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Mehla N, Mukhopadhyaya A, Ali S, Ali ME. Orchestration of ferro- and anti-ferromagnetic ordering in gold nanoclusters. NANOSCALE 2024; 16:13445-13456. [PMID: 38920340 DOI: 10.1039/d4nr00856a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/27/2024]
Abstract
The unpaired electron in the gold clusters (Aun, n = no. of Au atoms) with an odd number of total electrons is solely responsible for the magnetic properties in the small-sized Au nano-clusters. However, no such unpaired electron is available due to pairing in the even number of atom gold clusters and behaving as a diamagnetic entity similar to bulk gold. In this work, we unveiled the spin-density distribution of odd Aun clusters with n = 1 to 19 that reveals that a single unpaired electron gets distributed non-uniformly among all Au-atoms depending on the cluster size and morphology. The delocalization of the unpaired electron leads to the spin dilution approaching a value of ∼1/n spin moments on each atom for the higher clusters. Interestingly, small odd-numbered gold clusters possess spin-magnetic moments similar to the delocalized spin moments as of organic radicals. Can cooperative magnetic properties be obtained by coupling these individual magnetic gold nanoparticles? In this work, by applying state-of-the-art computational methodologies, we have demonstrated ferromagnetic or anti-ferromagnetic couplings between such magnetic nanoclusters upon designing suitable organic spacers. These findings will open up a new avenue of nanoscale magnetic materials combining organic spacers and odd-electron nano-clusters.
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Affiliation(s)
- Nisha Mehla
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India.
| | - Aritra Mukhopadhyaya
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India.
| | - Shahjad Ali
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India.
| | - Md Ehesan Ali
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India.
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2
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Naidji B, Hallez L, Et Taouil A, Rebetez M, Hihn JY. Effect of cavitation intensity control on self-assembling of alkanethiols on gold in room temperature ionic liquids. ULTRASONICS SONOCHEMISTRY 2021; 75:105610. [PMID: 34087756 PMCID: PMC8184662 DOI: 10.1016/j.ultsonch.2021.105610] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/14/2021] [Accepted: 05/25/2021] [Indexed: 05/14/2023]
Abstract
This study investigates the effect of cavitation intensity on self-assembling of alkanethiol molecules on gold in room temperature ionic liquids (RTILs) under low frequency ultrasound irradiation (20 kHz). The use of RTILs, with low vapor pressure, enabled cavitation activity to be controlled up to quenching through pressure decrease within an argon-saturated atmosphere. This control possibility was used to acquire deeper insights into the role of cavitation on self-assembling processes. It was shown by electrochemical, contact angles and Polarization Modulation - Infrared Reflection Absorption Spectroscopy (PM-IRRAS) measurements that cavitation activates orientation and organization of self-assembled monolayers (SAM). X-ray Photoelectron Spectroscopy (XPS) revealed that, even if chemical adsorption of molecules is highly activated under ultrasound irradiation, it is not dependent on acoustic cavitation intensity.
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Affiliation(s)
- B Naidji
- Institut UTINAM, UMR 6213 CNRS, Univ. Bourgogne-Franche-Comte, 30 Avenue de Observatoire, 25009 Cedex Besançon, France
| | - L Hallez
- Institut UTINAM, UMR 6213 CNRS, Univ. Bourgogne-Franche-Comte, 30 Avenue de Observatoire, 25009 Cedex Besançon, France
| | - A Et Taouil
- Institut UTINAM, UMR 6213 CNRS, Univ. Bourgogne-Franche-Comte, 30 Avenue de Observatoire, 25009 Cedex Besançon, France
| | - M Rebetez
- Institut UTINAM, UMR 6213 CNRS, Univ. Bourgogne-Franche-Comte, 30 Avenue de Observatoire, 25009 Cedex Besançon, France
| | - J-Y Hihn
- Institut UTINAM, UMR 6213 CNRS, Univ. Bourgogne-Franche-Comte, 30 Avenue de Observatoire, 25009 Cedex Besançon, France.
