Structure Of Organic Materials Research Articles

Bulk Hyperpolarization of Inorganic Materials.

Solid-state NMR spectroscopy is a well-established method to obtain atomic-level information about the structure of inorganic materials, but its use is often limited by low sensitivity. We review how solvent generated dynamic nuclear polarization can be used to increase sensitivity in solid-state NMR of inorganic materials, with emphasis on our recent method for hyperpolarization of proton-free bulk. We use selected examples to show how overall gains in sensitivity can be observed in both the surface and bulk spectra of inorganic compounds such as lithium titanate. The hyperpolarization methods reviewed here can be used to improve NMR sensitivity for a range of inorganic materials.

Maturity estimation for Type II-S kerogen using Raman spectroscopy – A case study from the Najmah and Makhul Formations in Kuwait

Raman spectroscopy is used to estimate thermal maturity of shale samples collected from seven wells in the Najmah Formation in Kuwait, encompassing a range of maturities between 0.80 and 1.40%VRE. The Najmah Formation contains kerogen Type II-S (S/C > 0.04) and therefore, maturity correlations for Type II are not applicable due to differences in organic material structure, kinetics and thermal transformation pathways. A new correlation is proposed for the purpose of thermal maturity estimation in Type II-S kerogens. The presented correlation is able to predict the thermal maturity, based on Raman spectra, with good accuracy when compared to the reflectance-derived thermal maturity values.

Conjugated Polymers in Bioelectronics.

The emerging field of organic bioelectronics bridges the electronic world of organic-semiconductor-based devices with the soft, predominantly ionic world of biology. This crosstalk can occur in both directions. For example, a biochemical reaction may change the doping state of an organic material, generating an electronic readout. Conversely, an electronic signal from a device may stimulate a biological event. Cutting-edge research in this field results in the development of a broad variety of meaningful applications, from biosensors and drug delivery systems to health monitoring devices and brain-machine interfaces. Conjugated polymers share similarities in chemical "nature" with biological molecules and can be engineered on various forms, including hydrogels that have Young's moduli similar to those of soft tissues and are ionically conducting. The structure of organic materials can be tuned through synthetic chemistry, and their biological properties can be controlled using a variety of functionalization strategies. Finally, organic electronic materials can be integrated with a variety of mechanical supports, giving rise to devices with form factors that enable integration with biological systems. While these developments are innovative and promising, it is important to note that the field is still in its infancy, with many unknowns and immense scope for exploration and highly collaborative research. The first part of this Account details the unique properties that render conjugated polymers excellent biointerfacing materials. We then offer an overview of the most common conjugated polymers that have been used as active layers in various organic bioelectronics devices, highlighting the importance of developing new materials. These materials are the most popular ethylenedioxythiophene derivatives as well as conjugated polyelectrolytes and ion-free organic semiconductors functionalized for the biological interface. We then discuss several applications and operation principles of state-of-the-art bioelectronics devices. These devices include electrodes applied to sense/trigger electrophysiological activity of cells as well as electrolyte-gated field-effect and electrochemical transistors used for sensing of biochemical markers. Another prime application example of conjugated polymers is cell actuators. External modulation of the redox state of the underlying conjugated polymer films controls the adhesion behavior and viability of cells. These smart surfaces can be also designed in the form of three-dimensional architectures because of the processability of conjugated polymers. As such, cell-loaded scaffolds based on electroactive polymers enable integrated sensing or stimulation within the engineered tissue itself. A last application example is organic neuromorphic devices, an alternative computing architecture that takes inspiration from biology and, in particular, from the way the brain works. Leveraging ion redistribution inside a conjugated polymer upon application of an electrical field and its coupling with electronic charges, conjugated polymers can be engineered to act as artificial neurons or synapses with complex, history-dependent behavior. We conclude this Account by highlighting main factors that need to be considered for the design of a conjugated polymer for applications in bioelectronics-although there can be various figures of merit given the broad range of applications, as emphasized in this Account.

Enhanced Computational Sampling of Perylene and Perylothiophene Packing with Rigid-Body Models.

