Browsing by Author "Sanjay Pant"

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Common fixed points of weakly compatible maps in symmetric spaces
(2012) Harish Chandra; Arvind Bhatt; Sanjay Pant
In this paper we obtain common fixed point theorems of weakly compatible maps on symmetric spaces. We prove that if S and T are weakly compatible maps satisfying property (E-A) along with strict contractive conditions, then they have common fixed points. Since these results are obtained without using full force of metric, they are improved generalization of results obtained by Pant ([10], [11]).
Corrigendum to “Reinvestigation of the photophysics of 3-aminobenzoic acid in neat and mixed binary solvents” [Spectrochim. Acta A Mol. Biomol. Spectrosc. 247 (2021) 119100] (Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy (2021) 247, (S1386142520310799), (10.1016/j.saa.2020.119100))
(Elsevier B.V., 2023) Shahid Husain; Mohan Singh Mehata; Nupur Pandey; Hirdyesh Mishra; Sanjay Pant
The author regrets the errors in the below sections and Tables in the published article. The author would like to apologize for any inconvenience caused. The corrections are highlighted in bold font in the Tables and text as follows: In Section 4.1. Table 1. Multiple linear regression fitting parameters of 3ABA using solvatochromic models in distinct solvents. [Table presented] • In the first line of column 2 (right column) on page no. 4, 49.63% should be replaced by 45.36%. In Section 4.2.2. • On page no. 7, 60% should be replaced by 60% (estimated at 317 nm and 0.5 mol fraction).• On page no. 7, 89.66% should be replaced by 89.66% (estimated at 427 nm and 0.5 mol fraction). In Section 4.2.3. • On page no. 7, 61.11% should be replaced by 61.11% (estimated at 316.5 nm and 0.5 mol fraction). Supplementary information Table S1. Steady-state spectral parameters of 3ABA along with solvatochromic solvent parameters. [Table presented] The values of [Formula presented] were taken from reference [3], α, β and π* from references [12,15,54] and SA, SB, SP and SDP from reference [18]. *SPP values were taken from references [55], J. Catalan, V Lopez, P. Perez, Liebigs Ann. (1995) 793–795 and J. Catalan, C. Dıaz, F. Garcia-Blanco, J. Org. Chem. 66 (2001) 5846–5852. © 2023 Elsevier B.V.
Effect of solvents and polymers microenvironment on the photophysical behaviour of 2,6-dihydroxy-4-methylquinoline: Applications in photovoltaic technologies
(Elsevier B.V., 2025) Rachana Chandra Joshi; Nupur Pandey; Shahid Husain; Ranjan Kumar; Nisha Fatma; Pankaj Pant; Sanjay Pant; Hirdyesh Mishra
Quinoline derivatives, including 2,6-dihydroxy-4-methylquinoline (26DH4MQ), are of growing interest due to their potential applications in medicine and optoelectronics. This study investigates the effect of solvent and polymer environments on the photophysical properties of 26DH4MQ, with a focus on its applicability in photovoltaic technologies. Fluorescence (FL) decay analysis, coupled with steady-state FL measurements in various solvents and polymers, confirmed that the FL decay time and spectral characteristics align with intramolecular charge transfer (ICT) behaviour. The Catalan Scale based on the multiple linear regression (MLR) method was employed to assess the impact of specific and non-specific interactions on this molecule's photophysical behaviour. The dipole moment of the excited state (ES) is found to be higher, which indicates increased polarization due to excited state ICT, causing possible changes in molecular geometry upon excitation. A good correlation appeared between experimental and electronic structure parameters obtained from DFT (density functional theory)/TD-DFT (its time extension) quantum chemical calculations, and the HOMO-LUMO energies were obtained and compared with values obtained by cyclic voltammetry. Using the values of HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital), we have estimated energy gap (ΔE), ionization potential (IP), electron affinity (EA), electronegativity (χ), chemical potential (μ), hardness (η), softness (σ), electrophilicity index (ω), electron-accepting power (ω+), and electron-donating power (ω-) of the 26DH4MQ were estimated. The electrophilic and nucleophilic sites were identified through molecular electrostatic potential (MEP) analysis, which plays a crucial role in photochemical reactions. The higher value of oscillator strength in THF solvent enhances the light harvesting efficiency (LHE), and the estimated value of power conversion efficiency (PCE) of the 26DH4MQ molecule is ∼ 40 %, making it a suitable material for enhancing solar cell efficiency. This study highlights the significant role of solvent/polymer environments on the photophysical and optoelectronic properties of 26DH4MQ, offering valuable insights for its development in advanced optoelectronic materials. © 2025
