%0 Journal Article %J Chemistry of Materials %D 2024 %T Competing Intermolecular and Molecule–Surface Interactions: Dipole–Dipole-Driven Patterns in Mixed Carborane Self-Assembled Monolayers %A Katherine E. White %A Erin M. Avery %A Edison Cummings %A Zixiang Hong %A Jens Langecker %A Aliaksei Vetushka %A Michal Dusek %A Jan Machacek %A Jakub Višnák %A Jan Endres %A Zdenek Bastl %A Ersen Mete %A Anastassia N. Alexandrova %A Tomas Base %A Paul S. Weiss %K 2D assembly %K boron %K carborane %K Cluster Molecules %K Dipole-dipole %K Molecular interactions %K Molecular structure %K scanning tunneling microscopy %K Supramolecular chemistry %X

Carboranedithiol isomers adsorbing with opposite orientations of their dipoles on surfaces are self-assembled together to form mixed monolayers where both lateral dipole–dipole and lateral thiol–thiolate (S–H···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–H···S interactions while accentuating the dipole–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.

%B Chemistry of Materials %V 36 %P 2085-2095 %8 February 8, 2024 %G eng %U https://pubs.acs.org/doi/10.1021/acs.chemmater.3c03210 %9 Article %& 2085 %R https://doi.org/10.1021/acs.chemmater.3c03210 %0 Journal Article %J Chemical Science %D 2023 %T Carborane-thiol protected copper nanoclusters: Stimuli-responsive materials with tunable phosphorescence %A Arijit Jana %A Madhuri Jash %A Wakeel Ahmed Dar %A Jayoti Roy %A Papri Chakraborty %A Paramasivam Ganesan %A Sergei Lebedkin %A Kaplan Kirakci %A Sujan Manna %A P. K. Sudhadevi Antharjanam %A Jan Machacek %A Monika Kucerakova %A Sundargopal Ghosh %A Kamil Lang %A Manfred Kappes %A Tomas Base %A T. Pradeep %K boron %K Cluster %K Copper %K Cu4L4 %K Phosphorescence %K Responsive %X

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’t show mechonoresponsive luminescence in contrast to other clusters, having bent Cu4S4 structures. Cu4@oCBT and Cu4@mCBT are thermally stable up to 400 °C. The Cu4@oCBT retained green emission even upon heating to 200 °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.

%B Chemical Science %V 14 %P 1613-1626 %8 12/2023 %G eng %U https://pubs.rsc.org/en/content/articlelanding/2023/sc/d2sc06578a %9 Article %& 1613 %R https://doi.org/10.1039/D2SC06578A %0 Journal Article %J ACS Nano %D 2021 %T Light-Activated Intercluster Conversion of an Atomically Precise Silver Nanocluster %A Arijit Jana %A Madhuri Jash %A Ajay Kumar Poonia %A Ganesan Paramasivam %A Md Rabiul Islam %A Papri Chakraborty %A Sudhadevi Antharjanam %A Jan Machacek %A Sundargopal Ghosh %A Kumaran Nair Valsala Devi Adarsh %A Tomas Base %A Thalappil Pradeep %K carboranes silver nanoclusters intercluster conversion near-infrared emission luminescence ultrafast electron dynamics %X

Noble metal nanoclusters protected with carboranes, a 12-vertex, nearly icosahedral boron–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– (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–vis absorption spectroscopy, mass spectrometry, transmission electron microscopy, X-ray photoelectron spectroscopy, infrared spectroscopy, and multinuclear magnetic resonance spectroscopy. Multiple UV–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 °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–Ag6 core–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– and [Ag35(CBDT)8(TPP)4]2– were formed after 8 h of light irradiation, and the second set comprised of [Ag30(CBDT)8(TPP)4]2–, [Ag26(CBDT)11(TPP)4]2–, and [Ag26(CBDT)7(TPP)7]2– 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.

%B ACS Nano %V 15 %P 15781-15793 %G eng %U https://pubs.acs.org/doi/abs/10.1021/acsnano.1c02602 %N 10 %9 Full Article %R https://doi.org/10.1021/acsnano.1c02602 %0 Journal Article %J Journal of Organometallic Chemistry %D 2015 %T Thermal isomerizations of monothiolated carboranes (HS)C2B10H11 and the solid-state investigation of 9-(HS)-1,2-C2B10H11 and 9-(HS)-1,7-C2B10H11 %A Tomas Base %A Jan Machacek %A Zuzana Hajkova %A Jens Langecker %A John D Kennedy %A Michael J Carr %K carborane %K Carboranethiol %K closo-dicarbadodecaborane thiol %K closo-dicarbadodecaboranes %K Cluster %K Dipole %K Isomer %K Isomerisation %K Thermal Stability %X

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.

