Crystalline Organic Compounds Research Articles

Development of Abraham model correlations for predicting the solubility of crystalline organic compounds and inorganic gases in ethyl formate

ABSTRACT Abraham model correlations are derived for predicting the solubility of crystalline organic compounds and inorganic gases dissolved in ethyl formate based on published experimental data gathered from the chemical literature. The mathematical expressions presented in the current study described the observed solubility data to within an overall standard deviation of 0.12 log units. Comparison of the Abraham model expressions for ethyl formate versus our recently published equations for ethyl acetate reveals that of the two organic solvents, ethyl acetate exhibits a better H-bond acceptor character, while ethyl formate engages in the stronger dipolar interactions with neighbouring solute molecules.

On the flexibility of 1,4-bis(phenylethynyl)benzene butyl ester organic crystal featuring mobile components

The quest for organic materials with compliant mechanical properties has significantly increased in the past few years in materials science and engineering. Crystalline organic compounds are excellent candidates for exploring and developing those long-lasting properties in the solid state since their fine structural functionalization may provide them with unique flexible behaviors. This study describes the 1,4-bis(phenylethynyl)benzene butyl ester synthesized in four steps and whose crystal can display elastic and elasto-plastic responses upon action with an external stimulus. A detailed characterization by single crystal X-ray diffraction revealed a layered crystal array that results from π-π stacking interactions, C–H⋯O and C-H⋯π bonds. Complementarily, variable temperature solid-state 13C and 2H NMR studies were carried out to probe the motion of the different components of the molecule and explore their possible association with the mechanical features. The compiled evidence indicates that the central phenylenes and the butyl groups experience molecular motion at different timescales, which, combined with the crystal array, facilitate the observed elastic and elasto-plastic flexibility. The results presented here not only contribute to advancing our understanding of flexible behavior but also could inspire potential applications such as flexible electronics.

НАПРЯМКИ ПОКРАЩЕННЯ ОСНОВНИХ ХАРАКТЕРИСТИК ТЕПЛОВИХ АКУМУЛЯТОРІВ ТА ТЕПЛОАКУМУЛЯЦІЙНИХ МАТЕРІАЛІВ

The article is devoted to the study of heat storage technologies as the main energy saving measure. The paper conducts a patent search and analyzes scientific papers that cover the issue and present the main material of existing technologies for thermal energy storage. The classification of the main types of heat accumulators (HA) and heat storage materials (HSM) is presented. Heat accumulators are classified: by the nature of accumulation; by the level of operating temperatures; by the duration of the charge-discharge period. The differences and design features of TAMs, advantages and disadvantages are analyzed. The main heat storage materials that are actually used or can be used in the future are identified. The thermophysical properties of heat storage materials, such as specific heat capacity, melting point, density, and density, are described.
 The methodology for calculating the volume of capacitive and phase-transition heat accumulators is determined based on the following initial data: the type of heat storage material, the type and thermal characteristics of the heat carrier, and the temperature drop of the heat storage material. Examples of the practical use of capacitive batteries are given, in particular, a tank battery in a solar heating system, as well as a gravel battery in a solar vegetable garden. The use of crystalline hydrates and organic low-melting compounds (fatty acids and paraffins) as phase-transition heat storage materials is described. The characteristics of thermochemical thermal accumulators, their principle of operation, and their advantages over capacitive and phase-transition accumulation units are presented. The reactions of enrichment of traditional carbon fuels are described, and examples of reactions that can be used as heat storage processes are given. Prospects for further research are identified.

Muon-spin relaxation investigation of magnetic bistability in a crystalline organic radical compound

We present the results of a muon-spin relaxation (μ+SR) investigation of the crystalline organic radical compound 4-(2-benzimidazolyl)-1,2,3,5-dithiadiazolyl (HbimDTDA), in which we demonstrate the hysteretic magnetic switching of the system that takes place at T=(274 ± 11)K caused by a structural phase transition. Muon-site analysis using electronic structure calculations suggests a range of candidate muon stopping sites. The sites are numerous and similar in energy but, significantly, differ between the two structural phases of the material. Despite the difference in the sites, the muon remains a faithful probe of the transition, revealing a dynamically-fluctuating magnetically disordered state in the low-temperature structural phase. In contrast, in the high temperature phase the relaxation is caused by static nuclear moments, with rapid electronic dynamics being motionally narrowed from the muon spectra.