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Poggini L, Lunghi A, Collauto A, Barbon A, Armelao L, Magnani A, Caneschi A, Totti F, Sorace L, Mannini M. Chemisorption of nitronyl-nitroxide radicals on gold surface: an assessment of morphology, exchange interaction and decoherence time. NANOSCALE 2021; 13:7613-7621. [PMID: 33881100 DOI: 10.1039/d1nr00640a] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A combined Tof-SIMS, XPS and STM characterization has been performed to study the deposition of a sulphur-functionalized nitronyl nitroxide radical on Au(111) clearly demonstrating the chemisorption of intact molecules. Continuous -wave EPR characterization showed that the radical molecules maintain their paramagnetic character. Pulsed EPR measurements allowed to determine the decoherence time of the nanostructure at 80 K, which turned out to be comparable to the one measured in frozen solution and longer than previously reported for many radicals and other paramagnetic molecules at much lower temperatures. Furthermore, we conducted a state-of-the-art ab initio molecular dynamics study, suggesting different possible scenarios for chemisorption geometries and predicting the energetically favoured geometry. Calculation of the magnetic properties indicates a partial non-innocent role of the gold surface in determining the magnetic interactions between radicals in packed structures. This suggests that the observed EPR spectrum is to be attributed to low-density domains of disordered radicals interacting via dipolar interactions.
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Affiliation(s)
- Lorenzo Poggini
- Department of Chemistry "Ugo Schiff" and INSTM Research Unit, University of Florence, I-50019 Sesto Fiorentino, Italy. and ICCOM-CNR, via Madonna del Piano 10, 50019 Sesto, Fiorentino, Italy.
| | - Alessandro Lunghi
- Department of Chemistry "Ugo Schiff" and INSTM Research Unit, University of Florence, I-50019 Sesto Fiorentino, Italy.
| | - Alberto Collauto
- Department of Chemical Sciences and INSTM Research Unit, University of Padua, I-35131 Padova, Italy
| | - Antonio Barbon
- Department of Chemical Sciences and INSTM Research Unit, University of Padua, I-35131 Padova, Italy
| | - Lidia Armelao
- Department of Chemical Sciences and INSTM Research Unit, University of Padua, I-35131 Padova, Italy and Institute of Condensed Matter Chemistry and Technologies for Energy, National Research Council of Italy, ICMATE-CNR, via Marzolo 1, 35131 Padua, Italy and Department of Chemical Sciences and Materials Technologies, National Research Council of Italy, DSCTM - CNR, Piazzale A. Moro 7, 00185 Rome, Italy
| | - Agnese Magnani
- Department of Biotechnologies, Chemistry and Pharmacy, and INSTM Research Unit, University of Siena, I-53100 Siena, Italy
| | - Andrea Caneschi
- DIEF - Department of Industrial Engineering and INSTM Research Unit, University of Florence, Via S. Marta 3, I-50139 Florence, Italy
| | - Federico Totti
- Department of Chemistry "Ugo Schiff" and INSTM Research Unit, University of Florence, I-50019 Sesto Fiorentino, Italy.
| | - Lorenzo Sorace
- Department of Chemistry "Ugo Schiff" and INSTM Research Unit, University of Florence, I-50019 Sesto Fiorentino, Italy.
| | - Matteo Mannini
- Department of Chemistry "Ugo Schiff" and INSTM Research Unit, University of Florence, I-50019 Sesto Fiorentino, Italy.
