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ABSTRACT: Star-shaped ladder-type ter(p-phenylene)s exhibit remarkably efficient multiphoton absorption properties with 2PA cross-section up to 2579 GM at 700 nm and 3PA cross-section up to 3.35 × 10(-76) cm(6) s(2) in the femtosecond regime for a blue-emissive molecule despite having such a short π-conjugated framework.
Chemical Communications 03/2013; · 6.17 Impact Factor
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ABSTRACT: Novel biocompatible cyanines show not only a very large two-photon cross-section of up to 5130 GM at 910 nm in aqueous medium for high-contrast and -brightness two-photon fluorescence live cell imaging but also highly selective subcellular localization properties including localization of mitochondria and lysosomes.
Chemical Communications 03/2013; · 6.17 Impact Factor
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ABSTRACT: We report the synthesis and investigation of multiphoton absorption properties of a novel series of diphenylamino-end-capped ladder-type oligo(p-phenylene)s which exhibit greatly enhanced and efficient multiphoton (from two- to five-photon) upconverted blue photoluminescence with which the record-high intrinsic three-photon absorption cross-section of 4.56 × 10(-76) cm(6) s(2) in the femtosecond regime has been obtained. Exceptionally efficient two- to five-photon-excited lasing in the blue region has also been demonstrated in which the highest two-photon-excited lasing efficiency of 0.34% has been achieved.
Journal of the American Chemical Society 04/2012; 134(17):7297-300. · 9.91 Impact Factor
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ABSTRACT: A series of luminescent multinuclear platinum(II) alkynyl complexes containing triethynylbenzene or 1,4-bis(3,5-diethynylphenyl)buta-1,3-diyne as cores has been successfully synthesized and characterized. The electronic absorption, emission, nanosecond transient absorption and electrochemical properties of these complexes have been reported. These complexes show long-lived emissions in degassed benzene solution and in alcoholic glass at 77 K. Moreover, they are found to exhibit two-photon absorption (2PA) and two-photon induced luminescence (TPIL) properties, and their two-photon absorption cross-sections have been determined to be 6-191 GM upon excitation at 720 nm. Through a systematic comparison, it has been found that tetra- and hexanuclear platinum(II) complexes show better 2PA and TPIL properties than their di- and trinuclear counterparts.
Dalton Transactions 08/2011; 40(40):10670-85. · 3.84 Impact Factor
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ABSTRACT: Remarkably strong multiphoton, from two- to five-photon, upconverted violet fluorescence is first observed on a calix[4]arene-based multi-dipolar assembly which is strongly enhanced as compared to that of the corresponding dipolar counterparts.
Chemical Communications 02/2011; 47(13):3879-81. · 6.17 Impact Factor
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ABSTRACT: Two series of quadrupolar diphenylamino-endcapped oligofluorenes, PhN-OF(n)-NPh (n=2-5) and PhN-OF(n)-TAZ-OF(n)-NPh (n=1-4), which have an electron-withdrawing 1,2,4-triazole (TAZ) moiety as central core, with D-π-A-π-D structural motif (D=donor, A=acceptor), have been synthesized by palladium-catalyzed Suzuki cross-coupling of 9,9-dibutyl-7-(diphenylamino)-2-fluorenylboronic acid and the corresponding (1,2,4-triazole-based) aryl halide as key step. On pumping with infrared femtosecond lasers, these oligomers showed very strong multiphoton-excited blue photoluminescence. These D-π-D and D-π-A-π-D quadrupolar oligofluorenes exhibit superior three-photon absorption properties compared to the respective D-π-A counterparts with a highest three-photon absorption cross-section (σ(3)) of up to 2.72×10(-77) cm(6) s(2) . Despite the comparable linear and multiphoton absorption properties of the two types of quadrupolar oligomers PhN-OF(n)-NPh and PhN-OF(n)-TAZ-OF(n)-NPh, only the former exhibit remarkably intense and highly efficient multiphoton-excited frequency-upconverted deep blue lasing, which gives rise to record high lasing efficiency of 0.097% and very narrow of full width at half-maximum of the lasing spectra. Our findings suggest that quadrupolar-type molecules/oligomers are superior for multiphoton excited frequency upconverted lasing to their dipolar counterparts and also provide important guidelines to design highly efficient three-photon absorption molecules for photoluminescence and lasing applications.
Chemistry 02/2011; 17(8):2518-26. · 5.93 Impact Factor
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ABSTRACT: 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.
