Interactions In Crystal Lattice Research Articles

Various polymorphs of calcium carbonate and poly(ethylene) glycol as thermal energy storage materials

AbstractThe present study investigates, thermal properties of polyethylene glycol (PEG) and various polymorphs of calcium carbonate (CaCO3) as blends. The prepared calcite, aragonite, and vaterite forms of CaCO3 were confirmed by x‐ray diffraction (XRD). Differential scanning calorimeter (DSC) revealed that, PEG‐calcite blend (composition 40/60 wt%), exhibited maximum enthalpy (112.9 ± 0.87 J/g). Aragonite and vaterite blends of similar composition displayed lower enthalpies (73.7 ± 0.61 J/g and 61.3 ± 0.75 J/g), which can be attributed to irregularities in crystal lattice and secondary interactions. Thermal gravimetric analysis (TGA) of PEG‐calcite revealed its impressive thermal stability, as blend was stable up to 423°C, higher than decomposition temperature of PEG. DSC analysis of PEG‐calcite after 50 cycles showcased excellent thermal reliability of blend, with enthalpy decreasing to only 108.5 ± 0.52 J/g. Stability of material was further supported by Fourier transform infrared spectroscopy (FTIR), where position and shape of peaks were found to be intact, suggesting no new compound formation. Field emission scanning electron microscopy (FESEM) suggested strong adhesion and wrapping of PEG around calcite particles, facilitated by cross‐hydrogen bonding between carbonate group and PEG. PEG‐calcite blend exhibited high thermal conductivity (0.74 ± 0.05 W/mK), highlighting potential applications in thermal management systems.

Exploring the polymorphism of selective androgen receptor modulator YK11

[(17α,20E)-17,20-[(1-methoxyethylidene)bis(oxy)]-3-oxo-19-norpregna-4,20-diene-21-carboxylic acid methyl ester], widely known under the name of YK11 is a synthetic agent with anabolic properties which belongs to the selective androgen receptor modulators group (SARMs). An extended polymorph screening was accomplished and the crystal structures of three YK11 polymorphs were determined by single crystal X-ray diffraction. The crystal features were analyzed by means of crystal lattice and intermolecular interaction energies as well. Furthermore, the polymorphs were investigated by powder X-ray diffraction, Fourier-Transform infrared spectroscopy and DSC thermal analysis.

Localized Spin Dimers and Structural Distortions in the Hexagonal Perovskite Ba3CaMo2O9.

Extended solid-state materials based on the hexagonal perovskite framework are typified by close competition between localized magnetic interactions and quasi-molecular electronic states. Here, we report the structural and magnetic properties of the new six-layer hexagonal perovskite Ba3CaMo2O9. Neutron diffraction experiments, combined with magnetic susceptibility measurements, show that the Mo2O9 dimers retain localized character down to 5 K and adopt nonmagnetic spin-singlet ground states. This is in contrast to the recently reported Ba3SrMo2O9 analogue, in which the Mo2O9 dimers spontaneously separate into a mixture of localized and quasi-molecular ground states. Structural distortions in both Ba3CaMo2O9 and Ba3SrMo2O9 have been studied with the aid of distortion mode analyses to elucidate the coupling between the crystal lattice and electronic interactions in 6H Mo5+ hexagonal perovskites.

Nano- and Crystal Engineering Approaches in the Development of Therapeutic Agents for Neoplastic Diseases