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Roy F, Et Taouil A, Lallemand F, Heintz O, Moutarlier V, Hihn JY. Alkanethiol self-assembling on gold: Influence of high frequency ultrasound on adsorption kinetics and electrochemical blocking. ULTRASONICS SONOCHEMISTRY 2018; 40:9-16. [PMID: 28254342 DOI: 10.1016/j.ultsonch.2017.02.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 01/30/2017] [Accepted: 02/09/2017] [Indexed: 06/06/2023]
Abstract
Self-assembling of undecanthiol (C11SH) on polycrystalline gold was investigated under two different conditions. The kinetics of C11SH grafting was studied without and under high frequency ultrasound irradiation. Two electrochemical experiments were extensively carried out in order to determine electrochemical surface blocking of adsorbed layers as a function of grafting time: chronoamperometry in-situ monitoring and cyclic voltammetry. Interestingly, the grafting process is highly accelerated under sonication, and C11SH modified substrates of good quality are obtained after 3h' immersion under ultrasound irradiation. This would allow elaboration of high-quality alkanethiol modified samples within much shorter times. Water contact angle measurements and X-ray Photoelectron Spectroscopy (XPS) confirmed the presence of adsorbed undecanthiol on the gold surface. A very close link between electrochemical blocking, surface hydrophobicity and species chemical grafting was established.
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Affiliation(s)
- Florian Roy
- Institut UTINAM, UMR 6213 CNRS, Univ Bourgogne Franche-Comté, 30 Avenue de l'Observatoire, 25009 Besançon Cedex, France
| | - Abdeslam Et Taouil
- Institut UTINAM, UMR 6213 CNRS, Univ Bourgogne Franche-Comté, 30 Avenue de l'Observatoire, 25009 Besançon Cedex, France
| | - Fabrice Lallemand
- Institut UTINAM, UMR 6213 CNRS, Univ Bourgogne Franche-Comté, 30 Avenue de l'Observatoire, 25009 Besançon Cedex, France
| | - Olivier Heintz
- ICB Laboratory, UMR 6303 CNRS, Univ Bourgogne Franche-Comté, 9, Av. Alain Savary, 21078 Dijon Cedex, France
| | - Virginie Moutarlier
- Institut UTINAM, UMR 6213 CNRS, Univ Bourgogne Franche-Comté, 30 Avenue de l'Observatoire, 25009 Besançon Cedex, France
| | - Jean-Yves Hihn
- Institut UTINAM, UMR 6213 CNRS, Univ Bourgogne Franche-Comté, 30 Avenue de l'Observatoire, 25009 Besançon Cedex, France.
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5
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Tuca E, Paci I. Computer simulations of self-assembled energy materials. MOLECULAR SIMULATION 2017. [DOI: 10.1080/08927022.2017.1306063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- E. Tuca
- Department of Chemistry, University of Victoria, Victoria, Canada
| | - I. Paci
- Department of Chemistry, University of Victoria, Victoria, Canada
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Choudhury D, Rajaraman G, Sarkar SK. Self limiting atomic layer deposition of Al2O3 on perovskite surfaces: a reality? NANOSCALE 2016; 8:7459-65. [PMID: 26987744 DOI: 10.1039/c5nr06974b] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The feasibility of self-saturated atomic layer deposition of Al2O3 on an organolead halide perovskite (MAPbI3-xClx) surface through a well known trimethylaluminium (TMA)-water (H2O) chemistry is studied. Though the sequential dosages of reactants form films on the perovskite surfaces, a self saturated growth is never observed. Self-saturation leads to the degradation of the material. Both experimental and density functional theory calculations are carried out for complete understanding of the growth mechanism of self-limiting Al2O3 on the perovskite surface.
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Affiliation(s)
- Devika Choudhury
- Department of Energy Science and Engineering, Indian Institute of Technology Bombay, Mumbai-400076, India.
| | - Gopalan Rajaraman
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai-400076, India
| | - Shaibal K Sarkar
- Department of Energy Science and Engineering, Indian Institute of Technology Bombay, Mumbai-400076, India.
