Papers by Dr. Prakash Chandra Mondal
arXiv (Cornell University), May 19, 2023
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's 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 (CISS) 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 ATPdependent DNA helicase (also known as Reptin) for the fabrication of bio-spintronic devices to investigate spin-selective electron transport through protein. Ferromagnetic materials are well-known for showing spin-polarization, which many chiral and biomolecules can mimic. We report spin-selective electron transmission through Rvb2 that exhibits 30% spin polarization at a low bias (+ 0.5 V) in a device configuration, Ni/Rvb2 protein/ITO measured under two different magnetic configurations. Our findings demonstrate that biomolecules can be put in circuit components without any expensive vacuum deposition for the top contact. Thus, it holds a remarkable potential to advance spin-selective electron transport in other biomolecules such as proteins, and peptides for biomedical applications.
arXiv (Cornell University), Mar 26, 2023
The present era has seen tremendous demands for low-cost electrochromic materials for visible-reg... more The present era has seen tremendous demands for low-cost electrochromic materials for visible-region multicolor display technology, paper-based, flexible, and wearable electronic devices, smart windows, and optoelectronic applications. Towards this goal, we report large-scale polyelectrochromic devices fabricated on rigid to flexible ITO substrates comprising novel anthracene containing viologen, (1,1'-bis(anthracen-9ylmethyl)-[4,4'-bipyridine]-1,1'-diium bromide, abbreviated as AnV 2+ ), and polythiophene (P3HT). Interestingly, the devices show three states of reversible visible color in response to the applied bias, sub-second to second switching time (0.7 s/1.6 s), and high coloration efficiency (484 cm 2 /C), longer cycling stability up to 3000 s (10 3 switching cycles). Thanks to the anthracenes moieties introduced to viologen that inhibit formation of undesired dimer of cation radicals formed in response to the applied bias, otherwise it would hamper the devices reconfiguration. The devices are fully characterized, and electrochromic performances are ensured by bias-dependent UV-Vis, and Raman spectroscopy. The fabricated electrochromic devices are tested with the commercially available low-cost cells to perform, which is highly desired for practical applications. The computational study facilitates the understanding of experimental results. The alternating current (AC)-based electrical impedance spectroscopy reveals that P3HT facilitates reducing charge transfer resistance of the devices. Our work shows CMOS compatibility and one of the best-performing devices that could pave the way for developing cost-effective flexible, and wearable electrochromic devices.
Materials advances, 2023
Chirality-induced metallic and metal-oxide nanoparticles (NPs) hold promising potential in chirop... more Chirality-induced metallic and metal-oxide nanoparticles (NPs) hold promising potential in chiroptical activity, asymmetric catalysis, chiral discrimination, and drug delivery. Herein, we report a simple but scalable method for the preparation of achiral, metallic colloidal Ag NPs in which chirality was imprinted using organic chiral inducers. Chirality can be imprinted into Ag NPs upon surface functionalization using L-and D-cysteine. The formation of nanostructure assemblies, morphology, and chemical compositions are ensured by electron microscopy (TEM, FE-SEM) and X-ray photoelectron spectroscopy (XPS). Amino acid-driven enhanced chiroptical activity, followed by anisotropy factors (g-factor) of the Ag core and thiolate adsorbates were investigated by CD spectroscopy. Strong chiroptical activity in cysteinemodified Ag NPs originates from metal-based interband electronic transitions (as transitions are highly energetic), which is absent in free chiral inducers. Considering the chiral ligands, individual or combined use for Ag NP surface modification as chemical inputs and CD signal as an output, an XOR logic gate was implemented. L-Cys@Ag and D-Cys@Ag NPs are integrated into electronic devices for DC-based electrical measurements (current-voltage, I-V) and AC-based electrical impedance spectroscopy (EIS) for deducing individual electrical components, followed by equivalent circuit modeling. The conductivity of the L-Cys driven-Ag NPs assembly decreases compared to the D-Cys Ag-NPs assemblies, thus ensuring a higher degree of Ag NPs surface modification than the former chiral inducer. The present work enriches the facile synthesis of chiral NPs and large-scale electrical devices that can be envisioned for chirality-driven photocatalysis, optoelectronic devices, bio-sensing, and molecular spintronics.
arXiv (Cornell University), May 2, 2022
Memory has always been a building block element for information technology. Emerging technologies... more Memory has always been a building block element for information technology. Emerging technologies such as artificial intelligence, big data, the internet of things, etc., require a novel kind of memory technology that can be energy efficient and have an exception data retention period. Among several existing memory technologies, resistive random-access memory (RRAM) is an answer to the above question as it is necessary to possess the combination of speed of RAM and nonvolatility, thus proving to be one of the most promising candidates to replace flash memory in next-generation non-volatile RAM applications. This review discusses the existing challenges and technological advancements made with RRAM, including switching mechanism, device structure, endurance, fatigue resistance, data retention period, and mechanism of resistive switching in inorganic oxides material used as a dielectric layer. Finally, a summary and a perspective on future research are presented.
arXiv (Cornell University), Jun 27, 2022
Metal-organic frameworks (MOFs) symbolize the particular class of hybrid crystalline, nano-porous... more Metal-organic frameworks (MOFs) symbolize the particular class of hybrid crystalline, nano-porous materials made of either discrete metal ions or clusters with organic linkers. Past studies on MOFs-based materials largely focused on porosity, chemical and structural diversity, gas sorption, sensing, drug delivery, catalysis, and separation applications. However, initial efforts either neglected or have not gained much attention to refine the electrical conductivity of MOFs materials. MOFs reported earlier with poor electrical conductivity (σ ˂ 10 -7 -10 -10 S cm -1 ) impeded to employ in electronics, optoelectronics, and renewable energy storage applications. To overcome this issue, the MOFs community has been engaged in improving electrical conductivity by adopting several intriguing strategies. We shed light on the charge transport mechanisms which are mainly two processes, either through a bond or through space. This review aims to showcase the current scenario on creatively designed MOF materials followed by fabrication advancement of high-quality molecular thin films, and semiconductor device fabrication for stimuli-responsive current-voltage (I-V) studies. Overall, the review addresses the pros and cons of the MOFs-based electronics, followed by our prediction on improvement MOFs composition, mechanically stable interfaces, device stacking, further relevant experiments which can be of great interest to the MOFs researchers in improving further devices performances.
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
The concept of utilizing a molecule bridged between two electrodes as a stable rectifying device ... more The concept of utilizing a molecule bridged between two electrodes as a stable rectifying device with the possibility of commercialization is a "holy grail" of molecular electronics. Molecular rectifiers do not only exploit the electronic function of the molecules but also offer the possibility of their direct integration into specific nano-electronic circuits. However, even after nearly three decades of extensive experimental and theoretical work, the concept of molecular rectifiers still has many unresolved aspects concerning both the fundamental understanding of the underlying phenomena and the practical realization. At the same time, recent advancements in molecular systems with rectification ratios exceeding 10 5 are highly promising and competitive to the existing silicon-based devices. Here, we provide an overview and critical analysis of the current state and recent progress in molecular rectification relying on the different design concepts and material platforms such as single molecules, self-assembled monolayers, molecular multilayers, heterostructures, and metal-organic frameworks and coordination polymers. The involvement of crucial parameters such as the energy of molecular orbitals, electrode-molecule coupling, and asymmetric shifting of the energy levels will be discussed. Finally, we conclude by critically addressing the challenges and prospects for progress in the field and perspectives for the commercialization of molecular rectifiers.
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...
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Papers by Dr. Prakash Chandra Mondal