Solvatochromism elucidated: UV/Vis and electrooptical absorption spectroscopy were used to elucidate the effect of solvent on the electrical and optical properties of three merocyanine dyes. Changes in the shape of the Vis absorption band in solvents of different polarity [e.g., the depicted dye in Et2O (black), AcOEt (blue), and MeCN (orange)] are explained by different excited‐state dipole moments of the respective vibronic transitions.

Solvatochromie erhellt: UV/Vis‐ und elektrooptische Absorptionsspektroskopie halfen, den Einfluss des Lösungsmittels auf die elektrischen und optischen Eigenschaften von drei Merocyaninfarbstoffen aufzuklären. Veränderungen der Vis‐Absorptionsbande in unterschiedlich polaren Lösungsmitteln [beim Beispielfarbstoff in Et2O (schwarz), AcOEt (blau) und MeCN (orange)] werden mit unterschiedlichen Dipolmomenten des angeregten Zustands des jeweiligen vibronischen Übergangs erklärt.

In this work we present an investigation of the non-linear optical (NLO) properties of two octupolar chromophores: [Zn(4,4'-bis(dibutylaminostyryl)-[2,2']-bipyridine)(3)](2+) and [Zn(4,4'-bis((E)-2-(N-(TEG)pyrrol-2-yl)vinyl)-[2,2']-bipyridine)(3)](2+) with Zn(ii) as the coordination center, using two-photon emission technique (TPE) in fs-pulse temporal regime. Compared to the free ligands, our results do not show a net increase in the two-photon absorption (TPA) cross-section for the octupolar complexes, once normalized to the ligand unit. This is in partial disagreement with a previous theoretical study investigating the first molecule where a significant increase of the TPA cross-section was predicted (X. J. Liu, et al., J. Chem. Phys., 2004, 120, 11 493).

A series of highly efficient and thermally stable second-order nonlinear optical (NLO) dipolar donor-auxiliary donor-acceptor chromophores have been synthesised in which a hydrazono group and a pyrrole ring act as donor and auxiliary donor components, respectively, in combination with different aromatic and heteroaromatic acceptors. The new dyes have been systematically investigated by NMR spectroscopy, absorption spectroscopy, NLO measurements and thermal stability studies. NLO properties have been studied in detail by electro-optical absorption (EOA) and hyper-Rayleigh scattering (HRS) measurements in 1,4-dioxane and DMSO, respectively. The results originating from the two different methods have been compared and analysed in detail. We found that the NLO properties measured by the EOA and HRS methods correlate with each other and converge to reveal the dye with the acceptor 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran as the most efficient system. The unprecedented combination of a strong donor hydrazono group and the auxiliary donor effects of pi-excessive heteroaromatic rings afforded NLO chromophores with very high values (mu(g)beta0(EOA) up to 2038 x 10(-48) esu and beta(HRS) up to 3980 x 10(-30) esu at 1.5 microm).