Cancer is a leading cause of death worldwide. It is a global quandary that requires the administration of many different active pharmaceutical ingredients (APIs) with different characteristics. As is the case with many APIs, cancer treatments exhibit poor aqueous solubility which can lead to low drug absorption, increased doses, and subsequently poor bioavailability and the occurrence of more adverse events. Several strategies have been envisaged to overcome this drawback, specifically for the treatment of neoplastic diseases. These include crystal engineering, in which new crystal structures are formed to improve drug physicochemical properties, and/or nanoengineering in which the reduction in particle size of the pristine crystal results in much improved physicochemical properties. Co-crystals, which are supramolecular complexes that comprise of an API and a co-crystal former (CCF) held together by non-covalent interactions in crystal lattice, have been developed to improve the performance of some anti-cancer drugs. Similarly, nanosizing through the formation of nanocrystals and, in some cases, the use of both crystal and nanoengineering to obtain nano co-crystals (NCC) have been used to increase the solubility as well as overall performance of many anticancer drugs. The formulation process of both micron and sub-micron crystalline formulations for the treatment of cancers makes use of relatively simple techniques and minimal amounts of excipients aside from stabilizers and co-formers. The flexibility of these crystalline formulations with regards to routes of administration and ability to target neoplastic tissue makes them ideal strategies for effectiveness of cancer treatments. In this review, we describe the use of crystalline formulations for the treatment of various neoplastic diseases. In addition, this review attempts to highlight the gaps in the current translation of these potential treatments into authorized medicines for use in clinical practice.

Structure, optical, thermal, SHG & photoluminescence studies of L-Serine cadmium chloride single crystals

Novel semi organic nonlinear optical single crystal of l-Serine Cadmium Chloride monohydrate has been synthesized by conventional slow evaporation method. The single crystal XRD have been employed to describe the crystal structure, space group, bond lengths, bond angles and co ordinates of hydrogen bond. The metal organic complexion between l-Serine and Cadmium chloride is taking place through oxygen atom of l-Serine. The lattice parameters obtained from PXRD technique have been found in good agreement with those obtained from SXRD. Williamson-Hall method has been used to determine the lattice strain of the grown crystal. The investigations of intermolecular interactions in LSCC crystal lattice are carried out by Hirshfeld surface analysis. The FTIR spectrum is utilized to determine the possible functional groups present in the crystal. The investigations on optical qualities of the crystal are carried out by incorporating UV–Visible and photoluminescence spectrum. The behaviour of refractive index below energy gap is carried out by Wemple – DiDomenico single oscillator model analysis. The thermal stability along with the decomposition temperature of the synthesized crystal is ascertained by thermogravimetric analysis. The kinetic and thermodynamic parameters of LSCC crystal have been calculated from C-R plot. Photoluminescence spectrum of the synthesized crystal was recorded by using an excitation wavelength of 320 nm. It suggested the suitability of the synthesized material as green laser diode. The SHG efficiency of LSCC crystal is clarified through the Kurtz-Perry technique.

Simulation of Thermal Cooling Curves in the Process to Ordering Alloys by the Monte Carlo Method

An algorithm is proposed for constructing curves of thermal cooling and ordering kinetics with a monotonic decrease in temperature for alloys to stoichiometric composition. Modeling is carried out by the Monte Carlo method in the model of a rigid crystal lattice and pair interatomic interactions. The application of the algorithm is illustrated by the example to a square lattice, taking into account interatomic interactions in the first two coordination spheres for alloys with the composition AB, A3B, and A3B5. The proposed model makes it possible to calculate individual sections of the phase diagrams to the state for binary alloys.

π‑Extended Boron Difluoride [NՈNBF2] Complex, Crystal Structure, Liquid NMR, Spectral, XRD/HSA Interactions: A DFT and TD-DFT Study

The novel tetrahedral 10-(4-carboxyphenyl)-2,8-diethyl-5,5-difluoro-1,3,7,9-tetramethyl- 5H-di-pyrrolo[1,2-c:2',1'-f][1,3,2]diazaborinin-4-ium-5-uide [NՈNBF2] BODIPY complex was prepared in a very good yield and via one-pot synthesis. The desired [NՈNBF2] has been used as a model complex for XRD/HSA interactions and DFT/B3LYP/6-311G(d,p) computations. The tetrahedral geometry around the boron center was demonstrated by DFT optimization and XRD-crystallography. The 1H, 11B, and 19F-NMR spectra were used also to support the high symmetrical BODIPY via π‑extended phenomena. Moreover, the values of the DFT-calculated structural bond lengths/angles and DFT-IR were matched to the corresponding experimental XRD and IR parameters, respectively. The crystal lattice interactions were correlated to Hirshfeld surface analysis (HSA) calculations. Calculations of the Mulliken Atomic Charge (MAC), Natural Population Analysis (NPA), Global reactivity descriptors (GRD), and Molecular Electrostatic Potential (MEP) quantum parameters were performed to support the XRD/HSA interactions result. Analysis of the predicted Density of States (DOS), molecular orbital, and time-dependent density functional theory (TD-DFT) calculations have been combined to explain the experimental UV-vis spectra and electron transfer behavior in [NՈNBF2] complex using MeOH and other four solvents.

