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This communication presents a structure–property study of a few novel pyridine-based difluoroborate compounds with a N–BF2–O core, which exhibit outstanding fluorescence properties. To exploit their potential for two-photon bioimaging, relationships between the two-photon action cross section and systematic structural modifications have been investigated and unravelled.

We report on the solvent influence on the two-photon absorption spectra of p -nitroaniline. Measurements of the two-photon absorption cross section values were performed in three solvents (1,4-dioxane, propylene carbonate, dimethyl sulfoxide) using the Z-scan technique. The most important finding in this report is the observation that two-photon absorption cross section value, corresponding to the intramolecular charge-transfer state, is significantly intensified with the solvent polarity increase. In the case of a strongly positive solvatochromic molecule, the two-level model correctly predicts the observed two-photon absorption cross section value increase caused by the solvent polarity change.

This communication presents a structure-property study of a few novel pyridine-based difluoroborate compounds with a N-BF

We report the synthesis and characterization of new organometallic assemblies consisting of a central Zn(II) tetraphenylporphyrin (ZnTPP) core surrounded by four Ru(II) alkynyl complexes ( trans -Ru(dppe) 2 R) appended at the para phenyl positions and acting as peripheral donor groups. The synthesis of the tetra-chlorido derivative 2 (R=Cl) is reported first, followed by that of three extended homologues ( 3 –X) obtained from this building block by substitution of the chlorido ligands by functionalized arylacetylenes (R=C C(4-C 6 H 4 X); X=NO 2 , H, OMe). Measurement of the nonlinear absorption properties of the pentametallic derivatives 3 –X reveals that these extended π-networks incorporating polarizable organometallic units behave as good two-photon absorbers in the visible and near-IR range.

This Letter reports a systematic study of solvent effect on two-photon absorption (2PA) spectra of a model chromophore, 4-dimethylamino-4′-nitrostilbene (DANS). The two-photon solvatochromic behavior of DANS was investigated in selected solvents using the Z-scan measurement technique. The obtained results demonstrate that the examined molecule possesses slightly different 2PA response in solvents of different polarity. A decrease in the two-photon absorption strength is observed when the solvent is changed from chloroform and dichloromethane to the more polar dimethyl sulfoxide.

In this study, we report on the influence of solvent on the two-photon absorption (2PA) spectra of Reichardt's dye (RD). The measurement of 2PA cross-sections is performed for three solvents (chloroform, dimethyl formamide, and dimethyl sulfoxide) using the Z-scan technique. The key finding of this study is the observation that the cross-section, corresponding to the 2PA of the intramolecular charge-transfer state, diminishes substantially upon increasing the solvent polarity. To unravel the solvent dependence of the 2PA cross-section, the electronic structure of RD is determined using a hybrid quantum mechanics/molecular mechanics (QM/MM) approach, in which polarization between the solute and solvent is taken into account by using a self-consistent scheme in the solvent polarization. The two-state approximation proves to be adequate for the studied system, and allowed the observed solvent-polarity-induced decrease of the 2PA cross-section to be related to the decrease of the transition moment and the increase in the excitation energy.

Both nonlinear absorption and nonlinear refraction are effects that are potentially useful for a plethora of applications in photonics, nanophotonics and biophotonics. Despite substantial attention given to these phenomena by researchers studying the merits of disparate systems such as organic materials, hybrid materials, metal-containing molecules and nanostructures, it is virtually impossible to compare the results obtained on different materials when varying parameters of the light beams and different techniques are employed. We have attempted to address the problem by studying the properties of various systems in a systematic way, within a wide range of wavelengths, and including the regions of onephoton, two-photon and three-photon absorption. The objects of our studies have been typical nonlinear chromophores, such as π-conjugated molecules, oligomers and polymers, organometallics and coordination complexes containing transition metals, organometallic dendrimers, small metal-containing clusters, and nanoparticles of various kinds, including semiconductor quantum dots, plasmonic particles and rare-earth doped nanocrystals. We discuss herein procedures to quantify the nonlinear response of all of these systems, by defining and comparing the merit factors relevant for various applications.