TY - JOUR T1 - Macropolyhedral syn-B18H22, the “Forgotten” Isomer JF - Journal of the American Chemical Society Y1 - 2023 A1 - Deepak Kumar Patel A1 - B. S. Sooraj A1 - Kaplan Kirakci A1 - Jan Machacek A1 - Monika Kucerakova A1 - Jonathan Bould A1 - Michal Dusek A1 - Martha Frey A1 - Christof Neumann A1 - Sundargopal Ghosh A1 - Andrey Turchanin A1 - Thalappil Pradeep A1 - Tomas Base KW - boron KW - boron hydride KW - Cluster KW - luminescence KW - macropolyhedral KW - NMR KW - PXRD KW - SAM KW - self-assembly KW - single crystal KW - solid state KW - syn-B18H22 KW - XPS AB -
The chemistry and physics of macropolyhedral B18H22 clusters have attracted significant attention due to the interesting photophysical properties of anti-B18H22 (blue emission, laser properties) and related potential applications. We have focused our attention on the “forgotten” syn-B18H22 isomer, which has received very little attention since its discovery compared to its anti-B18H22 isomer, presumably because numerous studies have reported this isomer as nonluminescent. In our study, we show that in crystalline form, syn-B18H22 exhibits blue fluorescence and becomes phosphorescent when substituted at various positions on the cluster, associated with peculiar microstructural-dependent effects. This work is a combined theoretical and experimental investigation that includes the synthesis, separation, structural characterization, and first elucidation of the photophysical properties of three different monothiol-substituted cluster isomers, [1-HS-syn-B18H21] 1, [3-HS-syn-B18H21] 3, and [4-HS-syn-B18H21] 4, of which isomers 1 and 4 have been proved to exist in two different polymorphic forms. All of these newly substituted macropolyhedral cluster derivatives (1, 3, and 4) have been fully characterized by NMR spectroscopy, mass spectrometry, single-crystal X-ray diffraction, IR spectroscopy, and luminescence spectroscopy. This study also presents the first report on the mechanochromic shift in the luminescence of a borane cluster and generally enriches the area of rather rare boron-based luminescent materials. In addition, we present the first results proving that they are useful constituents of carbon-free self-assembled monolayers.
VL - 145 UR - https://pubs.acs.org/doi/10.1021/jacs.3c05530 ER - TY - JOUR T1 - Icosahedral Carbaboranes with Peripheral Hydrogen– Chalcogenide Groups: Structures from Gas Electron Diffraction and Chemical Shielding in Solution JF - Chemistry A European Journal Y1 - 2019 A1 - Tomas Base A1 - Josef Holub A1 - Jindrich Fanfrlik A1 - Drahomir Hnyk A1 - Paul L Lane A1 - Derek A Wann A1 - Yury V Vishnevskiy A1 - Denis Tikhonov A1 - Christian G Reuter A1 - Norbert W Mitzel KW - carborane-diselenol KW - carborane-dithiol KW - gass phase electron diffraction KW - GPE KW - sturcture AB -Hydrochalcogeno carbaboranes: Icosahedral carbaboranes with thiol and selenol groups were prepared and their structures determined by gas electron diffraction augmented by ab initio calculated data (see figure). A method for quantifying the experimental contribution to the structural parameters was developed and tested. Comparison of NMR chemical shifts in solution with quantum‐chemically calculated values allowed further structural information to be retrieved.
