Showing papers on "Thiocyanate published in 2019"

Metal- and Solvent-Free Ultrasonic Multicomponent Synthesis of (Z)-β-Iodo Vinylthiocyanates

Abstract: An eco-friendly and practical method for the ultrasonic multicomponent synthesis of diverse (Z)-β-iodo vinylthiocyanates from cheap and commercially available alkynes, molecular iodine, and KSCN th...

Oligophosphine-thiocyanate Copper(I) and Silver(I) Complexes and Their Borane Derivatives Showing Delayed Fluorescence.

Abstract: The series of chelating phosphine ligands, which contain bidentate P2 (bis[(2-diphenylphosphino)phenyl] ether, DPEphos; 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, Xantphos; 1,2-bis(diphenylphosphino)benzene, dppb), tridentate P3 (bis(2-diphenylphosphinophenyl)phenylphosphine), and tetradentate P4 (tris(2-diphenylphosphino)phenylphosphine) ligands, was used for the preparation of the corresponding dinuclear [M(μ2-SCN)P2]2 (M = Cu, 1, 3, 5; M = Ag, 2, 4, 6) and mononuclear [CuNCS(P3/P4)] (7, 9) and [AgSCN(P3/P4)] (8, 10) complexes. The reactions of P4 with silver salts in a 1:2 molar ratio produce tetranuclear clusters [Ag2(μ3-SCN)(t-SCN)(P4)]2 (11) and [Ag2(μ3-SCN)(P4)]22+ (12). Complexes 7-11 bearing terminally coordinated SCN ligands were efficiently converted into derivatives 13-17 with the weakly coordinating -SCN:B(C6F5)3 isothiocyanatoborate ligand. Compounds 1 and 5-17 exhibit thermally activated delayed fluorescence (TADF) behavior in the solid state. The excited states of thiocyanate species are dominated by the ligand to ligand SCN → π(phosphine) charge transfer transitions mixed with a variable contribution of MLCT. The boronation of SCN groups changes the nature of both the S1 and T1 states to (L + M)LCT d,p(M, P) → π(phosphine). The localization of the excited states on the aromatic systems of the phosphine ligands determines a wide range of luminescence energies achieved for the title complexes (λem varies from 448 nm for 1 to 630 nm for 10c). The emission of compounds 10 and 15, based on the P4 ligand, strongly depends on the solid-state packing (λem = 505 and 625 nm for two crystalline forms of 15), which affects structural reorganizations accompanying the formation of electronically excited states.

Cd(II) Based Coordination Polymer Series: Fascinating Structures, Efficient Semiconductors, and Promising Nitro Aromatic Sensing

Abstract: Three Cd(II) based coordination polymers (CPs) (1–3) are designed using 3-aminoquinoline and 5-aminoquinoline based Schiff base ligands and thiocyanate and dicyanamide as bridging ligands. Pseudoha...

Photoredox-Catalyzed Intermolecular Radical Arylthiocyanation/Arylselenocyanation of Alkenes: Access to Aryl-Substituted Alkylthiocyanates/Alkylselenocyanates.

Abstract: An efficient and highly selective approach for intermolecular arylthiocyanation/arylselenocyanation of alkenes has been reported under mild conditions. Using diazonium salts as the arylating agent and ammonium thiocyanate as the thiocyanate source, chemoselective difunctionalization of alkenes has been done under irradiation of visible light. Both styrenes and acrylates work well to deliver various aryl-substituted alkylthiocyanates in good to excellent yields. In addition, hitherto unknown β-aryl alkylselenocyanates were also synthesized using the developed protocol with potassium selenocyanate.

One-Dimensional Cadmium Thiocyanate Perovskite Ferroelastics Tuned by Halogen Substitution

Abstract: Organic–inorganic hybrid molecular ferroelastics have gained widespread attention as a promising candidate for data storage, sensor, and mechanical switch applications. However, it remains a great ...

A potassium thiocyanate additive for hysteresis elimination in highly efficient perovskite solar cells

Abstract: Organic–inorganic hybrid perovskite solar cells, which are regarded as the most promising candidate for next-generation photovoltaic cells, have achieved extremely high power conversion efficiencies of over 23%. However, hysteresis, characterized as an inconsistent power output under varying electric fields, hinders their progress towards commercialization. In this paper, by introducing potassium thiocyanate into the perovskite precursor solution, we have successfully obtained a highly efficient methylammonium lead iodide (MAPbI3) perovskite solar cell with no hysteresis. The incorporation of potassium thiocyanate immensely enhances the crystallinity of MAPbI3 with lower defect density and longer carrier lifetime. The grain size increases to over 600 nm due to the positive synergy of potassium ions and thiocyanate ions, which is more than three times compared with that of the control sample. Decreased series resistance and increased recombination resistance reveal faster charge transport and less carrier recombination, respectively, contributing to hysteresis elimination. At the optimum concentration of the potassium thiocyanate additive, the perovskite solar cell achieves a high conversion efficiency of 19.6%.