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7
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Tuca E, Paci I. Fundamental aspects in surface self-assembly: theoretical implications of molecular polarity and shape. Phys Chem Chem Phys 2016; 18:6498-508. [PMID: 26864632 DOI: 10.1039/c5cp04479k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We investigate fundamental aspects of structure formation in molecular self-assembly, by examining the emergence of order upon adsorption of a series of model molecules. It is known that strongly polar diatomic molecules form three-dimensional crystals in the absence of a substrate. This tendency can be disrupted upon assembly on a solid surface, and various other types of order may arise. Depending on the relative strength of the interactions, disordered phases, two-dimensional crystals commensurate to the surface, and unmodified crystals were observed upon adsorption of simple dipoles in the present work. Introduction of steric features, in the form of a longer backbone or substituents external to the polar pair, led to even richer phase diagrams. The formation of two-dimensional phases with nematic (parallel) or antiparallel alignment was accomplished by altering the polarity of the end groups on needle-like molecules, whereas embedded charged groups made two-dimensional structure unstable for even very long molecules. These molecules preferred to align in long, often desorbed, molecular wires. The wealth of phases observed here parallel the results of experimental systematic or incidental studies of the relationships between molecular interactions and self-assembled patterns, and provide some insight into the molecular handles that self-assembly researchers can wield to guide the process towards a desired structural outcome.
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Affiliation(s)
- Emilian Tuca
- Department of Chemistry and the Centre for Advanced Materials and Related Technology, University of Victoria, Victoria, BC V8W 3V6, Canada.
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8
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Caneschi A, Gatteschi D, Totti F. Molecular magnets and surfaces: A promising marriage. A DFT insight. Coord Chem Rev 2015. [DOI: 10.1016/j.ccr.2014.11.016] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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9
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Totaro P, Poggini L, Favre A, Mannini M, Sainctavit P, Cornia A, Magnani A, Sessoli R. Tetrairon(III) single-molecule magnet monolayers on gold: insights from ToF-SIMS and isotopic labeling. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:8645-8649. [PMID: 25000391 DOI: 10.1021/la500846a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
To work as magnetic components in molecular electronics and spintronics, single-molecule magnets (SMMs) must be reliably interfaced with metals. The organization on gold of a Fe4 SMM carrying two acetyl-protected thiol groups has been studied by exploiting the surface sensitivity of time-of-flight secondary ion mass spectrometry (ToF-SIMS), additionally powered by the use of an isotopic labeling strategy. Deposition from millimolar dichloromethane solutions results in a higher surface coverage and better packed monolayers as compared with previous protocols based on more diluted solutions. Fe4 complexes are chemically tethered to the surface via a single Au-S bond while they still contain an intact SAc group.
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Affiliation(s)
- Pasquale Totaro
- Laboratory of Molecular Magnetism (LaMM), Dipartimento di Chimica "Ugo Schiff", Università degli Studi di Firenze & INSTM RU of Firenze , via della Lastruccia 3-13, 50019 Sesto Fiorentino, Florence, Italy
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10
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Fan XL, Xiao P, Ran RX, Lau WM. Self-assembled monolayers of CH3S from the adsorption of CH3SSCH3 on Au(111). Phys Chem Chem Phys 2014; 16:2533-41. [PMID: 24382397 DOI: 10.1039/c3cp54315c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
By performing density functional theory calculations, we have examined the adsorption of dimethyl disulfide (CH3SSCH3) on Au(111). In addition, we have also charted the reaction paths leading to dissociation of the S-S bond and the formation of thiolate-adatom species. Further, we have simulated the scanning tunneling microscopic (STM) images of the key adsorption intermediates and products and compared them with the experimental data available in the literature. In summary, our computations show that CH3SSCH3 adsorbs on Au(111) non-dissociatively with a moderate adsorption energy 0.42 eV for the trans-conformation which is 0.24 eV more stable than its cis-isomer. When the adsorbed trans-CH3SSCH3 dissociates at low temperature, the two CH3S fragments are retained by the closest neighboring sites and the trans-conformation of them prior to S-S dissociation can be preserved. The activation barrier to rotating the CH3S fragments on Au(111) is 0.17 eV so a moderate temperature rise can facilitate the transformation of the trans-conformation and generate a mixture of the trans- and cis-conformation. Our calculations also show that intrinsic defects such as gold adatoms (Auad) are active in CH3SSCH3 dissociation in two mechanisms: a direct mechanism in which CH3SSCH3 dissociation drives Auad formation and CH3S-Auad formation simultaneously, with leftover vacancies as by-products; a sequential mechanism in which Auad is present in advance and subsequently interacts with a nearby CH3S fragment to form CH3S-Auad. The respective activation barriers are 0.15 and 0.32 eV for the trans- and cis-CH3S-Auad-SCH3 complex along the direct mechanism, and 0.21 and 0.18 eV along the sequential mechanism.
