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Examining catalysts for CO2hydrogenation to methanol and ethanol, this review explores catalytic mechanisms, catalyst structural properties, and recent advancements in catalyst development for improved efficiency and selectivity.

The coal fly ash (CFA), which is the residue generated by coal-fired power plants, was converted into a valuable zeolite material known as zeolite P (ZNa-P) through thermal and acid pretreatments followed by microwave radiation. Various analytical techniques were utilized to analyze the resulting zeolite, including X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, BET analysis, and zeta potential measurement. The efficiency of ZNa-P in eliminating anionic dyes from aqueous solutions was exhibited by successfully removing acid red dye 66 (AR66) from a solution composed of water. To optimize the removal process, Central Composite Design (CCD) was applied to investigate the impact of four main parameters: solution pH, initial dye concentration, adsorbent mass, and contact time. The generated CCD database was modeled using Gaussian process regression (GPR) with the Lévy flight distribution (LFD) optimization algorithm. The GPR model was then used to determine optimal conditions for maximum AR66 absorption (3405.3 mg/g), with a pH of 2, initial dye concentration of 1000 mg/L, adsorbent mass of 0.2 g/L, and contact time of 11 minutes. Furthermore, the GPR model exhibited significantly lower error (32.58 mg/g) in predicting the experimental values compared to the CCD model (204.92 mg/g), highlighting the efficiency and superiority of the GPR model in this study.

The formation of crystalline materials typically follows the nucleation and crystal growth pathway, which enables scientists to engineer crystal properties, and the metastable status that exists before nucleation plays a decisive role in affecting the feasibility of crystallization. Over the past decade, there has been significant interest in stabilizing metastable states, such as amorphous structures, metastable polymorphism, and supersaturated solutions, which requires the inhibition of crystal nucleation and growth. Based on the theories of crystal nucleation and growth, this paper provides a comprehensive review of molecular-scale inhibition techniques and their corresponding mechanisms. Nature additives and tailored additives are the most important methods for modulating molecular assembly, which can be scanned or designed following the principles of molecular interactions and docking. Confining molecules within nanometric spaces such as nano- or microporous materials or artificial interfaces can hinder the motions of molecules, thus affecting nucleation. Additionally, physical fields including magnetic, ultrasonic, and electric fields are reviewed in comparison of the acceleration and inhibition of nucleation. Furthermore, we summarize the application scenarios where inhibiting nucleation and crystal growth is essential across various domains including pharmaceuticals, biominerals, ice crystallization, etc. Lastly, research and application prospects are proposed for further exploration of the inhibition of crystal nucleation and growth.

The design and synthesis of cocrystals have emerged as promising crystal engineering strategies for enhancing the physicochemical properties of a diverse range of target molecules. A prediction strategy to identify whether a pair of target and auxiliary molecules would form a cocrystal can greatly accelerate the process of cocrystal discovery. In this study, we compiled and performed DFT calculations for 12,776 molecules (6,388 cocrystals). All entries in the database were obtained from experimental attempts reported in the literature. Electrostatic potential (ESP) surfaces were then extracted from the DFT results and used for the development of four machine learning models (PointNet, ANN, RF, Ensemble). The Ensemble model, leveraging the complementary strengths of the PointNet, ANN, and RF models, demonstrated superior discriminatory performance with a BACC (0.942) and an AUC (0.986) on the unseen test data subset. To assess the performance of the models on individual molecules, we separated the cocrystals of caffeine, fumaric acid, and salicylic acid from the overall database. The Ensemble model exhibited remarkable robustness, classifying the 312 cocrystals in this subset into their respective classes, with an average BACC of 98%. Furthermore, through conducting data analysis, 132 batches of cocrystal instances were gathered. After three batches were excluded, our proposed models were tested with these previously unseen molecules both before and after implementation of a batchwise retraining method.

