Department of Chemistry

Ashoka University is a private university located in Sonipat, Haryana, India, focusing on liberal arts and sciences. It was established in 2014.&nbsp;It is guided by an academic council of academics and scholars from around the world. The council sets the university&#39;s academic standard, advising on matters of curriculum, faculty hiring and research.&nbsp;

Ashoka University offers a full-time 3 (+ 1) year undergraduate programme. The University comprises of&nbsp;2500 plus students, with a mix of both national and international students.&nbsp; &nbsp;

&nbsp;

&nbsp;

Ashoka University

In recent years, researchers have shifted their focus towards investigating the redox properties of ancillary ligand backbones for small molecule activation. Several metal complexes have been reported for electrocatalytic H2 evolution reaction (HER), providing valuable mechanistic insights. This process involves efficient coupling of electrons and protons. Redox‐active ligands stipulate internal electron transfer and promote effective orbital overlap between metal and ligand, thereby enabling efficient proton‐coupled electron transfer reactions. Understanding such catalytic mechanisms requires thorough spectroscopic and computational analyses. Herein, we summarize recent examples of molecular electrocatalysts based on 3d transition metals that have significantly influenced mechanistic pathways, thus emphasizing the multifaceted role of metal‐ligand cooperativity.

Chemistry-A European Journal

<a href="https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202302195">Exploring the multifarious role of ligand in electrocatalytic hydrogen evolution reaction pathways</a>

Cadmium (Cd2+), a heavy metal ion used in numerous industries, has toxic adverse effects on the environment; it is crucial to develop a quick and reliable method for Cd2+ determination. Fluorescent biomass-derived carbon quantum dots (CD) with rich carboxyl groups on the surface were synthesized using water amaranth leaves by hydrothermal method with a 12.1% quantum yield. The surface of CD was further modified with 1-pyrene carboxaldehyde (PC) to synthesize pyrene carboxaldehyde-carbon quantum dots (PC-CD). This study developed a fluorescent ratiometric nanosensor using a covalently functionalized CD with pyrene derivative and demonstrates highly selective identification capability towards Cd2+ over competing metal ions. The Nano sensor has significant selectivity towards Cd2+ in an excellent linear range of 0-70 μM with a detection limit as low as 15 nM and demonstrates excellent water solubility and biocompatibility. Transmission electron spectroscopy (TEM), Fourier Transform infrared spectroscopy (FT-IR), and X-ray photon spectroscopy (XPS) were used to identify the surface functionalization of PC-CD. Finally, the developed ratiometric sensor was used for detecting Cd2+ metal ions from various water effluents. © 2023 Elsevier Ltd.

World University root node

Journal of Environmental Chemical Engineering

A ratiometric fluorescent sensor based on dual-emissive carbon dot for the selective detection of Cd2+

Recent synthesis of sp-hybridized cyclo[18]carbon allotrope has attracted immense curiosity. Since then, a generous amount of theoretical studies concerning aromaticity, adsorption, and spectra of the molecule have been performed. However, very few stuides have been carried out concerning its reactivities and catalytic behaviour. In this article, a DFT-based inquisition has been reported regarding the reactivity of Si substituted cyclo[18]carbon molecule towards molecular N2. Results show that the Si substituted derivative is effective in producing adducts with molecular nitrogen. Charge calculations and IRC trapping methods indicate that only the Si center of C17Si and its (HOMO-1) level participate in N2 addition. The N-adduct so formed, is then found to spontaneously react with molecular H2. The addition of two H2 molecules to the activated nitrogen molecule to give respective amine derivatives have also been studied. The successful generation of the precursor of NH3 by C17Si lays a clear emphasis on its potentiality. © 2022 Wiley-VCH GmbH.

