Remarkable Selectivity and Photo-Cytotoxicity of an Oxidovanadium(IV) Complex of Curcumin in Visible Light

Oxidovanadium(IV) complexes of 2-(2'-pyridyl)-1,10-phenanthroline (pyphen), viz. VO(pyphen)(acac)](ClO4) (1), VO(pyphen)(anacac)](ClO4) (2) and VO(pyphen)(cur)](ClO4) (3), where acac is acetylacetonate (in 1), anacac is anthracenylacetylacetonate (in 2) and cur is curcumin monoanion (in 3) were synthesized, characterized and their photo-induced DNA cleavage activities and photo-cytotoxicities studied. The complexes are 1: 1 electrolytes in DMF. The one-electron paramagnetic complexes show a d-d band near 760 nm in DMF. Complexes 2 and 3 are blue and green emissive, respectively, in DMSO. The complexes exhibit irreversible V-IV/V-III reductive responses near -1.1 V and V-V/V-IV oxidative responses near 0.85 V vs. SCE in DMF-0.1 M TBAP. Complexes 2 and 3 display significant and selective photo-cytotoxicity upon irradiation with visible light giving an IC50 value of about 5 mu M against HeLa and MCF-7 cancer cells; they are significantly less-toxic against normal 3T3 control cells and in the absence of light. Complex 1 was used as a control. Both cytosolic and nuclear localization of the complexes were observed on the basis of fluorescence imaging. The complexes, avid binders to calf thymus (ct) DNA, were found to photocleave supercoiled pUC19 DNA upon irradiation with near-IR light (785 nm) by generating hydroxyl radical (OH) as the reactive oxygen species (ROS). Cell death events noted with HeLa and MCF-7 cell lines likely are attributable to apoptotic pathways involving light-assisted generation of intracellular ROS.

Remarkable visible light-triggered cytotoxicity of mitochondria targeting mixed-ligand cobalt(III) complexes of curcumin and phenanthroline bases binding to human serum albumin

Six new mixed-ligand cobalt(III) complexes of formulation Co(N-N)(2)(O-O)](ClO4)(2) (1-6), where N-N is a N,N-donor phenanthroline base, namely, 1,10-phenanthroline (phen in 1, 2), dipyrido3,2-d:2',3'-f] quinoxaline (dpq in 3, 4), and dipyrido3,2-a:2',3'-c]phenazine (dppz in 5, 6), O-O is acetylacetonate (acac in 1, 3, 5) or curcumin (bis(4-hydroxy-3-methoxyphenyl)-1,6-diene-3,5-dione, cur in 2, 4, 6), have been synthesized and characterized. The X-ray crystal structures of complex 1 (as PF6- salt, 1a) and 3 show distorted octahedral geometries formed by the CoN4O2 core. The complexes 1, 3 and 5 having the simple acac ligand are prepared as control species to understand the role of curcumin. The optimized geometries and the frontier orbitals of the curcumin complexes 2, 4, and 6 are obtained from the DFT calculations. The complexes 2, 4, and 6 having the photoactive curcumin moiety display an absorption band in the visible region near 420 nm and show remarkable photocytotoxicity in HeLa cancer cells with respective IC50 values of 7.4 mu M, 5.1 mu M and 1.6 mu M while being much less toxic in dark. MTT assay using complex 6 shows that it is not significantly photocytotoxic to MCF-10A normal cells. The control complexes having the acac ligand are non-toxic both in the presence and absence of light. The cell death is apoptotic in nature and triggered by the photogeneration of reactive oxygen species. Fluorescence imaging experiments on HeLa cells reveals that complex 6 accumulated primarily inside the mitochondria. Human serum albumin (HSA) binding experiments show that the complexes bind HSA with good affinity, but 6 binds with the highest affinity, with a K-b value of 9.8 x 10(5) M-1. Thus, complex 6 with its negligible toxicity in the dark and in normal cells but remarkable toxicity in visible light holds significant photochemotherapeutic potential.