Experimental, quantum chemical spectroscopic investigation, topological, molecular docking/dynamics and biological assessment studies of 2,6-Dihydroxy-4-methyl quinoline
(Elsevier B.V., 2025) Rachana Chandra Joshi; Shahid Husain; Nupur Pandey; Nisha Fatma; Divya Bisen; Ratnakar Upadhyay; Abhijit Debnath; Sanjay Pant; Hirdyesh Mishra
The present work is a comprehensive investigation of the spectral, electronic structure, bonding, and reactivity of the 2,6-dihydroxy-4-methylquinoline (26DH4MQ) molecule through a wide range of experimental and quantum chemical spectroscopic calculations techniques, along with its applications as nonlinear optical materials and biological assessments. The study utilized density functional theory (DFT) and time-dependent density functional theory (TD-DFT) with the B3LYP method and the 6-311G++(d,p) basis set to analyze the structural and molecular properties of 26DH4MQ. The findings from UV–Vis, FT-IR, and FT-NMR spectroscopy show a strong agreement between the experimentally obtained vibrational frequencies and chemical shifts and those predicted by computational methods. Local reactivity descriptors, such as the dual descriptor, Fukui functions, and the molecular electrostatic potential (MEP) map, were used to identify the reactive regions of the molecule. Additionally, natural bond orbital (NBO) analysis provided insights into the charge transfer characteristics of 26DH4MQ, which helps to stabilize the molecular system. The study also revealed notable nonlinear optical (NLO) properties, with polarizability (18.52 × 10–24e.s.u.) and first-order hyperpolarizability (2.26 × 10–30e.s.u.) values that surpass those of standard organic compounds, suggesting significant potential for optoelectronic applications. The biological evaluation of 26DH4MQ assessed its drug-likeness, toxicity, enzyme inhibition, and ADME (Absorption, Distribution, Metabolism, and Excretion) parameters, highlighting its pharmaceutical potential. Furthermore, molecular docking and dynamics studies illustrated the compound's interaction with proteins, indicating its potential role as an insulin inhibitor. © 2024 Elsevier B.V.
Photochemistry of 5-aminoquinoline in protic and aprotic solvents
(2011) Jagat P. Bridhkoti; Hirdyesh Mishra; H.C. Joshi; Sanjay Pant
Photophysical properties of 5-aminoquinoline (5AQ) have been investigated in various non-polar and polar (protic and aprotic) solvents using steady state and time resolved fluorescence. In aprotic solvents, the spectral maxima depend on the polarity. However, in protic solvents both the fluorescence intensity as well decay time show decrease depending on the hydrogen bonding ability of the solvent. The results suggest that photochemistry 5AQ is quite sensitive towards the polarity as well as protic character of the solvent. © 2011 Elsevier B.V. All rights reserved.
Polymer microenvironmental effects on the photophysics of cinchonine dication
(2010) Neeraj Kumar Joshi; Ranjana Rautela; Sanjay Pant; Hirdyesh Mishra
Photophysical properties of cinchonine dication (C1) have been studied in protic and aprotic polymers by monitoring steady state and time resolved measurements. It is found to be sensitive towards the microenvironment of polymers. Edge excitation red shifted emission (EERS) is observed in all polymeric matrices. However, the magnitude of EERS is relatively high in protic as compared to aprotic polymer. Isobestic point in excitation spectra and three decay components in time resolved measurements indicate more than two trapped chemical species in the heterogeneous environment of the polymer. Solutepolymer interactions are found to produce the third decay channel, unlike in solution phase and may be useful to understand the polymer microenvironment. © 2010 Elsevier B.V. All rights reserved.
