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Many essential similarities between the behavior and arrangement of biological structures and liquid crystals can be found. Moreover, some of biomacromolecules, such as DNA, are shown to exhibit lyotropic liquid crystalline phases both in vitro and in vivo. In this study, we used natural DNA concentration condition to form DNA liquid crystal (LC) phases as a simplified in vitro model of DNA self-ordering in cells. Due to the increasing interest in the use of nanoparticles as optical markers, we investigated possible applications of silver-doped gold nanoclusters (AuAgNCs) for one- and two-photon imaging in condensed DNA samples. We studied the influence of NCs doping on the DNA LC properties and the distribution of NCs within the liquid crystalline matrix. Depending on the type of DNA liquid crystalline phase we observed different emission patterns of AuAgNCs correlated with the degree of DNA ordering.

Nonlinear optical microscopy was employed to investigate the properties of microstructures of quinacridone, a hydrogen-bonded pigment, derivative of quinacridine. Recently, quinacridone hierarchical microstructures (μ-QNC) having different nature-inspired morphologies were reported, e.g. in the shape of hedgehogs formed by self-assembled nano-needles. We find that such microcrystals have structure-dependent linear optical properties and exhibit strong two-photon excited fluorescence when irradiated with a near-infrared femtosecond laser. μ-QNCs exhibit different nonlinear optical properties for different crystal structures, including the emergence of symmetry-forbidden second-harmonic generation.

Gold and silver nanoclusters aggregates have gained significant attention as their optical properties and chemical stability surpasses those of individual nanoclusters. Here, we present a systematic investigation of aggregation-induced changes of morphology and optical properties of glutathione-stabilized silver-doped gold nanoclusters (AuAg NCs). We show that the silver-doped clusters have the ability to spontaneously aggregate in solution, but in order to stabilize their structure and enhance the one-photon (1 P) and two-photon (2 P) properties we used poly(allylamine hydrochloride) (PAH) matrix. This resulted in obtaining NCs superstructures having narrow size distribution and efficient 1 P and 2 P excited photoluminescence.

We report on synthesis and optical properties of new organic compounds based on substituted pyrazole ring. The investigated pyrazoline derivatives (PRDs) exhibit efficient broadband photoluminescence which covers nearly whole visible spectrum. The experimental results are compared to quantum chemical calculations. Amplified spontaneous emission and photodegradation measurements were performed for hybrid systems based on selected PRDs doped into poly(methyl methacrylate) matrix proving the potential utility of such systems in lasing applications. Two-photon absorption (TPA) properties were characterized by the femtosecond Z-scan technique.

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.

The synthesis, structure and optical properties of water-soluble fluoride nanophosphors co-doped with Eu 3+ and Tb 3+ are presented. Nanocrystals of NaYF 4 were synthesized via a hydrothermal microwave-assisted technique. XRD, TEM, AFM, FTIR as well as photoluminescence (PL) spectra were used to characterize the doped nanocrystals. The average size of nanocrystals, determined from XRD, AFM and TEM measurements, was ca. 28 nm. It was found that energy transfer occurs between Tb 3+ and Eu 3+ ions embedded in NaYF 4 matrix, both in nanocrystals dispersed in chloroform and those in aqueous solution. We demonstrate that this simple colloidal system possesses the essential features required for both energy transfer and potential application in biolabeling.