A series of cyanine fluorophores based on fused aromatics as an electron donor for DNA sensing and two-photon bioimaging were synthesized, among which the carbazole-based biscyanine exhibits high sensitivity and efficiency as a fluorescent light-up probe for dsDNA, which shows selective binding toward the AT-rich regions. The synergetic effect of the bischromophoric skeleton gives a several-fold enhancement in a two-photon absorption cross-section as well as a 25- to 100-fold enhancement in two-photon excited fluorescence upon dsDNA binding.

A novel homologues series of diphenylamino and 1,2,4-triazole endcapped pi-conjugated oligofluorenes has been synthesized using palladium-catalyzed Suzuki cross-coupling of 9,9-dibutyl-7-(diphenylamino)-2-fluorenylboronic acid, and 1,2,4,-triazole-substituted oligofluorenyl halide was used as a key step. Efficient two- and three-photon excited photoluminescence and lasing were obtained by pumping with near-infrared femto-second lasers. The three-photon absorption cross-section enhances significantly up to 2.48 x 10(-78) cm(6) s(2) in the femtosecond regime with the length of the conjugation system. The emission is in the deep blue region and the best full width half-maximum (fwhm) of the three-photon lasing is narrower than 6 nm which is the narrowest ever reported. It was also shown that the nonlinear optics (NLO) effect increased parabolically with the conjugation length but without changing the emission wavelength. This demonstrates that varying the conjugation length is a very effective way to tailor an OF-based NLO device for deep blue application. Our findings open a new avenue to design highly efficient multiphoton absorption molecules for photoluminescence and lasing as well as provide a novel series of organic molecules that can be used in NLO applications and fundamental study.

The synthesis, characterization, photophysics, lipophilicity, and cellular properties of new phosphorescent ruthenium(II) polypyridine complexes functionalized with a dibenzocyclooctyne (DIBO) or amine moiety [Ru(N^N)2 (L)](PF6 )2 are reported (L=4-(13-N-(3,4:7,8-dibenzocyclooctyne-5-oxycarbonyl) amino-4,7,10-trioxa-tridecanyl-aminocarbonyl-oxy-methyl)-4'-methyl-2,2'-bipyridine bpy-DIBO, N^N=2,2'-bipyridine bpy (1 a), 1,10-phenanthroline phen (2 a); L=4-(13-amino-4,7,10-trioxa-tridecanylaminocarbonyl-oxy-methyl)-4'-methyl-2,2'-bipyridine bpy-NH2 , N^N=bpy (1 b), phen (2 b)). The strain-promoted alkyne-azide cycloaddition (SPAAC) reaction of the DIBO complexes 1 a and 2 a with benzyl azide were studied. Also, the DIBO complexes 1 a and 2 a can selectively label N-azidoglycans located on the surface of CHO-K1 and A549 cells that were pretreated with 1,3,4,6-tetra-O-acetyl-N-azidoacetyl-D-mannosamine (Ac4 ManNAz). Additionally, the intracellular trafficking and localization of these biomolecules were monitored using laser-scanning confocal microscopy. Interestingly, the biolabeling and cellular uptake efficiency of the DIBO complexes 1 a and 2 a were cell-line dependent, as revealed by flow cytometry and ICP-MS. Furthermore, the complexes showed good biocompatibility toward the Ac4 ManNAz-pretreated cells in the dark, but exhibited photoinduced cytotoxicity due to the generation of singlet oxygen.