We calculated the nonlinear optical properties of 24 azo-enaminone derivatives, incorporating solvent effects on their geometric and electronic structure, to assess the impact of the environment on these properties. Namely, we incorporated chloroform, tetrahydrofuran, acetone, ethanol, methanol, and dimethyl sulfoxide in our calculations and compared our results incorporating solvent effects with our gas-phase calculations. To account for the electron correlation effects on NLO properties, we performed the calculations at MP2/6-31G­(p)//MP2/6-31G­(d) level set. The polarizable continuum model was used to simulate the presence of the solvent. The exponents of p extra functions added to heavy atoms were obtained, imposing the maximization of the first hyperpolarizability. Two structural configurations (Z and E) of azo-enaminones were investigated to assess the isomeric effects of the electric properties. Our results show that both solvent polarity and relative strength of the donor groups have a significant impact on the electric properties but more strikingly on the first hyperpolarizability β.

A series of rationally designed, non‐symmetrical, 4,7‐π‐extended‐2,1,3‐benzothidiazole derivatives had their electronic and geometrical properties evaluated by means of DFT calculations. The data obtained from the calculated 2,1,3‐benzothiadiazole (BTD) intermediates allowed the design and synthesis of a final structure bearing a fluorine‐containing aromatic group on one side of the BTD ring and a C≡C spacer linking a long chain‐containing (C8) aromatic group on the other side. This specific molecular architecture is expected to display liquid crystalline behavior. The new designed structure was therefore synthesized in good overall yield using cross‐coupling reactions (Suzuki and Sonogashira reactions). Copyright © 2013 John Wiley & Sons, Ltd.

Well-defined structure-property relationships offer a conceptual basis to afford a priori design principles to develop novel π-conjugated molecular and polymer materials for nonlinear optical (NLO) applications. Here, we introduce the bond ellipticity alternation (BEA) as a robust parameter to assess the NLO characteristics of organic chromophores and illustrate its effectiveness in the case of streptocyanines. BEA is based on the symmetry of the electron density, a physical observable that can be determined from experimental X-ray electron densities or from quantum-chemical calculations. Through comparisons to the well-established bond-length alternation and π-bond order alternation parameters, we demonstrate the generality of BEA to foreshadow NLO characteristics and underline that, in the case of large electric fields, BEA is a more reliable descriptor. Hence, this study introduces BEA as a prominent descriptor of organic chromophores of interest for NLO applications.

No abstract

In this work, we described the synthesis of 10 new fluorescent 2,1,3-benzoselenadiazole small-molecule derivatives and their chemical- and photocharacterizations. The new derivatives could, for the first time, be successfully applied as selective live cell imaging probes (at nanomolar concentrations) and stained lipid-based structures preferentially. Density functional theory (DFT) calculations were used to help in understanding the photophysical data and the intramolecular charge-transfer (ICT) processes of the synthesized dyes. Some derivatives showed impressive cellular responses, allowing them to be tested as probes in a complex multicellular model (i.e., Caenorhabditis elegans). When compared with the commercially available dye, the new fluorescent compounds showed far better results both at the cellular level and inside the live worm. Inside the multicellular complex model, the tested probes also showed selectivity, a feature not observed when the commercial dye was used to carry out the bioimaging experiments.