https://doi.org/10.1140/epjb/s10051-025-01106-x
Research - Condensed Matter
Quantum chemical exploration of piperazinium nitrate: molecular stability, reactivity descriptors, electronic excitations, intermolecular interactions, and NLO activity
1
Department of Physics, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Saveetha University, 602 105, Thandalam, Chennai, India
2
Department of Physics, Dharmamurthi Rao Bahadur Calavala Cunnan Chetty Hindu College, 72, Pattabiram, Chennai, Tamil Nadu, India
3
Department of Physics, Panimalar Engineering College, 602 105, Chennai, India
4
Department of Physics, Rajalakshmi Engineering College, 602 105, Thandalam, Chennai, India
5
Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2 str.50-422, Wrocław, Poland
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Received:
4
September
2025
Accepted:
3
December
2025
Published online:
7
January
2026
Abstract
Single crystals of Piperazinium Nitrate were obtained by slow evaporation, crystallizing in a monoclinic system (P21/c), and stabilized by strong N–H···O hydrogen bonds in a three-dimensional network. structural integrity of the grown crystal was confirmed by X-ray diffraction (XRD) analysis. Experimental characterization using FT–IR and FT–Raman spectroscopy confirmed the presence of functional groups and characteristic vibrational modes corresponding to the molecular structure. Hirshfeld surface (HS) analysis and 2D fingerprint plots quantified the intermolecular contacts, highlighting the dominant role of hydrogen bonding in crystal packing and structural stability. HS analysis revealed that O···H interactions contribute 54.9% of the overall intermolecular contacts, confirming the dominance of hydrogen bonding in the crystal packing. Density Functional Theory (DFT) calculations at the B3LYP/6-311G (d, p) level were performed to optimize the molecular geometry and investigate the electronic structure, revealing a significant HOMO–LUMO energy gap of 5.391 eV, denoting the stability of molecule and low chemical reactivity. Time-Dependent DFT (TD-DFT) simulations of the UV–Visible (UV–Vis) spectrum provided insights into the electronic excitation behavior. The absorption peak at 255.76 nm, it exhibits the π → π* and n → π* electronic transitions in gas phase. Natural Bond Orbital (NBO) analysis indicated a strong intramolecular hyperconjugative interaction between the lone pair on LP(3) O2 and antibonding orbital of the N1–O4 bond, contributing 144.41 kJ mol−1 to molecular stabilization. Fukui function analysis identified the reactive sites susceptible to electrophilic and nucleophilic attack. Electron Localization Function (ELF) and Localized Orbital Locator (LOL) maps illustrated regions of electron localization and delocalization. Non-Covalent Interaction (NCI) analysis based on Reduced Density Gradient (RDG) plots revealed the presence of weak van der Waals forces and strong hydrogen bonding interactions. The calculated first-order hyperpolarizability (29.244 × 10⁻31 esu), which is 7.8 times greater than that of urea, and the calculated first-order hyperpolarizability confirms the strong NLO response and highlights the potential of the compound for nonlinear optical (NLO) and photonic applications.
Supplementary Information The online version contains supplementary material available at https://doi.org/10.1140/epjb/s10051-025-01106-x.
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© The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature 2025
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