Experimental and Quantum Chemical Approaches for Hydrazide-based Crystalline Organic Chromophores: Synthesis, SC-XRD, Spectroscopic and Nonlinear Optical Properties

Crystalline organic compounds, (E)-N-(2-(2-(2-hydroxybenzylidene)hydrazinecarbonyl)-phenyl) benzamide (NHBPB) and (E)-4-chloro-N-(2-(2-(2-hydroxybenzylidene)hydrazine-carbonyl) phenyl)benzene sulfonamide (CNHBP), were prepared through condensation of hydrazide derivatives of N-benzoylated and N-4-chlorobenzenesulfonylated derivatives of anthranilic acid with 2-hydroxybenzaldehyde. The structural interpretations were accomplished distinctly by single-crystal X-ray diffraction (SC-XRD) analysis and NMR studies. Accompanying the experimental studies, quantum chemical computations were employed to determine the non-linear optical (NLO) properties using the M06 and M06-2X functionals along with 6-311G (d,p) basis set. A comparative analysis was made in order to compare the geometrical parameters between XRD and DFT calculations and a good agreement was found. Frontier molecular orbital (FMO) analysis found a narrower HOMO/LUMO energy gap for NHBPB than CNHBP. Further, UV-Vis investigation revealed a red-shifted behavior for NHBPB (297.894 and 311.594 nm at M06-2X and M06 levels, respectively) owing to its smaller HOMO/LUMO energy gap. From the FMOs findings, Global Reactivity Parameters (GRPs) were also calculated and a relatively lower ionization potential and hardness with larger softness were found for NHBPB. The FMO and UV results indicated the greater polarizability in NHBPB as compared to CNHBP. Therefore, greater second hyperpolarizability response was noticed for NHBPB (2.749 ×105 and 1.945×105a.u at M06-2X and M006 functional, respectively). Additionally, comparative study with urea molecule showed good NLO responses for the foresaid compounds. These findings revealed that hydrazide-based compounds possess extremely high linear and nonlinear polarizabilities compared to most of the previously synthesized compounds which highlights their excellent properties for use in NLO materials.

Effect of intumescent flame retardants on non‐isothermal crystallization behavior of high‐density polyethylene

AbstractIn this study, the influence of the addition of intumescent flame retardants (IFRs) on the non‐isothermal crystallization of high‐density polyethylene (HDPE) was studied. The investigations were carried out for polyethylene compositions containing two different IFRs, ammonium polyphosphate (APP) and a mixture of copper phosphate and melamine phosphate (CUMP). Both IFRs have been incorporated with a constant amount of 20 wt%. Non‐isothermal kinetic parameters were calculated from differential scanning calorimetry (DSC) analysis using the Jeziorny and Mo methods. The research demonstrates the appropriateness of using the latter approach to evaluate the HDPE‐based crystallization process changes. The results of the obtained kinetic parameters describing HDPE crystallization were related to the activation energy assessed by the Friedman method, microscopic analysis performed using polarized light microscopy, and wide‐angle X‐ray scattering (WAXS). Despite the increase in the activation energy (EX) of the flame retarded polyethylene series, the degree of crystallinity was comparable to that of unmodified HDPE due to a limited dependence effect of EX on relative crystallinity. Investigations made using polarized light microscopy showed an increase in the density of spherulite impingement for HDPE/IFRs. Moreover, despite introducing crystalline organic compounds, polyethylene did not reveal any polymorphic changes according to WAXS.

