Papers by Dr. Prakash Chandra Mondal
New Journal of Chemistry, 2015
Monomolecular layers of Ru(ii)-4′carboxylicphenyl-terpyridyl complex are prepared on glass and IT... more Monomolecular layers of Ru(ii)-4′carboxylicphenyl-terpyridyl complex are prepared on glass and ITO-coated glass substrates. The optical, electrochemical and stability studies indicate that the present system is highly robust.
arXiv (Cornell University), Apr 29, 2022
Angewandte Chemie, Jul 19, 2023
Canadian Journal of Chemistry, Jul 1, 2022
Transparent conductive oxides such as indium tin oxide (ITO) substrates are commonly employed as ... more Transparent conductive oxides such as indium tin oxide (ITO) substrates are commonly employed as prime materials for optoelectronic applications. Enhancement in functions of such devices often compels stable and robust modification of the ITO substrate to improve its interfacial charge transfer characteristics. Thereby, in this work, naphthyl modifier multilayer films are fabricated on ITO substrate using conventional electrochemical reduction of 1-naphthyl diazonium salts (NAPH-D) via altering its concentration ranging from 2 mM to 12 mM with a step size of 2. Surface coverage was significantly tuned by varying NAPH-D concentration, keeping other parameters such as the number of scans and scan rate constant. For lower concentration (2 mM), the molecular thickness ~ 6 nm was obtained, whereas, with higher concentration (12 mM) produced around 15-18 nm thickness. Atomic force microscopy (AFM), cyclic voltammetry and electrochemical impedance spectroscopy (EIS) in the presence of a ferrocene redox probe also supports the formation of well packed molecular film grown on the ITO surface. Further, the wettability property of the grafted naphthyl film was investigated at different surface coverages and correlated with charge transfer resistance (R ct) obtained from EIS studies.
Canadian Journal of Chemistry, 2022
Transparent conductive oxides such as indium tin oxide (ITO) substrates are commonly employed as ... more Transparent conductive oxides such as indium tin oxide (ITO) substrates are commonly employed as prime materials for optoelectronic applications. Enhancement in functions of such devices often compels stable and robust modification of the ITO substrate to improve its interfacial charge transfer characteristics. Thereby, in this work, naphthyl modifier multilayer films are fabricated on ITO substrate using conventional electrochemical reduction of 1-naphthyl diazonium salts (NAPH-D) via altering its concentration ranging from 2 mM to 12 mM with a step size of 2. Surface coverage was significantly tuned by varying NAPH-D concentration, keeping other parameters such as the number of scans and scan rate constant. For lower concentrations (2 mM), the molecular thickness ∼6 nm was obtained, whereas higher concentrations (12 mM) produced around 15–18 nm thickness. Atomic force microscopy (AFM), cyclic voltammetry, and electrochemical impedance spectroscopy (EIS) in the presence of a ferroc...
The Journal of Chemical Physics
Bio-spinterfaces present numerous opportunities to study spintronics across the biomolecules atta... more Bio-spinterfaces present numerous opportunities to study spintronics across the biomolecules attached to (ferro)magnetic electrodes. While it offers various exciting phenomena to investigate, it is simultaneously challenging to make stable bio-spinterfaces as biomolecules are sensitive to many factors that it encounters during thin-film growth to device fabrication. The chirality-induced spin-selectivity effect is an exciting discovery, demonstrating an understanding that a specific electron’s spin (either up or down) passes through a chiral molecule. The present work utilizes Ustilago maydis Rvb2 protein, an ATP-dependent DNA helicase (also known as Reptin), to fabricate bio-spintronic devices to investigate spin-selective electron transport through the protein. Ferromagnetic materials are well-known for exhibiting spin-polarization, which many chiral and biomolecules can mimic. We report herein spin-selective electron transmission through Rvb2 that exhibits 30% spin polarization a...