ChemPhysChem

Activation and Conversion of Molecular Nitrogen to the Precursor of Ammonia on Silicon Substituted Cyclo[18]Carbon: a DFT Design

Organic molecules with an active dipole moment have a natural propensity to align in an antiparallel fashion in the solid state, resulting in zero macroscopic polarization. This primary limitation makes the material unresponsive to switching with electric fields, mechanical forces, and to intense laser light. A single-component organic material that bestows macroscopic dipole-driven electro-mechanical and optical functions, e.g., piezoelectric, ferroelectric and nonlinear optical (NLO) activity, is unprecedented due to the design challenges imparted by crystal symmetry and dipole orientations. Herein we report a crystalline organic material that self-assembles with a polar order (P1), and is endowed with a high piezoelectric coefficient (d33-47 pm V−1), as well as ferroelectric and Debye-type relaxor properties. In addition, it shows second harmonic generation (SHG) activity, which is more than five times that of the benchmark potassium dihydrogen phosphate. Piezoelectric force microscopy (PFM) images validated electro-mechanical deformations. Piezoresponse force spectroscopy (PFS) studies confirmed a signature butterfly-like amplitude and a phase loop. To the best of our knowledge, this is the first report of a folded supramolecular π-system that manifests unidirectionally oriented dipoles and exhibits piezoelectricity, ferroelectricity, and has excellent ability to generate second harmonic light. These findings can herald new design possibilities based on folded architectures to explore opto-, electro- and mechano-responsive multifaceted functions. © 2023 The Royal Society of Chemistry.

Chemical Science

A folded p-system with supramolecularly oriented dipoles: single-component piezoelectric relaxor with NLO activity

Dipolar coupled multi-spin systems have the potential to be used as molecular qubits. Herein we report the synthesis of a molecular multi-qubit model system with three individually addressable, weakly interacting, spin urn:x-wiley:14337851:media:anie202207947:anie202207947-math-0001 centres of differing g-values. We use pulsed Electron Paramagnetic Resonance (EPR) techniques to characterise and separately address the individual electron spin qubits; CuII, Cr7Ni ring and a nitroxide, to determine the strength of the inter-qubit dipolar interaction. Orientation selective Relaxation-Induced Dipolar Modulation Enhancement (os-RIDME) detecting across the CuII spectrum revealed a strongly correlated CuII-Cr7Ni ring relationship; detecting on the nitroxide resonance measured both the nitroxide and CuII or nitroxide and Cr7Ni ring correlations, with switchability of the interaction based on differing relaxation dynamics, indicating a handle for implementing EPR-based quantum information processing (QIP) algorithms.

Angewandte Chemie - International Edition

Modelling Conformational Flexibility in a Spectrally Addressable Molecular Multi-Qubit Model System

The requirement of an efficient energy storage device has become an exclusive requisite for technological and scientific innovations. In the present work, by using the 2D monolayer semiconductor-semiconductor and semiconductor-metal lateral interface structures as the model structure, we performed periodic DFT calculations to examine the possibility of 2D MoS2-MoSe2 and MoS2-NbS2 lateral heterostructures (LHS) as the electrodes of a battery. The MoS2-MoSe2 lateral interface is a semiconductor, whereas the MoS2-NbS2 lateral interface preserves metallic character. Besides, we found that Li/Na ion adsorption is more influential on the lateral heterostructure and is exothermic, with ultrafast diffusion, and is comparable to their monolayers. Meanwhile, the calculated open-circuit voltage is enormously low, like other widely investigated pristine 2D materials. The enhanced electrical conductivity, short diffusion distances, minutely low equilibrium voltage with good stability, large theoretical capacity and ultrahigh mechanical strength offered bare 2D TMDs lateral heterostructures as a potential candidate for LIBs/SIBs applications. This work broadens the possibility of applications based on 2D TMD-based semiconductor-semiconductor and semiconductor-metal lateral heterostructures. The lateral heterostructures can give an exciting new paradigm and offer exciting opportunities for potential applications in portable electronic devices

Applied Surface Science

2D MoS2-MoSe2 and MoS2-NbS2 lateral heterostructures as anode materials for LIBs/SIBs