Modulation of coordination in pincer-type isonicotinohydrazone Schiff base ligands by proton transfer

Abstract: We present here two different coordination polyhedra of pincer type N2O hydrazone based ligands supplemented with thiocyanate ions. The compounds namely [Hg(SCN)2(HL1)] (1) and [Hg(SCN)2(HL2)] (2) have a common isonicotinohydrazone fragment and have been prepared by using a coordination driven self-assembly of the Hg(SCN)2 with two different ligands including 2-benzoylpyridine-isonicotinoylhydrazone (HL1), and 2-acetylpyridine-isonicotinoylhydrazone (HL2). In compound 1 the ligand coordinates to the mercury center in the keto form (N–NHCO) whereas, in compound 2, the proton at the hydrazine group has been shifted to the uncoordinated pyridine ring and the ligand acted as a zwitterion. The structures provide a complementary system for proton transfer within the ligand molecule involving the keto–enol tautomerization of the amide group and 4-pyridyl N protonation. As a result, the relative location of orbitals and ligands in the complexes are different as well as the bonding strength and the coordination polyhedra. We have also studied electrostatically enhanced π⋯π (either conventional or involving the chelate ring) interactions observed in the solid state of both compounds and analyzed them using DFT calculations, molecular electrostatic potential surface and Bader's theory of atoms in molecules.

In situ inclusion of thiocyanate for highly luminescent and stable CH3NH3PbBr3 perovskite nanocrystals

Abstract: In this work, an in situ thiocyanate inclusion method for the fabrication of highly luminescent and stable CH3NH3PbBr3 perovskite nanocrystals (NCs) is developed, employing Pb(SCN)2 as the lead precursor to partially or totally replace PbBr2 in the ligand-assisted reprecipitation (LARP) process. The in situ approach not only avoids the introduction of impurity elements, but also more interestingly incorporation of thiocyanate can control the crystallinity, particle size, luminescence and stability of CH3NH3PbBr3 NCs in a simple and effective manner. By adjusting the thiocyanate concentration, the photoluminescence (PL) of the synthesized CH3NH3PbBr3 NCs can be tuned in a range of 473–526 nm, as characterized by narrow emission line widths of 21–28 nm and outstanding photoluminescence quantum yields (PLQYs) of 73% to 96%. Meanwhile, the stability of CH3NH3PbBr3 NCs can be greatly improved as the amount of thiocyanate increases. The improvement in the optical performance and stability of CH3NH3PbBr3 NCs is mainly due to the contribution of higher crystallinity and, more stable and defect-free surface passivation induced by the presence of thiocyanate. This work paves a novel way for preparing highly luminescent and stable CH3NH3PbBr3 NCs.

Yttrium and europium separation by solvent extraction with undiluted thiocyanate ionic liquids

Abstract: An yttrium/europium oxide obtained by the processing of fluorescent lamp waste powder was separated into its individual elements by solvent extraction with two undiluted ionic liquids, trihexyl(tetradecyl)phosphonium thiocyanate, [C101][SCN], and tricaprylmethylammonium thiocyanate, [A336][SCN]. The best extraction performances were observed for [C101][SCN], by using an organic-to-aqueous volume ratio of 1/10 and four counter-current extraction stages. The loaded organic phase was afterwards subjected to scrubbing with a solution of 3 mol L−1 CaCl2 + 0.8 mol L−1 NH4SCN to remove the co-extracted europium. Yttrium was quantitatively stripped from the scrubbed organic phase by deionized water. Yttrium and europium were finally recovered as hydroxides by precipitation with ammonia and then calcined to the corresponding oxides. The conditions thus defined for an efficient yttrium/europium separation from synthetic chloride solutions were afterwards tested on a leachate obtained from the dissolution of a real mixed oxide. The purity of Y2O3 with respect to the rare-earth content was 98.2%; the purity of Eu2O3 with respect to calcium was 98.7%.

Strongly coloured thiocyanate frameworks with perovskite-analogue structures

Abstract: We report the first examples of thiocyanate-based analogues of the cyanide Prussian blue compounds, MIII[Bi(SCN)6], M = Fe, Cr, Sc. These compounds adopt the primitive cubic pcu topology and show strict cation order. Optical absorption measurements show these compounds have band gaps within the visible and near IR region, suggesting that they may be useful for applications where light harvesting is key, such as photocatalysis. We also show that Cr[Bi(SCN)6] can reversibly uptake water into its framework structure pointing towards the possibility of using these frameworks for host/guest chemistry.