Crystal morphology plays a pivotal role in the production process of pharmaceutical compounds and influences the properties of the final product. Achieving control over crystal morphology, especially for thin and needle-like crystals, presents significant challenges to the industry. In this study, we investigate the crystal morphology of rufinamide (RUF) as a model compound with a notorious thread-like morphology. RUF polymorphs crystallize with markedly poor aspect ratios, with the most stable form (form A) exhibiting the thinnest morphology among all. Our initial attempts to modulate RUF crystal morphologies using solvent screening and habit-modifying additives proved unsuccessful. We explored cocrystals as a novel approach to enhance crystal morphology, given their wide application in improving various physicochemical properties of pharmaceutical solids. We employed trimesic acid (TMA) as the auxiliary compound for cocrystallization, resulting in the synthesis of RUF-TMA. The cocrystal was then subjected to solvent screening in pursuit of crystals with isometric morphology. We successfully obtained RUF-TMA cocrystals with an improved morphology using 3-pentanone as the solvent. This study offers a detailed exploration of five crystal structures, encompassing three polymorphs of RUF and two polymorphs of RUF-TMA. The elucidation of crystal structures is accompanied by a comprehensive characterization, including SCXRD, powder X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. This study provides valuable insights into controlling crystal morphology and highlights the potential of cocrystals in enhancing morphology when conventional techniques such as solvent and additive screening of pure active pharmaceutical ingredients fall short.

The current study developed a drug delivery system through the green chemistry-based synthesis of a biologically friendly metal-organic framework (bio-MOF) called Asp-Cu, which included copper ions and the environmentally friendly molecule L(+)-aspartic acid (Asp). For the first time, diclofenac sodium (DS) was loaded onto the synthesized bio-MOF simultaneously. The system’s efficiency was then improved by encapsulating it with sodium alginate (SA). FT-IR, SEM, BET, TGA, and XRD analyses confirmed that DS@Cu-ASP was successfully synthesized. DS@Asp-Cu was found to release the total load within 2 h when used with simulated stomach media. This challenge was overcome by coating DS@Cu-ASP with SA (SA@DS@Cu-ASP). SA@DS@Cu-ASP displayed limited drug release at pH 1.2, and a higher percentage of the drug was released at pH 6.8 and 7.4 due to the pH-responsive nature of SA. $I\textit {n vitro}$ cytotoxicity screening showed that SA@DS@Cu-ASP could be an appropriate biocompatible carrier with >90% cell viability. The on-command drug carrier was observed to be more applicable biocompatible with lower toxicity, as well as adequate loading properties and responsiveness, indicating its applicability as a feasible drug carrier with controlled release.

This research aims to find an effective method to incorporate the anti-inflammatory drug naproxen (NAP) into a prototype zirconium metal–organic frameworks nanohybrid (Zr-MOF@NAP) and aloe vera (AV) biopolymer (Zr-MOF@NAP/AV) as a specific intestinal delivery vehicle. NAP entrapment efficiency and loading capacity were found to be 87.0% and 44.0%, respectively (Zr-MOF@NAP/AV). During the initial 2 h in the simulated stomach media, Zr-MOF@NAP released about 100% of the loaded NAP. Zr-MOF@NAP was coated with AV in order to overcome this challenge. As a result of the pH-responsive nature of AV, Zr-MOF@NAP/AV showed limited drug release at pH 1.2 and a higher percentage of drug release at pH 6.8 and 7.4. MTT assay was used to determine the in vitro cytotoxicity of Zr-MOF@NAP and Zr-MOF@NAP/AV against human fibroblast cells (HFFF2), and these results showed good cytocompatibility.

Dyes are poisonous and carcinogenic substances that are harmful to human health. Therefore, this study demonstrates using bentonite as a natural absorbent to remove methylene blue (MB), blue cationic thiazine dye, by studying the effects of different adsorbed doses, contact times, initial concentrations, pH, and temperatures on the removal efficiency. According to the kinetics and thermodynamics results, the process was represented by a pseudo-2nd-order equation and found exothermic and spontaneous. The experimental equilibrium adsorption capacity was 56.90 mg/g while the maximum one was 93.55 mg/g by the Langmuir isotherm. The optimum conditions are 40.7 mg/L, 0.55 g, pH 8, and 30 min with the removal of 99.5% while ANOVA was utilized to find correlations describing the MB removal.

