The dihedral angle between the naphthalene unit and nitro-benzenesulfonic acid, 2-phenyl-ethyl and 4-phenyl-ethyl are 49.68(05), 82.96(06), and 81.94(07) respectively. <...> The structure is stabilized by intra- and intermolecular C—H…O hydrogen bonds. <...> Arene sulfonic acids and their derivatives are important materials of industrial chemistry: they serve as a basis to synthesize many pharmaceuticals, plant protecting agents, high-temperature polymers (polysulfones), food additives, dyes, detergents, antioxidants, and extractants. <...> Sulfonic acids are interesting and widely used chemical reagents. <...> Benzenesulfonic acid (BSA) is a very strong acid (pKa = –2.8, approximately equal to sulphuric acid), solid at room pressure and temperature and is very soluble in the usual organic solvents [ 2 ]. <...> Large amounts of sulfonated aromatic compounds are being produced as building blocks for the synthesis of dyes and detergents and released into the environment as waste during their manufacture and use [ 3 ]. <...> Due to the formation of intra- and intermolecular hydrogen bonds and high polarization of the sulfo groups in the presence of water, aromatic sulfonic acids are good model systems for the elucidation of the proton migration pathways in the crystal structures [ 4 ]. <...> A chemical diagram of compound 1 is shown in the Scheme. <...> The layers were separated and the aqueous layer was extracted using DCM (10 ml). <...> The organic layers were combined, dried and concentrated under vacuum to give 4-nitro-benzenesulfonic acid 2, 4-bis-(1-phenyl-ethyl)-naphthalen-1-yl ester 1 as an off-white solid. <...> The structure of the product was confirmed by its analytical data and finally confirmed by the X-ray crystal structure. <...> The vibrational bands with the wave numbers of 1531.44 cm–1 (asymmetric ArNO2 stretching), 1377.40 cm–1 (asymmetric SO2 stretching), and 1186.60 cm–1 (symmetric SO2 stretching) Characterization by spectroscopy. <...> The FT-IR data for title compound 1 is given in the were observed. 1H NMR. <...> The 1H NMR spectrum of title compound 1 was recorded using CDCl3 as the solvent and the data was given in the experimental section. <...> The methyl protons were observed as a multiplet at 1.60 ppm and CH moieties were observed as two quartets at 4.63 ppm and 4.75 ppm respectively. <...> The aromatic protons <...>