@article {168, title = {Carborane Nanomembranes}, journal = {ACS Nano}, year = {2025}, month = {02/2025}, type = {Full article}, abstract = {

e report on the fabrication of a boron-based two-dimensional (2D) material via electron irradiation-induced cross-linking of carborane self-assembled monolayers (SAMs) on crystalline silver substrates. The SAMs of 1,2-dicarba-closo-dodecarborane-9,12-dithiol (O9,12) were prepared on flat crystalline silver substrates and irradiated with low-energy electrons, resulting in a 2D nanomembrane. The mechanical stability and compact character of the carborane nano-membrane were improved by using 12-(1',12'-dicarba-closo-dodecarboran-1'-yl)-1,12-dicarba-closo-dodecarborane-1-thiol (1-HS-bis-pCB), a longer, rod-like SAM precursor with two para-carborane units linked linearly together. The self-assembly, cross-linking process, and transfer of the resulting membranes onto holey substrates were characterized with different complementary surface-sensitive techniques including X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and low-energy electron diffraction (LEED) as well as scanning tunneling and electron microscopies (STM, SEM) to provide insight on the structural changes within the cross-linked SAMs. The presented methodology has potential for the development of boron-based 2D materials for applications in electronic and optical devices.

}, keywords = {carboranes, electron irradiation induced chemical synthesis, molecular self-assembly, nanomembranes, two-dimensional materials}, doi = {https://doi.org/10.1021/acsnano.4c16611}, url = {https://pubs.acs.org/doi/10.1021/acsnano.4c16611}, author = {Martha Frey and Julian Picker and Christof Neumann and Jakub Višň{\'a}k and Jan Mach{\'a}ček and Oleg L Tok and Petr B{\'a}bor and Tomas Base and Andrey Turchanin} } @article {164, title = {Competing Intermolecular and Molecule{\textendash}Surface Interactions: Dipole{\textendash}Dipole-Driven Patterns in Mixed Carborane Self-Assembled Monolayers}, journal = {Chemistry of Materials}, volume = {36}, year = {2024}, month = {February 8, 2024}, pages = {2085-2095}, type = {Article}, chapter = {2085}, abstract = {

Carboranedithiol isomers adsorbing with opposite orientations of their dipoles on surfaces are self-assembled together to form mixed monolayers where both lateral dipole{\textendash}dipole and lateral thiol{\textendash}thiolate (S{\textendash}H{\textperiodcentered}{\textperiodcentered}{\textperiodcentered}S) interactions provide enhanced stability over single-component monolayers. We demonstrate the first instance of the ability to map individual isomers in a mixed monolayer using the model system carboranedithiols on Au{111}. The addition of methyl groups to one isomer provides both an enhanced dipole moment and extra apparent height for differentiation via scanning tunneling microscopy (STM). Associated computational investigations rationalize favorable interactions of mixed pairs and the associated stability changes that arise from these interactions. Both STM images and Monte Carlo simulations yield similarly structured mixed monolayers, where approximately 10\% of the molecules have reversed dipole moment orientations but no direct chemical attachment to the surface, leading to homogeneous monolayers with no apparent phase separation. Deprotonating the thiols by depositing the molecules under basic conditions eliminates the lateral S{\textendash}H{\textperiodcentered}{\textperiodcentered}{\textperiodcentered}S interactions while accentuating the dipole{\textendash}dipole forces. The molecular system investigated is composed of isomeric molecules with opposite orientations of dipoles and identical surface packing, which enables the mapping of individual molecules within the mixed monolayers and enables analyses of the contributions of the relatively weak lateral interactions to the overall stability of the assemblies.

}, keywords = {2D assembly, boron, carborane, Cluster Molecules, Dipole-dipole, Molecular interactions, Molecular structure, scanning tunneling microscopy, Supramolecular chemistry}, doi = {https://doi.org/10.1021/acs.chemmater.3c03210}, url = {https://pubs.acs.org/doi/10.1021/acs.chemmater.3c03210}, author = {Katherine E. White and Erin M. Avery and Edison Cummings and Zixiang Hong and Jens Langecker and Aliaksei Vetushka and Michal Dusek and Jan Machacek and Jakub Vi{\v s}n{\'a}k and Jan Endres and Zdenek Bastl and Ersen Mete and Anastassia N. Alexandrova and Tomas Base and Paul S. Weiss} } @article {156, title = {The Au25(SR)18 cluster carrying icosahedral dodecaborate and glutathione ligands: A spectroscopic view}, journal = {Journal of Physics and Chemistry of Solids}, year = {2020}, type = {Primary research article}, abstract = {

The functionality of Au25(S-glutathione)18 clusters change when some of the ligands in the cluster shell are replaced for other species. In this study we report on the synthesis and characterisation of a new cluster in which undecahydro-closo-dodecaborate thiolates are introduced as constituents of the shell surrounding the gold core. This is the first reported example in which the Au13 core of the Au25(S-glutathione)18 cluster is covered with an Au{\textendash}S{\textendash}B linkage instead of an Au{\textendash}S{\textendash}C on the dimeric shell units using a ligand exchange reaction. The spectra of the new cluster species clearly indicate a successful ligand exchange while retaining the gold core with undisrupted semirings containing both thiolate species. The resulting clusters were identified as Au25 [(S-glutathione)18-x (S-closo-borate)x-)] (x\ =\ 3, 4). Despite the achiral character of the closo-borate thiolates entering the semiring, increased chirality traces were observed in the high-energy region. Circular dichroism (CD) responses are ligand dependent and provide a fingerprint characteristic of the ligands present in the cluster. The next generation of such surface functionalized clusters provides unique base for computational and application studies.

