Search results for "Kulta"
showing 10 items of 67 documents
Towards Atomically Precise Supported Catalysts from Monolayer‐Protected Clusters: The Critical Role of the Support
2020
Abstract Controlling the size and uniformity of metal clusters with atomic precision is essential for fine‐tuning their catalytic properties, however for clusters deposited on supports, such control is challenging. Here, by combining X‐ray absorption spectroscopy and density functional theory calculations, it is shown that supports play a crucial role in the evolution of monolayer‐protected clusters into catalysts. Based on the acidic nature of the support, cluster‐support interactions lead either to fragmentation of the cluster into isolated Au–ligand species or ligand‐free metallic Au0 clusters. On Lewis acidic supports that bind metals strongly, the latter transformation occurs while pre…
Supramolecular systems based on gold(I) derivatives : molecular recognition of L-glutamine and polyQ
2017
L-glutamiinin ja polyglutamiinin molekyylintunnistuksessa käytettyjen uusien organometallikompleksien mielenkiintoiset luminesoivat ominaisuudet ovat peräisin 4-etynyylianiliiniligandista ja fosfaaniyksiköstä sekä molekyylien välisistä Au⋯Au vuorovaikutuksista. Heikkojen intermolekulaaristen vuorovaikutusten on havaittu johtavan kuitu- ja pallomaisten muotojen morfologisiin muutoksiin vierasmolekyylien läsnä ollessa. Muodostunut isäntä-vieras -kompleksi tuottaa erilaisen emission vierasmolekyylistä riippuen. Lisäksi [Au(4-etynyylianiliini)(PTA)]:n itsejärjestäytymisen termodynaamisia funktioita tutkittiin eri pitoisuuksissa ja lämpötiloissa NMR mittausten avulla. Nämä lineaariset kulta(I) -…
Kultalangalla kokonaiseksi
2019
Arvostelu teoksesta Nadeem Aslam: Kultainen legenda (The Golden Legend). Suom. Kirsi Luoma. 375 s. nonPeerReviewed
Highly Robust but Surface-Active : An N-Heterocyclic Carbene-Stabilized Au25 Nanocluster
2019
Surface organic ligands play a critical role in stabilizing atomically precise metal nanoclusters in solutions. However, it is still challenging to prepare highly robust ligated metal nanoclusters that are surface-active for liquid-phase catalysis without any pre-treatment. Now, an N-heterocyclic carbene-stabilized Au25 nanocluster with high thermal and air stabilities is presented as a homogenous catalyst for cycloisomerization of alkynyl amines to indoles. The nanocluster, characterized as [Au25(iPr2-bimy)10Br7]2+ (iPr2-bimy=1,3-diisopropylbenzimidazolin-2-ylidene) (1), was synthesized by direct reduction of AuSMe2Cl and iPr2-bimyAuBr with NaBH4 in one pot. X-ray crystallization analysis …
Plasmonic Resonant Nanoantennas Induce Changes in the Shape and the Intensity of Infrared Spectra of Phospholipids.
2021
Surface enhanced infrared absorption spectroscopic studies (SEIRAS) as a technique to study biological molecules in extremely low concentrations is greatly evolving. In order to use the technique for identification of the structure and interactions of such biological molecules, it is necessary to identify the effects of the plasmonic electric-field enhancement on the spectral signature. In this study the spectral properties of 1,2-Dipalmitoyl-sn-glycero-3 phosphothioethanol (DPPTE) phospholipid immobilized on gold nanoantennas, specifically designed to enhance the vibrational fingerprints of lipid molecules were studied. An AFM study demonstrates an organization of the DPPTE phospholipid in…
Thiolate Adsorption on Au(hkl) and Equilibrium Shape of Large Thiolate-covered Gold Nanoparticles
2013
The adsorption of thiolates on Au surfaces employing density-functional-theory calculations has been studied. The dissociative chemisorption of dimethyl disulfide (CH3S−SCH3) on 14 different Au(hkl) is used as a model system. We discuss trends on adsorption energies, bond lengths, and bond angles as the surface structure changes, considering every possible Au(hkl) with h, k, l ≤ 3 plus the kinked Au(421). Methanethiolate (CH3S-) prefers adsorption on bridge sites on all surfaces considered; hollow and on top sites are highly unfavourable. The interface tensions for Au(hkl)-thiolate interfaces is determined at low coverage. Using the interface tensions in a Wulff construction method, we cons…
Selective trapping of oligos to triangular gold nanoparticles utilizing dielectrophoresis
2014
Triangular shaped particles are an interesting research topic since there are three plasmonically active tips, which can be utilized in new molecular sensing application systems. In this research we used dielectrophoretic force to trap thiol-modified (5’- end) and Cy3-dye-labeled (3’-end) single-stranded DNA (ssDNA) oligonucleotides, size 40 nt (about 22 nm long), to the corners of the gold triangles. These gold triangles were 20 nm thick and side length was 1 μm. The trapping experiment was done under AC-circuit and the gathering of the oligos to the triangles was studied in situ under confocal microscope. The theoretical values for dielectrophoretic force with different voltages were simu…
Selective recovery of gold from electronic waste using 3D-printed scavenger
2017
Around 10% of the worldwide annual production of gold is used for manufacturing of electronic devices. According to the European Commission, waste electric and electronic equipment is the fastest growing waste stream in the European Union. This has generated the need for an effective method to recover gold from electronic waste. Here, we report a simple, effective, and highly selective nylon-12-based three-dimensional (3D)-printed scavenger objects for gold recovery directly from an aqua regia extract of a printed circuit board waste. Using the easy to handle and reusable 3D-printed meshes or columns, gold can be selectively captured both in a batch and continuous flow processes by dipping …
The Important Role of the Nuclearity, Rigidity, and Solubility of Phosphane Ligands in the Biological Activity of Gold(I) Complexes
2018
A series of 4-ethynylaniline gold(I) complexes containing monophosphane (1,3,5-triaza-7-phosphaadamantane (pta; 2), 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane (3), and PR3 , with R=naphthyl (4), phenyl (5), and ethyl (6)) and diphosphane (bis(diphenylphosphino)acetylene (dppa; 7), trans-1,2-bis(diphenylphosphino)ethene (dppet; 8), 1,2-bis(diphenylphosphino)ethane (dppe; 9), and 1,3-bis(diphenylphosphino)propane (dppp; 10)) ligands have been synthesized and their efficiency against tumor cells evaluated. The cytotoxicity of complexes 2-10 was evaluated in human colorectal (HCT116) and ovarian (A2780) carcinoma as well as in normal human fibroblasts. All the complexes showed a hi…
Au70S20(PPh3)12: an intermediate sized metalloid gold cluster stabilized by the Au4S4 ring motif and Au-PPh3 groups
2018
Reducing (Ph3P)AuSC(SiMe3)3 with L-Selectride® gives the medium-sized metalloid gold cluster Au70S20(PPh3)12. Computational studies show that the phosphine bound Au-atoms not only stabilize the electronic structure of Au70S20(PPh3)12, but also behave as electron acceptors leading to auride-like gold atoms on the exterior.