Spectroscopic profiling and molecular docking of novel chalcone derivative (2E)-1-(3,4-dimethoxyphenyl)-3-(4-n-propyloxyphenyl)-2-propen-1-one- A prospective respiratory drug

The present study explores the wide potent applications of an organic pharmacophore (2E)-1-(3,4-dimethoxyphenyl)-3-(4-n-propyloxyphenyl)-2propen-1-one(DMPP)using experimental and theoretical analysis for the design of prospective respiratory drugs using docking simulations for virtual screening with different strategies. The theoretical analysis was done using Gaussian 09Wsoftware. Optimized geometry, vibrational frequencies were deduced from B3LYP/6–311++G(d,p) basis set. To understand the structure and functional groups of DMPP, UV–Vis, FT-Raman, FT-IR and NMR, ESI-HR mass spectral analysis spectral studies was compared in solid phase and gas phase and found to be in good accord with each other. Fukui functions, Electron Localization Function (ELF) and Localized Orbital Locator (LOL) were studied to diagnose the most active reactive sites of DMPP. Natural Bond Orbital (NBO) and AIM (Atoms Inside Molecule) analysis revealed the inner stability of the compound under investigation. The in vitro and virtual screening of DMPP discloses worthy cytotoxic behavior against normal (VERO) cell lines and anticancer activity with A549-Human Lung cancer cell line, and also proclaims good response against COVID-19 virus. In comparison with the standard clinical trials, the obtained results unveil that the crystalline organic compound is a new material with promising results via molecular docking studies. Thus the diverse methods used in the present study proves the effectiveness of DMPP to be suitable for a respiratory drug where extended in vitro and in vivo research has to be extended towards clinical trials.

Synthesis, single-crystal exploration, and theoretical insights of arylsulfonylated 2-amino-6-methylpyrimidin derivatives

Recently, syntheses and quantum chemical insights in the structures and properties of crystalline organic compounds have attracted significant attention of the scientific community. In the current work we report the synthesis of two arylsulfonylated 2-amino-6-methylpyrimidin derivatives, A and B . X-ray diffraction technique confirmed the structures of both compounds. The single-crystal analysis showed the presence of various non-covalent interactions that are responsible for their structural stabilities. Theoretical calculations of A and B were performed at the B3LYP/6–311++ G (d,p) level. The calculated structures of both compounds were found to be in good agreement with the experimentally reported structural parameters. Frontier molecular orbital (FMO) analysis showed that employing different moieties to bind with the 2-amino-6-methylpyrimidin-4-ol group causes certain changes to the FMOs energies and energy gaps, thus affecting the stability, reactivity, and other properties of the resulting compounds. The Natural Bond Order (NBO) analysis showed high stabilization energies within the molecules of both compounds. The calculated global reactivity parameters (GRP) confirmed noticeable stability of both compounds, showing the compound B to be more stable than the compound A . • Synthesis of two arylsulfonylated 2-amino-6-methylpyrimidin derivatives reported. • Various non-covalent interactions responsible for their structural stabilities. • Calculated structures in good agreement with the experimentally reported. • NBO analysis showed high stabilization energies within the molecules of both compounds. • Global reactivity parameters confirmed noticeable stability of both compounds.

Inter-laboratory comparison of water solubility methods applied to difficult-to-test substances

Water solubility is perhaps the single most important physical–chemical property determining the environmental fate and effects of organic compounds. Its determination is particularly challenging for compounds with extremely low solubility, frequently referred to as “difficult-to-test” substances and having solubility’s generally less than 0.1 mg/L. The existing regulatory water solubility test for these compounds is the column elution method. Its applicability, however, is limited, to non-volatile solid or crystalline hydrophobic organic compounds. There currently exists no test guideline for measuring the water solubility of very hydrophobic liquid, and potentially volatile, difficult-to-test compounds. This paper describes a “slow-stir” water solubility methodology along with results of a ring trial across five laboratories evaluating the method’s performance. The slow-stir method was applied to n-hexylcyclohexane, a volatile, liquid hydrophobic hydrocarbon. In order to benchmark the inter-laboratory variability associated with the proposed slow-stir method, the five laboratories separately determined the solubility of dodecahydrotriphenylene, a hydrophobic solid compound using the existing column elution guideline. Results across the participating laboratories indicated comparable reproducibility with relative standard deviations (RSD) of 20% or less reported for each test compound – solubility method pair. The inter-laboratory RSD was 16% for n-hexylcyclohexane (mean 14 µg/L, n = 5) using the slow-stir method. For dodecahydrotriphenylene, the inter-laboratory RSD was 20% (mean 2.6 µg/L, n = 4) using the existing column elution method. This study outlines approaches that should be followed and the experimental parameters that have been deemed important for an expanded ring trial of the slow-stir water solubility method.

