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A specific series of chromophores ( CN1 , CN2 , CN3 , and CN4 ) have been synthesized, in which contained a triphenylamine moiety as the electron donor (D), a cyanoacetic acid moiety as the electron acceptor (A), vinylene or phenylethyne as the π -bridge, and ethyoxyl groups as auxiliary electron donor (D′) to construct the D- π -A or D′–D- π -A molecular configuration. Photophysical properties of them were systematically investigated. These results show that the chromophores display a solvatochromism (blue shift) and large Stokes shifts for their absorption bands with increasing polarity of the solvent. Furthermore, the chromophore CN4 shows the strongest intensity of two-photon excited fluorescence and largest two-photon absorption cross section (2783 GM) in the near infrared region. Finally, the connections between the structures and properties are systematically investigated relying on the information from linear and nonlinear optical properties, crytsal structures and quantum chemical calculation. [ABSTRACT FROM AUTHOR]

Cis-trans isomer and polymorphism of 9-(4-(4-nitrostyryl)phenyl)-9H-carbzole (Dye 1 ) were obtained unexpectedly. Each isomer has two polymorphs, which was characterized by X-ray single crystal diffraction. Polymorphs T1 and T2 are trans -configuration and both crystallize in monoclinic space group P 21/c. Polymorphs C1 and C2 are cis -configuration and crystallize in triclinic space group P -1 and monoclinic space group P 21/c, respectively. Trans -isomer shows better stability and higher density than that of cis -isomer, but cis -isomer displays better solubility than that of trans -isomer. The molecular structures and packing arrangements of the four kinds of crystals show different features. The twisted conformation of cis -isomer effectively avoids π-π interactions and close packing. Both the trans and cis isomers show remarkable aggregation-induced emission effect in the acetonitrile/water mixture. In addition, fluorescence cell imaging experiment proves the potential application of the two isomers of dye 1 . [ABSTRACT FROM AUTHOR]

A fluorescent chemosensor (L) for Mg 2+ has been synthesized and characterized, which exhibits turn-on fluorescence response for Mg 2+ only in alcohol solvent (methanol or ethanol) with high sensitivity and selectivity. But in both nonpolar and polar solvents (cyclohexane, DCM, DMSO or MeCN), L showed negligible fluorescent response for Mg 2+ . In order to discover the unique phenomenon, optical measurements, liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) and a high performance liquid chromatography with a fluorescence detector (HPLC–FLD) of L and L with Mg 2+ ions in solvents were studied. In alcohol solvent, [L + alcohol molecule] was formed and the mechanism aspect of L concerning the remarkable fluorescence response for Mg 2+ has been discussed. [ABSTRACT FROM AUTHOR]

Abstract: Two novel soluble chemosensors (L1, L2) modified by aza-crown ether groups have been synthesized by one-step facile reaction. The chemosensors were fully characterized by IR, 1H NMR, 13C NMR and MS spectra. The recognition abilities of two sensors with a range of metal ions were evaluated. The results showed that L1 was a specialized sensor for Cu2+ and L2 was a multi-functional sensor being able to recognize Al3+ and Cr3+ via two different optical behaviors, which demonstrated the subtle structural changes of sensors can have a remarkable effect on recognizing metal ions. [Copyright &y& Elsevier]

Abstract: An organic chromophore (4-[N, N- bis(2′-chloroethyl)anilino] ethenyl N-methyl pyridinium-N- methyl iodide) L was synthesized and fully characterized by elemental analysis, IR, 1HNMR spectra and single crystal X-ray diffraction analysis. One and two-photon fluorescence spectra for it were studied. Interestingly, L exhibited obvious two-photon absorption in the range from 700–850nm in DMSO solution. The interactions between the chromophore and calf thymus DNA were investigated by absorption, fluorescence spectra and viscosity experiments. The results showed that the chromophore could interact with DNA in the mode of intercalation and be effectively used as fluorescent staining dye for cell imaging applications. Furthermore, the cell viability data for MCF-7 (Human breast carcinoma) cells indicated that the low-micromolar concentrations of the L are essentially non-toxic and can be applied in brighter two-photon fluorescent (TPF) bioimaging. [Copyright &y& Elsevier]

Abstract: The structures of four novel organic–inorganic hybrid dyes, namely trans-4-(4′-(N,N-Dialkylaminostyryl))-N-Methyl-pyridinium[Mo6O19 2−] [alkyl = Et(POM1), Pr(POM2), n-Bu(POM3) and Me, hydroxyethyl(POM4)], were characterized by single crystal X-ray diffraction analysis. Hybridization of the organic chromophores with polyoxometalate enhanced their two-photon absorption cross sections and thermal stability. The linear optical properties of the hybrid dyes were investigated using absorption and fluorescence spectra in both the solution and solid states. The two-photon absorption cross section δ and coefficient β were obtained using the Z-scan technique. Correlations between dye structure and optical property were investigated. [Copyright &y& Elsevier]