Two coupled molecules were successfully synthesized by condensation of amine-donor-substituted barbituric acid derivativies as nonlinear optical chromophores. A flexible spacer of the alkyl chain with different lengths of carbon chains (5 and 6 carbons) was introduced between two chromophores, which prevented crystallization and aggregation of molecules. Two coupled molecules (B-Cn-B, n=5, 6) had glass-transition temperatures on a second heating around 81 and 76$^{circ}C$ without melting points, respectively. To explore the linear optical properties, thin-films were prepared and examined by a photometry method using Nd:YVO$_4$ CW laser. Also, microscopic and macroscopic nonlinear optical properties were measured by Hyper-Rayleigh Scattering (HRS) and the Maker Fringes method using Nd:YAG ps pulse laser, respectively. In spite of the moderate hyperpolarizabilities of coupled molecules, the second order NLO coefficient (d$\_$33/) was larger than the conventional Disperse Red 1 doped PMMA polymeric system.