@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 {161, title = {Carborane-thiol protected copper nanoclusters: Stimuli-responsive materials with tunable phosphorescence}, journal = {Chemical Science}, volume = {14}, year = {2023}, month = {12/2023}, pages = {1613-1626}, type = {Article}, chapter = {1613}, abstract = {

Atomically precise nanomaterials with tunable solid-state luminescence attract global interest. In this work, we present a new class of thermally stable isostructural tetranuclear copper nanoclusters (NCs), shortly Cu4@oCBT, Cu4@mCBT and Cu4@ICBT, protected by nearly isomeric carborane thiols: ortho-carborane-9-thiol, meta-carborane-9-thiol and ortho-carborane 12-iodo 9-thiol, respectively. They have a square planar Cu4 core and a butterfly-shaped Cu4S4 staple, which is appended with four respective carboranes. For Cu4@ICBT, strain generated by the bulky iodine substituents on the carboranes makes the Cu4S4 staple flatter in comparison to other clusters. High-resolution electrospray ionization mass spectrometry (HR ESI-MS) and collision energy-dependent fragmentation, along with other spectroscopic and microscopic studies confirm their molecular structure. Although none of these clusters show any visible luminescence in solution, bright μs-long phosphorescence is observed in their crystalline forms. The Cu4@oCBT and Cu4@mCBT NCs are green emitting with quantum yields (Ф) of 81 and 59 \%, respectively, whereas Cu4@ICBT is orange emitting with a Φ of 18 \%. Density functional theory (DFT) calculations reveal the nature of their respective electronic transitions. The green luminescence of Cu4@oCBT and Cu4@mCBT clusters get shifted to yellow after mechanical grinding, but it is regenerated after exposure to solvent vapour, whereas the orange emission of Cu4@ICBT is not affected by mechanical grinding. Structurally flatten Cu4@ICBT didn{\textquoteright}t show mechonoresponsive luminescence in contrast to other clusters, having bent Cu4S4 structures. Cu4@oCBT and Cu4@mCBT are thermally stable up to 400 {\textdegree}C. The Cu4@oCBT retained green emission even upon heating to 200 {\textdegree}C under ambient conditions, while Cu4@mCBT changed from green to yellow in the same window. This is the first report on structurally flexible carborane thiol appended Cu4 NCs having stimuli-responsive tunable solid-state phosphorescence.

}, keywords = {boron, Cluster, Copper, Cu4L4, Phosphorescence, Responsive}, doi = {https://doi.org/10.1039/D2SC06578A}, url = {https://pubs.rsc.org/en/content/articlelanding/2023/sc/d2sc06578a}, author = {Arijit Jana and Madhuri Jash and Wakeel Ahmed Dar and Jayoti Roy and Papri Chakraborty and Paramasivam Ganesan and Sergei Lebedkin and Kaplan Kirakci and Sujan Manna and P. K. Sudhadevi Antharjanam and Jan Machacek and Monika Kucerakova and Sundargopal Ghosh and Kamil Lang and Manfred Kappes and Tomas Base and T. Pradeep} } @article {157, title = {Light-Activated Intercluster Conversion of an Atomically Precise Silver Nanocluster}, journal = {ACS Nano}, volume = {15}, year = {2021}, pages = {15781-15793}, type = {Full Article}, abstract = {

Noble metal nanoclusters protected with carboranes, a 12-vertex, nearly icosahedral boron{\textendash}carbon framework system, have received immense attention due to their different physicochemical properties. We have synthesized ortho-carborane-1,2-dithiol (CBDT) and triphenylphosphine (TPP) coprotected [Ag42(CBDT)15(TPP)4]2{\textendash} (shortly Ag42) using a ligand-exchange induced structural transformation reaction starting from [Ag18H16(TPP)10]2+ (shortly Ag18). The formation of Ag42 was confirmed using UV{\textendash}vis absorption spectroscopy, mass spectrometry, transmission electron microscopy, X-ray photoelectron spectroscopy, infrared spectroscopy, and multinuclear magnetic resonance spectroscopy. Multiple UV{\textendash}vis optical absorption features, which exhibit characteristic patterns, confirmed its molecular nature. Ag42 is the highest nuclearity silver nanocluster protected with carboranes reported so far. Although these clusters are thermally stable up to 200 {\textdegree}C in their solid state, light-irradiation of its solutions in dichloromethane results in its structural conversion to [Ag14(CBDT)6(TPP)6] (shortly Ag14). Single crystal X-ray diffraction of Ag14 exhibits Ag8{\textendash}Ag6 core{\textendash}shell structure of this nanocluster. Other spectroscopic and microscopic studies also confirm the formation of Ag14. Time-dependent mass spectrometry revealed that this light-activated intercluster conversion went through two sets of intermediate clusters. The first set of intermediates, [Ag37(CBDT)12(TPP)4]3{\textendash} and [Ag35(CBDT)8(TPP)4]2{\textendash} were formed after 8 h of light irradiation, and the second set comprised of [Ag30(CBDT)8(TPP)4]2{\textendash}, [Ag26(CBDT)11(TPP)4]2{\textendash}, and [Ag26(CBDT)7(TPP)7]2{\textendash} were formed after 16 h of irradiation. After 24 h, the conversion to Ag14 was complete. Density functional theory calculations reveal that the kernel-centered excited state molecular orbitals of Ag42 are responsible for light-activated transformation. Interestingly, Ag42 showed near-infrared emission at 980 nm (1.26 eV) with a lifetime of \>1.5 μs, indicating phosphorescence, while Ag14 shows red luminescence at 626 nm (1.98 eV) with a lifetime of 550 ps, indicating fluorescence. Femtosecond and nanosecond transient absorption showed the transitions between their electronic energy levels and associated carrier dynamics. Formation of the stable excited states of Ag42 is shown to be responsible for the core transformation.

