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 - Decaborane Thiols as Building Blocks for Self-Assembled Monolayers on Metal Surfaces JF - Inorganic Chemistry Y1 - 2012 A1 - Jonathan Bould A1 - Jan Machacek A1 - Michael G S Londesborough A1 - Ramon Macias A1 - John D Kennedy A1 - Zdenek Bastl A1 - Patrik Rupper A1 - Tomas Base AB -

Three nido-decaborane thiol cluster compounds, [1-(HS)-nido-B10H13] 1, [2-(HS)-nido-B10H13] 2, and [1,2-(HS)2-nido-B10H12] 3 have been characterized using NMR spectroscopy, single-crystal X-ray diffraction analysis, and quantum-chemical calculations. In the solid state, 1, 2, and 3 feature weak intermolecular hydrogen bonding between the sulfur atom and the relatively positive bridging hydrogen atoms on the open face of an adjacent cluster. Density functional theory (DFT) calculations show that the value of the interaction energy is approximately proportional to the number of hydrogen atoms involved in the interaction and that these values are consistent with a related bridging-hydrogen atom interaction calculated for a B18H22 C6H6 solvate. Self-assembled monolayers (SAMs) of 1, 2, and 3 on gold and silver surfaces have been prepared and characterized using X-ray photoelectron spectroscopy. The variations in the measured sulfur binding energies, as thiolates on the surface, correlate with the (CC2) calculated atomic charge for the relevant boron vertices and for the associated sulfur substituents for the parent B10H13(SH) compounds. The calculated charges also correlate with the measured and DFT-calculated thiol 1H chemical shifts. Wetting-angle measurements indicate that the hydrophilic open face of the cluster is directed upward from the substrate surface, allowing the bridging hydrogen atoms to exhibit a similar reactivity to that of the bulk compound. Thus, [PtMe2(PMe2Ph)2] reacts with the exposed and acidic B VL - 51 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 - Carborane-thiol-silver interactions. A comparative study of the molecular protection of silver surfaces JF - Surface and Coatings Technology Y1 - 2010 A1 - Tomas Base A1 - Zdenek Bastl A1 - Vladimir Havranek A1 - Kamil Lang A1 - Jonathan Bould A1 - Michael G S Londesborough A1 - Jan Machacek A1 - Jaromir Plesek AB -

The interaction between flat silver surfaces and carboranethiol derivatives, and its relevance regarding the molecular protection of silver against corrosion by hydrogen sulphide, are reported here. A comparison of the protective qualities of four carboranethiols (1-HS-1,2-C2B10H11, 1,2-(HS)2-1,2-C2B10H10, 9,12-(HS)2-1,2-C2B10H10, and 1,12-(HS)2-1,2-C2B10H10) with several organic thiols (1-butanethiol, 1-octanethiol, 1-dodecanethiol, benzene-1,2-dithiol, benzenethiol, and sodium 2-mercaptoethanesulphonate) is provided. All these derivatives are categorized according to their capacity to inhibit the interaction of silver with H2S in the presence of water molecules in the gas phase. We found that significantly better molecular protection for silver surfaces is afforded by the carboranethiol derivatives, and, of these, 9,12-(HS)2-1,2-C2B10H10 proved to be particularly effective. The corrosion of silver by H2S is accompanied by well-defined colour changes from lustrous silver, through yellow, violet, blue, and finally to grey. This sequence has not been reported before and it is used in this study as a qualitative indicator of the extent of silver corrosion. Our results are supported by reflectance UV

VL - 204 UR - http://www.sciencedirect.com/science/article/pii/S0257897210001106 ER - TY - JOUR T1 - An Experimental Solution to the "Missing Hydrogens" Question Surrounding the Macropolyhedral 19-Vertex Boron Hydride Monoanion [B19H22](-), a Simplification of Its Synthesis, and Its Use As an Intermediate in the First Example of syn-B18H22 to anti-B18H22 JF - Inorganic Chemistry Y1 - 2010 A1 - Michael G S Londesborough A1 - Jonathan Bould A1 - Tomas Base A1 - Drahomir Hnyk A1 - Mario Bakardjiev A1 - Josef Holub A1 - Ivana Cisarova A1 - John D Kennedy VL - 49 UR - http://pubs.acs.org/doi/abs/10.1021/ic901976y IS - 9 ER -