Evaluating the high-pressure structural response and crystal lattice interactions of the magnetically-bistable organic radical TTTA

Paramagnetic suppression in TTTA at pressure is caused by a steady decrease in the separation between moieties containing the radical electron along π-stacking chains with no phase transition.

Pushing the limits of solubility prediction via quality-oriented data selection.

SummaryAccurate prediction of the solubility of chemical substances in solvents remains a challenge. The sparsity of high-quality solubility data is recognized as the biggest hurdle in the development of robust data-driven methods for practical use. Nonetheless, the effects of the quality and quantity of data on aqueous solubility predictions have not yet been scrutinized. In this study, the roles of the size and the quality of data sets on the performances of the solubility prediction models are unraveled, and the concepts of actual and observed performances are introduced. In an effort to curtail the gap between actual and observed performances, a quality-oriented data selection method, which evaluates the quality of data and extracts the most accurate part of it through statistical validation, is designed. Applying this method on the largest publicly available solubility database and using a consensus machine learning approach, a top-performing solubility prediction model is achieved.

Cu(II) coordination polymer bearing diazenyl-benzoic ligand: Synthesis, physico-chemical and XRD/HSA-interactions

New binuclear copper(II) complex [Cu2L2] zig-zag coordination polymer (CCP) have been synthesized via one-pot copper(II) acetate/(E)-2-((2-hydroxynaphthalen-1-yl)diazenyl)benzoic dye through an in situ aqua doubly deprotonated ligand substitution reaction. The coordination polymer complex was characterized by spectroscopic and CHN-elemental analysis. The crystal structure has been specified by the XRD-method exhibiting that the Cu(II) center geometry is with five-coordinated distorted tetragonal pyramidal. The desired CCP structure chains are connected into a 2D-Supramolecular assembly via one C-H…O H-bond and enhanced by a π–π stacking interactions. These interconnections strengthened the lattice of CCP that originated the formation of super thermal CCP complexes. The fundamental vibrational wavenumbers and electron transfer in the free ligand are combined with the complex before and after coordination to demonstrate the spectral behavior of L−2 in the desired zig-zag CCP. The 2D-fingerprint (2D-FP) and Hirshfeld surface analysis (HSA) computations were served to prove the 2D-network packed crystal lattice interactions.

Microtuning of the Wide-Bandgap Perovskite Lattice Plane for Efficient and Robust High-Voltage Planar Solar Cells Exceeding 1.5 V