Crystal structure, Hirshfeld surface analysis and DFT studies of N-(4-acetylphenyl)quinoline-3-carboxamide

Crystalline organic compound, N-(4-acetylphenyl)quinoline-3-carboxamide (4) was readily prepared using our previously reported experimental procedure by the reaction of quinoline-3-carboxylic acid (1) with thionyl chloride to generate the acid chloride in situ followed by the coupling itself with 4-aminoacetophenone (3). This report describes the in-depth structural analysis thereof. The spectral characterization was done using FT-IR, 1H-NMR, 13C-NMR and UV-Vis spectroscopy, while its 3D-structure confirmed unambiguously by single crystal X-ray diffraction. The title compound crystallizes in the monoclinic system with the P21/c space group, Z = 4. The crystal packing is mainly controlled by N–H•••O, and C–H•••O hydrogen bond interactions. Molecular geometry optimizations were conducted using the DFT method at the B3LYP/6-31G+(d,p) level of theory and the theoretical UV-Vis spectrum was found to be in good agreement with the experimental spectrum.

Combination of Negative, Positive, and Near-Zero Thermal Expansion in Bis(imidazolium) Terephthalate with a Helical Hydrogen-Bonded Network

A variable-temperature single-crystal X-ray diffraction study revealed an unusual thermal expansion property of a bis(imidazolium) terephthalate salt with a helical hydrogen-bonded network. The anomalous thermal expansion was investigated by X-ray diffraction, infrared, and Raman spectroscopy techniques. Positive, negative, and near-zero thermal expansion were observed along the crystallographic b, c, and a axes, respectively. The anomalous thermal expansion can be explained at the atomic level by the “bond-rotation effect”. The hydrogen-bonded, flexible network in the crystal structure resembles a folding trellis that undergoes a scissorlike motion, resulting in abnormal thermal behavior. Thermal expansion induced by a scissor motion of the helical hydrogen-bonded network in a crystalline organic compound has not been reported before.

Thermal expansion properties of organic crystals: a CSD study.

The thermal expansion properties of crystalline organic compounds are investigated by data mining of the Cambridge Structural Database (CSD). The mean volumetric thermal expansion coefficient is 168.8 × 10−6 K−1 and the mean uniaxial thermal expansion coefficient is 71.4 × 10−6 K−1, based on 745 and 1129 different observations, respectively. Normal and anomalous coefficients can be identified using these values and the associated standard deviations. The anisotropy of the thermal expansion is also evaluated and found to have a very broad distribution. 4719 different structures, comprising 4093 different molecular compounds and 626 additional polymorphs have been analyzed on their thermal expansion properties. Approximately 34% of these structures may have at least one orthogonal axis with negative thermal expansion, much more than generally believed. Moreover 127 structures have been identified which could have negative volumetric thermal expansion. Experimental validation using a robust protocol with data collected at more than 2 different temperatures is required to validate these cases.

Spin Symmetry Breaking: Superparamagnetic and Spin Glass-Like Behavior Observed in Rod-Like Liquid Crystalline Organic Compounds Contacting Nitroxide Radical Spins

Liquid crystalline (LC) organic radicals were expected to show a novel non-linear magnetic response to external magnetic and electric fields due to their coherent collective molecular motion. We have found that a series of chiral and achiral all-organic LC radicals having one or two five-membered cyclic nitroxide radical (PROXYL) units in the core position and, thereby, with a negative dielectric anisotropy exhibit spin glass (SG)-like superparamagnetic features, such as a magnetic hysteresis (referred to as ‘positive magneto-LC effect’), and thermal and impurity effects during a heating and cooling cycle in weak magnetic fields. Furthermore, for the first time, a nonlinear magneto-electric (ME) effect has been detected with respect to one of the LC radicals showing a ferroelectric (chiral Smectic C) phase. The mechanism of the positive magneto-LC effect is proposed and discussed by comparison of our experimental results with the well-known magnetic properties of SG materials and on the basis of the experimental results of a nonlinear ME effect. A recent theoretical study by means of molecular dynamic simulation and density functional theory calculations suggesting the high possibility of conservation of the memory of spin-spin interactions between magnetic moments owing to the ceaseless molecular contacts in the LC and isotropic states is briefly mentioned as well.

