Experimental measurements and density functional theory analysis of a novel Mannich base: structural and nonlinear optical perspectives

Abstract

The Mannich derivative 1-(phenyl(pyrrolidin-1-yl)methyl)naphthalen-2-ol (PPM) was synthesized and crystallized for the first time by slow evaporation under ambient conditions. Single-crystal X-ray diffraction revealed an orthorhombic lattice belonging to the non-centrosymmetric space group Pna2₁. Functional group identification was achieved through FT-IR spectroscopy, while ¹H and ¹³C NMR spectra provided insights into the proton and carbon environments. Optical studies showed a cutoff wavelength at 360.4 nm, corresponding to a band gap of 3.16 eV, and photoluminescence measurements exhibited a prominent emission at 415.5 nm, indicating blue-light emission. Nonlinear optical characterization by the powder SHG method demonstrated conversion efficiencies 4.34 and 1.67 times greater than KDP and urea, respectively. The material further displayed a high laser damage resistance with a threshold of 1.15 GW cm⁻². Density functional theory calculations supported the experimental results, revealing pronounced nonlinear optical behaviour.