Molecular arrangement in condensed monolayer phases

Solid dispersions are one of the most promising strategies to improve the oral bioavailability of poorly water soluble drugs. By reducing drug particle size to the absolute minimum, and hence improving drug wettability, bioavailability may be significantly improved. This article reviews the various preparation techniques for solid dispersion and compiles some of the recent technology transfers. The different types of solid dispersions based on the molecular arrangement have been highlighted. Some of the practical aspects to be considered for the preparation of solid dispersions, such as selection of carrier, solvent and methods of physicochemical characterization, along with an insight into the molecular arrangement of drugs in solid dispersions are also discussed. In this review, it is intended to discuss the recent advances related on the area of solid dispersions.

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Comparative study of conventional and microwave heating of polyacrylonitrile-based fibres

Journal of Polymer Engineering ◽

10.1515/polyeng-2020-0167 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Guozhen Zhao ◽

Jianhua Liu ◽

Lei Xu ◽

Shenghui Guo

Keyword(s):

Microwave Heating ◽

Surface Defects ◽

Energy Dispersive Spectrometer ◽

Xrd Analysis ◽

Economic Benefits ◽

Heating Time ◽

Oxidation Temperature ◽

Conventional Heating ◽

Heating Method ◽

Molecular Arrangement

Abstract The effects of the conventional heating method and the microwave heating method on polyacrylonitrile-based fibres in the temperature range of 180–280 °C were investigated. Fourier transform infrared spectroscopy, X-ray wide-angle scattering, Raman spectroscopy, energy-dispersive spectrometer, scanning electron microscopy and bulk density were used to characterise the properties of the samples. Results show that the microwave heating method can shorten the pre-oxidation time, reduce pre-oxidation temperature and reduce the number of surface defects. The pre-oxidised fibres obtained by the microwave heating method exhibit not only good crystallite size but also a smooth surface. Atomic morphology and molecular arrangement are orderly inside the fibre. The FT-IR spectrum shows that the oxidation reaction occurs at 220 °C, and the CI value of PAN fibers stabilised by microwave heating is the larger than the fibers stabilised by conventional heating. XRD analysis shows that fibers stabilised by microwave heating have low stack domains. The SEM and Raman spectra indicate that hydrogen peroxide can improve the surface finish of the fibers and reduce defects. Microwave heating can reduce the pre-oxidation temperature by about 20 °C and shorten the heating time. The economic benefits of using this method are significantly improved.

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Polyimide-Derived Carbon-Coated Li4Ti5O12 as High-Rate Anode Materials for Lithium Ion Batteries

Polymers ◽

10.3390/polym13111672 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1672

Author(s):

Shih-Chieh Hsu ◽

Tzu-Ten Huang ◽

Yen-Ju Wu ◽

Cheng-Zhang Lu ◽

Huei Chu Weng ◽

...

Keyword(s):

Carbon Source ◽

Electrochemical Performance ◽

Anode Materials ◽

Lithium Ion ◽

High Rate ◽

Rate Performance ◽

Molecular Arrangement ◽

Thermal Imidization ◽

Carbon Coated ◽

Graphite Structure

Carbon-coated Li4Ti5O12 (LTO) has been prepared using polyimide (PI) as a carbon source via the thermal imidization of polyamic acid (PAA) followed by a carbonization process. In this study, the PI with different structures based on pyromellitic dianhydride (PMDA), 4,4′-oxydianiline (ODA), and p-phenylenediamine (p-PDA) moieties have been synthesized. The effect of the PI structure on the electrochemical performance of the carbon-coated LTO has been investigated. The results indicate that the molecular arrangement of PI can be improved when the rigid p-PDA units are introduced into the PI backbone. The carbons derived from the p-PDA-based PI show a more regular graphite structure with fewer defects and higher conductivity. As a result, the carbon-coated LTO exhibits a better rate performance with a discharge capacity of 137.5 mAh/g at 20 C, which is almost 1.5 times larger than that of bare LTO (94.4 mAh/g).

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Controlling the molecular arrangement of racemates through weak interactions: the synergy between π-interactions and halogen bonds

Chemical Communications ◽

10.1039/d1cc01700d ◽

2021 ◽

Author(s):

Carlos Romero-Nieto ◽

A. de Cózar ◽

Elzbieta Regulska ◽

John B. Mullenix ◽

Frank Rominger ◽

...