Molecular simulations have the potential to advance the understanding of how the structure of organic materials can be engineered through the choice of chemical components but are limited by computational costs. The computational costs can be significantly lowered through the use of modeling approximations that capture the relevant features of a system, while lowering algorithmic complexity or by decreasing the degrees of freedom that must be integrated. Such methods include coarse-graining techniques, approximating long-range electrostatics with short-range potentials, and the use of rigid bodies to replace flexible bonded constraints between atoms. To understand whether and to what degree these techniques can be leveraged to enhance the understanding of planar organic molecules, we investigate the morphologies predicted by molecular dynamic simulations using simplified molecular models of perylene and perylothiophene. Approximately, 10 000 wall-clock hours of graphics processing unit-accelerated simulations are performed using both rigid and flexible models to test their efficiency and predictive capability with the two chemistries. We characterize the 1191 resulting morphologies using simulated X-ray diffraction and cluster analysis to distinguish structural transitions, summarized by four phase diagrams. We find that the morphologies generated by the rigid model of perylene and perylothiophene match with those generated by the flexible model. We find that ordered, hexagonally packed columnar phases are thermodynamically favored over a wide range of densities and temperatures for both molecules, in qualitative agreement with experiments. Furthermore, we find the rigid model to be more computationally efficient for both molecules, providing more samples per second and shorter times to equilibrium. Owing to the structural accuracy and improved computational efficiency of modeling polyaromatic groups as rigid bodies, we recommend this modeling choice for enhancing the sampling in polyaromatic molecular simulations.

Kinetically Controlling the Polymerization of Microgels for Synthesis of Silver Nanoparticles in a Confined Space.

Controllable synthesis of materials is a dream of scientists, which is closing to the reality after the advancement of fundamental studies. It is generally believed that the structure of materials is controlled by thermodynamics and kinetics. When the materials are formed in a condition far away from equilibrium, the kinetic factors play an important role in shaping materials. The aim of this paper is to evaluate whether the diffusion and reaction also influence the structure of organic materials. We take the preparation of poly(N-isopropylamide) microgels as an example. The diffusion of chemicals is regulated by changing the viscosity of solvents while the reaction is regulated by changing the amount of initiators. It is found that slow diffusion and reaction are in favor of propagation reaction, which leads to the formation of long polymer chains. The microgels composed of these long chains have high swelling ratio. On the other hand, the microgels formed in the high diffusion and reaction consists of shorts chains and demonstrates low swelling ratio. In the followings, we used the microgels as reactor to synthesize silver particles. It is found that the size and the density of silver particles are dependent on the swelling ratio of microgels. This study indicates that controlling chemical diffusion and reaction is a general approach to regulate the structure of materials.

Modelling of the Electric Field Applied to the Ensembles of Microparticles

The paper deals with modelling of the time varying electric field, applied to composites structures of inorganic materials (containing metal and metal oxide). The structural changes at the initials stages of sintering, characterised by the number of contact per particle and an increase of the areas of interparticle contact have been modelled and examined. The aim of study was estimation of the electric field strength, current density, power losses and forces, acting along the contact area between particles. The field models have been obtained using finite element method and QuickField 5.6 software package.

In situ 광전자분광/역광전자분광 분석을 이용한 유기물 계면의 전자구조 연구

In situ 광전자분광/역광전자분광 분석을 이용한 유기물 계면의 전자구조 연구

Study of Molecular Behaviors of Renewable Polymers Using the Langmuir Technique

The Langmuir film method has been widely used to investigate the properties of ultrathin films with defined and controllable structures of organic materials, using electronic and optoelectronic devices. In this study, the renewable poly(I-lactide) (PLLA) and the stereochemical PLAs (scPLA) with different ratios of d-lactide (DLA) and LLA units were synthesized, and a degree of complexation between DLA and LLA unit sequences was controlled by mixing scPLA and PDLA. Monolayer behaviors of PLLA/scPLA mixtures were measured using the Langmuir film method. At a constant surface pressure, the areas occupied by the monolayers decreased when they were exposed to alkaline subphase. This indicates that the oligomers generated by hydrolysis dissolve into subphase. The extent of area reduction in the initial stage was increased with the optical impurity in the mixtures, which prevents the formation of complexes.

Progress of Novel Inkjet Technique for Inorganic Materials Preparation

In the last few years,inkjet technique has attracted great attention for its use as a form-free fabrication method for building 3-D structure of inorganic materials and combinatorial material chips.This article reviews the progress of inorganic materials prepared by inkjet technique,including the development of inkjet printing system,the properties of different ink,applications,challenges and the hot of recent research.The fabrication of conducting circuits and setup of an electromagnetic inkjet fabricating system for material chip preparation in author's lab is briefly introduced as well.

