The chemical reaction of 7-acetyl-6-hydroxy-3-mercapto-1,6-dimethyl-8-phenyl-5,6,7,8-tetrahydroisoquinoline-4-carbonitrile withN-(naphthalene-1-yl)-2-chloroacetamide in ethanol in the presence ofanhydrous sodium acetate results in the synthesis of a5,6,7,8-tetrahydroisoquinoline derivative with name7-Acetyl-4-cyano-1,6-dimethyl-6-hydroxy-8-phenyl-3-[N-(naphthalen-1-yl)carbamoylmethylthio]-5,6,7,8-tetrahydroisoquinoline (ACCT). Thesynthesized compound is characterized by FT-IR, 1 H, and 13 C NMRspectroscopy. Furthermore, the crystal structure is verified by single crystalX-ray diffraction (XRD), which shows that the molecular configuration ofACCT is stabilized by N─H … N bonding. Infinite C(11) molecular chains areformed by O─H … O bonding that runs along the b-axis, and consecutivechains are further interlinked by C─H … O bonding. Hirshfeld surfaceanalysis reveals the role of intermolecular interaction in crystal packing, whereH … H and C—H … O interactions have notable percentage contributions.Dispersioninteractions provides the dominant stabilization forsupramolecular assembly, followed in significance by electrostaticinteractions. Electronic structure calculations and aromaticity analysis revealthe reactivity of the synthesized compound at the M062x/def2tzvp method.With the help of DFT simulations, the crucial role of van der Waals forces andcharge transfer in modifying optical and non-linear optical (NLO) propertieshas been underscored. Ab initio molecular dynamics study reveals thethermodynamic and kinetic behavior at room temperature.