Barium sulfate crystallization dependence on upper rim calix[4]arene functional groups

Although the effects of p-sulfonated and p-phosphonated calix[4]arene on barium sulfate morphology are similar, their ability to form mesocrystals of material are markedly different. The p-phosphonated calix[4]arene results in the formation of fibre bundles similar to those previously observed during barium sulfate crystallization in the presence of di-block copolymers. The isostructural sulfonated calix[4]arene, however, affords material consistent with the initial formation of mesocrystals which subsequently fuse. This material shows significant beam damage when viewed under a transmission electron microscope (TEM) suggesting incorporation of the sulfonated calix[4]arene, although there was no evidence of this from X-ray diffraction and atomic force microscopy (AFM) studies. We hypothesise that this calixarene is incorporated without significant change in structure of the material, and that the interaction of the macrocycle with the barium sulfate lattice is sufficiently weak that surface AFM imaging is effective in removing it from the surface

Vortex fluidic mediated synthesis of TiO2 nanoparticle/MXene composites

Oxidation of MXene in a vortex fluidic device (VFD) operating under continuous flow results in exfoliation and fragmentation into nanoparticles of surface oxidised 2D material with further oxidation of the nanoparticles into anatase (TiO 2 ). These MXene and anatase nanoparticles co‐assemble into stable micron sized spheres which are topologically smooth, decorating the surface of exfoliated MXene. The formation of this composite material in the dynamic thin film in the VFD was optimised by systematically exploring the operating parameters of the microfluidic platform, determined at 45 o tilt angle for the 20 mm diamater glass tube spinning at 5k rpm, with a flow rate of a colloidal dispersion of MXene in aqueous H 2 O 2 (30%) at 0.75 mL/min, concentration of MXene 0.5 mg/mL

Continuous flow vortex fluidic-mediated exfoliation and fragmentation of two-dimensional MXene

MXene (Ti2CTx) is exfoliated in a vortex fluidic device (VFD), as a thin film microfluidic platform, under continuous flow conditions, down to ca 3 nm thin multi-layered twodimensional (2D) material, as determined using AFM. The optimized process, under an inert atmosphere of nitrogen to avoid oxidation of the material, was established by systematically exploring the operating parameters of the VFD, along with the concentration of the dispersed starting material and the choice of solvent, which was a 1 : 1 mixture of isopropyl alcohol and water. There is also some fragmentation of the 2D material into nanoparticles ca 68 nm in diameter

Small molecules induce mesocrystal formation: nanoparticle aggregation directed by self-assembling calixarenes

Calixarenes have been shown to induce mesocrystal formation of barium sulfate, despite being relatively low molecular weight additives. Scanning probe microscopy has shown that a possible mechanism is the self-assembling properties of the calixarene resulting in steric stabilization of the nanoparticles, comparable to that typically requiring polymeric additives

Shear induced carboplatin binding within the cavity of a phospholipid mimic for increased anticancer efficacy

Vesicles 107 ± 19 nm in diameter, based on the self-assembly of tetra-para-phosphonomethyl calix[4]-arene bearing n-hexyl moieties attached to the phenolic oxygen centres, are effective in binding carboplatin within the cavity of the macrocycle under shear induced within a dynamic thin film in a continuous flow vortex fluidic device. Post shearing the vesicles maintain similar diameters and retain carboplatin within the cavity of the calixarene in a hierarchical structure, with their size and morphology investigated using DLS, TEM, SEM and AFM. Location of the carboplatin was confirmed using NMR, FTIR, ESI-MS and EFTEM, with molecular modelling favouring the polar groups of carboplatin hydrogen bonded to phosphonic acid moieties and the four member cyclobutane ring directed into the cavity of the calixarene. The loading efficiency and release profile of carboplatin was investigated using LC-TOF/MS, with the high loading of the drug achieved under shear and preferential released at pH 5.5, offering scope for anti-cancer drug delivery. The hierarchical structured vesicles increase the efficacy of carboplatin by 4.5 fold on ovarian cancer cells, lowered the IC<inf>50</inf> concentration by 10 fold, and markedly increased the percent of cells in the S-phase (DNA replication) of the cell cycle

Thermochemistry of Alane Complexes for Hydrogen Storage: A Theoretical and Experimental Comparison

Knowledge of the relative stabilities of alane (AlH3) complexes with electron donors is essential for identifying hydrogen storage materials for vehicular applications that can be regenerated by off-board methods; however, almost no thermodynamic data are available to make this assessment. To fill this gap, we employed the G4(MP2) method to determine heats of formation, entropies, and Gibbs free energies of formation for thirty-eight alane complexes with NH3-nRn (R = Me, Et; n = 0-3), pyridine, pyrazine, triethylenediamine (TEDA), quinuclidine, OH2-nRn (R = Me, Et; n = 0-2), dioxane, and tetrahydrofuran (THF). Monomer, bis, and selected dimer complex geometries were considered. Using these data, we computed the thermodynamics of the key formation and dehydrogenation reactions that would occur during hydrogen delivery and alane regeneration, from which trends in complex stability were identified. These predictions were tested by synthesizing six amine-alane complexes involving trimethylamine, triethylamine, dimethylethylamine, TEDA, quinuclidine, and hexamine, and obtaining upper limits of delta G for their formation from metallic aluminum. Combining these computational and experimental results, we establish a criterion for complex stability relevant to hydrogen storage that can be used to assess potential ligands prior to attempting synthesis of the alane complex. Based on this, we conclude that only a subset of the tertiary amine complexes considered and none of the ether complexes can be successfully formed by direct reaction with aluminum and regenerated in an alane-based hydrogen storage system.Comment: Accepted by the Journal of Physical Chemistry

