<p>Two new unsymmetrically substituted 1,3,5-triazinanes, namely 1-(4-chlorophenyl)-3,5-dicyclohexyl-1,3,5-triazinane (<b>C2</b>) and 1-(4-bromophenyl)-3,5-dicyclohexyl-1,3,5-triazinane (<b>C3</b>), were synthesized in high yields via condensation of 4-chlorophenylamine or 4-bromophenylamine with cyclohexylamine and excess formalin. Their structures were characterized using FTIR, Raman, ¹H NMR, ¹³C NMR, single-crystal X-ray diffraction, and UV–vis spectroscopy, revealing chair conformations with di-axial alkyl/aryl groups and an equatorial alkyl group. Two additional compounds, 1-(p-fluorophenyl)-3,5-dicyclohexyl-1,3,5-triazinane (<b>C1</b>) and 1-(p-iodophenyl)-3,5-dicyclohexyl-1,3,5-triazinane (<b>C4</b>), were studied theoretically to assess the impact of halogen substituents (F, Cl, Br, I) on molecular properties. Hirshfeld surface analysis elucidated intermolecular interactions in <b>C2</b> and <b>C3</b>, with dominant H···H, H···X/X···H, and CH···π contacts. The structural and spectroscopic properties of compounds <b>C2</b> and <b>C3</b> and models <b>C1</b> and <b>C4</b> in the ground state were investigated using density functional theory with the B3LYP hybrid functional and GD3BJ empirical dispersion correction. A good agreement was observed between the computed and experimental results. Solvent effects on molecular geometry and electronic absorption spectra were found to be negligible, confirming the stability of the compounds across different environments. Furthermore, the nonlinear optical properties of the synthesized compound, along with structurally related models <b>C1</b> and <b>C4</b>, were evaluated using theoretical calculations.</p>