The molar fraction solubilities of l-, d-, and dl-citrulline were first determined in aqueous solutions with different concentrations of (R)-1,3-butanediol from 283.15 to 328.15 K under 101.3 kPa using the gravimetric method. Then, based on solid-state characterizations such as powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, thermal gravity analysis (TGA), differential scanning calorimetry (DSC), and ternary phase diagram, the nature of crystalline dl-citrulline was considered to be a racemic compound. Then, the rates and parameters of primary nucleation of three species in mixtures of water and (R)-1,3-butanediol were experimentally derived through the classical nucleation theory (CNT). After that, topological electrostatic potentials and radial distribution functions were analyzed for exploring the intermolecular interactions between the molecules, and the Yasuoka–Matsumoto (YM) method was employed to simulate the nucleation process. However, the calculated nucleation rates by YM were shown to be 2 orders of magnitude greater than those derived through CNT. Finally, the effect of additives on the appearance probability (P) of racemic and enantiomeric nuclei from the same dl-citrulline solutions at a supersaturation ratio of 2.63 was statistically investigated from 140 nucleation experiments. It was interestingly found that there was only a minor difference between the appearance probabilities of both enantiomeric crystals among 20 batches of nucleations in the absence of additives; however, in the presence of additives, enantiomeric crystals with the same chirality as the additives were totally inhibited, which were utilized for the chiral enrichment of the studied racemic system. By coupling the addition of additives and seeds, l-citrulline or d-citrulline crystals with optical purity above 99% can be produced with a yield up to 25.4% through chiral enrichment from an initial eeof 88%.

The formation of multicomponent crystals depends on many factors; therefore it is extremely challenging to predict and select the appropriate coformers (CCFs) to prepare functional multicomponent crystals. In this study, we selected the 2,4-dichlorophenoxyacetic acid (2,4-D) molecule and 10 N-heterocyclic compounds with similar structures to investigate the main factors affecting the synthesis of multicomponent crystals. On screening of multicomponent crystals by solution crystallization, we obtained nine kinds of multicomponent crystals of 2,4-D with different colors, including a hydrate of the 2,4-D-PYE cocrystal. However, 1,3-bis(4-pyridyl)propane (BPP) failed to form multicomponent crystals with 2,4-D using the solution crystallization methods. The influence of CCF on the formation of multicomponent crystals was discussed from three aspects: hydrogen bond donor and acceptor capacity (molecular electrostatic potential (MEP) surface, hydrogen bond acceptor ability h_ema calculated by Molecular Operating Environment software, and interaction site-pairing energy differences (ΔEsite-pair)), thermodynamic enthalpy (the excess enthalpy ΔHex), and structural factors (molecular complementarity (MC) and molecular flexibility (Kier flex)). Molecular flexibility is the main reason no multicomponent crystals are formed between BPP and 2,4-D. A logistic regression calculation indicates that the formation of multicomponent crystals of 2,4-D is mainly affected by ΔEsite-pairand MEP values. The cases considered in this study not only expand the crystal structure landscape of the 2,4-D but also provide a reference for the effective prediction and design of multicomponent crystals, in general.

Graphical abstract: Magnetic drug targeting model of anticancer dasatinib magnetic nanomicelles (DAS-MNM) released in an internal thoracic artery blood flow for breast cancer therapy.