Relationships among geochemical indices of coal and carbonaceous materials and implication for hydrocarbon potential evaluation

A worldwide dataset of organic material from 553 samples belonging to coal and carbonaceous materials was used to analyze the evolution of hydrogen index (HI) and bitumen index (BI) with increasing thermal maturity. Basic statistical analyses were applied to detect the boundary lines of HImax and BImax in delineating the upper and lower limits of the HI and BI bands for the majority of samples. In addition, cross-plots of HI or BI versus maturity (Ro% and T max) also provide criteria for defining the HImax and BImax boundary lines. The constructed HI and BI bands are broad at low maturities and become narrower with increasing thermal maturities. The petroleum generation potential is completely exhausted at the vitrinite reflectance of 2.0–2.2% or T max of 510–520°C. An increase in HI implies extra petroleum generation which was related to changes in structure of organic materials. A declining BI means that the oil expulsion window starts to occur at the vitrinite reflectance range of 0.75–1.05%. The petroleum potential can be divided into four different areas based on the cross-plot of HI versus Ro%. The highest petroleum potential area is located in section II with Ro = 0.6–1.0% and HI > 100. The oil generation potential is rapidly exhausted at section III with Ro > 1.0%. This result is also in accordance with the result of curve regression of HI versus Ro% based on 80 samples with Ro = 1.02–3.43% (R 2 = 0.72). Overall, the total oil window can be extended up to Ro = ~1.25–1.95%. Finally, in the cross-plots of S1 versus S2, shale or C-shale exhibits a higher and slowly decreased slope, compared with a lower and then sharply increased slope of coal samples, which is attributable to their compositional difference in organic material.

Effect of mechanical activation on the structure of inorganic materials with different bonding types

Particle-size analysis and x-ray diffraction data are presented for potassium chloride, silicon, barium peroxide, and calcium peroxide mechanically activated in a disintegrator. The microstrain and block size in the mechanically activated materials are nonlinear functions of milling time. The type of chemical bonding is shown to play a key role in determining the nature of milling-induced structural changes.

Theoretical study of inelastic X-ray scattering spectra for organic materials: Molecular excitation coupled with molecular exciton descriptions

Inelastic X-ray scattering (IXS) spectrum provides a powerful tool to investigate the electronic structure of organic materials, in complimentary to the conventional optical spectra. Starting from a single molecule, then a dimer, and finally a cluster of molecular aggregate, we developed a Frenkel exciton model to describe the IXS process based on the quantum chemical calculations for the molecular excitations in the organic crystal of open-ring photomerocyanine form of spirooxazine (Py-SO). It is shown that the quantum chemical calculation combined with Frenkel exciton model can well describe the experimental measurements in terms of (i) the overall features of the IXS spectra from 2 to 10 eV, (ii) the dispersion behavior of the lowest exciton band, and (iii) the momentum-transfer dependence of the peak intensity. The roles of molecular excited state and the intermolecular interactions have been discussed for the IXS spectra.

Vive la Chimie

Vive la Chimie

Development of Experimental Methods for Determining the Electronic Structure of Organic Materials

The principles and developments of experimental methods for determining the energy parameters governing the electronic structure of organic molecules and solids are reviewed with some historical descriptions. The energy parameters discussed are ionization energy of a molecule (Ig) and solid (Is), electron affinity of a molecule (Ag) and solid (As), and the energies of the vacuum level (VL) and the Fermi level (EF). The work function (Φ) can be also derived as the difference between the last two. Various types of spectroscopic and electrical measurements are discussed with typical examples, including the range of applicability and the merits and the demerits. Recent microscopic techniques for obtaining local information are also described.

BIOLOGICAL SYSTEMS AND MATERIALS: A REVIEW OF THE FIELD OF BIOMECHANICS AND THE ROLE OF THE SOCIETY FOR EXPERIMENTAL MECHANICS

The field of biological materials and systems is extensive, representing an interdisciplinary topic encompassing mechanics, materials science, and the breadth of engineering disciplines in conjunction with biology and medicine. The biological world has evolved a diverse array of structures and materials that offer unique and desirable properties of significant interest to the engineering world. The local variations in material composition and the intricate hierarchical structures of organic materials result in complicated constitutive responses. Characterizing and understanding these responses impact the field of medicine and provide inspiration for new materials and new areas of study. The unique requirements associated with implants provide opportunities to develop new materials and structures, and employ existing materials to new problems. The membership of the SEM, through the Biological Materials and Systems TD, has embraced the opportunity to take on a central role in developing this new field as evidenced by the many publications referenced here, bringing a strong background of classical mechanics to the investigation of organic materials, the study of implant materials, and the development of new materials and structures based on inspiration from the natural world.