Ferrocene since its inception in the year 1951, has been extensively exploited as a crucial redox probe to unravel electrochemical charge-transfer dynamics in a variety of platforms ranging from solution-based systems and molecular thin-films to solid-state molecular electronics and spintronic devices. Having completed almost 71&nbsp;years of its existence, ferrocene has now become one of the most widely studied organometallic compounds. Several experimental and theoretical frameworks are made to understand ferrocene's electronic and electrochemical properties. Ferrocene is an 18-electron metallocene that shows interesting metal–ligand coordination and has led to the preparation of a great number of important molecules. Ferrocene and its numerous derivatives have brought a breakthrough in metallocene chemistry. Ferrocene represents a chemically and thermally stable system that undergoes reversible electrochemical oxidation and reduction processes. Ferrocene-based self-assembled monolayers (SAMs) are considered as model system for performing on-surface redox reactions and have been applied to create nanoelectronic devices for molecular switching, rectification, and low-voltage operational memory devices. The present review discusses the recent progress made toward a ferrocene-containing molecular system that have been utilized in redox reactions, surface attachment, spin-dependent electrochemical processes to understand spin polarization, photo-electrochemistry, and molecular electronic devices. This review provides an excellent platform for understanding the electrochemical properties and the rational design of ferrocene-based molecular systems for optoelectronic applications.

COORDINATION CHEMISTRY REVIEWS

Ferrocene as an iconic redox marker: From solution chemistry to molecular electronic devices

Ru–Bis(pyridyl)borate complex (CAT) is an efficient catalyst for ammonia borane (AB) dehydrogenation. Although the mechanistic pathway of this catalyst has been theoretically investigated previously, the gap between the experimental findings and the computational results could not be bridged thus far. In our study, using density functional theory calculations, we elucidate the mechanism of AB dehydrogenation of CAT at a variable degree of ligand hydrogenation. Our results confirm that the acetonitrile ligands get reduced in the presence of AB and remain hydrogenated. Moreover, in line with experiments, we find that AB dehydrogenation on CAT proceeds via a concerted mechanism (with the free energy energetic span between 25.4 and 32.5 kcal/mol). We find that the ligand reduction alters the electronic structure and activity of CAT and the highest activity of the catalyst is expected at the fifth degree of hydrogenation of ligands with an energetic span of 25.4 kcal/mol. Additionally, the mechanism for the removal of molecular H2 from the catalysts also alters with the degree of ligand hydrogenation. Furthermore, our results show that optimal H2 binding free energy calculations can be used as a descriptor to identify the most active sites. Finally, this work demonstrates that ligand reduction improves the activity of the catalyst. These results highlight the importance of ligand hydrogenation in probing the activity and operating mechanism of the Ru–bis(pyridyl)borate complexes for AB dehydrogenation. Further, we identify a plausible dimer structure and rationalized experimental observation that the deactivation chemistry of this catalyst is different from the Shvo’s catalyst.

Inorganic Chemistry

Unraveling the Mechanistic Details of Ru-Bis(pyridyl)borate Complex Catalyst for the Dehydrogenation of Ammonia Borane

Polymer beads have been used as the core of magnetic particles for around twenty years. Here we report studies to attach polymetallic complexes to polymer beads for the first time, producing beads of around 115 microns diameter that are attached to 1014 hybrid inorganic-organic [2]rotaxanes. The bead is then formally a [1014] rotaxane. The number of complexes attached is counted by EPR spectroscopy after including TEMPO radicals within the thread of the hybrid [2]rotaxanes.

Fulltext

Communications Chemistry

Decorating polymer beads with 1014 inorganic-organic [2]rotaxanes as shown by spin counting

Nanomaterials that can perform cascading functions in the domain of rapidity and strength of self-assembly, able to immobilize a large mass with minimum energy, and generate optical signal hold potential to contain recurring oil-spills and remediation of land or water bodies. Herein, we report the stimuli-free, phase-selective immobilization of naturally occurring heavy crude oil. Molecule(s) described herein are capable of forming nanofibers with large-area junction zones and instantaneously immobilize petroleum products (PPs), and also report the event with a turn-on emission. The extraordinary efficiency of 0.4 kg immobilizer per ton of petrol and wide operational temperature range (up to 330–360 K) stems from the rapid creation of advanced assemblies having strength (&gt;105 Pa) akin to the robust polymeric fibers. Thus, this new generation of intelligent nanomaterials with ingrained information to carry out multiple and complex function in tandem offers bright prospects to control and effectively detect the oil spill menace in a proficient manner.