Purpose: To obtain multicomponent crystals and salts of dasatinib, a weakly basic oral anticancer agent, to improve its solubility and dissolution rate. Methods: Liquid-assisted grinding using a mortar and pestle and ball milling were used for multicomponent crystallization screening. Differential scanning calorimetry, infrared spectroscopy, dynamic vapor sorption, powder X-ray diffraction, and single-crystal X-ray diffraction studies were conducted for the solid-state characterization. Results: Binary phase diagrams through thermal analysis were developed for various multicomponent crystals. Crystal structure analysis showed that dasatinib gained a proton from succinic acid and turned into a salt. The dissolution profile and equilibrium solubility at pH 3.6 buffer showed that dasatinib release was significantly faster than dasatinib–succinic acid–water salt. Similarly, during the first 120 min, the dissolution profile at pH 3.6 buffer showed that the dasatinib release was significantly faster, but the latter multicomponent crystal disintegrated into a free hydrated dasatinib and l-glutamic acid, and consequently, the solubility was decreased. Conclusions: Solubility and dissolution measurements conducted at pH 3.6 and 7.2 aqueous buffer media revealed that the salt with succinic acid and the multicomponent crystal with l-glutamic acid improved the apparent solubility and dissolution rate of the resulting multicomponent crystals compared to the free dasatinib.

Using bio-based metal-organic frameworks (bio-MOFs) holds promise for innovative approaches in cancer treatment by leveraging the unique properties of these materials for targeted therapeutic applications. In this study, a novel bio-Schiff base ligand derived from vanillin was successfully synthesized, and it was used to create a bio-based copper-based MOF through a one-pot solvothermal method. The bio-MOF was then comprehensively characterized and utilized to encapsulate the anticancer drug curcumin (CUR). The BET analysis revealed an average pore diameter of approximately 2.25 nm for the bio-MOF, highlighting its suitability for CUR loading due to its smaller size relative to the pore diameter. The entrapment efficiency and loading capacity of CUR were established at approximately 84.35% and 28.11%, respectively, resulting in CUR@bio-MOF. Furthermore, the CUR@bio-MOF was coated with the carboxymethyl cellulose (CMC) biopolymer, resulting in the CMC/CUR@bio-MOF biocomposite hydrogel designed for pH-responsive delivery under physiological conditions at pH 7.4 and the acidic environment of tumor cells at a pH of 5.0. The in vitroCUR release study indicated that the CMC/bio-MOF exhibited more attractive performances than the pristine bio-MOF. Analysis of CUR release from bio-MOF and CMC/bio-MOF aligned most closely with the Higuchi model at both pH levels of 5.0 and 7.4. In vitrocytotoxicity screening displayed the high efficacy of CUR@bio-MOF against cancer cells. Furthermore, using confocal laser microscopy, it was observed that CUR@bio-MOF exhibited the ability to efficiently deliver drugs into cells. The findings presented here indicate that the developed bio-based carrier is an effective delivery system for the controlled and pH-sensitive release of curcumin.

Polymer composites exhibiting exceptional characteristics, including high thermal conductivity, thermal stability, mechanical strength, and flame resistance, offer significant potential for contemporary electronic applications. Their appeal is further heightened by features such as straightforward manufacturing processes, cost-effectiveness, and consistent physical and chemical properties. In this study, a bio-derived ligand was synthesized from vanillin through a Schiff base reaction. Subsequently, this ligand was employed in the synthesis of a silver complex (Ag-complex) through a Schiff base ligand-mediated process designed to extract silver ions from a wastewater stream. Moreover, the Ag-complex served as an additive to enhance the flame resistance and amplify the thermal conductivity of an epoxy resin (EP). The results from thermogravimetric analysis (TGA) revealed that the Ag-complex promoted the formation of char in the EP composites. Specifically, the EP composite containing 20.0 wt% of the Ag-complex exhibited a significantly increased limiting oxygen index (LOI) of 27.0%, and demonstrated improved thermal conductivity. Additionally, this composite showed a substantial reduction (47.84%) in heat release rate (HRR), a noteworthy decrease of 45.16% in total heat release (THR), and a marked decline in smoke production rate (SPR) by 26.15%, along with reductions in CO production rate (52.34%) and CO2production rate (29.53%). Furthermore, the EP composite containing 20.0 wt% of the Ag-complex displayed superior tensile strength compared to the unmodified EP. This research introduces an innovative approach for developing fire-resistant EP with enhanced thermal conductivity, achieved by repurposing waste materials derived from water decontamination adsorbents.

