TY - JOUR T1 - Carborane-thiol protected copper nanoclusters: Stimuli-responsive materials with tunable phosphorescence JF - Chemical Science Y1 - 2023 A1 - Arijit Jana A1 - Madhuri Jash A1 - Wakeel Ahmed Dar A1 - Jayoti Roy A1 - Papri Chakraborty A1 - Paramasivam Ganesan A1 - Sergei Lebedkin A1 - Kaplan Kirakci A1 - Sujan Manna A1 - P. K. Sudhadevi Antharjanam A1 - Jan Machacek A1 - Monika Kucerakova A1 - Sundargopal Ghosh A1 - Kamil Lang A1 - Manfred Kappes A1 - Tomas Base A1 - T. Pradeep KW - boron KW - Cluster KW - Copper KW - Cu4L4 KW - Phosphorescence KW - Responsive AB -
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.
VL - 14 UR - https://pubs.rsc.org/en/content/articlelanding/2023/sc/d2sc06578a ER - TY - JOUR T1 - A Luminescent Cu4 Cluster Film Grown by Electrospray Deposition: A Nitroaromatic Vapour Sensor JF - Nanoscale Y1 - 2023 A1 - Arijit Jana A1 - B K Spoorthi A1 - Akhil S Nair A1 - Biswarup Pathak A1 - Tomas Base A1 - Thalappil Pradeep KW - carborane KW - Copper KW - luminescence KW - nanocluster KW - nitro organic KW - sensor AB -We present the fabrication and use of a film of carborane-thiol protected tetranuclear copper cluster with characteristic orange luminescence using ambient electrospray deposition (ESD). Charged microdroplets of the clusters produced by an electrospray tip deposit clusters at an air-water interface to form a film. Different microscopic and spectroscopic techniques characterized the porous surface structure of the film. Visible and rapid quenching of the emission of the film upon exposure to 2-nitrotoluene (2-NT) vapours at ambient condition was observed. Density functional theory (DFT) calculations established the favourable binding sites of 2-NT with the cluster. Desorption of 2-NT upon heating recovered the original luminescence, demonstrating the reusability of the sensor. Stable emission upon exposure to different organic solvents and quenching of it upon the exposure to 2, 4-dinitrotoluene and picric acid showed selectivity of the film to nitroaromatic species.
UR - https://pubs.rsc.org/en/content/articlelanding/2023/nr/d3nr00416c ER - 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 - Carboranethiol-Protected Propeller-Shaped Photoresponsive Silver Nanomolecule JF - Inorganic Chemistry Y1 - 2022 A1 - Arijit Jana A1 - Parvathy M Unnikrishnan A1 - Ajay K Poonia A1 - Jayoti Roy A1 - Madhuri Jash A1 - Ganesan Paramasivam A1 - Jan Machacek A1 - Kumaran Nair Valsala Devi Adarsh A1 - Tomas Base A1 - Thalappil Pradeep KW - Ag21 KW - boron KW - carborane KW - clusters KW - double rotor KW - luminescence KW - silver KW - thiol AB -We report the synthesis, structural characterization, and photophysical properties of a propeller-shaped Ag21 nano-molecule with six rotary arms, protected with m-carborane-9-thiol (MCT) and triphenylphosphine (TPP) ligands. Structural analysis reveals that the nanomolecule has an Ag13 central icosahedral core with six directly connected silver atoms and two more silver atoms connected through three Ag−S−Ag bridging motifs. While 12 MCT ligands protect the core through metal−thiolate bonds in a 3−6−3-layered fashion, two TPP ligands solely protect the two bridging silver atoms. Interestingly, the rotational orientation of a silver sulfide staple motif is opposite to the orientation of carborane ligands, resembling the existence of a bidirectional rotational orientation in the nanomolecule. Careful analysis reveals that the orientation of carborane ligands on the cluster’s surface resembles an assembly of double rotors. The zero circular dichroism signal indicates its achiral nature in solution. There are multiple absorption peaks in its UV−vis absorption spectrum, characteristic of a quantized electronic structure. The spectrum appears as a fingerprint for the cluster. High-resolution electrospray ionization
mass spectrometry proves the structure and composition of the nanocluster in solution, and systematic fragmentation of the molecular ion starts with the loss of surface-bound ligands with increasing collision energy. Its multiple optical absorption features are in good agreement with the theoretically calculated spectrum. The cluster shows a narrow near-IR emission at 814 nm with a Stokes shift of 355 nm. The Ag21 nanomolecule is thermally stable at ambient conditions up to 100 °C. However, white-light illumination (lamp power = 120−160 W) shows photosensitivity, and this induces structural distortion, as confirmed by changes in the Raman and electronic absorption spectra. Femtosecond and nanosecond transient absorption studies reveal an exceptionally stable excited state having a lifetime of 3.26 ± 0.02 μs for the carriers, spread over a broad wavelength region of 500−650 nm. The formation of core-centered long-lived carriers in the excited state is responsible for the observed light-activated structural distortion.
