Among the molecules studies, PPAB-2 showed the highest βtot value, while PPAB-1 showed the lowest βtot value. The higher βtot of PPAB-3 than the PPAB-1 could be assigned to the unidirectional charge transfer in the former, as indicated by the ratio of βtot to βvec close to unity. The βtot of the three molecules are investigated in different solvents in which the results clearly indicate that the inclusion of the solvation effect leads to a substantial increase in the βtot values of the compounds under investigation. As the extend of ICT is known to enhance with increasing solvent polarity, we can infer that the ICT plays a significant role in shaping the NLO response of the PPAB (1-3). The βtot value of the molecules in acetonitrile solvent is much higher compared to the values observed in the less polar solvents. This finding suggests that the presence of a polarizable environment can effectively modulate the NLO response. The increase in β by modifying the dielectric environment around the chromophore is a potential method to greatly improve the performance of nonlinear optical systems. The components of the μ as well as that of β are provided in Table . The results indicate that unlike PPAB-1, the hyperpolarizability of PPAB-3 dominated by only one component (βy), indicating unidirectional charge transfer in the later. Therefore, these results indicate that the β values of the PPAB molecules can be tuned using suitable donor and acceptor groups that facilitates unidirectional charge transfer.