%B Journal of Organometallic Chemistry %G eng %U http://www.sciencedirect.com/science/article/pii/S0022328X15300462 %R 10.1016/j.jorganchem.2015.06.020 %0 Journal Article %J Inorganic Chemistry %D 2010 %T 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 %A Michael G S Londesborough %A Jonathan Bould %A Tomas Base %A Drahomir Hnyk %A Mario Bakardjiev %A Josef Holub %A Ivana Cisarova %A John D Kennedy %B Inorganic Chemistry %V 49 %G eng %U http://pubs.acs.org/doi/abs/10.1021/ic901976y %N 9 %& 4092 %R 10.1021/IC901976y %0 Journal Article %J J. Phys. Chem. C %D 2008 %T Gold Micrometer Crystals Modified with Carboranethiol Derivatives %A Tomas Base %A Zdenek Bastl %A Miroslav Slouf %A Mariana Klementova %A Jan Subrt %A Aliaksei Vetushka %A Martin Ledinsky %A Antonin Fejfar %A Jan Machacek %A Michael J Carr %A Michael G S Londesborough %X

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.

%B J. Phys. Chem. C %V 112 %G eng %U http://pubs.acs.org/doi/abs/10.1021/jp802281s %N 37 %& 14446 %R 10.1021/jp802281s %0 Conference Proceedings %B 12th International Meeting on Boron Chemistry (IMEBORON-XII) %D 2005 %T Carborane Thiol-modified Gold Surfaces. A Study and Comparison of Modified Cluster and Flat Surfaces %A Tomas Base %A Zdenek Bastl %A Zbynek Plzak %A Tomas Grygar %A Jaromir Plesek %A Michael J Carr %B 12th International Meeting on Boron Chemistry (IMEBORON-XII) %C Sendai, Japan, 11 %G eng %0 Journal Article %J Langmuir %D 2005 %T Carboranethiol-Modified Gold Surfaces. A Study and Comparison of Modified Cluster and Flat Surfaces %A Tomas Base %A Zdenek Bastl %A Zbynek Plzak %A Tomas Grygar %A Jaromir Plesek %A Michael J Carr %A Vaclav Malina %A Jan Subrt %A Jaroslav Bohacek %A Eva Vecernikova %A Otomar Kriz %X

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 %B Langmuir %V 21 %G eng %U http://pubs.acs.org/doi/abs/10.1021/la051122d %N 17 %& 7776 %R 10.1021/la051122d %0 Journal Article %J Collection of Czechoslovak Chemical Communications %D 2003 %T Synthesis and catalytic activity of spaced ferrocene oxazolines %A Petr Stepnicka %A Tomas Base %A Ivana Cisarova %A Jiri Kubista %A Stepan Vyskocil %A Martin Sticha %B Collection of Czechoslovak Chemical Communications %V 68 %G eng %U http://cccc.uochb.cas.cz/68/7/1206/ %N 7 %& 1206 %R 10.1135/cccc20031206 %0 Journal Article %J Inorganic Chemistry Communications %D 2002 %T Acid-catalyzed self-alkylation of FcCH(2)NHPh. Solid-state structures of FcCH(2)NHPh and (FcCH(2))2NPh %A Tomas Base %A Ivana Cisarova %A Petr Stepnicka %B Inorganic Chemistry Communications %V 5 %G eng %U http://www.sciencedirect.com/science/article/pii/S138770030100346X %N 1 %& 46 %R 10.1016/S1387-7003(01)00346-X %0 Journal Article %J Chemical Science %D 0 %T Carborane-thiol protected copper nanoclusters: Stimuli-responsive materials with tunable phosphorescence %A Arijit Jana %A Madhuri Jash %A Wakeel A Dar %A Jayoti Roy %A Papri Chakraborty %A Paramasivam Ganesan %A Sergei Lebedkin %A Kaplan Kirakci %A Sujan Manna %A P. K. Sudhadevi Antharjanam %A Jan Machacek %A Monika Kucerakova %A Sundargopal Ghosh %A Kamil Lang %A Manfred Kappes %A Tomas Base %A T. Pradeep %K boron %K carborane %K Cluster %K Copper %K Phosphorescence %K Responsive %K thiol %X

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’t show mechonoresponsive luminescence in contrast to other clusters, having bent Cu4S4 structures. Cu4@oCBT and Cu4@mCBT are thermally stable up to 400 °C. The Cu4@oCBT retained green emission even upon heating to 200 °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.

%B Chemical Science %G eng %U https://pubs.rsc.org/en/content/articlelanding/2023/sc/d2sc06578a %R https://doi.org/10.1039/D2SC06578A