Polymorphism is one of the most important challenges in pharmaceutical manufacturing. However, the strategy to crystallize the desired polymorph has not been extensively investigated, especially in continuous crystallization. In this work, a numerical model, incorporating the population balance modeling, was developed considering the nucleation and growth rates of metastable and stable forms of a number of pharmaceutical solids. The impact of relative nucleation and growth kinetics of the two polymorphs on the polymorphic outcome was studied in batch and MSMPR (mixed suspension and mixed product removal) crystallizers. In both modes of operation, the simulation results show that the growth rate has a more significant effect than the birth rate. In batch crystallizers, an indicator has been proposed to analyze the time window to remove the metastable form. In MSMPR crystallizer, this indicator can be used to check whether the operating conditions (crystallizer temperature, residence time, and inlet concentration) can alter the steady-state polymorph. It is found that at high crystallizer temperature, low inlet concentration, and long residence time, the production of the stable form is favored.

The thermodynamic solubility of γ-pyrazinamide in 13 solvents (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, acetone, acetonitrile, water, 1,4-dioxane, methyl acetate, ethyl acetate, and n-propyl acetate) was measured by a dynamic method from 278.15 to 318.15 K. The results were modified by four models (λhequation, Apelblat equation, Wilson model, and nonrandom two-liquid (NRTL) model), and all of the relative standard deviation (RSD) values were less than 6%, indicating that the correlated data is in good agreement with the experiments. The thermodynamic parameters of mixing (ΔmixH, ΔmixG, and ΔmixS) were calculated by the NRTL model. Furthermore, the physicochemical properties of different solvents were investigated to visualize the solvent effects. The results indicated that for the ester and alcohol systems, the “like dissolves like” principle and mass transfer rules were the main factors that affect the solubility, and for other solvents, hydrogen bond donor propensities played the key role.

In this work, the capability of Raman spectroscopy to measure the solution concentration and slurry density simultaneously and quantitatively was studied. Paracetamol–ethanol and l-glutamic acid–water systems were chosen as model systems. Different preprocessing methods (spectra range selection, baseline removal, direct orthogonal signal correction (DOSC), or no processing) and multivariable analysis techniques (characteristic peaks regression (CPR), principal component regression (PCR), partial least-squares regression (PLSR), and artificial neural network (ANN)) were applied and compared based on the root mean squared error (RMSE). It was demonstrated that the solution and solids concentration can be extracted separately from Raman spectroscopy. On the one hand, it is found that DOSC preprocessing can improve the fitting performance of the linear regression models (CPR, PCR, and PLSR) but not for ANN model. On the other hand, the ANN method, owing to its nonlinear prediction ability, better predicted the results than the linear models when the signal was weak.

Matérial Institut Lavoisier (MIL)-101, one of the metal–organic frameworks containing numerous coordinatively unsaturated sites, as well as high specific surface area, was synthetized under different protocols for CO2adsorption and separation from N2. To improve its CO2adsorption capacity, different amounts [10, 25, and 40 wt % of tetraethylenepentamine (TEPA)] were grafted to the parental MIL-101. Results revealed that TEPA-MIL-101 (40 wt %) showed one of the highest CO2adsorption capacities (i.e., 3.76 mmol g–1at 298 K at 1 bar) among existing MIL-101 and its modified moieties. This amount was 1.56 times greater than parental MIL-101 (in spite of having superior textural properties), which adsorbed 2.41 mmol g–1CO2at the same operational conditions. This can be attributed to the presence of polar functional groups in the porous structure of MIL-101 that enhance the interaction between CO2active sites on the adsorbent surface. Isosteric heat of adsorption of CO2and N2on TEPA-MIL-101 (40 wt %) were 35 and 18 kJ mol–1, respectively, based on the temperature-dependent form of the Freundlich model in the Clausius–Clapeyron equation. Ideal adsorption solution theory (IAST) was used for determination of CO2/N2selectivity for a binary gas mixture, including 15% CO2and 85% N2at 298 K and at 1 bar. TEPA-MIL-101 (40 wt %) showed an exceptional CO2/N2selectivity of 220. Adsorption kinetics study demonstrated that the Avrami model was the best model for fitting the experimental data, which denotes that more than one pathway exists in CO2and N2adsorption.

