Infrared spectra (4,000-400 cm(-1)) and Raman spectra (1,700-40 cm(-1)) of the liquid and two crystalline solids of isopropylbenzene (cumene) and isopropylbenzene-d(12) have been recorded. The spectra indicate that in the liquid and crystalline solids isopropylbenzene exists in planar conformation only (CH bond is in the plane of the benzene ring). An assignment of the observed band wave numbers both isopropylbenzene and isopropylbenzene-d(12) is discussed by comparison with normal mode wave numbers and IR intensities calculated from ab initio 6-31G (d) force fields.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/j.saa.2008.03.008 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Time-resolved Brownian tomography of single nanocrystals in liquid during oxidative etching.
Nat Commun
January 2025
School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul, Republic of Korea.
Colloidal nanocrystals inherently undergo structural changes during chemical reactions. The robust structure-property relationships, originating from their nanoscale dimensions, underscore the significance of comprehending the dynamic structural behavior of nanocrystals in reactive chemical media. Moreover, the complexity and heterogeneity inherent in their atomic structures require tracking of structural transitions in individual nanocrystals at three-dimensional (3D) atomic resolution.
View Article and Find Full Text PDFOn the formation and stability mechanisms of diverse lipid-based nanostructures for drug delivery.
Adv Colloid Interface Sci
January 2025
Department of Chemistry and Biotechnology, School of Science, Computing and Engineering Technologies, Swinburne University of Technology, Melbourne, Australia.
In the evolving landscape of nanotechnology and pharmaceuticals, lipid nanostructures have emerged as pivotal areas of research due to their unique ability to mimic biological membranes and encapsulate active molecules. These nanostructures offer promising avenues for drug delivery, vaccine development, and diagnostic applications. This comprehensive review explores the complex mechanisms underlying the formation and stability of various lipid nanostructures, including lipid liquid crystalline nanoparticles and solid lipid nanoparticles.
View Article and Find Full Text PDFAssessing the Impacts of Drug Loading and Polymer Type on Dissolution Behavior and Diffusive Flux of GDC-6893 Amorphous Solid Dispersions.
J Pharm Sci
January 2025
Department of Synthetic Molecule Pharmaceutical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA. Electronic address:
It is desirable but remains challenging to develop high drug load amorphous solid dispersions (ASDs) without compromising their quality attributes and bio-performance. In this work, we investigated the impacts of formulation variables, such as drug loading (DL) and polymer type, on dissolution behavior, diffusive flux, and in vitro drug absorption of ASDs of a high T compound, GDC-6893. ASDs with two polymers (HPMCAS and PVPVA) and various DLs (20 - 80%) were produced by spray drying and their drug-polymer miscibility was evaluated using solid-state nuclear magnetic resonance (ssNMR).
View Article and Find Full Text PDFMethyl side-groups control the 3̄ phase in core-non-symmetric aryloyl-hydrazine-based molecules.
Phys Chem Chem Phys
January 2025
Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, Yanagido, Gifu 501-1193, Japan.
Control of the formation of liquid crystalline 3̄ gyroid phases and their nanostructures is critical to advance materials chemistry based on the structural feature of three-dimensional helical networks. Here, we present that introducing methyl side-group(s) and slight non-symmetry into aryloyl-hydrazine-based molecules is unexpectedly crucial for their formation and can be a new design strategy through tuning intermolecular interactions: the two chemical modifications in the core portion of the chain-core-chain type molecules effectively lower and extend the 3̄ phase temperature ranges with the increased twist angle between neighboring molecules along the network. The detailed analyses of the aggregation structure revealed the change in the core assembly mode from the double-layered core mode of the mother molecule (without methyl groups) to the single-layered core mode.
View Article and Find Full Text PDFChemical and physical properties of orthoconic liquid crystals: H NMR spectroscopy and molecular dynamics simulations.
Soft Matter
January 2025
Dipartimento di Chimica e Chimica Industriale, University of Pisa, via Moruzzi 13, Pisa 56124, Italy.
In the field of chiral smectic liquid crystals, orthoconic antiferroelectric liquid crystals (OAFLCs) have attracted the interest of the scientific community due to the very high tilt angle, close to 45°, and the consequent optical properties. In the present study, the first H NMR investigation is reported on two samples, namely 3F5HPhF9 and 3F7HPhF8, showing the phase sequence isotropic-SmC*-SmC* and the phase sequence isotropic-SmA-SmC*-SmC*, respectively, when cooling from the isotropic to the crystalline phases. To this aim, the liquid crystals were doped with a small amount of deuterated probe biphenyl-4,4'-diol-d.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!