ACS applied materials & interfaces, Jan 8, 2015
Surface-confined hetero-metallic molecular triads (SURHMTs) were fabricated on SiO×-based solid s... more Surface-confined hetero-metallic molecular triads (SURHMTs) were fabricated on SiO×-based solid substrates using optically-rich and redox-active Fe, Os, and Ru based terpyridyl complexes as metallo-ligands and Cu2+ ions as linkers. Optical and electrochemical studies reveal efficient electronic intra-molecular communication in these assemblies. The UV-vis spectra of the triads exhibit a superposition of the metal-to-ligand charge-transfer bands of individual complexes, providing a significant enlargement of the optical window, useful for application. Similarly, cyclic voltammograms of SURHMT layers show a variety of redox peaks corresponding to individual complexes as well as multi-redox states at a low potential. Interaction of a representative SURHMT assembly with redox active NOBF4 was investigated and used as a basis for configuring molecular logic gates.
Nature Reviews Chemistry, 2023
The use of molecules bridged between two electrodes as a stable rectifier is an important goal in... more The use of molecules bridged between two electrodes as a stable rectifier is an important goal in molecular electronics. Until recently, however, and despite extensive experimental and theoretical work, many aspects of our fundamental understanding and practical challenges have remained unresolved and prevented the realization of such devices. Recent advances in custom-designed molecular systems with rectification ratios exceeding 105 have now made these systems potentially competitive with existing silicon-based devices. Here, we provide an overview and critical analysis of recent progress in molecular rectification within single molecules, self-assembled monolayers, molecular multilayers, heterostructures, and metal–organic frameworks and coordination polymers. Examples of conceptually important and best-performing systems are discussed, alongside their rectification mechanisms. We present an outlook for the field, as well as prospects for the commercialization of molecular rectifiers.
Coordination Chemistry Reviews
Ferrocene, since its discovery in 1951, has been extensively exploited as a redox probe in a vari... more Ferrocene, since its discovery in 1951, has been extensively exploited as a redox probe in a variety of processes ranging from solution chemistry, medicinal chemistry, supramolecular chemistry, surface chemistry to solid-state molecular electronic and spintronic circuit elements to unravel electrochemical charge-transfer dynamics. Ferrocene represents an extremely chemically and thermally stable, and highly reproducible redox probe that undergoes reversible one-electron oxidation and reduction occurring at the interfaces of electrode/ferrocene solution in response to applied anodic and cathodic potentials, respectively. It has been almost 70 years after its discovery and has become one of the most widely studied and model organometallic compounds not only for probing electrochemical charge-transfer process but also as molecular building blocks for the synthesis of chiral organometallic catalysts, potential drug candidates, polymeric compounds, electrochemical sensors, to name a few. Ferrocene and its derivatives have been a breakthrough in many aspects due to its versatile reactivity, fascinating chemical structures, unconventional metal-ligand coordination, and the magic number of electrons (18 e-). The present review discusses the recent progress made towards ferrocene-containing molecular systems exploited for redox reactions, surface attachment, spindependent electrochemical process to probe spin polarization, photo-electrochemistry, and integration into prototype molecular electronic devices. Overall, the present reviews demonstrate a piece of collective information about the recent advancements made towards the ferrocene and its derivatives that have been utilized as iconic redox markers.