}, keywords = {carboranes silver nanoclusters intercluster conversion near-infrared emission luminescence ultrafast electron dynamics}, doi = {https://doi.org/10.1021/acsnano.1c02602}, url = {https://pubs.acs.org/doi/abs/10.1021/acsnano.1c02602}, author = {Arijit Jana and Madhuri Jash and Ajay Kumar Poonia and Ganesan Paramasivam and Md Rabiul Islam and Papri Chakraborty and Sudhadevi Antharjanam and Jan Machacek and Sundargopal Ghosh and Kumaran Nair Valsala Devi Adarsh and Tomas Base and Thalappil Pradeep} } @article {140, title = {Thermal isomerizations of monothiolated carboranes (HS)C2B10H11 and the solid-state investigation of 9-(HS)-1,2-C2B10H11 and 9-(HS)-1,7-C2B10H11}, journal = {Journal of Organometallic Chemistry}, volume = {798}, year = {2015}, month = {12/2015}, pages = {132-140}, type = {Full article}, chapter = {132}, abstract = {

At 300-500 C, three C-thiolated closo-dicarbadodecaborane isomers 1-(HS)-1,2-C2B10H11 (1-o), 1-(HS)-1,7-C2B10H11 (1-m), and 1-(HS)-1,12-C2B10H11 (1-p), and two B-thiolated isomers 9-(HS)-1,7-C2B10H11 (9-m) and 9-(HS)-1,2-C2B10H11 (9-o) show two types of reaction: first, removal of an SH group from the closo-dicarbadodecaborane skeleton, and second, skeletal isomerizations from ortho to meta to para that lead to new isomers. A previously unreported SH skip from carbon-to-boron is also observed. The effect of the thiol group on the skeletal rearrangement is discussed. The isomerisation products are assigned on the basis of correlation of their computationally obtained dipole moments with their gas-chromatographic retention times. Computational results on molecular energies for the mono-thiolated species show good agreement between the calculated relative stabilities and the incidence and relative quantities of the isomerization products. Two of the starting B-thiolated isomers, 9-o and 9-m, were characterized using single-crystal X-ray diffraction analyses and their crystallographic packings as well as some selected structural parameters are discussed. All starting compounds were characterized using multinuclear NMR spectroscopy.

}, keywords = {carborane, Carboranethiol, closo-dicarbadodecaborane thiol, closo-dicarbadodecaboranes, Cluster, Dipole, Isomer, Isomerisation, Thermal Stability}, doi = {10.1016/j.jorganchem.2015.06.020}, url = {http://www.sciencedirect.com/science/article/pii/S0022328X15300462}, author = {Tomas Base and Jan Machacek and Zuzana Hajkova and Jens Langecker and John D Kennedy and Michael J Carr} } @article {124, title = {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}, journal = {Inorganic Chemistry}, volume = {49}, year = {2010}, month = {03/2010}, pages = {4092{\textendash}4098}, type = {Full article}, chapter = {4092}, abstract = {

The macropolyhedral [B19H22]- monoanion 1 and the dianion [B19H21]2-2 are synthesized in consistent 86-92\% yields by the reaction of [PSH]+[syn-B18H21]- with BH3(SMe2) in 1,2-Cl2C2H4 at 72 {\textdegree}C. [{\textquoteleft}PS{\textquoteright} is an abbreviation for {\textquoteleft}Proton Sponge{\textquoteright}, 1,8-bis-(dimethylamino)naphthalene. {\textquoteleft}PSH{\textquoteright} is its protonated derivative.] The molecular structures of 1 and 2 were elucidated as their [PS{BH2}]+ and [PS{BH2}]2+ salts 1a and 2a by single-crystal X-ray diffraction studies, in which all atoms were located, and supported by mass spectrometric analyses together with calculations of the cluster molecular geometries (ab ignitio and/or DFT) and of 11B chemical shifts based on GIAO-DFT shielding tensors. Acidification of dianion 2 with CF3COOH in acetonitrile, H2SO4 in dichloromethane, or aqueous HCl results in the clean formation of the monoanion [B19H22]-1. Conversely, shaking a concentrated acetonitrile solution of 1 in 0.5 M aqueous NaOH cleanly yields the [B19H21]2- dianion 2. Reaction of a dichloromethane solution of 1 with a 36\% aqueous solution of HCHO in the presence of H2SO4 quantitatively converts 1 at room temperature to a 1:1 mixture of the syn- and anti-isomers of B18H22. This cluster dismantling process is the first example of a syn- to anti-B18H22 isomer conversion.

