Nonlinear optical (NLO) activity is the phenomenon that originates from the action of intramolecular charge transfer (ICT) [1]. NLO materials own very diversified applications in photonic devices, optoelectronics, telecommunications, optical data storage, frequency mixing, THz generation, and many more. For the construction of potential NLO materials, the formation or substitution of the donor-acceptor (D-A) moieties within the probe molecules [2]. The substitution is proven to tune the dipole moment and polarizability of the molecules. Polymers are the category of compounds having a varied domain of structures, functional groups, and bonds. In this context, polymers are the best selection in terms of substitution because they give wide binding positions for the dopants. Over the past few decades, considerable efforts have been contributed to the designing and synthesis of potential polymeric structures owing to large NLO effects, mechanical endurance, low driving voltage, and ease of processing. The non-centrosymmetric alignment of polymers, which is a key requirement to secure macroscopic NLO effects makes polymers a fair selection for designing desirable materials with induced NLO effects. Usually, the polymers have varied availability of functional groups throughout the structures, which makes them immense anisotropic in nature, and thus, vast values of hyperpolarizability are possible in the case of polymers.
There are numerous kinds of polymers that were employed for the synthesis of NLO materials. Julolidine-based chromophores were also employed for the formation of high second harmonic materials [3]. Melamine is a common kind of polymer that is tuned with different functional groups and used for NLO applications [4]. Quinoxaline is one of the polymers that was used for the formation of π-bridged channels for NLO materials [5]. Methacrylate monomers containing styryl quinoline moieties as ideal dopants were employed for obtaining enhanced nonlinear optical properties using DFT tools [6]. Apart from this, a vast amount of polymers had been previously used for designing novel NLO materials.
Keeping this in mind, the structure of 4-amino 6-chloro benzene was further modified by substituting two sulfonamide groups at 1 and 3 carbon of the benzene ring giving rise to a polymeric structure 4-Amino-6-chloro-1,3-benzenedisulfonamide. The density functional theory (DFT) was employed to account for the quantum chemical properties of the designed polymer. The atomic charges, global reactivity descriptors, and charge surfaces were employed to establish the chemical reactivity of the title polymer. The occurrence of electronic excitation within the polymer, absorption spectra, and density of states spectra were studied. The immense charge delocalization was reported using the parallel surfaces to the highest occupied and lowest unoccupied molecular orbitals. The availability of the substituted functional groups was verified by the FT-IR vibrational modes corresponding to each functional group., hyperpolarizability, dipole moment, charge transfer, band gap, etc.