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.
VL - 15 UR - https://pubs.acs.org/doi/abs/10.1021/acsnano.1c02602 IS - 10 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 - Nucleated Crystallization of Isotactic Polypropylene in Multilayered Sandwich Nanocomposites with Gold Particles JF - Journal of Applied Polymer Science Y1 - 2012 A1 - Miroslav Slouf A1 - Antonin Sikora A1 - Ewa Pavlova A1 - Helena Vlkova A1 - Josef Baldrian A1 - Tomas Base A1 - Ewa Piorkowska VL - 125 UR - http://onlinelibrary.wiley.com/doi/10.1002/app.36589/abstract 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 - The adhesion and growth of vascular smooth muscle cells in cultures on carboranethiol-modified gold films JF - Engineering of Biomaterials Y1 - 2008 A1 - Martn Parize A1 - Tomas Base A1 - Michael G S Londesborough A1 - Vera Lisa A1 - Lucie Bacakova VL - 11 UR - http://neutron.ujf.cas.cz/vdg/LC06041/2008_W_Parizek_1.pdf ER - TY - Generic T1 - Carborane Thiol-modified Gold Surfaces. A Study and Comparison of Modified Cluster and Flat Surfaces T2 - 12th International Meeting on Boron Chemistry (IMEBORON-XII) Y1 - 2005 A1 - Tomas Base A1 - Zdenek Bastl A1 - Zbynek Plzak A1 - Tomas Grygar A1 - Jaromir Plesek A1 - Michael J Carr JF - 12th International Meeting on Boron Chemistry (IMEBORON-XII) CY - Sendai, Japan, 11 ER - TY - JOUR T1 - Carboranethiol-Modified Gold Surfaces. A Study and Comparison of Modified Cluster and Flat Surfaces JF - Langmuir Y1 - 2005 A1 - Tomas Base A1 - Zdenek Bastl A1 - Zbynek Plzak A1 - Tomas Grygar A1 - Jaromir Plesek A1 - Michael J Carr A1 - Vaclav Malina A1 - Jan Subrt A1 - Jaroslav Bohacek A1 - Eva Vecernikova A1 - Otomar Kriz AB -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 VL - 21 UR - http://pubs.acs.org/doi/abs/10.1021/la051122d IS - 17 ER - TY - JOUR T1 - Carborane-thiol protected copper nanoclusters: Stimuli-responsive materials with tunable phosphorescence JF - Chemical Science Y1 - 0 A1 - Arijit Jana A1 - Madhuri Jash A1 - Wakeel A Dar A1 - Jayoti Roy A1 - Papri Chakraborty A1 - Paramasivam Ganesan A1 - Sergei Lebedkin A1 - Kaplan Kirakci A1 - Sujan Manna A1 - P. K. Sudhadevi Antharjanam A1 - Jan Machacek A1 - Monika Kucerakova A1 - Sundargopal Ghosh A1 - Kamil Lang A1 - Manfred Kappes A1 - Tomas Base A1 - T. Pradeep KW - boron KW - carborane KW - Cluster KW - Copper KW - Phosphorescence KW - Responsive KW - thiol AB -
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.
UR - https://pubs.rsc.org/en/content/articlelanding/2023/sc/d2sc06578a ER -