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Affiliation(s)
- Xiao-Li Fan
- School of Materials Science and Engineering, State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, 127 YouYi Western Road, Xi'an, Shaanxi 710072, China.
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11
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Qin Z, Cong R, Wu X, Liu Z, Xie H, Tang Z, Jiang L, Fan H. Photoelectron velocity-map imaging spectroscopic and theoretical study on the reactivity of the gold atom toward CH3SH, CH3OH, and H2O. J Chem Phys 2013; 139:034315. [PMID: 23883035 DOI: 10.1063/1.4813631] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Photoelectron velocity-map imaging spectroscopy has been used to study the reaction of the anionic gold atom with the HR (R = SCH3, OCH3, OH) molecules. The solvated [Au···HR](-) and inserted [HAuR](-) products have been experimentally observed for R = SCH3, whereas only solvated [Au⋯HR](-) products were found for R = OCH3 and OH. This significant difference in the photoelectron spectra suggests the different reactivity of the Au(-) toward the CH3SH, CH3OH, and H2O molecules. Second order Møller-Plesset perturbation theory and coupled-cluster single double triple excitation calculations have been performed to aid the structural assignment of the spectra and to explore the reaction mechanism. Activation energies for the isomerizations of the solvated structures to the inserted ones in the Au(-)∕Au + HR reactions (R = OCH3 and OH) are predicted to be much higher than those for the Au(-)∕Au + CH3SH reactions, supporting the experimental observation. Theoretical calculations provide the evidence that the intriguing [HAuSCH3](-) product may be formed by the attachment of the electron onto the neutral HAuSCH3 species or the isomerization from the anionic [Au···HSCH3](-) one. These findings should be helpful for understanding the feature that the thiols are able to form the staple motifs, whereas CH3OH and H2O are not.
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Affiliation(s)
- Zhengbo Qin
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
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12
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Fischer JA, Zoldan VC, Benitez G, Rubert AA, Ramirez EA, Carro P, Salvarezza RC, Pasa AA, Vela ME. Sulfidization of Au(111) from thioacetic acid: an experimental and theoretical study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:15278-15285. [PMID: 23002810 DOI: 10.1021/la303059u] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We have studied the adsorption of thioacetic acid (TAAH) on Au(111) from solution deposition. The close proximity of the SH groups to CO groups makes this molecule very attractive for exploring the effect of the functional group on the stability of the S-C and S-Au bonds. Although thioacetic acid was supposed to decompose slowly in water by hydrolysis supplying hydrogen sulfide, this behavior is not expected in nonpolar solvents such as toluene or hexane. Therefore, we have used these solvents for TAAH self-assembly on the Au(111) surface. The characterization of the adsorbates has been done by electrochemical techniques, X-ray photoelectron spectroscopy (XPS), and scanning tunneling microscopy (STM). We have found that even in nonpolar solvents thioacetic acid decomposes to S. The results have been discussed on the basis that the adsorbed species suffer a cleavage on the Au surface, leaving the S attached to it. The dissociation is a spontaneous process that reaches the final state very fast once it is energetically favorable, as can be interpreted from DFT calculations. The thioacetic acid adsorption reveals the strong effect that produces a functional group and the key role of the S-H bond cleavage in the self-assembly process.
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Affiliation(s)
- Jeison A Fischer
- Laboratório de Filmes Finos e Superfícies, Departamento de Física, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
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