Monolayer and Bilayer Formation of Molecular 2D Networks Assembled at the Liquid/Solid Interfaces by Solution-Based Drop-Cast Method

In recent years, extending self-assembled structures from two-dimensions (2D) to three-dimensions (3D) has been a paradigm in surface supramolecular chemistry and contemporary nanotechnology. Using organic molecules of p-terphenyl-3,5,3′,5′-tetracarboxylic acid (TPTC), and scanning tunneling microscopy (STM), we present a simple route, that is the control of the solute solubility in a sample solution, to achieve the vertical growth of supramolecular self-assemblies, which would otherwise form monolayers at the organic solvent/graphite interface. Presumably, the bilayer formations were based on π-conjugated overlapped molecular dimers that worked as nuclei to induce the yielding of the second layer. We also tested other molecules, including trimesic acid (TMA) and 1,3,5-tris(4-carboxyphenyl)-benzene (BTB), as well as the further application of our methodology, demonstrating the facile preparation of layered assemblies.

Trimesic Acid-Functionalized Chitosan: A Novel And Efficient Multifunctional Organocatalyst For Green Synthesis of Polyhydroquinolines And Acridinediones Under Mild Conditions

Trimesic acid-functionalized chitosan (Cs/ECH-TMA) material was prepared through a simple procedure by using chitosan (Cs), epichlorohydrin (ECH) and trimesic acid (TMA). The obtained bio-based Cs/ECH-TMA material was characterized using energy-dispersive X-ray (EDX) and Fourier-transform infrared spectroscopy (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) analysis. The Cs/ECH-TMA material was successfully used, as a multifunctional heterogeneous and sustainable catalyst, for efficient and expeditious synthesis of medicinally important polyhydroquinoline (PHQ) and polyhydroacridinedione (PHA) scaffolds through the Hantzsch condensation in a one-pot reaction. Indeed, the heterogeneous Cs/ECH-TMA material can be considered as a synergistic multifunctional organocatalyst due to the presence of a large number of acidic active sites in its structure as well as hydrophilicity. Both PHQs and PHAs were synthesized in the presence of biodegradable heterogeneous Cs/ECH-TMA catalytic system from their corresponding substrates in EtOH under reflux conditions and high to quantitative yields. The Cs/ECH-TMA catalyst is recyclable and can be reused at least four times without significant loss of its catalytic activity.

Adsorption of Carbon Dioxide by Metal Organic Framework for Indoor Air Quality Enhancement

Air pollution has become a severe environmental issue among millions of people around the globe. However, the risk of exposure to indoor air pollution is much higher than outdoor air pollution. The most effective way to improve indoor air quality (IAQ) by reducing the indoor CO2 content is by capturing and storing. There are several types of adsorbents used to capture CO2, namely physical adsorbents and chemical adsorbents. Metal-Organic Framework (MOF) is one of the recent interests arising physical adsorbents which possesses high adsorption capability. In this study, MOFs fabricated with different metals and organic ligands were used to evaluate their performance in CO2 adsorption under an enclosed office space. Magnesium, chromium, and copper metals were used as the main element in the MOF fabrication coupled with trimesic acid as an organic ligand. The MOFs’ morphologies generally illustrated that magnesium MOF exhibited a dispersed nanorod flask crystal, chromium MOF showed agglomeration crystal, whereas fine crystal rod was observed in copper MOF. The elemental analysis from EDX and XRD confirmed that the metals were successfully embedded with the organic ligand, which is similar to the literature studies. The CO2 gas adsorption study suggested that magnesium MOF fabricated with trimesic acid possess superior CO2 adsorption capability as the recorded CO2 concentration reduced from 960 ± 73 ppm to 895 ± 57 under 2 hours continuous sampling time. The CO2 adsorption study reveals that the magnesium MOF with trimesic acid ligand yields a promising result on indoor CO2 concentration reduction. This result suggested that the MOF possesses a great potential to be applied in the indoor air quality enhancement with the integration to the existing air purification and/or filtration system.

UoC-6: a first MOF based on a perfluorinated trimesate ligand

Reaction of Sc(NO3)3·5H2O with K(H2 pF-BTC) – the monopotassium salt of perfluorinated trimesic acid – led to the formation of single crystals of [ Sc ( p F − BTC ) ( H 2 O ) 3 ] ∞ 1 ⋅ 4 H 2 O ${}_{\infty }{}^{1}[\text{Sc}(pF-\text{BTC}){({\text{H}}_{2}\text{O})}_{3}]\cdot 4{\text{H}}_{2}\text{O}$ ( P 1 ‾ $P‾{1}$ , Z = 2). DTA/TGA measurements revealed that all water molecules were released below 200 °C. Using powder synchrotron radiation diffraction data, the crystal structure of the residue of the dehydration was elucidated and the results confirmed the formula [ Sc ( p F − BTC ) ] ∞ 3 ${}_{\infty }{}^{3}[\text{Sc}(pF-\text{BTC})]$ (Fddd, Z = 16). The compound is similar, but not isostructural to the recently published UoC-4 (I41/amd, Z = 8; UoC: University of Cologne) with a difluorinated trimesate (dF-BTC3–) as connecting linker. Both compounds can be classified as metal-organic frameworks (MOFs) consisting of a 3D network of Sc3+ nodes connected by the fluorinated trimesate ligands. They contain small pores, but their opening windows are too small for any guest molecules to pass. Remarkably, UoC-4 with a lower symmetric ligand (dF-BTC3–) crystallizes in a higher symmetry space group (I41/amd) than UoC-6 (Fddd). This can be rationalized by increasing torsion angles of the carboxylate moieties in the pF-BTC3– ligand.