VL - 25 UR - https://onlinelibrary.wiley.com/doi/10.1002/chem.201805145 IS - 9 ER - TY - JOUR T1 - Adsorption of oriented carborane dipoles on a silver surface JF - Physica Status Solidi B Y1 - 2016 A1 - Aliaksei Vetushka A1 - Laetitia Bernard A1 - Olga Guseva A1 - Zdenek Bastl A1 - Jiří Plocek A1 - Ivo Tomandl A1 - Antonin Fejfar A1 - Tomas Base A1 - Patrik Schmutz KW - carborane KW - Kelvin probe force microscopy KW - self-assembled monolayers KW - silver KW - time-of-flight secondary ion mass spectrometry KW - X-ray photoelectron spectroscopy AB -Modification of surfaces with self-assembled mono-layers (SAMs) represents a powerful and innovative tool for adjusting physical and chemical properties of surfaces. The adsorption of isomeric molecules with relatively strong and oppositely oriented molecular dipoles, 1,2-(HS)2-1,2-C2B10H10 and 9,12-(HS)2-1,2-C2B10H10, on a flat silver surface is investigated in order to adjust its work function in a desired way. Time-offlight secondary ion mass spectroscopy (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) are used to prove that both isomers (i) chemisorb on a silver surface as thiolates and (ii) exhibit comparable surface densities. Densely packed surfaces of both SAMs are additionally investigated by electrochemical impedance spectroscopy, and effective surface passivation is observed. Co-deposition of both derivatives is shown to enable effective and fine adjustment of the surface work function value within a range of 1V, which is confirmed by Kelvin probe force microscopy (KPFM). Experimental data indicate faster SAM formation for the former isomer. Contribution of the interface Ag–S bonds to the work function changes is quantified.
VL - 253 IS - 3 ER - TY - JOUR T1 - Carbon-substituted 9,12-dimercapto-1,2-dicarba-closo-dodecaboranes via a 9,12-bis(methoxy-methylthio)-1,2-dicarba-closo-dodecaborane precursor JF - Polyhedron Y1 - 2012 A1 - Jens Langecker A1 - Karla Fejfarova A1 - Michal Dusek A1 - Daniel Rentsch A1 - Tomas Base VL - 45 UR - http://www.sciencedirect.com/science/article/pii/S0277538712005207 ER - TY - JOUR T1 - Reversible Capture of Small Molecules On Bimetallaborane Clusters: Synthesis, Structural Characterization, and Photophysical Aspects JF - Inorganic Chemistry Y1 - 2011 A1 - Jonathan Bould A1 - Tomas Base A1 - Michael G S Londesborough A1 - Luis A Oro A1 - Ramon Macias A1 - John D Kennedy A1 - Pavel Kubat A1 - Marcel Fuciman A1 - Tomas Polivka A1 - Kamil Lang VL - 50 UR - http://pubs.acs.org/doi/abs/10.1021%2Fic200374k ER - TY - JOUR T1 - Gold Micrometer Crystals Modified with Carboranethiol Derivatives JF - J. Phys. Chem. C Y1 - 2008 A1 - Tomas Base A1 - Zdenek Bastl A1 - Miroslav Slouf A1 - Mariana Klementova A1 - Jan Subrt A1 - Aliaksei Vetushka A1 - Martin Ledinsky A1 - Antonin Fejfar A1 - Jan Machacek A1 - Michael J Carr A1 - Michael G S Londesborough AB -The preparation and characterization of micrometer gold and silver single-crystals of well-defined shapes are reported here. The shapes of the crystals can be described as plates, polyhedra, and wires. The orientation of the crystal faces was studied using electron and X-ray powder diffraction techniques, and a (111) orientation of the large faces of gold plates was experimentally shown. The surface morphology of the crystal faces was studied by atomic force microscopy. Modifications of gold microplates with the thiolated carborane clusters 1,2-(HS)2-1,2-C2B10H10 (1), 9,12-(HS)2-1,2-C2B10H10 (2), and 1,12-(HS)2-1,12-C2B10H10 (3) are described. The carboranethiol molecules 1 and 2 show dipole moments of 4.1 and 5.9 D. In comparison, the thiolate derivative of compound 1 has a dipole moment of 4.7 D in the opposite direction to 1, and the thiolate form of compound 2 has a dipole moment of 16.7 D in the same direction. On the basis of X-ray photoelectron spectroscopy (XPS) analyses and values of work functions, we revealed that the molecules of 1 and 2 attached to the gold surface have similar electron distribution and dipole moments as within the free thiol derivatives. Following the modification of microplate gold crystals with 3, a monolayer of gold nanoparticles was attached on top of the carborane moieties. The composition of the surface species was studied using XPS. Dynamic contact angles of water on the modified gold surfaces are also discussed.
VL - 112 UR - http://pubs.acs.org/doi/abs/10.1021/jp802281s IS - 37 ER -