}, keywords = {Chirality, Coating, Optoelectronic nanomaterials, Spectroscopy}, doi = {https://doi.org/10.1016/j.jpcs.2020.109838}, url = {https://www.sciencedirect.com/science/article/pii/S0022369720307411?via\%3Dihub}, author = {Eva Valusova and Maria Kanuchova and Tomas Base and Viktor Viglasky and Marian Antalik} } @article {153, title = {Icosahedral Carbaboranes with Peripheral Hydrogen{\textendash} Chalcogenide Groups: Structures from Gas Electron Diffraction and Chemical Shielding in Solution}, journal = {Chemistry A European Journal}, volume = {25}, year = {2019}, month = {February 11, 201}, pages = {2313-2321}, type = {Full paper}, chapter = {2313}, abstract = {

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.

}, keywords = {carborane-diselenol, carborane-dithiol, gass phase electron diffraction, GPE, sturcture}, doi = {DOI : 10.1002/chem.201805145}, url = {https://onlinelibrary.wiley.com/doi/10.1002/chem.201805145}, author = {Tomas Base and Josef Holub and Jindrich Fanfrlik and Drahomir Hnyk and Paul L Lane and Derek A Wann and Yury V Vishnevskiy and Denis Tikhonov and Christian G Reuter and Norbert W Mitzel} } @article {141, title = {Adsorption of oriented carborane dipoles on a silver surface}, journal = {Physica Status Solidi B}, volume = {253}, year = {2016}, month = {10 DEC 2015}, pages = {591-600}, abstract = {

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{\textendash}S bonds to the work function changes is quantified.

}, keywords = {carborane, Kelvin probe force microscopy, self-assembled monolayers, silver, time-of-flight secondary ion mass spectrometry, X-ray photoelectron spectroscopy}, doi = {10.1002/pssb.201552446}, author = {Aliaksei Vetushka and Laetitia Bernard and Olga Guseva and Zdenek Bastl and Ji{\v r}{\'\i} Plocek and Ivo Tomandl and Antonin Fejfar and Tomas Base and Patrik Schmutz} } @article {121, title = {Nucleated Crystallization of Isotactic Polypropylene in Multilayered Sandwich Nanocomposites with Gold Particles}, journal = {Journal of Applied Polymer Science}, volume = {125}, year = {2012}, chapter = {4338}, doi = {10.1002/app.36589}, url = {http://onlinelibrary.wiley.com/doi/10.1002/app.36589/abstract}, author = {Miroslav Slouf and Antonin Sikora and Ewa Pavlova and Helena Vlkova and Josef Baldrian and Tomas Base and Ewa Piorkowska} } @article {116, title = {Gold Micrometer Crystals Modified with Carboranethiol Derivatives}, journal = {J. Phys. Chem. C}, volume = {112}, year = {2008}, chapter = {14446}, abstract = {

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.

}, doi = {10.1021/jp802281s}, url = {http://pubs.acs.org/doi/abs/10.1021/jp802281s}, author = {Tomas Base and Zdenek Bastl and Miroslav Slouf and Mariana Klementova and Jan Subrt and Aliaksei Vetushka and Martin Ledinsky and Antonin Fejfar and Jan Machacek and Michael J Carr and Michael G S Londesborough} } @article {115, title = {Carboranethiol-Modified Gold Surfaces. A Study and Comparison of Modified Cluster and Flat Surfaces}, journal = {Langmuir}, volume = {21}, year = {2005}, chapter = {7776}, abstract = {

Four different carboranethiol derivatives were used to modify the surfaces of gold nanoparticles and flat gold films. The novel materials engendered from these modifications are extraordinarily stable species with surfaces that support self-assembled monolayers of 1-(HS)-1,2-C2B10H11, 1,2-(HS)2-1,2-C2B10H10, 1,12-(HS)2-1,12-C2B10H10, and 9,12-(HS)2-1,2-C2B10H10, respectively. Surprisingly, characterization of these materials revealed that a number of molecules of the carboranethiol derivatives are incorporated inside the nanoparticles. This structural feature was studied using a number of techniques, including X-ray photoelectron spectroscopy (XPS), UV }, doi = {10.1021/la051122d}, url = {http://pubs.acs.org/doi/abs/10.1021/la051122d}, author = {Tomas Base and Zdenek Bastl and Zbynek Plzak and Tomas Grygar and Jaromir Plesek and Michael J Carr and Vaclav Malina and Jan Subrt and Jaroslav Bohacek and Eva Vecernikova and Otomar Kriz} } @article {125, title = {Synthesis and catalytic activity of spaced ferrocene oxazolines}, journal = {Collection of Czechoslovak Chemical Communications}, volume = {68}, year = {2003}, chapter = {1206}, doi = {10.1135/cccc20031206}, url = {http://cccc.uochb.cas.cz/68/7/1206/}, author = {Petr Stepnicka and Tomas Base and Ivana Cisarova and Jiri Kubista and Stepan Vyskocil and Martin Sticha} }