1Department of Physics, University of Lucknow, University Road, India
2Department of Physics, Veer Kunwar Singh University, India
3Laboratory of Natural Products & Organic Synthesis, Department of Chemistry, Visva-Bharati (a Central University), India
Submission: September 10, 2017; Published: September 18, 2017
*Corresponding author: Neeraj Misra, Department of Physics, University of Lucknow, University Road, India. Email: [email protected]
How to cite this article: Abhishek K, Ambrish K S, Ratnesh K, Goutam B, Neeraj M. Nonlinear Optical Property Of 6�-Amino-5-Fluoro-2-Oxo-3�-Propyl-
2�H-Spiro[Indoline-3,4�-Pyrano[2,3-C]Pyrazole]-5�-Carbonitrile- A Theoretical Approach. Organic & Medicinal Chem IJ. 2017; 3(4): 555617. DOI: 10.19080/OMCIJ.2017.03.555617
We present a DFT based study of the non-liniear optical property of 6'-Amino-5-fluoro-2-oxo-3'-propyl-2'H-spiro[indoline-3,4'-pyrano[2,3-c] pyrazole]-5'-carbonitrile. The geometry optimization first static hyperpolarizability, dipole moment and polarizability of the compound are performed using B3LYP/6-311+G(d,p) level of theory. The calculated hyperpolarizability, dipole moment and polarizability of the title compound is compared with urea at the same level of theory. The study reveals that the title compound possesses large value than urea hence in general may have potential application in the development of nonlinear optical material.
The Nonlinear Optics (NLO) of materials was started after the Kerr's observations of quadratic electric field induced changes in the refraction index, known as the Kerr effect  in 1875. This was followed by the observation of the Pockel's effect. The organic compounds with large optical nonlinearities have become the focus of current research in view of their potential applications in various photonic technologies, including all optical switching and data processing. Organic molecules that exhibit extended pi conjugation, in particular, show enhanced second order NLO properties. The equilibrium geometry and NLO property of 6'-Amino-5-fluoro-2-oxo-3'-propyl-2'H- spiro[indoline-3,4'-pyrano[2,3-c]pyrazole]-5'-carbonitrile have been calculated by using Density Functional Theory (DFT).
In the present study all the DFT calculations were performed with the help of Gaussian 09 program  using a hybrid functional B3LYP and employing 6-311+G (d,p) as a basis set. The geometry of the title compound was fully optimized without any constraint in Potential Energy Surface (PES). The optimized structure of the molecule has been visualized by the use of the Gauss View 5.0 molecular visualization program .
The optimized geometry of the 6'-Amino-5-fluoro-2-oxo- 3'-propyl-2'W-spiro[indoline-3,4'-pyrano[2,3-c]pyrazole]-5'- carbonitrile is shown in Figure 1 with proper atomic labeling. The compounds that shows asymmetric polarization induced by electron donor and acceptor groups in pi electron conjugated molecules are candidates for electro optic and NLO applications  (Figure 1).
The NLO property provides useful information for optical modulation, optical switching and optical logic for the developing new technologies in area of communication. Previously, It has been reported that molecules having conjugated pi electrons are found to possess large values of polarizability [5-8]. The intramolecular charge transfer from electron rich system to electron poor system through a conjugated path can induce a large aberration in both the molecular dipole as well as molecular polarizability. The abnormally high value of hyperpolarizability β, which is a critical parameter of non linear activity of molecular systems, can be presumably linked to intramolecular charge transfer, as a consequence of electron cloud movement through pi conjugated system. The first-order hyperpolarizability (β0) and related properties (μ0 and |α0|) of 6'-Amino-5-fluoro-2- oxo-3'-propyl-2'W-spiro[indoline-3,4'-pyrano[2,3-c]pyrazole]- 5'-carbonitrile have been calculated at the B3LYP/6-311+G (d, p) level of theory. First hyperpolarizability is a third rank tensor of order three that can be described by a 3x3x3 matrix. The 27 components of the order 3 matrix can be reduced to 10 components using the Kleinman Symmetry  and it can be presented in the lower tetrahedral format. The components of P0 are defined as the coefficient in the Taylor series expansion of the energy in the external electric field.
The total dipole moment (β0), anisotropy of the polarizability( |α0|), the mean polarizability (Δα ) and the total first hyperpolarizability (β0) using x, y and z components are
Molecule is listed in Table 1. It can be seen that the calculated β0 and μ0 values of title compound are more than the value of urea and are also listed in Table 1. Hence it can be said that the molecule exhibits promising nonlinear optical property (Table 1).
We have performed theoretical study on molecular structure and NLO properties of 6'-Amino-5-fluoro-2-oxo-3'-propyl-2'H- spiro[indoline-3,4'-pyrano[2,3-c]pyrazole]-5'-carbonitrile with the help of density functional theory. Significantly high non linearity is observed in first order molecular hyperpolarizability and polarizability. So this molecule may have potential application in the development of NLO materials.