Journal of the American Chemical Society, 2021
Small Methods, 2018
to engage in the design and synthesis of suitable organic molecules, giving birth to a new resear... more to engage in the design and synthesis of suitable organic molecules, giving birth to a new research domain known as "organic spintronics." [2] Organic molecules are fascinating, as they possess a number of convenient characteristics such as: (i) tunable optoelectronic properties, (ii) versatile chemical functionalities, (iii) longer spindiffusion length, (iv) they can be easily assembled on metal/semiconductor surfaces, and (v) they have unique interfacial properties, which include the molecular quantum confinement effect. Overall, these distinctive factors pave the way to the production of organic, and/or hybrid, solid-state devices. [3] Interestingly, chiral molecules are capable of transporting preferential spin for long distances without losing spin coherence or with negligible spin diffusion. [4] In pioneering work in 1999, Ron Naaman and co-workers experimentally observed that the transmission of electrons passing through chiral molecular films is spin specific, that is, a specific chiral molecule allows only one type of electron spin to be transported through the molecule, and this effect has been termed as the "chiral-induced spin selectivity" (CISS) effect. [4] According to the CISS effect (Figure 1), charge transport Chiro-Spintronics
Journal of the American Chemical Society, 2018
The internal potential profile and electric field are major factors controlling the electronic be... more The internal potential profile and electric field are major factors controlling the electronic behavior of molecular electronic junctions consisting of ∼1−10 nm thick layers of molecules oriented in parallel between conducting contacts. The potential profile is assumed linear in the simplest cases, but can be affected by internal dipoles, charge polarization, and electronic coupling between the contacts and the molecular layer. Electrochemical processes in solutions or the solid state are entirely dependent on modification of the electric field by electrolyte ions, which screen the electrodes and form the ionic double layers that are fundamental to electrode kinetics and widespread applications. The current report investigates the effects of mobile ions on nominally solid-state molecular junctions containing aromatic molecules covalently bonded between flat, conducting carbon surfaces, focusing on changes in device conductance when ions are introduced into an otherwise conventional junction design. Small changes in conductance were observed when a polar molecule, acetonitrile, was present in the junction, and a large decrease of conductance was observed when both acetonitrile (ACN) and lithium ions (Li +) were present. Transient experiments revealed that conductance changes occur on a microsecond−millisecond time scale, and are accompanied by significant alteration of device impedance and temperature dependence. A single molecular junction containing lithium benzoate could be reversibly transformed from symmetric current−voltage behavior to a rectifier by repetitive bias scans. The results are consistent with fieldinduced reorientation of acetonitrile molecules and Li + ion motion, which screen the electrodes and modify the internal potential profile and provide a potentially useful means to dynamically alter junction electronic behavior.
The Journal of Physical Chemistry C, 2019
Robust opto-electroactive monolayers of three different Ru II-terpyridyl complexes with aminoand ... more Robust opto-electroactive monolayers of three different Ru II-terpyridyl complexes with aminoand pyridyl-termination are fabricated on SiO ×-based substrates using siloxane-based attachment chemistry and either pyridyl or amine linkage to the preliminary prepared template. The UV-vis spectra of these monolayers display the characteristic metal-to-ligand charge-transfer bands, with a bathochromic shift as compared to the spectra of the respective metallo-ligands dissolved in acetonitrile solution. This shift is noticeably larger for the pyridyl-linked monolayers as compared to the amino-linked film, correlating qualitatively with the molecular grafting density. Cyclic voltammograms of the monolayers covalently attached onto ITO electrodes show reversible switching between the two redox states (Ru +2 to Ru +3 and vice-versa), with a typical one-electron redox behavior. The sensing response of the monolayers to a series of different metal ions was tested, with the amino-decorated films showing a particularly high sensitivity to Hg II and a closeto-linear response to this analyte in the ppm concentration range.
Chemphyschem : a European journal of chemical physics and physical chemistry, Jan 5, 2018
We report the experimental results of a study of the electron-transfer processes of redox-active ... more We report the experimental results of a study of the electron-transfer processes of redox-active metalloproteins bound to mixed self-assembled monolayers (SAMs) on magnetic (nickel or ultrathin gold-coated nickel) or nonmagnetic (gold) electrodes. Metalloproteins, such as hemoglobin (Hb), Cytochrome C (Cyt C), and Cyt C oxidase, are attached through electrostatic interactions to the free carboxylate or imidazole groups present in the mixed SAMs. The formation of both mixed SAMs and SAM/metalloprotein heterostructures were confirmed by using advanced surface analysis techniques, such as polarization modulation infrared reflection absorption spectroscopy and aqueous contact angle measurements. Electrochemical measurements indicated a stronger electronic coupling between Hb and Cyt C oxidase and the mixed-SAM-coated gold or gold-coated-nickel electrodes, whereas a weaker coupling was found between the protein and the pure nickel electrode. Surface coverage and the electron-transfer rat...