Iodide-free tribromide-based perovskites, with their wide bandgap of over 2.0 eV, are highly regarded as potential candidates for a photoelectrochemical water splitting system and the topmost cell in tandem solar cell. Herein, we report on the importance of microtuning of the crystal lattice by cesium incorporation into the A-site on low temperature processed formamidinium lead tribromide (CH(NH2)2PbBr3 = FAPbBr3) perovskite films. The partial incorporation of cesium bromide (CsBr) into the FAPbBr3 film tunes crystal-lattice interactions, resulting in a high-purity cubic crystal system with preferred orientation. An entirely low temperature processed planar photovoltaic device assembled with FAPbBr3 containing 8% Cs (Cs0.08FA0.92PbBr3) exhibited an optimum PCE (power conversion efficiency) of 8.56% with a Voc (open-circuit voltage) of 1.516 V, which is higher than the PCE of 7.07% and Voc of 1.428 V of the FAPbBr3 device. Photoluminescence-intensity and temporal-imaging measurements were conducted by laser scanning confocal time-resolved microscopy (LCTM), which revealed that CsBr incorporation into a FAPbBr3 film significantly suppresses the nonradiative recombination pathways and homogenizes the spatial distribution of photoluminescence. It was visualized that the incorporation of CsBr in FAPbBr3 directly affects the bulk defect and photoluminescence properties, which provides evidence that Cs ions surely alleviate the segregation and aggregation of ions in the perovskite film. Notably, the Cs0.08FA0.92PbBr3 film, with a carrier lifetime of about 270 ns, exhibited a 1.37-fold longer radiative recombination time than that (210 ns) observed for the FAPbBr3 film. Furthermore, aging experiments without encapsulation under ambient (in air for 2000 h) and severe (65 °C and 65% RH for 500 h) conditions revealed that the Cs0.08FA0.92PbBr3 devices were more robust than the FAPbBr3 devices.

Structure of HIV-1 RT/dsRNA initiation complex prior to nucleotide incorporation

The initiation phase of HIV reverse transcription has features that are distinct from its elongation phase. The first structure of a reverse transcription initiation complex (RTIC) that trapped the complex after incorporation of one ddCMP nucleotide was published recently [Larsen KP, et al. (2018) Nature 557:118-122]. Here we report a crystal structure of a catalytically active HIV-1 RT/dsRNA complex that mimics the state of the RTIC before the first nucleotide incorporation. The structure reveals that the dsRNA-bound conformation of RT is closer to that of RT bound to a nonnucleoside RT inhibitor (NNRTI) and dsDNA; a hyperextended thumb conformation helps to accommodate the relatively wide dsRNA duplex. The RNA primer 3' end is positioned 5 Å away from the polymerase site; however, unlike in an NNRTI-bound state in which structural elements of RT restrict the movement of the primer, the primer terminus of dsRNA is not blocked from reaching the active site of RT. The observed structural changes and energetic cost of bringing the primer 3' end to the priming site are hypothesized to explain the slower nucleotide incorporation rate of the RTIC. An unusual crystal lattice interaction of dsRNA with its symmetry mate is reminiscent of the RNA architecture within the extended vRNA-tRNALys3 in the RTIC. This RT/dsRNA complex captures the key structural characteristics and components of the RTIC, including the RT conformational changes and interactions with the dsRNA primer-binding site region, and these features have implications for better understanding of RT initiation.

Preparation, molecular structure, thermal properties, electrical conductivity analysis and dielectric relaxation of a new hybrid compound (NH2C5H3ClNH)2ZnBr4·H2O

Preparation, structural elucidation, Hirshfeld surface analysis, thermal analysis and impedance spectroscopy study are carried out for an interesting organic–inorganic hybrid compound (NH2C5H3ClNH)2ZnBr4·H2O. X-ray diffraction analysis reveals that the title compound belongs to the triclinic crystallographic system with the space group P-1 with Z = 2 and the following unit cell dimensions: a = 7.3209(9) A, b = 8.4407(10) A, c = 16.923(2) A, α(°) = 82.975(6), β(°) = 85.118(6) and γ(°) = 74.398(6). The crystal structure is composed of two protonated 4-amino-2-chloropyridinium cations, tetrabromozincate anions and a water molecule which are held together by a number of hydrogen bonds forming infinite chains. In addition, crystal structure is stabilized with π…π interactions (Cg–Cg and Zn-Cl…Cg, with Cg is the 4-amino-2-chloropyridinium rings) which have also been investigated in terms of their corresponding Hirshfeld surface and the breakdown of fingerprint. To quantify intermolecular interactions in crystal lattice, FT-IR spectroscopy has been used to distinguish the different chemical functional groups and their environments in this molecule. The dielectric conductivity of this compound has been measured in the temperature range 298–438 K and the frequency range 209 Hz–5 MHz. The analysis of the experimental data of the impedance spectroscopy based on the activation energy shows that this material is an ionic–protonic conductor at low temperature and becomes an electronic one at high temperature. This work aims to reveal the thermal properties of a new zinc (II) based organic–inorganic hybrid and the conductivity properties that this compound exhibits.