Organic Letters 05/2010; 12(10):2194-7. · 5.86 Impact Factor
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ABSTRACT: The non-coplanar substituted phenyl rings at the 9-position of a fluorenyl unit can be involved in pi-electron delocalization in which the resulting oligofluorenes exhibit a very large enhancement of two-photon absorption cross sections up to 2559 GM at 710 nm.
Chemical Communications 10/2009; · 6.17 Impact Factor
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ABSTRACT: A novel series of diphenylamino- and 1,2,4-triazole-end-capped, fluorene-based, pi-conjugated oligomers that includes extended oligofluorenes and oligothienylfluorenes has been synthesized by means of the palladium-catalyzed Suzuki cross-coupling of 9,9-dibutyl-7-(diphenylamino)-2-fluorenylboronic acid and the corresponding 1,2,4,-triazole-based aryl halide as a key step. It was demonstrated that efficient two- and three-photon excited photoluminescence and lasing in the blue region are obtained by pumping near-infrared femtosecond lasers on these materials. Although the absorption and emission maxima of the highly fluorescent and extended oligofluorenes reach a saturation limit, there exists an effective conjugation length for an optimum three-photon absorption cross section in the homologous oligofluorene series. On the other hand, the multiphoton excited emission spectrum and lasing wavelength can easily be modified or tuned by an incorporation of thienyl unit(s) into the fluorene-based pi-conjugated core with which exceptionally large three-photon absorption cross sections up to 3.59 x 10(-77) cm6 s2 in the femtosecond regime have been obtained, thereby highlighting the potential of this series of photonic materials. The optimized full width at half-maximum of the cavityless three-photon upconverted blue lasing spectra are sharply narrowed to approximately 6 nm with an efficiency of up to 0.013%.
Chemistry 09/2009; 15(43):11681-91. · 5.93 Impact Factor
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ABSTRACT: A novel series of monodisperse, multi-dipolar zigzag oligoaryleneethynylenes DA(n) and D-Ar-A(n), bearing electron-donating dibenzothiophene and electron-accepting dibenzothiophene dioxide as arenes, with up to six charge-transfer (dipolar) units have been designed and synthesized by palladium-catalyzed Sonogashira coupling reactions. The linear and nonlinear optical properties of these multi-dipolar oligoaryleneethynylenes can easily be modified or enhanced by incorporating/extending with various central aryleneethynyl moieties such as phenylethynyl, oligo(9,9-dibutylfluorenyl)ethynyl, and oligothienylethynyl within the donor-acceptor units. Interestingly, the absorption and emission of these zigzag oligoaryleneethynylenes are not dependent on the number of covalently linked dipolar chromophores; however, the fluorescence quantum efficiencies consistently decrease with increased number of covalently linked dipolar units. These zigzag oligoaryleneethynylenes exhibit a linear increase in the two-photon absorption (TPA) cross-sections with increased number of covalently linked dipolar units without red-shifting the absorption and emission spectra. In addition, very large TPA cross-sections in the femtosecond regime (sigma(800) = 1306 GM in DMF or sigma(750) = 1522 GM in CH(2)Cl(2)) were obtained for D-TF-A(4) despite the moderate strength of the donor-acceptor pair. Our results suggest that the TPA properties of these zigzag oligoaryleneethynylenes including TPA wavelength and TPA cross-section can easily be tuned by means of modifying the central aryleneethynylene units and increasing the number of dipolar units, respectively. This approach provides an alternative means to tune or enhance the TPA cross-section at a specific wavelength.
The Journal of Organic Chemistry 09/2007; 72(18):6672-9. · 4.45 Impact Factor
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ABSTRACT: The coupling of surface plasmons to the photonic modes in hexagonal textured metallic microcavity was studied. Two types of sample structures (symmetric and asymmetric) were investigated. Both angle-resolved transmission and photoluminescent measurements showed the presence of surface plasmon modes for the textured metallic microcavity samples. For the asymmetric structured sample, the bandgap was observed at the Brillouin zone edge. The simulation of the photonic band structure using decoupled approximation for the standing wave modes agrees with the experimental result. We have derived the surface modes due to various interfaces in the microcavity. It was found that the surface plasmon modes from metal/air interface are most dominant, and was observed to couple strongly with both the transverse electric and transverse magnetic modes. Light extraction enhancement due to surface plasmon coupling was achieved with directional enhancement as much as 12 times compared with planar microcavity for the symmetric structured sample.