Tin(II) thiocyanate Sn(NCS)2 – a wide band gap coordination polymer semiconductor with a 2D structure

Abstract: Semiconductors based on tin(II) show promising hole-transport characteristics due to the 5s electrons that form the valence band. In this paper, we report the synthesis and comprehensive characterization of tin(II) thiocyanate [Sn(NCS)2] and identify it as a novel transparent coordination polymer semiconductor. The single crystal X-ray analysis reveals covalently-bonded 1D polymeric chains that form a 2D structure through Sn–S tetrel bonds. Density functional theory calculations also confirm the importance of the van der Waals interactions between the 2D sheets. Furthermore, we show that the s character of Sn(II) is maintained at the top of the valence band, resulting in dispersed states with a small hole effective mass. The coordination with NCS ligands also leads to a conduction band which is high in energy, giving rise to a wide band gap and excellent transparency in the visible spectrum. This is the first report on the electronic properties of Sn(NCS)2 which highlights the potential of developing new transparent semiconductors based on thiocyanate coordination polymers.

Copper-Catalyzed Electrophilic Thiolation of Organozinc Halides by Using N-Thiophthalimides Leading to Polyfunctional Thioethers

Abstract: (Hetero)aryl, benzylic, and alkyl zinc halides were thiolated with N-thiophthalimides at 25 °C within 1 h in the presence of 5-10 % Cu(OAc)2 ⋅H2 O to furnish the corresponding polyfunctionalized thioethers in good yields. This electrophilic thiolation was extended to the introduction of trifluoromethylthio (SCF3 ), thiocyanate (SCN), and selenophenyl (SePh) groups. The utility of this method was shown in a seven-step synthesis of a potent cathepsin D inhibitor in 34 % overall yield.

Synergistic Effect of Pseudo-Halide Thiocyanate Anion and Cesium Cation on Realizing High-Performance Pinhole-Free MA-Based Wide-Band Gap Perovskites

Abstract: The performance of wide-band gap perovskite solar cells has a profound impact on the multijunction tandem device efficiency. However, once bromide (Br–) has been adopted to substitute the iodide (I...

Comparative Genomics of Thiohalobacter thiocyanaticus HRh1T and Guyparkeria sp. SCN-R1, Halophilic Chemolithoautotrophic Sulfur-Oxidizing Gammaproteobacteria Capable of Using Thiocyanate as Energy Source

Abstract: The genomes of Thiohalobacter thiocyanaticus and Guyparkeria (formerly known as Halothiobacillus) sp. SCN-R1, two gammaproteobacterial halophilic sulfur-oxidizing bacteria (SOB) capable of thiocyanate oxidation via the "cyanate pathway", have been analyzed with a particular focus on their thiocyanate-oxidizing potential and sulfur oxidation pathways. Both genomes encode homologs of the enzyme thiocyanate dehydrogenase (TcDH) that oxidizes thiocyanate via the "cyanate pathway" in members of the haloalkaliphilic SOB of the genus Thioalkalivibrio. However, despite the presence of conservative motives indicative of TcDH, the putative TcDH of the halophilic SOB have a low overall amino acid similarity to the Thioalkalivibrio enzyme, and also the surrounding genes in the TcDH locus were different. In particular, an alternative copper transport system Cus is present instead of Cop and a putative zero-valent sulfur acceptor protein gene appears just before TcDH. Moreover, in contrast to the thiocyanate-oxidizing Thioalkalivibrio species, both genomes of the halophilic SOB contained a gene encoding the enzyme cyanate hydratase. The sulfur-oxidizing pathway in the genome of Thiohalobacter includes a Fcc type of sulfide dehydrogenase, a rDsr complex/AprAB/Sat for oxidation of zero-valent sulfur to sulfate, and an incomplete Sox pathway, lacking SoxCD. The sulfur oxidation pathway reconstructed from the genome of Guyparkeria sp. SCN-R1 was more similar to that of members of the Thiomicrospira-Hydrogenovibrio group, including a Fcc type of sulfide dehydrogenase and a complete Sox complex. One of the outstanding properties of Thiohalobacter is the presence of a Na+-dependent ATP synthase, which is rarely found in aerobic Prokaryotes.Overall, the results showed that, despite an obvious difference in the general sulfur-oxidation pathways, halophilic and haloalkaliphilic SOB belonging to different genera within the Gammaproteobacteria developed a similar unique thiocyanate-degrading mechanism based on the direct oxidative attack on the sulfane atom of thiocyanate.