In this work, the solubilities of (R)- and (R,S)-crizotinib in six solvents including methanol, ethanol, 1-propanol, 1-butanol, ethyl acetate, and n-hexane were first measured by a static method in the temperature range from 273.15 to 323.15 K at atmospheric pressure. Then, molecular simulations were performed to predict the crystal structures of (R)-crizotinib and (R,S)-crizotinib from their powder X-ray diffractograms and the solubilities in the above organic solvents using the Gibbs free energy calculation approach via the sublimation cycle. The results showed that the solubilities of (R)- and (R,S)-crizotinib in the selected solvents generally increased with the increasing temperature, and at room temperature the molar fraction solubility order was methanol > 1-butanol > 1-propanol > ethanol > ethyl acetate > n-hexane. The (R)-crizotinib crystal had a monoclinic unit cell, while the (R,S)-crizotinib crystal had a triclinic one. In particular, though it was first applied to the solubility estimation for water-insoluble drug compounds in organic solvents, the Gibbs energy calculation approach developed gave a desirable solubility prediction performance with a root-mean-square error (RMSE) of 0.7638 log Sunits for (R)-crizotinib and 1.1577 log Sunits for (R,S)-crizotinib in the selected solvents, respectively. Furthermore, the difference in the solubilities of (R)-crizotinib in different solvents mainly resulted from the different Gibbs free energies for solvation between solute and solvent other than those for sublimation. However, as to the difference in the solubilities of (R)- and (R,S)-crizotinib in the same solvent, the Gibbs free energy for sublimation made more of a contribution than that for solvation. Finally, on the basis of the solid-state characterization, the nature of crystalline (R,S)-crizotinib was confirmed to be a racemic compound. All these results shall provide pharmaceutical industry with a better understanding of this chiral system for crystallization resolution.

A route for the indirect carbonation of different minerals using (NH4)2SO4(AS) as a recyclable reagent has been recently proposed. For saving energy, the extraction of alkaline components, such as calcium and magnesium, is typically expected to occur at the roasting stage. To enhance the extraction efficiency, the kinetics and mechanism of the reaction between AS and blast furnace slag (BFS), a Ca/Mg-containing mineral, were investigated in this study. The results showed that the reaction consists of two steps: the decomposition of AS into ammonium bisulfate (ABS) and the reaction between the ABS and the BFS. Isothermal kinetics and equal conversion methods were used to determine the apparent activation energy and reaction-controlling steps in different temperature ranges. The results showed that the decomposition of AS was a chemical-reaction-controlled step with an apparent activation energy of 102 kJ·mol–1. On the other hand, the reaction between ABS and BFS, which was very quick, was controlled by the ABS supply. During the reaction, a product accumulation layer was generated around the nonreactive BFS particles. However, it was found that ABS can easily pass through this layer and react with the BFS core. The formation of ABS was the limiting step in the roasting process.

Continuous crystallization has gained growing interest in the pharmaceutical industry due to its high productivity and consistency of the product quality. Significant progress on the control of mixed-suspension mixed-product removal (MSMPR) product properties with the aspects of crystal size distribution, polymorphism, and crystal shape has been achieved. This review aims to summarize different property control methods and put forward new viewpoints on process control by applying a secondary nucleation mechanism. The review begins with a brief introduction to the characteristics and mechanisms of secondary nucleation, followed by an attempt to investigate the underlying phenomena involved in secondary nucleation. Then, the steady-state conditions of continuous crystallization from mathematical and mechanism analyses are discussed. Subsequently, the focus is on a variety of approaches that have been implemented in continuous crystallization processes to enable crystals to meet different critical quality attributes. Among them, by applying a secondary nucleation mechanism, new design strategies for crystal size and polymorph control in continuous crystallization are proposed. Furthermore, the possible relationship between the secondary nucleation threshold and crystal shape distribution is elaborated using a theoretical analysis and selecting supporting experimental evidence from the literature.