IEEE Journal on Selected Areas in Communications 08/2005; · 3.41 Impact Factor
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ABSTRACT: Dimerization of monoporphyrinate lanthanide complexes [Yb(Por)(H(2)O)(3)]Cl, (Por = TTP(2-), TMPP(2-) and TPP(2-)) in the presence of sterically hindered tripodal ligand, zinc Schiff-base, dilute HCl, K(2)CO(3) solution, 4,4'-bipyridine (bipy), and basic 8-hydroxyquinaldine (HQ) solution was observed in CH(2)Cl(2) at room temperature. Six neutral dimeric lanthanide porphyrinate complexes, [Yb(TTP)(mu-OH)](2)(mu-THF) (1), [Yb(TMPP)(mu-OH)(H(2)O)](2) (2), [Yb(TPP)(mu-OH)(mu-H(2)O)](2) (4), [Yb(TMPP)(mu-Cl)(H(2)O)](2) (5), [Yb(TMPP)(mu-OH)](2)(THF) (6) and [Yb(TPP)](2)(mu-OH)(mu-Q) (7), were obtained. X-Ray diffraction studies showed that for the dimers, the two lanthanide ions were bridged by OH(-), Cl(-) or H(2)O. Photoluminescent studies showed that the porphyrinate dianion acted as an antenna, transferred its absorbed visible energy to the lanthanide ion and enabled the latter emitting in the near-infrared (NIR) region. In general, the NIR emission is more intense for the dimers than for the monomers, and the NIR emission intensity decreases as the number of O-H oscillators present in the molecule increases.
Dalton Transactions 01/2005; · 3.84 Impact Factor
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ABSTRACT: In the presence of Ln3+ (Ln = La, Eu, Gd, Tb, Dy, Ho, Er, Tm or Lu), tris(2-aminoethyl)amine condensed with three equivalents of 3-(2′-pyridyl)-5-tert-butyl-2-hydroxybenzaldehyde in methanol to give the neutral Schiff-base complex LnIIIL (Ln = La 1, Eu 2, Gd 3, Tb 4, Dy 5, Ho 6, Er 7, Tm 8 and Lu 9; H3L = tris{[3′-(2′′-pyridyl)-5′-tert-butyl-2′-hydroxybenzylidene-2-imino]ethyl}amine). The structures of compounds 4−7 were determined by X-ray crystallography. The crystal structure analyses revealed that the Schiff base behaves as a tri-deprotonated heptadentate ligand encapsulating the lanthanide metal ion within the N4O3 cavity, with all the pyridyl groups being pendant. Solution spectroscopic data suggest that the LnIIIL complexes remain intact in methanol and exist as nine-coordinate non-electrolytes with the lanthanide metal ions coordinated to the N4O3 cavity of the tripodal Schiff base and two solvent molecules. The solution photoluminescent properties of these lanthanide Schiff-base complexes were also examined. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Berichte der deutschen chemischen Gesellschaft 01/2004; 2004(4):829 - 836. · 2.94 Impact Factor
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ABSTRACT: Twelve neutral stable complexes of ytterbium(III) and erbium(III) coordinated by anionic hydridotris(pyrazol-1-yl)borate and meso-tetraphenylporphyrinate, and its derivatives with different substituents in the para position of the phenyl groups, were prepared and characterized. Crystal structure analyses revealed that seven nitrogen atoms, four from the porphyrinate dianion and three from the anionic tripodal ligand, are symmetrically coordinated to the lanthanide ions. Photophysical investigations of the complexes showed an enhancement of near-infrared photoluminescence as compared to aqua-coordinated monoporphyrinate lanthanide complexes. The solvent effect and substituent effects on the photoluminescent properties of the complexes were also investigated (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).
Berichte der deutschen chemischen Gesellschaft 01/2004; 2004(4):837 - 845. · 2.94 Impact Factor
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ABSTRACT: Fluorescence spectrum of EuS4N complex at low temperature is very different from that at room temperature. When temperature changes, shapes of both excitation and emission spectra change dramatically at about 160 K, which is taken as an indicator of the structural change of EuS4N. Peak splitting of 5D0-->7F0 also indicates that there are two different types of coordination structure for Eu3+ ions at low temperature, while only one at room temperature. Thermal effect for the structure transition is also deduced from the relation between fluorescence intensity and temperature changing manner. These results were in good accordance with directly measurement on sample temperature. The reason for the structure change is also discussed from the structure of the EuS4N complex. This study proved that lanthanide luminescent probe, as a complementarity to X-ray diffraction technique, should be an effective tool in low temperature crystal structure study.