Investigations based on non-covalent interactions in 1-(4-chloromethylbenzoyl)-3-(4, 6-di-substituted pyrimidine-2-yl)thioureas: Synthesis, characterizations and quantum chemical calculations

1-(4-chloromethylbenzoyl)-3-(4, 6-di-substituted pyrimidine-2-yl)thioureas (1 and 2) have been synthesized using the reaction of 4-chloromethylbenzoyl isothiocyanate with 4-chloro-6-methoxypyrimidine-2-amine and 4, 6-di-methylpyrimidine-2-amine in dry tetrahydrofuran. The two compounds were characterized by FT-IR and FT-Raman (vibrational spectra), multinuclear (1H and 13C) NMR, single crystal X-ray diffraction, mass spectrometry and elemental analyses techniques. The reduced density gradient (RDG) function, which provides abundant visualization as a wide range of real space, was used to analysis the intramolecular non-covalent interactions. Besides, non-covalent interactions were discovered by us in title compounds, including hydrogen bonds, CH--lone pairs, O⋯S, van der Waals interactions and steric/ring closure effects. Hirshfeld surfaces and their two-dimensional fingerprint plots were performed to explain the intermolecular interactions in crystal lattice. The vibrational spectra (FT-IR and FT-Raman), as well as the NBO analysis have been studied using the B3LYP/6–311++G (d, p) level of approximation.

Organic solar cells and physics education

This paper explains the operational principles of a home-made organic solar cell with the representation of an electron-cycle on an energy-level diagram. We present test data for a home-made organic solar cell which operates as a galvanic cell and current source in an electrical circuit. To determine the maximum power of the cell, the optimal current was estimated with a linear approximation. Using different light sources and dyes, the electrical properties of organic solar cells were compared. The solar cells were studied by looking at spectrophotometric data from different sensitizer dyes, generated by a do-it-yourself diffraction grating spectroscope. The sensitizer dyes of solar cells were tested by the diffraction grating spectroscope. The data were analysed on a light-intensity−wavelength diagram to discover which photons were absorbed and to understand the colours of the fruits containing these dyes. In terms of theoretical applications, the paper underlines the analogous nature of organic solar cells, a conventional single p−n junction solar cell and the light-dependent reactions of photosynthesis, using energy-level diagrams of electron-cycles. To conclude, a classification of photon−electron interactions in molecular systems and crystal lattices is offered, to show the importance of organic solar cells.

Synthesis, crystal structure, hirshfeld surface analyses and physical properties of a new hybrid compound: [C3N6H8]2PbCl5.Cl

One-dimensional chain structure of a novel (1-D) lead (II) complex with a formula of [C3N6H8]2PbCl5.Cl was obtained by slow evaporation at room temperature and characterized by X-ray diffraction patterns, FT-IR and FT-Raman spectroscopy, differential scanning calorimetry and dielectric technique. This compound was found to crystallize in the monoclinic system with P21/m space group. It shows inorganic layers built by infinite chains, parallel to the (ac) planes between which the organic cations are intercalated. In this structure a one self-assembly of predetermined (1-D) [PbCl53−]n polyhedra chains and non-coordinating discrete anions are connected to positively charged [C3N6H8]2+ by means of intermolecular hydrogen bonds (N-H⋯Cl and N-H⋯N). The hydrogen bond plays an important role as the main cohesion. Hirshfeld surfaces and the breakdown of fingerprint plots were used to visualize and explore the title compound for quantifying intermolecular interactions in crystal lattice. FT-IR and FT-Raman spectroscopy were used to distinguish the different chemical functional groups and their environments in this molecule. The differential scanning calorimetry spectrum (DSC) show four peaks at 339, 357, 388 K and 416 K. The temperature dependence of the electrical conductivity (σdc and σac), and fp of the bulk part confirms the observed transitions in the calorimetric study. The dielectric-type material is protonic-electronic conductor as proton jumps in hydrogen bonds (hopping process) at low temperature and becomes an electronic one at high temperature.

