewis pair catalysis. This first parameterization of pyridine sterics is a fundamental basis for the future development of predictive reactivity models and for guiding new applications of bulky and chiral pyridines in organocatalysis, frustrated Lewis pairs, and transition‐metal catalysis.

Reactivity and Steric Parameters from 2D to 3D Bulky Pyridines: Increasing Steric Demand at Nitrogen with Chiral Azatriptycenes.

Sterically hindered pyridines embedded in a three-dimensional triptycene framework have been synthesized, and their resolution by chiral HPLC enabled access to unprecedented enantiopure pyridines exceeding the known steric limits. The design principles for new axially chiral pyridine derivatives are then described. To rationalize their associations with Lewis acids and transition metals, a comprehensive determination of the steric and electronic parameters for this new class of pyridines was performed. This led to the general parameterization of the steric parameters (percent buried volume %VBur, Tolman cone angle θ, and He8_steric descriptor) for a large set of two- and three-dimensional pyridine derivatives. These parameters are shown to describe quantitatively their interactions with carbon- and boron-centered Lewis acids and were used to predict the ΔG° of association with the prototypical B(C6F5)3 Lewis acid widely used in frustrated Lewis pair catalysis. This first parameterization of pyridine sterics is a fundamental basis for the future development of predictive reactivity models and for guiding new applications of bulky and chiral pyridines in organocatalysis, frustrated Lewis pairs, and transition-metal catalysis.

Evaluation and analysis of the adsorption mechanism of three emerging pharmaceutical pollutants on a phosphorised carbon-based adsorbent: Application of advanced analytical models to overcome the limitation of classical models

The double layer adsorption of sulfamethoxazole, ketoprofen and carbamazepine on a phosphorus carbon-based adsorbent was analyzed using statistical physics models. The objective of this research was to provide a physicochemical analysis of the adsorption mechanism of these organic compounds via the calculation of both steric and energetic parameters. Results showed that the adsorption mechanism of these pharmaceuticals was multimolecular where the presence of molecular aggregates (mainly dimers) could be expected in the aqueous solution. This adsorbent showed adsorption capacities at saturation from 15 to 36 mg/g for tested pharmaceutical molecules. The ketoprofen adsorption was exothermic, while the adsorption of sulfamethoxazole and carbamazepine was endothermic. The adsorption mechanism of these molecules involved physical interaction forces with interaction energies from 5.95 to 19.66 kJ/mol. These results contribute with insights on the adsorption mechanisms of pharmaceutical pollutants. The identification of molecular aggregates, the calculation of maximum adsorption capacities and the characterization of thermodynamic behavior provide crucial information for the understanding of these adsorption systems and to optimize their removal operating conditions. These findings have direct implications for wastewater treatment and environmental remediation associated with pharmaceutical pollution where advanced adsorption technologies are required.

Transferability of Buckingham Parameters for Short-Range Repulsion between Topological Atoms.

The repulsive part of the Buckingham potential, with parameters A and B, can be used to model deformation energies and steric energies. Both are calculated using the interacting quantum atom energy decomposition scheme where the latter is obtained from the former by a charge-transfer-based energy correction. These energies relate to short-range interactions, specifically the deformation of electron density and steric hindrance, respectively, when topological atoms approach each other. In this work, we calculate and fit the energies of carbonyl carbon, carbonyl oxygen, and, where possible, amine nitrogen atoms to the repulsive part of the Buckingham potential for 26 molecules. We find that while the steric energies of all atom pairs studied display exponential behavior with respect to distance, some deformation energy data do not. The obtained parameters are shown to be transferable by calculating root-mean-square errors of fitted potentials with respect to energy data of the same atom in, as far as possible, all other molecules from our data set. We observed that 36% and 10% of these errors were smaller than 4 kJ mol-1 for steric and deformation energy, respectively. Thus, we find that steric energy parameters are more transferable than deformation energy parameters. Finally, we speculate about the physical meaning of the A and B parameters and the implications of the strong exponential and exponential-linear piecewise relationships that we observe between them.

Understanding the adsorption of Reactive red 2 onto metal hydroxide sludge: analysis with physico-statistical steric and energetic perspectives.

