3 research outputs found
Three in one : mesogenic aromatic acid as a liquid crystal matrix, a chiral dopant in liquid crystals and a stabilizer for nanoparticles
Studies of thermodynamics of the N*-I phase transitions and optical properties of the new liquid crystal - (R)-2-[4″-(trans-4-butylcyclohexyl)-2′-chloro-p-terphenyl-4-oxy] propanoic acid are carried out. The aim of these studies is to analyze the capabilities of that liquid crystal to simultaneously serve as a matrix for inorganic semiconductor nanoparticles (NP) as well as a chiral dopant for liquid crystals and a chiral ligand stabilizing the surface of CdSe NPs. The chiral doping of a nematic liquid crystal was proven by the measurements of selective transmittance of the visible light. The embedding of NPs in a nematic liquid crystal leads to the increase in TN⁎I, which is explained by the shape anisotropy of the NPs. The anisotropy of the ligand shell may result from the interaction between the ligand and LC matrix inducing the change of the spherical shape of the shell toward the ellipsoidal one. TN⁎I of the liquid crystal matrix of (R)-2-[4″-(trans-4-butylcyclohexyl)-2′-chloro-p-terphenyl-4-oxy] propanoic acid (R-MPA) decreases with the embedding of NPs stabilized by the same ligands, which is in a good agreement with prior experimental results and theory, but there exists a considerable quantitative difference
Metal-Organic Architectures Assembled from Multifunctional Polycarboxylates: Hydrothermal Self-Assembly, Structures, and Catalytic Activity in Alkane Oxidation
A three-component aqueous reaction system comprising copper(II) acetate (metal node), poly(carboxylic acid) with a phenylpyridine or biphenyl core (main building block), and 1,10-phenanthroline (crystallization mediator) was investigated under hydrothermal conditions. As a result, four new coordination compounds were self-assembled, namely, {[Cu(μ 3 -cpna)(phen)]·H 2 O} n (1), {[Cu(μ-Hbtc)(phen)]·H 2 O} n (2), {[Cu(μ 3 -Hcpic)(phen)]·2H 2 O} n (3), and [Cu 6 (μ-Hcptc) 6 (phen) 6 ]·6H 2 O (4), where H 2 cpna = 5-(2′-carboxylphenyl)nicotinic acid, H 3 btc = biphenyl-2,4,4′-tricarboxylic acid, H 3 cpic = 4-(5-carboxypyridin-2-yl)isophthalic acid, H 3 cptc = 2-(4-carboxypyridin-3-yl)terephthalic acid, and phen = 1,10-phenanthroline. Crystal structures of compounds 1-3 reveal that they are 1D coordination polymers with a ladder, linear, or double-chain structure, while product 4 is a 0D hexanuclear complex. All of the structures are extended further [1D â†' 2D (1 and 2), 1D â†' 3D (3), and 0D â†' 3D (4)] into hydrogen-bonded networks. The type of a multicarboxylate building block has a considerable effect on the final structures of 1-4. The magnetic behavior and thermal stability of 1-4 were also investigated. Besides, these copper(II) derivatives efficiently catalyze the oxidation of cycloalkanes with hydrogen peroxide under mild conditions. The obtained products are the unique examples of copper derivatives that were assembled from H 2 cpna, H 3 btc, H 3 cpic, and H 3 cptc, thus opening up their use as multicarboxylate ligands toward the design of copper-organic architectures. © 2019 American Chemical Society
New silver (thio)semicarbazide derivatives: Synthesis, structural features, and antimicrobial activity
Two novel semicarbazide [HL1, 1, 1-((4-nitrophenyl)(phenyl)methylene)semicarbazide] and thiosemicarbazide [HL2, 2, 1-((4-nitrophenyl)(phenyl)methylene)thiosemicarbazide] ligands were generated from 4-nitrobenzophenone and the corresponding (thio)semicarbazide precursors. Compounds 1 and 2 were fully characterized and their X-ray crystal structures were established. These organic derivatives were further applied as bioactive building blocks for the self-assembly synthesis of silver(i) coordination compounds. The reactions of silver(i) nitrate with HL1/HL2 in the presence of aqueous NH4OH resulted in new silver(i) coordination compounds formulated as [Ag(HL1)(NO3)]·H2O (3) and [Ag6(μ3-L2)6] (4). These complexes were characterized by standard methods (FT-IR, NMR, ESI-MS, and elemental analysis) as well as single-crystal X-ray diffraction. The structure of 3 features a two-coordinate silver(i) center with a distorted linear {AgNO} geometry, wherein an unusual coordination of HL1 through the nitrogen atom of the amine group is realized. The structure of 4 reveals a discrete Ag6 cluster composed of two joined trisilver(i) rings, wherein the three-coordinate Ag(i) centers adopt an {AgNS2} environment. The antimicrobial activity of 1-4 was screened against Gram-positive (S. epidermidis and S. aureus) and Gram-negative (P. aeruginosa and E. coli) bacteria. Compound 4 presented antimicrobial activity against Gram-positive bacteria, including the ability to impair biofilm formation. This study thus contributes to a still limited research area on the development of new silver coordination compounds with potential antibiofilm activity. © 2020 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique