Molecular evolution pathways during nucleation of small organic molecules: solute-rich pre-nucleation species enable control over the nucleation process

2020 ◽  
Vol 22 (33) ◽  
pp. 18663-18671
Author(s):  
Shuyi Zong ◽  
Jingkang Wang ◽  
Xin Huang ◽  
Ting Wang ◽  
Qi Liu ◽  
...  
Keyword(s):  
Molecular Evolution ◽  
Small Molecules ◽  
Organic Molecules ◽  
Nucleation Process ◽  
Small Organic Molecules

The pre-nucleation clusters played a key role in the process of crystallization of organic small molecules, indicating that the dynamics of nucleation could be regulated by changing the structure and size of the pre-nucleation clusters.

scholarly journals Correlations between retention volume and molecular size parameters in gel permeation chromatography of small molecules

1975 ◽  
Vol 28 (1) ◽  
pp. 189 ◽  
Author(s):  
RA Shanks
Keyword(s):  
Molecular Weight ◽  
Small Molecules ◽  
Organic Molecules ◽  
Retention Volume ◽  
Molecular Size ◽  
Gel Permeation Chromatography ◽  
Molar Volumes ◽  
Small Organic Molecules ◽  
Molecular Dimension ◽  
Gel Permeation

Gel permeation columns of Bio Beads S-X8 have been used to provide separation of oligomers and other small organic molecules. Results show successful separations up to molecular weight c. 600. The retention times of compounds have been correlated with the largest molecular dimension of the molecules and also with molar volumes.

Carbon Nanostructures Produced by Liquid Phase Exfoliation of Graphite in the Presence of Small Organic Molecules

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Jesús I. Tapia ◽  
Mildred Quintana
Keyword(s):  
Liquid Phase ◽  
Small Molecules ◽  
Carbon Nanostructures ◽  
Organic Molecules ◽  
Chemical Nature ◽  
Spectroscopy Analysis ◽  
Small Organic Molecules ◽  
Transmission Electron ◽  
Secondary Reactions ◽  
Carbon Nanoscrolls

AbstractWe report on the formation of different carbon nanostructures by ultrasonication of graphite in DMF upon the addition of 3 different small molecules: ferrocene carboxylic acid, dimethylamino methyl-ferrocene, and benzyl aldehyde. Our results confirm that acoustic cavitation in organic solvents generates free radicals which enable or are involved in secondary reactions. During the ultrasonication process, the addition of small molecules induces the formation of different carbon nanostructures mainly depending on the chemical nature of the molecule, as observed by transmission electron microscopy (TEM). Raman spectroscopy analysis confirms that small molecules act as radical scavengers reducing the damage caused by cavitation to graphene sheets producing long nanoribbons, squared sheets, or carbon nanoscrolls. Importantly, this strategy allows the production of different carbon nanostructures in liquid-phase making them readily available for their chemical functionalization or for their incorporation into hybrids materials enabling the development of new advanced biological applications.

Fluorescent Carbon Dots and their Applications in Sensing of Small Organic Molecules

2021 ◽  
Vol 17 ◽  
Author(s):  
Sakib Hussain Laghari ◽  
Najma Memon ◽  
Muhammad Yar Khuhawer ◽  
Taj Muhammad Jahangir
Keyword(s):  
Small Molecules ◽  
Fluorescent Probes ◽  
Carbon Dots ◽  
Organic Molecules ◽  
Fluorescent Properties ◽  
Small Organic Molecules ◽  
Uv Visible ◽  
Size Of Particles ◽  
Fluorescent Carbon Dots ◽  
Fluorescent Carbon

Background: Fluorescence-based sensing is considered highly sensitive and fluorescent probes with improved properties are always desired. Fluorescent carbon dots (CDs) are newly emerging quasi-spherical nanoparticles of less than 10 nm in size and belong to the carbon nano-material’s family. CDs have great potential as fluorescent probes and currently are under open deliberation by the researchers due to their striking properties such as low environmental hazard, high selectivity, greater sensitivity, good biocompatibility, tunable fluorescent properties and excitation dependent multicolor emission behavior. Introduction: This review demonstrates various available methods for fabrication of fluorescent CDs, capping of CDs and characterization with various techniques including UV-visible, FT-IR, and TEM. Analytical applications using CDs for the sensing of small organic molecules, specifically nitroaromatic compounds in the environmental samples are complied. Methods: The review covers literature related to synthesis and characterization of carbon dots. It includes around 171 research articles in this field. Results: Carbon dots can be synthesized using numerous routes. In all cases CDs possess spectral properties with little variation in wavelength maxima. Optical properties of CDs can be tuned by compositing these with metallic quantum dots or by modifying their surface with desired functionalities. HR-TEM is needed to see the morphology and size of particles whereas UV-Visible and FTIR are indispensable tools for this kind of research. These particles are successfully applied to sense small molecules in some matrices. Conclusion: Carbon dots are bright stars in fluorescent sensing of small molecules. However, more research is needed to determine small organic molecules in diversified areas of analysis.