This theoretical investigation delves into the analysis of Reactive red 2 (RR-2) adsorption isotherms on metal hydroxide employing a sophisticated double-layer model characterized by dual-energy levels within the realm of physical adsorption phenomena. An examination of five distinct statistical physics frameworks was undertaken to elucidate the modeling and interpretation of equilibrium data. Expression for the physico-chemical parameters involved in the adsorption phenomena was derived based on statistical physics treatment. Fitting experimental adsorption isotherms (308-333K) to a DAMTBS has revealed the number of anchored molecules per site, occupied receptor site density, and the number of adsorbed layers. The steric parameter n varies between 0.92 and 1.05. More importantly, it is evidenced that the adhesion mechanism of (RR-2) onto metal hydroxide as determined by the estimated adsorption energies (< 40kJ/mol) supports a spontaneous and exothermic physisorption process. Thermodynamic potential functions such as entropy, Gibbs free energy, and internal energy have been computed based on the most suitable model. This research advances our physical understanding of how metal hydroxide captures dye molecules RR-2 through adsorption reaction for water depollution treatment.

Synthesis of Fluorinated Nucleosides/Nucleotides and Their Antiviral Properties.

The FDA has approved several drugs based on the fluorinated nucleoside pharmacophore, and numerous drugs are currently in clinical trials. Fluorine-containing nucleos(t)ides offer significant antiviral and anticancer activity. The insertion of a fluorine atom, either in the base or sugar of nucleos(t)ides, alters its electronic and steric parameters and transforms the lipophilicity, pharmacodynamic, and pharmacokinetic properties of these moieties. The fluorine atom restricts the oxidative metabolism of drugs and provides enzymatic metabolic stability towards the glycosidic bond of the nucleos(t)ide. The incorporation of fluorine also demonstrates additional hydrogen bonding interactions in receptors with enhanced biological profiles. The present article discusses the synthetic methodology and antiviral activities of FDA-approved drugs and ongoing fluoro-containing nucleos(t)ide drug candidates in clinical trials.

Statistical physics analysis of the adsorption of reactive red 141 dye on residual avocado peel (Persea americana) chemically modified with H2SO4 and HNO3

The preparation and adsorption properties of avocado peels treated with H2SO4 and HNO3 for the removal of reactive red 141 dye are reported in this manuscript. Equilibrium adsorption of this organic dye on the two adsorbents was experimentally quantified at pH 6.5 and 298.15–328.15 K. An advanced physical model that assumed the formation of a finite number of layers of the adsorbed pollutant molecules on the adsorption sites was used to estimate the steric and energetic parameters of the dye adsorption mechanism. The modeling results showed dye molecular aggregation, in which each adsorption site of avocado peels treated with H2SO4 and HNO3 adsorbed several dye molecules simultaneously at different temperatures. The results also demonstrated that dye adsorption on avocado peels treated with these acids was exothermic. The estimated adsorption energies for the dye-treated biomass and dye-dye interactions indicated a physisorption associated with van der Waals forces and hydrogen bonding. The outcomes of this study contribute with insights into the adsorption mechanisms of dye molecules using treated avocado peels with the aim of developing sustainable water treatment methods according with a circular economy approach.

Physical Analysis and Mathematical Modeling of the Hydrogen Storage Process in the MmNi4.2Mn0.8 Compound.

The results of an experimental and mathematical study into the MmNi4.2Mn0.8 compound's hydrogen storage properties are presented in the present research. Plotting and discussion of the experimental isotherms (P-C-T) for different starting temperatures (288 K, 298 K, 308 K, and 318 K) were carried out first. Then, the enthalpy and entropy of formation (ΔH0, ΔS0) were deduced from the plot of van't Hoff. Following that, the P-C-T were contrasted with a mathematical model developed via statistical physics modeling. The steric and energetic parameters, such as the number of the receiving sites (n1, n2), their densities (Nm1, Nm2), and the energy parameters (P1, P2) of the system, were calculated thanks to the excellent agreement between the numerical and experimental results. Therefore, plotting and discussing these parameters in relation to temperature preceded their application in determining the amount of hydrogen in each type of site per unit of metal ([H/M]1, [H/M]2) as well as for the entire system [H/M] versus temperature and pressure besides the absorption energies associated with each kind of site (ΔE1, ΔE2) and the thermodynamic functions (free energy, Gibbs energy, and entropy) that control the absorption reaction.