Theoretical study of static electric properties of benzothiazole containing push–pull systems as potential candidates for NLO materials

Abstract

The dipole moments µ, static polarizabilities α , and first hyperpolarizabilities β vec of benzothiazole based push-pull chromophores have been theoretically investigated by means of SCF-HF and DFT (B3LYP, B3PW91) methods with cc-pVDZ basis sets at geometries optimized with 3-21G basis sets. The main attention has been paid to hyperpolarizability β vec as a microscopic quantity directly linked with the nonlinear optical (NLO) response of materials with the aim to choose the most suitable candidate(s) for NLO materials from the set of 24 molecules. The 4-dimethylamino-4 -nitrostilbene (DANS) has also been included as a reference compound. The influence of various structural modifications of benzothiazole containing chromophores on µ, α , and β vec has been studied. These modifications involve the variation in unsaturated chain length connecting the aromatic units, different positions of electron withdrawing NO 2 and CN group attached to four possible positions in benzothiazole fragment, addition of the second NO 2 group, and the replacement of benzene by five-membered heteroaromatic rings (pyrrole, furan, thiophene) at N(CH 3 ) 2 site. The structural parameters, frontier orbitals and relative stabilities of these systems are also reported. The DFT scheme exaggerates the magnitude as well as the chain length dependence of β vec with respect to the HF results. Both B3LYP and B3PW91 functionals give very close results. The DFT optimized structures are characterized by larger delocalization, planarity, and polarization of substituents. The best candidates for NLO materials have been identified from the studied series based on the β vec values.

QSAR studies for prediction of cross-β sheet aggregate binding affinity and selectivity

“…Finally, certain members of the series have been extensively characterized with respect to optical and electrical properties. 15–19 The results confirm polarizability as a major descriptor of relative binding affinity of the series for cross-β sheet aggregates, and show how this parameter can be maximized in neutral analogs.…”

Electric properties of formaldehyde, thioformaldehyde, urea, formamide, and thioformamide—Post‐HF and DFT study

“…Since many of π‐conjugated molecules constitute suitable components of nonlinear optical (NLO) devices, searching for density functionals that provide at least qualitative prediction of polarizabilities and hyperpolarizabilities in these structures 20, 21 has become a challenge for theoretical quantum chemists.…”

The twentieth year in Structural Chemistry

“…Quantum chemical computations can assist to assess these properties, as recent codes are able to calculate the first hyperpolarizabilities. Benková et al [52] determined these properties for 24 benzothiazole-based push-pull systems and suggested the best NLO candidates on the basis of the computed data.…”