Green Synthesis, SC-XRD, Non-Covalent Interactive Potential and Electronic Communication via DFT Exploration of Pyridine-Based Hydrazone

Ultrasound-based synthesis at room temperature produces valuable compounds greener and safer than most other methods. This study presents the sonochemical fabrication and characterization of a pyridine-based halogenated hydrazone, (E)-2-((6-chloropyridin-2-yl)oxy)-N′-(2-hydroxybenzylidene) acetohydrazide (HBPAH). The NMR spectroscopic technique was used to determine the structure, while SC-XRD confirmed its crystalline nature. Our structural studies revealed that strong, inter-molecular attractive forces stabilize this crystalline organic compound. Moreover, the compound was optimized at the B3LYP/6-311G(d,p) level using the Crystallographic Information File (CIF). Natural bonding orbital (NBO) and natural population analysis (NPA) were performed at the same level using optimized geometry. Time-dependent density functional theory (DFT) was performed at the B3LYP/6-311G (d,p) method to calculate the frontier molecular orbitals (FMOs) and molecular electrostatic potential (MEP). The global reactivity descriptors were determined using HOMO and LUMO energy gaps. Theoretical calculations based on the Quantum Theory of Atoms in Molecules (QT-AIM) and Hirshfeld analyses identified the non-covalent and covalent interactions of the HBPAH compound. Consequently, QT-AIM and Hirshfeld analyses agree with experimental results.

Efficient Synthesis, SC-XRD, and Theoretical Studies of O-Benzenesulfonylated Pyrimidines: Role of Noncovalent Interaction Influence in Their Supramolecular Network.

Crystalline organic compounds, 2-amino-6-methylpyrimidin-4-yl benzenesulfonate (AMPBS) and 2,6-diaminopyrimidin-4-yl benzenesulfonate (DAPBS), were prepared via O-benzenesulfonylation of 2-amino-6-methylpyrimidin-4-ol 1 and 2,6-diaminopyrimidin-4-ol 2, respectively. The structural interpretations were achieved unambiguously by single-crystal X-ray diffraction (SC-XRD) analysis. The Hirshfeld surface study showed that C–H···O, N–H···N, and especially C–H···C hydrogen bond interactions are the key contributors to the intermolecular stabilization in the crystal. Density functional theory (DFT) studies were used to obtain a better understanding of natural bond orbitals (NBOs) and nonlinear optical (NLO) analysis for AMPBS and DAPBS at the B3LYP/6-311G(d,p) level. The time-dependent density functional theory (TD-DFT)/CAM-B3LYP/6-311G(d,p) level was employed for frontier molecular orbital analysis of both compounds. DFT-based vibrations for C–H, C=N, N–H, and stretching for C–C were found to be in good agreement with the experimental data. Overall, the theoretical findings were acquired in correspondence to the SC-XRD-based parameters. Intracharge transfer occurred in AMPBS and DAPBS compounds, which was evaluated through FMO activity. Global reactivity indices had been acquired utilizing energies of HOMO–LUMO orbitals. Overall, the theoretical findings related to AMPBS and DAPBS consist of promising correspondence to experimental findings. The theoretical-based study also exhibited that both AMPBS and DAPBS compounds contain promising NLO features.

Atomistic simulations of Epoxy/Water/Aluminum systems using the ReaxFF method

The molecular dynamics (MD) method can be a reliable tool for studying of organic coating/metallic substrate systems, however its accuracy is limited to the force field governing the dynamics of systems. These systems can be divided into three parts: (i) organic phase, (ii) substrate, (iii) interface between the organic phase and substrate. In this work, three recent ReaxFF descriptions were selected. A set of complex experimental data and density functional calculations was selected as the reference point. The density and structural analysis of a wide range of crystalline organic compounds were studied. The density, structural analysis, and self-diffusion constant of water at room temperature were obtained. The glass transition temperature of three different cross-linked epoxy were obtained and compared with the reported experimental results. The interaction energies of different configurations of epoxy and water over an alumina substrate were studied. Additionally, the reaction of water with aluminum was studied. The accuracy of these ReaxFF descriptions in reproducing the reference data was assessed. The results show there is a single ReaxFF description for accurate simulation of C/H/N/O/Al systems, which enables atomistic simulations of complex epoxy coatings/aluminum substrates systems.

