Benzothiazole pyrazole containing emissive azo dyes decorated with ESIPT core: Linear and non linear optical properties, Z scan, optical limiting, laser damage threshold with comparative DFT studies

• Published in: Journal of molecular structure 2020-03, Vol.1203, p.127401, Article 127401
• Main Authors: Ghanavatkar, Chaitannya W., Mishra, Virendra R., Sekar, Nagaiyan, Mathew, Elizabeth, Thomas, Sijo S., Joe, Isaac H.
• Format: Article
• Language: English
• Subjects: Benzothiazole-pyrazole; DFT; Emissive azo dyes; ESIPT; LDT; NLO; Z-scan
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2019.127401

Positional isomers of “benzothiazoles-pyrazole based azo dyes containing separate with ESIPT core” are analyzed for their “linear and non-linear optical (NLO)” properties. Dyes are emissive in ACN having Stokes shift in the range of 75 nm. Spectroscopic properties are further utilized to calculate band gap by CV. Band gap obtained by DFT and cyclic voltammetry (CV) are in good agreement with each other. Vertical excitation in six different functionals is compared with experimental absorption maxima. Non-linear absorptive coefficient (β), nonlinear refractive index (ƞ2), third-order non-linear optical susceptibility (χ3) and optical limiting (OL) in acetone, ethanol and DMSO are obtained using Z-scan technique and results are appreciable than previously reported dyes. Satisfactory laser damage threshold (LDT) values are in the range of 7.9–9.7 × 1013 W/m2. TGA study indicates that these compounds are useful in several high-temperature processes in the construction of electronic and optical devices. The geometry of the dyes are optimized at “B3LYP/6-311 + G (d,p) level”. “Molecular Electrostatic Potential” (MEP), “Frontier Molecular Orbitals” (FMO) are presented using “Density Functional Theory (DFT)” to gain structural insights. Relatively new electrophilicity descriptor- “Hyperhardness” for both the molecules are calculated which suggests the stability of molecules. Global hybrid (GH) functional (B3LYP, BHandHLYP) and range separated hybrid (RSH) (CAM-B3LYP, ωB97, ωB97X, and ωB97XD) functional are used to calculate linear and NLO properties. ωB97 is a more suitable functional observed for determining βo and γ. Direct relation in-between “dipole moment” (μ) and “linear polarizability” (α) is also presented. These dyes can emerge as attractive NLOphores in optoelectronic applications. [Display omitted] •Benzothiazoles-pyrazole clubbed emissive azo dyes with Stokes shift 86–131 nm.•Z-scan and optical limiting (OL) results are appreciable. TGA and laser damage threshold analysis also showed significant results.•DFT computation gave structural insights such as MEP and NLO properties HOMO-LUMO gaps were compared by using theoretical (DFT) and experimental (CV) methods.•Dipole moment and linear polarizability are correlated.