Laser irradiated vortex fluidic mediated synthesis of luminescent carbon nanodots under continuous flow

Published on 15 January 2018.Carbon nanodots (CDs) with size dependent fluorescence are synthesized from multi-walled carbon nanotubes (MWCNTs) under continuous flow in a vortex fluidic device (VFD) when irradiated by a pulsed laser with a wavelength of 1064 nm, without subsequent passivation procedures. The CDs have a relatively narrow size distribution averaging ca. 6 nm in diameter, and have low cytotoxicity and high colloidal stability with the highest emission intensity of the solution at 450 nm under a 345 nm excitation wavelength. Further downstream processing on the as-processed CDs revealed tunability of the emission from 450 nm to 325 nm.Xuan Luo, Ahmed Hussein Mohammed Al-Antaki, Kasturi Vimalanathan, Jillian Moffatt, Kun Zheng, Yichao Zou, Jin Zou, Xiaofei Duan, Robert N. Lamb, Shujun Wang, Qin Li, Wei Zhang and Colin L. Rasto

Impact of tunable oligophosphonates on barium sulfate crystallization

Calixarenes can be used as well-defined scaffolds for investigating structure–activity relationships of additives and their impact on crystallization. In this work, we present the crystal growth modification of barium sulfate by p-phosphonic acid calix[n]arenes that vary in size (n = 4, 5, 6, and 8) and thus vary in the size of the internal cavity for the same functionality in the upper rim. The tetrameric, hexameric, and octameric macrocycles induce nanoparticle formation with clear superstructure. In the case of the hexameric calix[6]arene, the initial mesocrystalline superstructure fuses over time to form almost hollow spheres, while the mesocrystals formed in the presence of the tetramer and octamer are stable over an extended period. The pentameric calix[5]arene forms more disordered aggregates of single crystals. Thermogravimetric data shows that a significant proportion of the mass of the barium sulfate-containing solid is the macrocycle, regardless of the choice of macrocycle

The HITRAN2020 molecular spectroscopic database

The HITRAN database is a compilation of molecular spectroscopic parameters. It was established in the early 1970s and is used by various computer codes to predict and simulate the transmission and emission of light in gaseous media (with an emphasis on terrestrial and planetary atmospheres). The HITRAN compilation is composed of five major components: the line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, experimental infrared absorption cross-sections (for molecules where it is not yet feasible for representation in a line-by-line form), collision-induced absorption data, aerosol indices of refraction, and general tables (including partition sums) that apply globally to the data. This paper describes the contents of the 2020 quadrennial edition of HITRAN. The HITRAN2020 edition takes advantage of recent experimental and theoretical data that were meticulously validated, in particular, against laboratory and atmospheric spectra. The new edition replaces the previous HITRAN edition of 2016 (including its updates during the intervening years). All five components of HITRAN have undergone major updates. In particular, the extent of the updates in the HITRAN2020 edition range from updating a few lines of specific molecules to complete replacements of the lists, and also the introduction of additional isotopologues and new (to HITRAN) molecules: SO, CH3F, GeH4, CS2, CH3I and NF3. Many new vibrational bands were added, extending the spectral coverage and completeness of the line lists. Also, the accuracy of the parameters for major atmospheric absorbers has been increased substantially, often featuring sub-percent uncertainties. Broadening parameters associated with the ambient pressure of water vapor were introduced to HITRAN for the first time and are now available for several molecules. The HITRAN2020 edition continues to take advantage of the relational structure and efficient interface available at www.hitran.org and the HITRAN Application Programming Interface (HAPI). The functionality of both tools has been extended for the new edition

The HITRAN2020 Molecular Spectroscopic Database

The HITRAN database is a compilation of molecular spectroscopic parameters. It was established in the early 1970s and is used by various computer codes to predict and simulate the transmission and emission of light in gaseous media (with an emphasis on terrestrial and planetary atmospheres). The HITRAN compilation is composed of five major components: the line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, experimental infrared absorption cross-sections (for molecules where it is not yet feasible for representation in a line-by-line form), collision-induced absorption data, aerosol indices of refraction, and general tables (including partition sums) that apply globally to the data. This paper describes the contents of the 2020 quadrennial edition of HITRAN. The HITRAN2020 edition takes advantage of recent experimental and theoretical data that were meticulously validated, in particular, against laboratory and atmospheric spectra. The new edition replaces the previous HITRAN edition of 2016 (including its updates during the intervening years). All five components of HITRAN have undergone major updates. In particular, the extent of the updates in the HITRAN2020 edition range from updating a few lines of specific molecules to complete replacements of the lists, and also the introduction of additional isotopologues and new (to HITRAN) molecules: SO, CH3F, GeH4, CS2, CH3I and NF3. Many new vibrational bands were added, extending the spectral coverage and completeness of the line lists. Also, the accuracy of the parameters for major atmospheric absorbers has been increased substantially, often featuring sub-percent uncertainties. Broadening parameters associated with the ambient pressure of water vapor were introduced to HITRAN for the first time and are now available for several molecules. The HITRAN2020 edition continues to take advantage of the relational structure and efficient interface available at www.hitran.org and the HITRAN Application Programming Interface (HAPI). The functionality of both tools has been extended for the new edition