Reinvestigation of the photophysics of 3-aminobenzoic acid in neat and mixed binary solvents
(Elsevier B.V., 2021) Shahid Husain; Mohan Singh Mehata; Nupur Pandey; Hirdyesh Mishra; Sanjay Pant
The present study elucidates the reinvestigation of the photophysical behavior of 3-aminobenzoic acid (3ABA) in solvents of different polarities using the steady-state spectroscopic techniques. Kamlet-Taft and Catalan solvatochromic models have been used to analyze the solvatochromic changes in neat solvents. The hydrogen bond donating ability of the solvent was found to be the main parameter affecting the spectral behavior of 3ABA. The solvatochromic characteristics of 3ABA have also been examined in binary solvent mixtures viz. acetonitrile (ACN)-methanol (MeOH) and benzene (BEN)-MeOH using the concept of preferential solvation. The preferential solvation of 3ABA shows unusual behavior for BEN-MeOH binary mixture and described unnoticed sigmoidal behavior in the ground state and synergistic impact in the excited state. Besides, the 3ABA was studied theoretically by quantum chemical calculations using (HF) Hartree-Fock and (DFT/B3LYP) density functional theories and its electronic absorption bands have been assigned by time-dependent density functional theory (TD-DFT). The effect of solvents on 3ABA was considered using a IEF-PCM-TDDFT (integral equation formalism of the polarizable continuum model- TDDFT) method. Thus, the theoretical results were found to be closer to the experimental results. © 2020 Elsevier B.V.
Revisiting the photochemistry 2,5-dihydroxy benzoic acid (gentisic acid): Solvent and pH effect
(John Wiley and Sons Ltd, 2021) Meena Adhikari; Neeraj K. Joshi; Hem C. Joshi; Mohan S. Mehata; Hirdyesh Mishra; Sanjay Pant
In the present study, we have reinvestigated photochemistry of 2,5-dihydroxy benzoic acid (DHBA) in a series of organic solvents of different polarities and the aqueous solution of varying pH from 1 to 14. The investigation was carried out using steady-state and nanosecond (ns) time-domain fluorescence measurement techniques at room temperature. Some hitherto not explored spectral features with new insight on different forms of DHBA are reported. It is found that DHBA exists as monoanionic and neutral forms in various polar protic, aprotic, and nonpolar solvents. In aqueous solution (pH 1 to 14), neutral, monoanionic, and dianion forms are found to be responsible for the observed optical spectral profiles. The observed significant Stokes shift in emission is attributed to species undergoing excited-state intramolecular proton transfer (ESIPT) in different solvents. The analysis presented in this work elucidates and validate the presence of various species and conformers of DHBA. © 2020 John Wiley & Sons, Ltd.
Spectral and time domain fluorescence spectroscopy of gentisic acid molecule in protic and aprotic polymer matrix
(Elsevier B.V., 2022) Meena Adhikari; Sanjay Pant; Hirdyesh Mishra
In the present work, the effect of polymer microenvironment on the photophysics of gentisic acid molecule [2,5-dihydroxybenzoic acid] (GA), steady-state and time-domain fluorescence measurements at different pH conditions were carried out in protic [polyvinyl alcohol PVA] and aprotic [polymethyl methacrylate (PMMA)] polymer matrices. Change in the proticity of the microenvironment of the polymer traps different ionic species along with the neutral form of rotamer P and R conformers of GA molecule, are found to be responsible for the change in the spectral, multi-exponential decay behaviour. In protic polymer, the appearance of a single emission band indicates, dissociation of the GA molecule is very high, and it present as a monoanion along with hydrogen-bonded P and R rotamers. However, in the basic polymer film, most of the conformers of R converted to the anion. In contrast, protonation slows down the dissociation of both P and R forms in the acidic film. Unlike PVA matrix, in PMMA, dual emission band appears due to slow dissociation of GA molecule and hydrogen-bonded rotamer P, and R form exists with monoanion species. The magnitude of large stokes shifted red emission due to excited-state intramolecular proton transfers (ESIPT) found grater in rotamer P compared to its anionic species (green emission) and a blue emission corresponds to rotamer R. © 2021 Elsevier B.V.