Keyword(s):

Weak Interactions ◽

Halogen Bonds ◽

Π Interactions ◽

Molecular Arrangement ◽

Π Stacking

The combination of halogend bonds from PO and N-moieties with π-stacking leads to sort out R- and S-isomers into homoleptic, porous assemblies.

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Rational compatibility in ternary matrix enables all-small-molecule organic solar cells with over 16% efficiency

Energy & Environmental Science ◽

10.1039/d1ee00496d ◽

2021 ◽

Author(s):

Mengyun Jiang ◽

Hairui Bai ◽

Hongfu Zhi ◽

Lu Yan ◽

Han Young Woo ◽

...

Keyword(s):

Solar Cells ◽

Phase Separation ◽

Small Molecule ◽

Organic Solar Cells ◽

Charge Generation ◽

Molecular Arrangement ◽

Efficient Charge

How to manipulate the phase separation and molecular arrangement to meet the need of efficient charge generation and extraction remains as the long-standing challenge in all-small-molecule organic solar cells (ASM-OSCs)....

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Crystal structure and lattice energetics of 10-methylacridinium halides

Australian Journal of Chemistry ◽

10.1071/ch00026 ◽

2000 ◽

Vol 53 (8) ◽

pp. 627 ◽

Cited By ~ 7

Author(s):

Piotr Storoniak ◽

Karol Krzyminski ◽

Pawel Dokurno ◽

Antoni Konitz ◽

Jerzy Blazejowski

Keyword(s):

Crystal Lattice ◽

Lattice Energy ◽

Enthalpies Of Formation ◽

Triclinic Space Group ◽

X Ray ◽

Molecular Arrangement ◽

Van Der Waals Contacts ◽

Chloride Monohydrate ◽

Insight Into

The crystal structures of 10-methylacridinium chloride monohydrate, bromide monohydrate and iodide were determined by X-ray analysis. The compounds crystallize in the triclinic space group, P¯1, with 2 molecules in the unit cell. The molecular arrangement in the crystals revealed that hydrogen bonds (in hydrates) and van der Waals contacts play a significant part in intermolecular interactions. To discover their nature, contributions to the crystal lattice energy arising from electrostatic (the most important since the compounds form ionic crystals), dispersive and repulsive interactions were calculated. Enthalpies of formation of the salts, their stability and susceptibility to decomposition could be predicted from a combination of crystal lattice energies with values of other thermochemical characteristics obtained theoretically or taken from the literature. The role of water in the stabilization of the crystal lattice of the hydrates is also explained. The information gathered has given an insight into the features and behaviour of compounds which can be regarded as models of a large group of aromatic quaternary nitrogen salts.

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Determining the C60 molecular arrangement in thin films by means of X-ray diffraction

Journal of Applied Crystallography ◽

10.1107/s002188981103531x ◽

2011 ◽

Vol 44 (5) ◽

pp. 983-990 ◽

Cited By ~ 24

Author(s):

Chris Elschner ◽

Alexandr A. Levin ◽

Lutz Wilde ◽

Jörg Grenzer ◽

Christian Schroer ◽

...

Keyword(s):

Thin Films ◽

Structural Information ◽

Grazing Incidence ◽

Test Material ◽

C60 Fullerene ◽

Diffraction Measurement ◽

X Ray Diffraction ◽

X Ray ◽

Molecular Arrangement ◽

Diffraction Patterns

The electrical and optical properties of molecular thin films are widely used, for instance in organic electronics, and depend strongly on the molecular arrangement of the organic layers. It is shown here how atomic structural information can be obtained from molecular films without further knowledge of the single-crystal structure. C60 fullerene was chosen as a representative test material. A 250 nm C60 film was investigated by grazing-incidence X-ray diffraction and the data compared with a Bragg–Brentano X-ray diffraction measurement of the corresponding C60 powder. The diffraction patterns of both powder and film were used to calculate the pair distribution function (PDF), which allowed an investigation of the short-range order of the structures. With the help of the PDF, a structure model for the C60 molecular arrangement was determined for both C60 powder and thin film. The results agree very well with a classical whole-pattern fitting approach for the C60 diffraction patterns.

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