Search results for "hydroxide"
showing 10 items of 317 documents
Aggregation of [Ln(12)(III)] clusters by the dianion of 3-formylsalicylic acid. Synthesis, crystal structures, magnetic and luminescence properties
2019
Three isostrucutral dodecanuclear clusters with the general formula [Ln(12)(fsa)(12)(mu f(3)-OH)(12)(DMF)(12)]center dot nDMF (fsa(2-) is the dianion of 3-formylsalicylic acid; Ln = Eu 1, Gd 2, Dy 3) have been obtained from the reaction of fromylsalicyclic acid (H(2)fsa), tetrabutylammonium hydroxide and Ln(NO3)(3)center dot 6H(2)O in methanol/DMF. Their structure consists of four vertex-sharing heterocubanes. Each heterocubane unit is assembled from four Ln(III) ions, three mu(3)-OH groups and one mu(3)-oxygen atom arising from the fsa(2-) carboxylato group. The photophysical properties of the europium derivative investigated at both 300 and 80 K sustain a relative intense emission obtaine…
Long-term evolution of luminescent properties in CdI2 crystals
2016
Fresh and aged melt-grown or gas-phase grown CdI2 crystals are studied by means of low-temperature photoluminescence spectroscopy. Noticeable transformations of emission spectra are observed after long-term aging. The formation of nanostructures containing cadmium oxide and cadmium hydroxide as well as the changes in local surrounding of iodine atoms and the possible growth of polytypic modifications of CdI2 are taken into account when considering the diversity of optical spectra.
Unveiling the Occurrence of Co(III) in NiCo Layered Electroactive Hydroxides: The Role of Distorted Environments
2020
Co- and Ni-based layered hydroxides constitute a unique class of two-dimensional inorganic materials with exceptional chemical diversity, physicochemical properties and outstanding performance as supercapacitors and overall water splitting catalysts. Recently, the occurrence of Co(III) in these phases has been proposed as a key factor that enhance their electrochemical performance. However, the origin of this centers and control over its contents remains as an open question. We employed the Epoxide Route to synthesize a whole set of α-NiCo layered hydroxides. The PXRD and XAS characterization alert about the occurrence of Co(III) as a consequence of the increment in the Ni content. DFT+U si…
Organotin(IV) derivatives containing heteroditopic pyridyl-quinolin-8-olate ligands: Synthesis and structures
2021
Abstract Six novel neutral organotin(IV) complexes, viz. [n-Bu2Sn(L4-PyAQ)2] 1, [Bz2Sn(L4-PyAQ)2] 2, [Ph2Sn(L4-PyAQ)2] 3, [Ph2Sn(L3-PyAQ)2] 4, [Bz3Sn(L4-PyAQ)] 5 and [Ph3Sn(L4-PyAQ)] 6 have been synthesized via reactions of 3/4-pyridyl-quinolin-8-ol pro-ligands, with appropriate diorganotin oxide and triorganotin hydroxide precursors, respectively. The compounds 1-6 were characterized in solution by means of NMR spectroscopy while the solid-state structures of 1, 6, and of the solvates 2·1.5C6H6, 3·0.25C6H6, 2·4·C6H6, and 5·0.5H2O were authenticated by single crystal X-ray diffraction analysis. In the solid-state, the tin centers in 1-2·4·C6H6 are hexacoordinated and reveal a distorted cis-…
A Strongly Luminescent Chromium(III) Complex Acid
2018
The synthesis, structure, reactivity, and photophysical properties of a novel acidic, luminescent chromium(III) complex [Cr(H2 tpda)2 ]3+ (23+ ) bearing the tridentate H2 tpda (2,6-bis(2-pyridylamino)pyridine) ligand are presented. Excitation of 23+ at 442 nm results in strong, long-lived NIR luminescence at 782 nm in water and in acetonitrile. X-ray diffraction analysis and IR spectroscopy reveal hydrogen-bonding interactions of the counter ions to the NH groups of 23+ in the solid state. Deprotonation of the NH groups of 23+ by using a non-nucleophilic Schwesinger base in CH3 CN switches off the luminescence. Re-protonation by using HClO4 restores the emission. In water, the pKa value of …
Halide-Mediated Modification of Magnetism and Electronic Structure of α-Co(II) Hydroxides: Synthesis, Characterization, and DFT+U Simulations.
2019
The present study introduces a comprehensive exploration in terms of physicochemical characterization and calculations based on density functional theory with Hubbard's correction (DFT+U) of the whole family of α-Co(II) hydroxyhalide (F, Cl, Br, I). These samples were synthesized at room temperature by employing a one-pot approach based on the epoxide route. A thorough characterization (powder X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis/mass spectroscopy, and magnetic and conductivity measurements) corroborated by simulation is presented that analyzes the structural, magnetic, and electronic aspects. Beyond the inherent tendency of intercalated anions to …
Consolidation of earthen building materials: a comparative study
2019
The consolidation and protection of mud bricks are a challenge in the field of conservation of archeological sites. One of the solutions is represented by the coverage of the entire excavation that assures a protection against mud dissolution. Unfortunately, this is not always feasible, both for economical and practical issues. For these reasons, alternative solutions are needed. In this work, laboratory experimentation has been carried out in order to test the efficacy of some products to slow down the dissolution process and increase the brick toughness. Three typologies of raw materials taken from different outcrops (one from the Republic of Azerbaijan and two from Calabria region, Italy…
Induced post-traumatic apexification: 20 year follow-up and morphological study after new fracture.
2018
Apexification is an endodontic technique used in immature necrotic teeth, the primary goal of which is to induce a calcified barrier in roots with open apices and to promote the continuation of apical root development. A 7-year-old patient with a coronal fracture in a maxillary central incisor was treated with an apexification technique using calcium hydroxide. The apical closure was obtained after one year, then a permanent root canal filling was performed. The tooth was monitored for a period of 20 years, up to when a trauma caused its extraction. The newly formed root was analyzed macroscopically, histologically and through scanning electron microscopy. A morphologically normal root was …
Physical evaluation of a new pulp capping material developed from portland cement
2016
Background This study examined the effects of addition of 10% and 25% by weight calcium hydroxide on the physicochemical properties of Portland cement associated with 20% bismuth oxide in order to develop a new pulp capping material. Material and Methods The solubility, pH value, setting time, compressive strength, and push out bond strength of modified Portland were evaluated and compared to those of mineral trioxide aggregate (MTA) and Portland cement containing 20% bismuth oxide. Results The statistical analysis was performed with ANOVA and Duncan’s post-hoc test. The results show that the strength properties and push out bond strength of Portland cement were adversely affected by additi…
Emerging switchable ultraviolet photoluminescence in dehydrated Zn/Al layered double hydroxide nanoplatelets
2019
AbstractLayered double hydroxides show intriguing physical and chemical properties arising by their intrinsic self-assembled stacking of molecular-thick 2D nanosheets, enhanced active surface area, hosting of guest species by intercalation and anion exchanging capabilities. Here, we report on the unprecedented emerging intense ultraviolet photoluminescence in Zn/Al layered double hydroxide high-aspect-ratio nanoplatelets, which we discovered to be fully activated by drying under vacuum condition and thermal desorption as well. Photoluminescence and its quenching were reproducibly switched by a dehydration–hydration process. Photoluminescence properties were comprehensively evaluated, such a…