Superhydrophobic surfaces can be quickly formed with supramolecular materials. Incorporating low-molecular-weight gelators (LMWGs) with perfluorinated chains generates xerogel coatings with low surface energies and high roughness. Here, we examine and compare the properties of the xerogel coatings formed with eight different LMWGs. These LMWGs all have a trans-1,2-diamidocyclohexane core and two perfluorinated ponytails, whose lengths vary from three to ten carbon atoms (CF3 to CF10). Investigation of the xerogels aims to provide in-depth information on the chain length effect. LMWGs with a higher degree of fluorination (CF7 to CF10) form superhydrophobic xerogel coatings with very low surface energies. Scanning electron microscopy images of the coatings show that the aggregates of CF5 and CF7 are fibrous, while the others are crystal-like. Aggregates of CF10 are particularly small and further assemble into a porous structure on the micrometer scale. To test their stabilities, the xerogel coatings were flushed multiple times with a standardized water flush test. The removal of material from the surface in these flushes was monitored by a combination of the water contact angle, contact angle hysteresis, and coating thickness measurements. A new method based on image processing techniques was developed to reliably determine the change of the coating thickness. The CF7, CF9, and CF10 surfaces show consistent hydrophobicity and coating durability after repetitive flushing tests. The length of the perfluorinated side chains thus has a significant effect on the morphology of the deposited xerogel coatings, their roughness, and, in consequence, their hydrophobicity and mechanical durability.

Mechanochemistry offers a unique opportunity to modify and manipulate crystal forms, often providing new products as compared with conventional solution methods. While promising, there is little known about how to...

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Structure-properties relationship of new Cd-benzylphosphonates differing in their fluorine content.

Water treatment with activated carbon (AC) is an established method for the removal of organic micropollutants and natural organic matter. However, it is not yet possible to predict the removal of individual pollutants. An appropriate material characterization, matching adsorption processes in water, might be the missing piece in the puzzle. To this end, this study examined 25 different commercially available ACs to evaluate their material properties. Frequently reported analyses, including N$$_2$$ 2 adsorption/desorption, CHNS(O), point of zero charge (PZC) analysis, and X-ray photoelectron spectroscopy, were conducted on a selected subset of powdered ACs. Inorganic elements examined using X-ray fluorescence and X-ray diffraction spectroscopy revealed that relative elemental contents were distinctive to the individual AC’s raw material and activation procedure. This study also is the first to use thermogravimetric analysis (TGA) coupled to Fourier-transform infrared spectroscopy (FTIR) to conduct quantitative analyses of functional surface oxygen groups (SOGs: carboxylic acid, anhydride, lactone, phenol, carbonyl, and pyrone groups) on such a large number of ACs. The comparably economical TGA method was found to provide good surrogates for the PZC by pyrolytic mass loss up to 600 $$^{\circ }$$ ∘ C (ML$$_{600}$$ 600 ), for the oxygen content by ML$$_{1000}$$ 1000 and for the carbon content by oxidation. Mass loss profiles depict the AC’s chemistry like fingerprints. Furthermore, we found that SOG contents determined by TGA-FTIR covered a wide individual range and depended on the raw material and production process of the AC. TGA and TGA-FTIR might therefore be used to identify the suitability of a particular AC for a variety of target substances in different target waters. This can help practitioners to control AC use in waterworks or wastewater treatment plants.

The preparation of new active pharmaceutical ingredient (API) multicomponent crystal forms, especially co-crystals and salts, is being considered as a reliable strategy to improve API solubility and bioavailability. In this study, three novel imidazole-based salts of the poorly water-soluble salicylic acid (SA) are reported exhibiting a remarkable improvement in solubility and dissolution rate properties. All structures were solved by powder X-ray diffraction. Multiple complementary techniques were used to solve co-crystal/salt ambiguities: density functional theory calculations, Raman and 1H/13C solid-state NMR spectroscopies. In all molecular salts, the crystal packing interactions are based on a common charged assisted +N-H(SA)⋯O−(co-former) hydrogen bond interaction. The presence of an extra methyl group in different positions of the co-former, induced different supramolecular arrangements, yielding salts with different physicochemical properties. All salts present much higher solubility and dissolution rate than pure SA. The most promising results were obtained for the salts with imidazole and 1-methylimidazole co-formers.

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A new hetero-bimetallic polyoxometalate (POM) nano-ring was synthesized in a one-pot procedure. The structure consists of tetrameric units containing four bismuthsubstituted monolacunary Keggin anions including distorted [BiO 8 ] cubes. The nano-ring is formed via self-assembly from metal precursors in aqueous acidic medium. The compound (NH 4 ) 16 [(BiPMo 11 O 39 ) 4 ] • 22 H 2 O; (P 4 Bi 4 Mo 44 ) was characterized by single-crystal X-ray diffraction, extended X-ray absorption fine structure spectroscopy (EXAFS), Raman spectroscopy, matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF), and thermogravimetry/differential scanning calorimetry mass spectrometry (TG-DSC-MS). The formation of the nano-ring in solution was studied by timeresolved in situ small-and wide-angle X-ray scattering (SAXS/ WAXS) and in situ EXAFS measurements at the MoÀ K and the BiÀ L 3 edge indicating a two-step process consisting of condensation of Mo-anions and formation of BiÀ Mo-units followed by a rapid self-assembly to yield the final tetrameric ring structure.Polyoxometalates (POMs) are structurally well-defined nanosized metal-oxo cluster anions consisting of early transition metals like niobium, vanadium, molybdenum, or tungsten cations in high oxidation states. [1] The structural variety of POMs offers the possibility to fine-tune their properties towards applications in biomedicine, [2] catalysis, [3] and material chemistry. [4] Among the POM structures derivatives of the Keggin-type [5] are especially interesting offering access to different substitutions within the POM-based materials. The variability is particularly well-established in polyoxomolybdate and -oxotungstate chemistry, where clusters featuring one or several metal cation binding sites (i. e., lacunary POMs) are formed. [6] Particularly, trivalent cations, such as Ce 3 + , Gd 3 + , and Co 3 + have been employed, since their high coordination number and flexible environment, allows for the formation of more complex architectures and superstructures. [7] Among the main group elements, Bi 3 + is used for connecting POM structures. [2a,b,7d,8] Bi 3 + -containing POMs are investigated for their use in biomedical applications, [2b] as proton conductors, [7d,9] and as catalysts. [10] In Bi-containing POMs, Bi 3 + cations typically adopt a trigonal-pyramidal coordination geometry. [8a,10,11] Hanaya et al. reported the successful preparation of three types of bismuth-tungsten oxide nanoclusters using lacunary silico-tungstates. Structuredirecting properties of Bi 3 + lone electron pair result in the formation of binuclear and tetranuclear cluster architectures. [8a] Villanneau et al. reported two bismuth-substituted structures [Bi{M 5 O 13 (OMe) 4 (NO)} 2 ] 3À (M=Mo, W), in which the Bi 3 + ions connect two monolacunary Lindqvist-type clusters, resulting in an unusual 8-fold coordination geometry around Bi 3 + . [12] First heteropolytungstates exhibiting a similar 8-fold squareantiprismatic coordination geometry were charact...