Small Organic Molecules for Electrically Re-writable Non-volatile Polymer Memory Devices

2010 ◽  
Vol 1250 ◽  
Author(s):  
Iulia Salaoru ◽  
Shashi Paul
Keyword(s):  
Small Molecules ◽  
Polymer Matrix ◽  
Organic Molecules ◽  
Electrical Conductance ◽  
Metal Structure ◽  
Organic Polymer ◽  
Memory Devices ◽  
Electrical Behaviour ◽  
Small Organic Molecules ◽  
Polymer Memory

AbstractThe usage of organic materials in the manufacture of electronic polymer memory devices is on the rise. Polymer memory devices are fabricated by depositing a blend (an admixture of organic polymer, small molecules and nanoparticles) between two metal electrodes. The primary aim is to produce devices that exhibit two distinct electrical conductance states when a voltage is applied. These two states can be viewed as the realisation of non-volatile memory. This is an interesting development; however, there are a number of theories that have been proposed to explain the observed electrical behaviour. We have proposed a model that is based on electric dipole formation in the polymer matrix. Here, we investigate further the proposed model by deliberately creating electric dipoles in a polymer matrix using electron donors (8-Hydroxyquinoline, Tetrathiafulvalene and Bis(ethylenedithio)tetrathiafulvalene) and electron acceptors (7,7,8,8-Tetracyanoquinodimethane, Tetracyanoethylene and Fullerene) small molecules.Two types of structures were investigated (i) a metal/blend of polymer and small molecules/metal (MOM), device and (ii) a metal/insulator/blend of small molecules and polymer/semiconductor (MIS) architecture. A blend of polymer and small organic molecules was prepared in methanol and spin-coated onto a glass substrate marked with thin aluminium (Al) tracks; a top Al contact was then evaporated onto the blend after drying - this resulted in a metal-organic-metal structure. The MIS structures consisted of an ohmic bottom Al contact, p-type Si, a polymer blend (two small organic molecules and insulating polymer), followed by polyvinyl acetate and finally a top, circular Al electrode. In-depth FTIR studies were carried out to understand the observed electrical behaviour. An electrical analysis of these structures was performed using an HP4140B picoammeter and an HP 4192A impedance analyser at a frequency of 1 MHz.

scholarly journals Desorption/ionization on silicon for small molecules:a promising alternative to MALDI TOF.

2003 ◽  
Vol 50 (3) ◽  
pp. 783-787 ◽  
Author(s):  
Agnieszka Kraj ◽  
Tomasz Dylag ◽  
Anna Gorecka-Drzazga ◽  
Sylwester Bargiel ◽  
Jan Dziubanand ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Small Molecules ◽  
Molecular Mass ◽  
Organic Molecules ◽  
Mass Region ◽  
Promising Alternative ◽  
Small Organic Molecules ◽  
Desorption Ionization ◽  
Maldi Tof ◽  
Detection And Identification

A method has been developed for laser desorption/ionization of catecholamines from porous silicon. This methodology is particularly attractive for analysis of small molecules. MALDI TOF mass spectrometry, although a very sensitive technique, utilizes matrices that need to be mixed with the sample prior to their analysis. Each matrix produces its own background, particularly in the low-molecular mass region. Therefore, detection and identification of molecules below 400 Da can be difficult. Desorption/ionization of samples deposited on porous silicon does not require addition of a matrix, thus, spectra in the low-molecular mass region can be clearly readable. Here, we describe a method for the analysis of catecholamines. While MALDI TOF is superior for proteomics/peptidomics, desorption/ionization from porous silicon can extend the operating range of a mass spectrometer for studies on metabolomics (small organic molecules and their metabolites, such as chemical neurotransmitters, prostaglandins, steroids, etc.).

Assessing electronic properties of desymmetrized heterocyclic patterns: towards tuning small molecules for photovoltaic applications

MRS Advances ◽  
2020 ◽  
Vol 5 (61) ◽  
pp. 3171-3184
Author(s):  
Oscar González-Antonio ◽  
Rebeca Yépez ◽  
María Magdalena Vázquez-Alvarado ◽  
Blas Flores-Pérez ◽  
Norberto Farfán ◽  
...  
Keyword(s):  
Small Molecules ◽  
Heterocyclic Compounds ◽  
Computational Analysis ◽  
Organic Molecules ◽  
Spectroscopic Properties ◽  
Small Organic Molecules ◽  
Photovoltaic Materials ◽  
Photovoltaic Applications ◽  
Donor Acceptor ◽  
Homo Lumo

AbstractA series of highly attainable desymmetrized heterocyclic compounds with Donor-Acceptor-Donor-Acceptor-X (D-A-D-X) architectures were synthesized. The structures, where X corresponds to a heteroaromatic portion (pyridine, ferrocene, thiadiazolopyridine), were designed through computational analysis. Molecular geometries for all compounds were studied and parameters of charge transfer were computed in order to analyse the behaviour in each architecture. Spectroscopic properties (maximum absorption wavelengths, extinction coefficients and HOMO-LUMO gaps) were predicted and measured experimentally. UV-Vis absorption profiles and values of HOMO-LUMO optical gaps (in the vicinity of 2.0 eV), together with the computational results, are properties that position the obtained systems, as potential candidates for developing efficient photovoltaic materials based on synthetically accessible small organic molecules.