Chemphyschem : a European journal of chemical physics and physical chemistry, Jan 14, 2017
Well-defined Fe(II)-terpyridyl monolayers were fabricated on SiOx and conductive ITO-coated glass... more Well-defined Fe(II)-terpyridyl monolayers were fabricated on SiOx and conductive ITO-coated glass substrates via covalent bond formation between the metallo-organic complexes and a pre-assembled coupling layer. Three different homo- and heteroleptic complexes with the terminal pyridyl, amine, and phenyl groups were tested. All the films were found to be densely packed, homogeneous, and consisting of upright standing molecules. They exhibited high thermal (up to ~220°C) and temporal (up to 5h at 100°C) stability. The UV-vis spectra of the monolayers showed a pronounced metal-to-ligand charge-transfer bands with a significant red-shift as compared to the solution spectra of the respective metallo-ligands in the case of pendant pyridyl group quaternized with the coupling layer, while the shift was significantly smaller when the coupling layer was bonded to the primary amine (NH2) group of the complex. The cyclic voltammograms of the monolayers showed reversible, one-electron redox beh...
Nano letters, 2016
The combination of photonics and spintronics opens new ways to transfer and process information. ... more The combination of photonics and spintronics opens new ways to transfer and process information. It is shown here that in systems in which organic molecules and semiconductor nanoparticles are combined, matching these technologies results in interesting new phenomena. We report on light induced and spin-dependent charge transfer process through helical oligopeptide-CdSe nanoparticles' (NPs) architectures deposited on ferromagnetic substrates with small coercive force (∼100-200 Oe). The spin control is achieved by the application of the chirality-induced spin-dependent electron transfer effect and is probed by two different methods: spin-controlled electrochemichemistry and photoluminescence (PL) at room temperature. The injected spin could be controlled by excitation of the nanoparticles. By switching the direction of the magnetic field of the substrate, the PL intensity could be alternated.
New J. Chem., 2016
Heteroleptic terpyridyl complexes of Fe(ii) and Ru(ii) are synthesized. They are characterized us... more Heteroleptic terpyridyl complexes of Fe(ii) and Ru(ii) are synthesized. They are characterized using complimentary techniques and their optical and electrochemical properties are studied. A detailed computational study was also performed.
Lecture Notes in Computer Science, 2013
Logical form in logic and logical form (LF) in the Minimalist architecture of language are two di... more Logical form in logic and logical form (LF) in the Minimalist architecture of language are two different forms of representational models of semantic facts. They are distinct in their form and in how they represent some natural language phenomena. This paper aims to argue that the differences between logical form and LF have profound implications for the question about the nature of semantic interpretation. First, this can tell us whether semantic interpretation is computational and if so, in what sense. Second, this can also shed light on the ontology of semantic interpretation in the sense that the forms (that is, logical form and LF) in which semantic facts are expressed may also uncover where in the world semantic interpretation as such can be located. This can have surprising repercussions for reasoning in natural language as well.
Advanced materials (Deerfield Beach, Fla.), 2015
Conductive organic polymers are used in organic-based light-emitting diodes (OLEDs). It is expect... more Conductive organic polymers are used in organic-based light-emitting diodes (OLEDs). It is expected that by controlling the spin of the electrons that are injected from and into these devices, their energy efficiency will increase significantly. The work by C. Fontanesi, R. Naaman, and co-workers on page 1924 shows that the polymers themselves can serve as a spin filter, and this may allow the operation of spin-OLEDs without any magnetic component.
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Papers by Dr. Prakash Chandra Mondal