Insight into Autonomic Healing of Growing Crystal around Impurity

The construction and destruction of an ordered structure play important roles in the practical performance of materials. Of special current interest are their kinetics and pathways, with crystallization being the classical example. Here we consider the orientation of the crystal lattice and hydrodynamic interactions in the framework of dynamic density functional theory to reveal the self-assembly behavior from disordered liquid to ordered FCC crystal around a hard-spherical impurity. The existence of impurity induces a new crystal growth scenario. The whole process can be divided into three stages: aggregation, self-healing, and growth. The growth rates in such stages show different features. Although the impurity causes serious lattice defects, the self-healing attribute of lattices enforces themselves to rearrange to a perfect crystal structure after about five repetition periods. As a general theoretical approach, dynamic density functional theory can be further extended to other disorder–order transit...

Estimating Percent Crystallinity of Polyethylene as a Function of Temperature by Raman Spectroscopy Multivariate Curve Resolution by Alternating Least Squares

We have recently demonstrated a methodology to estimate the percent crystallinity (PC) of polymers directly with Raman spectroscopy and multivariate curve resolution (MCR) by alternating least-squares (ALS). In the MCR-ALS methodology, the Raman spectrum of a semicrystalline polymer is separated into two constituent components (crystalline and molten/amorphous) and their corresponding concentrations. The methodology necessitates that the Raman spectrum at any temperature be a linear combination of two MCR spectral components (one molten and one crystalline). This is true in the case of simple systems such as crystalline pendant alkyl domains in polymers (Samuel et al. Anal. Chem. 2016, 88, 4644). However, in the case of main chain polymer crystals (e.g., polyethylene), the situation can be complicated owing to several molecular changes in the lattice in addition to conformational reorganizations during melting. Under this circumstance, a simple two-state model may not be adequate and we describe the modifications required to treat such systems, keeping the basic principles of the proposed methodology unchanged. A comparative study with wide-angle X-ray scattering (WAXS) and Raman spectroscopy is also performed to substantiate our findings. In addition to estimating percent crystallinity (PC), our methodology is capable of revealing additional information, such as interchain interactions in crystal lattice, that in principle will help distinguishing polymorphic transformations, subtle changes in lamellar lattice dimensions, and other phase changes in polymers.

Close contacts and noncovalent interactions in crystals.

Close contacts, defined as interatomic separations less than the sum of the respective van der Waals radii, are commonly invoked to identify attractive nonbonded interactions in crystal lattices. While this is often effective, it can also be misleading because (a) there are significant uncertainties associated with van der Waals radii, and (b) it may not be valid to attribute the interactions solely to specific pairs of atoms. The interactions within crystal lattices are Coulombic, and the strongest positive and/or negative regions do not always correspond to the positions of atoms; they are sometimes located between atoms. Examples of both types are given and discussed, focusing in particular upon σ-hole interactions.

芳香族化合物的太赫兹频段动力学及定量分析

The optical properties and characteristic spectral features of benzene, naphthalene, azobenzene, azobenzene-benzene mixtures and naphthalene-benzene mixture are investigated in the terahertz region using terahertz time-domain spectroscopy. To further resolve the origins of characteristic spectral features of aromatic compounds in terahertz region, the vibrational properties of benzene, naphthalene and azobenzene are studied using Gaussian 03 software package. The absorption of benzene, naphthalene originate from the induced dipole moment by molecular collision, crystal lattice vibration and interaction between molecular layers, respectively. The bending vibration of azobenzene is the major factor of absorption in terahertz region. Moreover, the quantitative analysis of azobenzene-benzene mixtures and naphthalene-benzene mixtures are studied. The refractive index of mixtures is found to vary linearly with concentration. The results can be used for the component and concentraion prediction of mixtures on the basis of Lambert-Beer law.