Asymmetric small organic molecule-based NIR-II fluorophores for high performance tumor phototheranostics

2021 ◽  
Author(s):  
Qi Wang ◽  
Xinrui Niu ◽  
Lingqiang Yang ◽  
Jia-Wei Liu ◽  
Jing Wang ◽  
...  
Keyword(s):  
Optical Properties ◽  
Small Molecules ◽  
High Purity ◽  
High Performance ◽  
Organic Molecule ◽  
Organic Molecules ◽  
Great Promise ◽  
Small Organic Molecules ◽  
Small Organic Molecule ◽  
Chemical Structures

Small organic molecules hold great promise for phototheranostics due to their well-defined chemical structures and optical properties, excellent biodegradation and biocompatibility, high purity, and outstanding repeatability. Nevertheless, many small molecules...

SMALL MOLECULES ADSORBED ON SILICON SURFACES: TWO CASES THROUGH TIME

2017 ◽  
Vol 24 (06) ◽  
pp. 1830001 ◽  
Author(s):  
MARILENA CARBONE
Keyword(s):  
Small Molecules ◽  
Electronic Structures ◽  
Adsorption Mechanism ◽  
Organic Molecules ◽  
Dissociative Adsorption ◽  
Silicon Surfaces ◽  
Small Organic Molecules ◽  
Adsorption Mechanisms ◽  
Open Case ◽  
Silicon Based

The adsorption of small organic molecules on silicon surfaces has been long a subject of investigations, as it provides the fundamental basis of silicon-based technologies in many fields. Several approaches were used, both theoretical and experimental, on many types of adsorbate-substrate systems aiming at determining preferential sites and geometries of adsorption, stable configurations, transition barriers, adsorption mechanisms, electronic structures among others. The research efforts, though, did not always bring to conclusive arguments and on some systems investigations are still going on following the evolution of the experimental techniques and computational methods. In this review, two case studies are reported: benzene and methanol on Si(100)2[Formula: see text]1, i.e. examples of a molecular and a dissociative adsorption. The adsorption of benzene on Si(100)2[Formula: see text]1 is still an open case, as it may adsorb in di-[Formula: see text] or tetra-[Formula: see text] bonded configurations, but contrasting evidences have been reported so far, on which of the two is the most stable one and the debate is still open. The adsorption of methanol is less controversial and it is widely accepted it is dissociative with breakage of the O–H at low coverages. But also in this case, investigations are going on to elucidate the adsorption mechanism.

Disodium cromoglycate: exploiting its properties as a NMR weak-aligning medium for small organic molecules

2014 ◽  
Vol 12 (12) ◽  
pp. 1957-1965 ◽  
Author(s):  
Eduardo Troche-Pesqueira ◽  
María-Magdalena Cid ◽  
Armando Navarro-Vázquez
Keyword(s):  
Small Molecules ◽  
Organic Molecules ◽  
Disodium Cromoglycate ◽  
Small Organic Molecules

Disodium cromoglycate (cromolyn) is an easy-to-prepare water-compatible NMR weak aligning medium for small molecules.

scholarly journals Determination of the Effective Hydrodynamic Radii of Small Molecules by Viscometry

1961 ◽  
Vol 44 (6) ◽  
pp. 1189-1199 ◽  
Author(s):  
Stanley G. Schultz ◽  
A. K. Solomon
Keyword(s):  
Small Molecules ◽  
Organic Molecules ◽  
Surrounding Medium ◽  
Solute Molecule ◽  
Molecular Models ◽  
Small Organic Molecules ◽  
Empirical Correction ◽  
Water Of Hydration ◽  
Dilute Aqueous Solution

The effective hydrodynamic radii of small uncharged molecules in dilute aqueous solution were determined using Einstein's classical theory of viscosity. The radii thus obtained are those of a hypothetical sphere whose hydrodynamic behavior is the same as that of the solute molecule plus that water of hydration which is too firmly bound to partake in the viscous shearing process. The results obtained compare favorably with radii determined from molecular models constructed in accordance with atomic dimensions compiled by Pauling. Although the application of the Einstein theory to molecules whose size is comparable to that of water represents a considerable extrapolation, the results suggest that this deviation from the assumptions of the theory, in the case of the molecules studied, is of second order importance. Employing the viscometric radii, we have formulated an empirical correction of the Stokes-Einstein diffusion equation. This correction is similar in form to those previously proposed by Cunningham (22) and Millikan (21) and is of particular significance when the solute molecule is comparable in size to the discontinuities of the surrounding medium. The molecular radii of a number of small organic molecules obtained by means of the corrected Stokes-Einstein equation do not differ significantly from the radii obtained from molecular models of these compounds.

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