Development of Abraham model correlations for describing solute transfer into 2-methyl-1-butanol from both water and the gas phase from experimental solubility data of crystalline organic compounds

ABSTRACT Experimental solubilities have been measured at 298.15 K for benzil, biphenyl, pyrene, fluoranthene, acenaphthene, xanthene, fluorene, 1,2,4,5-tetramethylbenzene, 4-tert-butylbenzoic acid, benzoic acid, 4-chloro-3-nitrobenzoic acid, 4-methoxybenzoic acid, 3,4,5-trimethoxybenzoic acid, 3-methyl-4-nitrobenzoic acid, 4-aminobenzoic acid, diphenyl sulphone, 2-ethylanthraquinone, thioxanthen-9-one, thianthrene, o-acetoacetanisidide, sorbic acid, 1,4-dichloro-2-nitrobenzene, 1,4-dibromobenzene, salicylamide, benzoin and trans-stilbene. Results of experimental measurements were combined with published solubility data taken from the published literature to derive Abraham model correlations for transfer of solutes into 2-methyl-1-butanol. The reported Abraham model correlations describe the observed solute transfer coefficients to within an overall average standard deviation of approximately 0.08 log units.

Comment on “Measurement and Modeling of Solubility of para-tert-Butylbenzoic Acid in Pure and Mixed Organic Solvents at Different Temperatures” and “Determination of Solubility and Thermodynamic Properties of Benzophenone in Different Pure Solvents”

Errors are discovered in the tabulated thermodynamic properties for dissolution of tert-butylbenzoic acid and benzophenone dissolved in organic monosolvents. The thermodynamic properties of dissolution were reported in two recently published papers. Specifically, the dissolution properties that were reported by Aniya et al. and by Ouyang et al. do not obey the standard thermodynamic relationship of ΔdissG = ΔdissH – TΔdissS, where ΔdissG, ΔdissH, and ΔdissS are respectively the Gibbs energy of dissolution, the enthalpy of dissolution, and the entropy of the dissolution of crystalline organic compounds in the organic solvent at the solution temperature, T.

Intersystem Crossing Mechanisms in the Room Temperature Phosphorescence of Crystalline Organic Compounds

Abstract Reports on the room temperature phosphorescence of metal-free organic crystals have been surging in the past few years. Together with interests in the rare phenomenon, these compounds have attracted attention for such potential applications as bio-imaging probes, oxygen sensors, and organic light-emitting diodes. For common organic compounds, phosphorescence is the emission from a triplet excited state, which is usually produced from a singlet excited state through intersystem crossing, a forbidden spin-flip of an electron. The mechanism of the forbidden process is the key to understanding such rare phenomenon and designing new phosphorescence materials. In this account, we make commentaries on the main intersystem crossing mechanisms proposed to date of the room temperature phosphorescence of heavy-atom-free, crystalline organic compounds, focusing on our own findings.

Impact of formulation and operating parameters on particle size and grinding media wear in wet media milling of organic compounds – A case study for pyrene

This study presents the influence of process and formulation parameters on fine grinding of the crystalline organic model compound pyrene. Submicron particles were produced by wet media milling in water. By applying an electrosteric stabilization and optimized process parameters, particle sizes below 100nm were obtained. Additionally, the influence of formulation and process parameters on grinding media wear were investigated. The product formulation with an ionic surfactant and a nonionic polymer was identified as a significant parameter to reduce the grinding wear. Furthermore, the set of operating parameters as well as the choice of grinding media material were found as key parameters to reduce product contamination. Grinding media wear is proportional to the specific energy input and can be minimized by optimizing the stress energy of grinding media.