Search

A common issue in studies on liquid-phase chemical processes is that the natural solid nanoimpurities present in reagent-grade chemicals are ignored. Little is known about these impurities' nature, sizes, concentrations, and behavior, yet they significantly affect the efficiency of antiscalants in municipal and laboratory solutions. Recent research has focused on: (i) estimating nanoimpurity concentrations in in-house deionized water and semiconductor-grade isopropanol using "light sheet" optical ultramicroscopy, and (ii) visualizing antiscalant sorption on these impurities. Using a fluorescent-tagged antiscalant aminobis(methylenephosphonic acid) (ADMP-F), we tracked its affinity to particulate matter in deionized water and reagent-grade KCl solutions. Our study showed that the total concentration of nanoparticles with a size larger than 20 nm is about 106 units/mL in deionized water and 105 units/mL in isopropanol. Extrapolation of these values to a size ≥1 nm resulted in concentrations of 1011 and 108 units/mL. The addition of KCl or ADMP-F significantly increased foreign nanoparticle populations. ADMP-F is selectively adsorbed by only some impurities, while most antiscalant molecules remain as true solution. To our knowledge, this is the first instance of fluorescently labeled aminoalkylphosphonates being able to differentiate particulate matter traces in reagent-grade purity solutions. Therefore, the role of nanoparticles as crystallization centers should be seriously reconsidered, especially in their important application in scale inhibition. [ABSTRACT FROM AUTHOR]

Equipment scaling leads to reduced production efficiency in a wide range of industrial applications worldwide. Various antiscaling agents are currently commonly used to mitigate this problem. However, irrespective of their long and successful application in water treatment technologies, little is known about the mechanisms of scale inhibition, particularly the localization of scale inhibitors on scale deposits. The lack of such knowledge is a limiting factor in the development of applications for antiscalants. Meanwhile, fluorescent fragments integrated into scale inhibitor molecules have provided a successful solution to the problem. The focus of this study is, therefore, on the synthesis and investigation of a novel fluorescent antiscalant: (2-(6-morpholino-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)yl)ethylazanediyl)bis(methylenephosphonic acid) (ADMP-F) which is an analog of the commercial antiscalant: aminotris(methylenephosphonic acid) (ATMP). ADMP-F has been found to effectively control the precipitation of CaCO3 and CaSO4 in solution and is a promising tracer for organophosphonate scale inhibitors. ADMP-F was compared with two other fluorescent antiscalants—polyacrylate (PAA-F1) and bisphosphonate (HEDP-F)—and was found to be highly effective: PAA-F1 > ADMP-F >> HEDP-F (CaCO3) and PAA-F1 > ADMP-F > HEDP-F (CaSO4·2H2O). The visualization of the antiscalants on the deposits provides unique information on their location and reveals differences in the "antiscalant-deposit" interactions for scale inhibitors of different natures. For these reasons, a number of important refinements to the mechanisms of scale inhibition are proposed. [ABSTRACT FROM AUTHOR]

Solid deposits onto equipment surfaces represent a serious problem all over the world. Mitigation of this process is provided by chemical inhibitors. However, irrespective of successful antiscalant application, the mechanisms of scale inhibition are still not very clear. Thus, the present review summarizes recent advances in novel fluorescent‐tagged antiscalants (polyacarboxylates, phosphonates) application for scale inhibition mechanisms study. Some paradoxical effects, detected during gypsum and barite scale formation visualization are described and interpreted within the "nanodust" concept. It is demonstrated, that the solid nanoimpurities, naturally occurring in both industrial and deionized water samples, are definitely playing a key role in any crystal nucleation process. Such nanoimpurities are responsible for the bulk heterogeneous nucleation in a supersaturated salt solution. Scale inhibitor molecules block and isolate exactly these "nanodust" nucleation centers and therefore retards crystallization process on the whole. The advantages of fluorescent antiscalants to provide a new look at scale inhibition phenomenon and inhibition mechanisms are discussed. Among these, there is a possibility to distinguish particular scale inhibitors in their blends, and an opportunity to track an antiscalant location along the process of scale formation and deposition. Besides, a need of antiscalants testament procedure unification is considered, and a possible role of fluorescent reagents in such a procedure elaboration is indicated. [ABSTRACT FROM AUTHOR]

The synthetic cytokinins are the matter of the utmost importance and the subject of highly intensive studies due to the high activity in prevention of leaves fading, mobilization of nutrients, stem growth, etc. In a present study seven novel N-alkoxycarbonylaminoethyl-N’-arylureas are synthesized and tested for biological activity along with kartolin-2 and chlorocholine chloride taken as references. The results of the preliminary tests on tobacco cell culture (growth tests under controlled conditions) showed that tested compounds have an evident, although multidirectional effect on the metabolic processes. Results of the wheat drought resistance tests demonstrated the superior positive effect of 1–2, 5 and 7 in water retardation as refereed to control compounds, kartolin-2 and chlorocholine chloride. The results of frost resistance of winter wheat tested in the presence of 5 and 6 revealed their activity substantially exceeding the references. Thus the novel regulators seem to be very promising candidates as plant growth regulators and stress protectants. [ABSTRACT FROM AUTHOR]

Two convenient procedures for the synthesis of thia- and azacrown ether containing 4-nitro-1,8-naphthalimides have been developed. The first procedure is based on the amination of 1,8-naphthalic anhydride with crown-containing anilines. The second procedure includes the macrocyclization reaction of N-[1,2-bis(2-haloethoxy)phenyl] naphthalimide derivative with terminal thiols or methylamines. A strategy based on a macrocyclization is flexible and variable and also allows the use of the synthetic approach for more complex compounds. [ABSTRACT FROM AUTHOR]

Polyaminopolycarboxylates are attractive ligands for binding cationic radionuclides for synthesis of radiopharmaceuticals with target delivery to tumor cells. Nowadays beta emitting Y−90 and Lu−177 are used as therapeutic agents, while Ac−225 and Bi−213 are considered as perspective for alpha therapy. In the present study new data on complexation of Y3+, Lu3+, Ac3+ and Bi3+ with 2,2'-(15-formyl-2,3,5,6,8,9,11,12-octahydrobenzo [b][,,,,]trioxadiazacyclopentadecine-4,10- diyl)diacetic acid are presented. For ligand and complexes characterization potentiometric titration, solvent extraction, chromatography and solubility techniques were applied. The highest values of stability constants within the range of log K = 5.8 - 7.5 were found for Ac3+ and REE. Fast complex formation is established which is beneficial for practical applications in radiopharmaceutical synthesis. [ABSTRACT FROM AUTHOR]

This research concerns the analysis of the proton and metal ion binding of amide macrocycles of different structures and sizes by potentiometric, 1H NMR and X-ray diffraction methods. Protonated ligands exist as a 3D network structures. The ligands form 1:1 complexes with heavy metal ions (Cu2+, Cd2+, Pb2+, Zn2+, and Ni2+) in aqueous solutions and demonstrate the high selectivity towards Cu2+ cations. The pyridine-2,6-dicarbamide fragment provides structural rigidity to crown ether, resulting the molecule has an open cavity and faster kinetics of metal complexes formation. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]