Synthesis, characterization, computational study and nonlinear absorption properties of 4-(2-aminomethyl)pyridinium dipicrate

Sultana, Shabnam ; Pardos, Jorge (Universidad de Zaragoza) ; Zangrando, Ennio ; Echeverría, Jorge ; Das, Chandan ; Ramakrishna, Dileep ; Manjunatha, K.B. ; Sanyal, Ria

Resumen: A new picrate salt of nitrogen-rich 4-(2-aminomethyl)pyridinium (PA_4AP) has been successfully crystallized in 2:1 stoichiometry confirming the acid-base proton-transfer. The crystal lattice is marked by H-bond and π-stacking interactions leading to a supramolecular architecture where picrate anions are sandwiched in between the 4-(2-aminomethyl)pyridinium (4AP) cations. Characterization techniques like elemental analysis, PXRD, UV-vis, FT-IR, ESI-MS and 1H/13C-NMR spectroscopy have proved the crystallinity and purity of the complex salt. Then, nonlinear optical (NLO) properties of picric acid (HPA) and PA_4AP has been investigated in DMF solution by irradiating 532 nm Q-switched Nd:YAG nanosecond laser. The open aperture Z-scan curves indicate nonlinear absorption (NLA) behaviour in both the samples. The normalized transmittance (NT) dropped from 100% to 84% and 78% in PA and PA_4AP, respectively, indicating optical limiting (OL) response from both the samples. The NLA coefficient, ß (1.5 × 10−11 m/W) and OL threshold (1.5 × 1013 W/m2) of PA_4AP was found to be higher than the values of HPA, suggesting hydrogen-bonding mediated NLO behaviour marked by reverse saturable absorption mechanisms. DFT calculations performed on optimized HPA and PA_4AP structures in comparison to the crystallographic structure of PA_4AP theoretically predict the smallest HOMO-LUMO gap (1.574 eV), the highest electrophilicity (19.203 eV), and the lowest chemical hardness (0.787 eV) for the crystallographic PA_4AP species compared to the other systems. The experimental results confirm the superior third-order NLO performance of the PA_4AP material driven by hydrogen bond interactions in the supramolecular scaffold. © 2026 Elsevier B.V.

Idioma: Inglés

DOI: 10.1016/j.molstruc.2026.145493

Año: 2026

Publicado en: JOURNAL OF MOLECULAR STRUCTURE 1359 (2026), 145493
ISSN: 0022-2860

Tipo y forma: Article (Published version)

Área (Departamento): Área Química Orgánica (Dpto. Química Orgánica)