}, keywords = {anti-B18H22, conversion, macropolyhedral borane clusters, syn-B18H22}, doi = {https://doi.org/10.1021/ic901976y}, url = {http://pubs.acs.org/doi/abs/10.1021/ic901976y}, author = {Michael G S Londesborough and Jonathan Bould and Tomas Base and Drahomir Hnyk and Mario Bakardjiev and Josef Holub and Ivana Cisarova and John D Kennedy} } @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} } @proceedings {134, title = {Carborane Thiol-modified Gold Surfaces. A Study and Comparison of Modified Cluster and Flat Surfaces}, journal = {12th International Meeting on Boron Chemistry (IMEBORON-XII)}, year = {2005}, address = {Sendai, Japan, 11 }, author = {Tomas Base and Zdenek Bastl and Zbynek Plzak and Tomas Grygar and Jaromir Plesek and Michael J Carr} } @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} } @article {126, title = {Acid-catalyzed self-alkylation of FcCH(2)NHPh. Solid-state structures of FcCH(2)NHPh and (FcCH(2))2NPh}, journal = {Inorganic Chemistry Communications}, volume = {5}, year = {2002}, chapter = {46}, doi = {10.1016/S1387-7003(01)00346-X }, url = {http://www.sciencedirect.com/science/article/pii/S138770030100346X}, author = {Tomas Base and Ivana Cisarova and Petr Stepnicka} } @article {160, title = {Carborane-thiol protected copper nanoclusters: Stimuli-responsive materials with tunable phosphorescence }, journal = {Chemical Science}, abstract = {

Atomically precise nanomaterials with tunable solid-state luminescence attract global interest. In this work, we present a new class of thermally stable isostructural tetranuclear copper nanoclusters (NCs), shortly Cu4@oCBT, Cu4@mCBT and Cu4@ICBT, protected by nearly isomeric carborane thiols: ortho-carborane-9-thiol, meta-carborane-9-thiol and ortho-carborane 12-iodo 9-thiol, respectively. They have a square planar Cu4 core and a butterfly-shaped Cu4S4 staple, which is appended with four respective carboranes. For Cu4@ICBT, strain generated by the bulky iodine substituents on the carboranes makes the Cu4S4 staple flatter in comparison to other clusters. High-resolution electrospray ionization mass spectrometry (HR ESI-MS) and collision energy-dependent fragmentation, along with other spectroscopic and microscopic studies confirm their molecular structure. Although none of these clusters show any visible luminescence in solution, bright μs-long phosphorescence is observed in their crystalline forms. The Cu4@oCBT and Cu4@mCBT NCs are green emitting with quantum yields (Ф) of 81 and 59 \%, respectively, whereas Cu4@ICBT is orange emitting with a Φ of 18 \%. Density functional theory (DFT) calculations reveal the nature of their respective electronic transitions. The green luminescence of Cu4@oCBT and Cu4@mCBT clusters get shifted to yellow after mechanical grinding, but it is regenerated after exposure to solvent vapour, whereas the orange emission of Cu4@ICBT is not affected by mechanical grinding. Structurally flatten Cu4@ICBT didn{\textquoteright}t show mechonoresponsive luminescence in contrast to other clusters, having bent Cu4S4 structures. Cu4@oCBT and Cu4@mCBT are thermally stable up to 400 {\textdegree}C. The Cu4@oCBT retained green emission even upon heating to 200 {\textdegree}C under ambient conditions, while Cu4@mCBT changed from green to yellow in the same window. This is the first report on structurally flexible carborane thiol appended Cu4 NCs having stimuli-responsive tunable solid-state phosphorescence.

}, keywords = {boron, carborane, Cluster, Copper, Phosphorescence, Responsive, thiol}, doi = {https://doi.org/10.1039/D2SC06578A}, url = {https://pubs.rsc.org/en/content/articlelanding/2023/sc/d2sc06578a}, author = {Arijit Jana and Madhuri Jash and Wakeel A Dar and Jayoti Roy and Papri Chakraborty and Paramasivam Ganesan and Sergei Lebedkin and Kaplan Kirakci and Sujan Manna and P. K. Sudhadevi Antharjanam and Jan Machacek and Monika Kucerakova and Sundargopal Ghosh and Kamil Lang and Manfred Kappes and Tomas Base and T. Pradeep} }