Conformation and Assembly of Polypeptide Scaffolds in Templating the Synthesis of Silica: An Example of a Polylysine Macromolecular “Switch”

Although the role of polycationic macromolecules in catalyzing the synthesis of silica structures is well established, detailed understanding of the mechanisms behind the production of silica structures of controlled morphologies remains unclear. In this study, we have used both poly-L-lysine (PLL) and/or poly-D-lysine (PDL) for silica synthesis to investigate mechanisms controlling inorganic morphologies. The formation of both spherical silica particles and hexagonal plates was observed. The formation of hexagonal plates was suggested, via circular dichroic spectroscopy (CD), to result from the assembly of helical polylysine molecules. We confirm that the formation of PLL helices is a prerequisite to the hexagonal silica synthesis. In addition, we present for the first time that the handedness of the helicity of the macromolecule does not affect the formation of hexagonal silica. We also show, by using two different silica precursors, that the precursor does not have a direct effect on the formation of hexagonal silica plates. Furthermore, when polylysine helices were converted to beta-sheet structure, only silica particles were obtained, thus suggesting that the adoption of a helical conformation by PLL is required for the formation of hexagonally organized silica. These results demonstrate that the change in polylysine conformation can act as a "switch" in silica structure formation and suggest the potential for controlling morphologies and structures of inorganic materials via control of the conformation of soft macromolecular templates.

Rational Growth of Various α-MnO2 Hierarchical Structures and β-MnO2 Nanorods via a Homogeneous Catalytic Route

Heterogeneous catalytic reactions involved in the vapor−liquid−solid (VLS) or solution−liquid−solid (SLS) growth of 1-D nanostructures have been intensively investigated in recent years. But how to control the homogeneous catalytic route and apply it to design new structures of materials has rarely been discussed. In this work, a homogeneous catalyst was successfully controlled via changing the catalyst feed way, and three novel α-MnO2 hierarchical structures, namely, urchin-like structures, sphere networks, and nanowire networks, were selectively synthesized at room temperature. β-MnO2 nanorods were also prepared via this method at higher temperatures. The present work indicates that the homogeneous catalytic route not only can produce one certain structure of inorganic materials but also can be rationally controlled and therefore used to grow more new structures. On the other hand, this homogeneous catalytic method is a solution-based self-assembly route, providing a simple, mild, and template-free way to the fabrication of hierarchical structures.

Maximizing information obtained from secondary ion mass spectra of organic thin films using multivariate analysis

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) can give a detailed description of the surface chemistry and structure of organic materials. The high mass resolution and high mass range mass spectra obtainable from modern ToF-SIMS instruments offer the ability to rapidly obtain large amounts of data. Distillation of that data into usable information presents a significant problem in the analysis of ToF-SIMS data from organic materials. Multivariate data analysis techniques have become increasingly common for assisting with the interpretation of complex ToF-SIMS data sets. This study presents an overview of principal component analysis (PCA) and partial least squares regression (PLSR) for analyzing the ToF-SIMS spectra of alkanethiol self-assembled monolayers (SAMs) adsorbed onto gold substrates and polymer molecular depth profiles obtained using an SF 5 + primary ion beam. The effect of data pretreatment on the information obtained from multivariate analysis of these data sets has been explored. Multivariate analysis is an important tool for maximizing the information obtained from the ToF-SIMS spectra of organic thin films.

Characterization of tris (8-hydroxyquinoline) aluminum (Alq3) by energy-filtering transmission electron microscopy

Electronic structure of tris (8-hydroxyquinoline) aluminum (Alq3) was characterized by energy-filtering transmission electron microscopy (EFTEM). Three energy loss peaks were observed with reasonable energy resolution of 0.5–0.7 eV. These peaks were ascribed to the ionization (6.4 eV), La1 transition (3.3 eV) and Bb1 transition (4.7 eV) processes in this material, respectively. The present result indicates that EFTEM provides an effective means to characterize the electronic structure of organic materials with nanometer resolution.

Computational Design and Prediction of Interesting Not‐Yet‐Synthesized Structures of Inorganic Materials by Using Building Unit Concepts

AbstractFor Abstract see ChemInform Abstract in Full Text.