Guang pu xue yu guang pu fen xi = Guang pu 08/2002; 22(4):562-5. · 0.84 Impact Factor
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ABSTRACT: Four copper complexes with hydroxylated bipyridyl-like ligands, namely [Cu(2)(ophen)(2)] (1), [Cu(4)(ophen)(4)(tp)] (2), [Cu(4)(obpy)(4)(tp)] (3), and [Cu(4)(obpy)(4)(dpdc)].2H(2)O (4), (Hophen=2-hydroxy-1,10-phenanthroline, Hobpy=6-hydroxy-2,2'-bipyridine, tp=terephthalate, dpdc=diphenyl-4,4'-dicarboxylate) have been synthesized hydrothermally. X-ray single-crystal structural analyses of these complexes reveal that 1,10-phenanthroline (phen) or 2,2'-bipyridine (bpy) ligands are hydroxylated into ophen or obpy during the reaction, which provides structural evidence for the long-time argued Gillard mechanism. The dinuclear copper(I) complex 1 has three supramolecular isomers in the solid state, in which short copper-copper distances (2.66-2.68 A) indicate weak metal-metal bonding interactions. Each of the mixed-valence copper(i,ii) complexes 2-4 consists of a pair of [Cu(2)(ophen)(2)](+) or [Cu(2)(obpy)(2)](+) fragments bridged by a dicarboxylate ligand into a neutral tetranuclear dumbbell structure. Dinuclear 1 is an intermediate in the formation of 2 and can be converted into 2 in the presence of additional copper(II) salt and tp ligands under hydrothermal conditions. In addition to the ophen-centered pi-->pi* excited-state emission, 1 shows strong emissions at ambient temperature, which may be tentatively assigned as an admixture of copper-centered d-->s,p and MLCT excited states.
Chemistry 07/2002; 8(14):3187-94. · 5.93 Impact Factor
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ABSTRACT: Three terbium coordination complexes have been synthesized. Bright green emission from these compounds can be obtained under infrared pulsed laser pumping. The detail photophysics demonstrates it is due to two-photon absorption of the ligand. In addition, the effect of different ligands on upconversion efficiency was compared and discussed. This study demonstrates that enhanced two-photon induced lanthanide emission can be achieved when it is sensitized with suitable organic ligands. The estimated upconversion efficiency was 1% with an excitation energy of 1.2 W/cm2 under nanosecond pulse excitation, suggesting their potential applications in two-photon area.
Chemical Physics Letters.
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ABSTRACT: A series of luminescent trinuclear platinum(II) alkynyl complexes containing dihydro-5H-diindeno[1,2-a;1′,2′-c]fluorene (truxene) as the core and aryl alkynyl ligands with different electronic properties at the periphery has been successfully synthesized and characterized. The electronic absorption, emission, nanosecond transient absorption and electrochemical properties of these complexes have been reported. These complexes showed long-lived emissions in degassed benzene solution at room temperature, and their emissions have been assigned to originate from triplet states of intraligand (IL) character with some mixing of metal-to-ligand charge-transfer (MLCT) character. The luminescent platinum(II) alkynyl complexes are found to show two-photon absorption (2PA) and two-photon induced luminescence (TPIL) properties, and their two-photon absorption cross-sections have been determined to be 6–51 GM upon excitation at 720 nm.Graphical abstractA series of luminescent trinuclear platinum(II) alkynyl complexes containing dihydro-5H-diindeno[1,2-a;1′,2′-c]fluorene (truxene) as the core and aryl alkynyl ligands with different electronic properties at the periphery has been synthesized and characterized. The electronic absorption, emission, nanosecond transient absorption, electrochemical, two-photon absorption and two-photon induced luminescence properties of them have been reported.Research highlights► Luminescent truxene-containing platinum(II) alkynyl complexes has been reported. ► The complexes were found to be emissive with rich vibronic-structured emission bands. ► Their 2PA σ2 values were found to be in the range of 6–51 GM. ► The emissions could be readily tuned by incorporating different alkynyl ligands.
Journal of Organometallic Chemistry 696(6):1163-1173. · 2.38 Impact Factor
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ABSTRACT: Eight monoporphyrinate lanthanide complexes of the general formula [Ln(Por)(H2O)3]Cl (Ln=Yb3+ and Er3+, Por=tetraphenylporphyrin dianion (TPP2−) and its para-substituted derivatives) were prepared and characterized by elemental analyses, MS, IR and UV-Vis spectra. Photoluminescence studies showed that porphyrinate dianion absorbed the visible light, transferred the energy to lanthanide ions and enabled the later emitting in the near-infrared region. The effects of substituent and solvent on the photoluminescence efficiency were also discussed.
Synthetic Metals.