Dose Rate Effects in Fluorescence Chemical Dosimeters Exposed to Picosecond Electron Pulses: An Accurate Measurement of Low Doses at High Dose Rates

The development of ultra-intense electron pulse for applications needs to be accompanied by the implementation of a practical dosimetry system. In this study four different systems were investigated as dosimeters for low doses with a very high-dose-rate source. First, the effects of ultra-short pulses were investigated for the yields of the Fricke dosimeter based on acidic solutions of ferrous sulfate; it was established that the yields were not significantly affected by the high dose rates, so the Fricke dosimeter system was used as a reference. Then, aqueous solutions of three compounds as fluorescence chemical dosimeters were utilized, each operated at a different solution pH: terephthalic acid - basic, trimesic acid - acidic, and coumarin-3- carboxylic acid (C3CA) - neutral. Fluorescence chemical dosimeters offer an attractive alternative to chemical dosimeters based on optical absorption for measuring biologically relevant low doses because of their higher sensitivity. The effects of very intense dose rate (TGy/s) from pulses of fast electrons generated by a picosecond linear accelerator on the chemical yields of fluorescence chemical dosimeters were investigated at low peak doses (<20 Gy) and compared with yields determined under low-dose-rate irradiation from a 60 Co gamma-ray source (mGy/s). For the terephthalate and the trimesic acid dosimeters changes in the yields were not detected within the estimated (∼10%) precision of the experiments, but, due to the complexity of the mechanism of the hydroxyl radical initiated reactions in solutions of the relevant aromatic compounds, significant reductions of the chemical yield (–60%) were observed when the C3CA dosimeter was irradiated with the ultra-short pulses.

Synthesis of bismuth-based coordination polymer for biomedical applications

Metal organic frameworks (MOFs) are of great interest for biomedicine due to their high loading capacity of various drugs, dyes, and other small molecules. In vivo application of MOFs requires small sizes of nanoparticles and their high colloidal stability. Here we designed the first nano-sized MOFs composed of bismuth and trimesic acid by a rapid microwave-assisted solvothermal method. After coating of the prepared nanoparticles with polyacrylic acid they show improved colloidal stability in aqueous solutions. These particles have 2.2 times higher X-ray attenuation ability than a clinically used BaSO4 agent. Also, they demonstrate high loading efficiency for organic dyes: 35.5 % w/w for Rose bengal and 17.9 % w/w for Rhodamine B.

The Structure and Property of Two Different Metal-Organic Frameworks Based on N/O-Donor Mixed Ligands

Two different metal-organic frameworks (MOFs) [Cd2(AZN)(HAZN)(btc)(Hbtc)·4H2O]·2H2O (1), and [Zn3(AZN)2(btc)2·4H2O] (2) were synthesized by the reactions of different metal salts with mixed ligands of 1-(4-(1H-imidazol-5-yl)phenyl)-1H-1,2,4-triazole (AZN) and trimesic acid (H3btc). The different metal centers in the reaction condition have important impact on the resulting structures of MOFs 1 and 2. Compound 1 is a one-dimensional (1D) chain structure, while 2 features a three-dimensional (3D) framework with 3-fold interpenetration topology of Point (Schläfli) symbol of (6·82)4(62·82·102). Furthermore, the luminescent properties have been studied for MOFs 1 and 2.

Sodium Chloroacetate Modified Polyethyleneimine/Trimesic Acid Nanofiltration Membrane to Improve Antifouling Performance

Nanofiltration (NF) is a separation technology with broad application prospects. Membrane fouling is an important bottleneck-restricting technology development. In the past, we prepared a positively charged polyethyleneimine/trimesic acid (PEI/TMA) NF membrane with excellent performance. Inevitably, it also faces poor resistance to protein contamination. Improving the antifouling ability of the PEI/TMA membrane can be achieved by considering the hydrophilicity and chargeability of the membrane surface. In this work, sodium chloroacetate (ClCH2COONa) is used as a modifier and is grafted onto the membrane surface. Additionally, 0.5% ClCH2COONa and 10 h modification time are the best conditions. Compared with the original membrane (M0, 17.2 L m−2 h−1), the initial flux of the modified membrane (M0-e, 30 L m−2 h−1) was effectively increased. After filtering the bovine albumin (BSA) solution, the original membrane flux dropped by 47% and the modified membrane dropped by 6.2%. The modification greatly improved the antipollution performance of the PEI/TMA membrane.