Bi-doped BaF2 crystal for broadband near-infrared light source

Bi-doped BaF2 crystal was grown by the temperature gradient technique and its spectral properties were investigated. The absorption, emission and excitation spectra were measured at room temperature. Two broadband emissions centered at 1070 and 1500 nm were observed in Bi-doped BaF2 crystal. This extraordinary luminescence should be ascribed to Bi-related centers at distinct sites. We suggest Bi2+ or Bi+ centers adjacent to F vacancy defects are the origins of the observed NIR emissions. (C) 2009 Optical Society of America

Transparent Ni2+-doped lithium-alumino-silicate glass-ceramics for broadband near-infrared light source

Broadband infrared luminescence centred at around 1300 nm with full-width at half maximum of about 342 nm was observed from transparent Ni2+-doped lithium-alumino-silicate glass-ceramics embedded with beta-eucryptite crystallines. The room temperature fluorescent lifetime was 98 mu s. The transparent glass-ceramics may have potential applications in a widely tunable laser and a super-broadband optical amplifier for optical communications.

Synthesis and near-infrared luminescent properties of some ruthenium complexes

A series of seven ruthenium complexes with different ligands were synthesized and their optical, electrochemical and photoluminescent properties were characterized. Electroluminescent properties of these complexes were further evaluated using a light-emitting electrochemical cell with a configuration of indium tin oxide (ITO)/complex (100 nm)/Au (100 nm).

1.54 mu m near-infrared photoluminescent and electroluminescent properties of a new Erbium (111) organic complex

The crystal structure of Er(PM)(3)(TP)(2) [PM = 1-Phenyl-3-methyl-4-isobutyryl-5-pyrazoloiie, TP = triphenyl phosphine oxide] was reported and its photoluminescence properties were studied by UV-vis absorption, excited, and emission spectra. The Judd-ofelt theory was introduced to calculate the radiative transition rate and the radiative decay time of 3.65 ms for the I-4(13/2) -> I-4(15/2) transition of Er3+ ion in this complex.

Band Gap Tunable, Donor-Acceptor-Donor Charge-Transfer Heteroquinoid-Based Chromophores: Near Infrared Photoluminescence and Electroluminescence

A series of D-pi-A-pi-D type of near-infrared (NIR) fluorescent compounds based on benzobis(thia diazole) and its selenium analogues were synthesized and fully characterized by H-1 and C-13 NMR, high-resolution mass spectrometry, and elemental analysis. The absorption fluorescence, and electrochemical properties were also studied. Photoluminescence of these chromophores ranges from 900 to 1600 nm and their band gaps are between 1.19 and 0.56 eV.

Near-infrared polymer light-emitting diodes based on infrared dye doped poly(N-vinylcarbazole) film

Infrared light-emitting diodes possess potential applications in optical communication and safety detection. in this paper, we fabricated near-infrared light-emitting diodes possess potential applications in optical communication and safety detection. in this paper, we fabricated near-infrared polymer light-emitting diode employing a commercial near-infrared (NIR) organic dye as an emissive dopant dispersed within poly(N-vinylcarbazole) (PVK) by spin-casting method. The used device structure was indium tin oxide/3,4-polyethylene-dioxythiophene-polystyrene sulfonate/PVK: NIR dye/Al.

Synthesis, characterization, and near-infrared luminescent properties of the ternary thulium complex covalently bonded to mesoporous MCM-41

The crystal structure of a ternary Tm(DBM)(3)phen complex (DBM - dibenzoylmethane; phen = 1. 10-phenanthroline) and the synthesis of hybrid mesoporous material in which the complex covalently bonded to mesoporous MCM-41 are reported. Crystal data: Tm(DBM)(3)phen C59H47N2O7Tm, monoclinic P21/c, a = 19.3216(12) A, b = 10.6691(7) A, c = 23.0165(15)A, alpha = 90, beta = 91.6330(10), gamma = 90, V = 4742.8(5) A(3), Z = 4. The properties of the Tm(DBM)(3)phen complex and the corresponding hybrid mesoporous material [Tm(DBM)(3)phen-MCM-41] have been studied. The results reveal that the Tm(DBM)(3)phen complex is successfully covalently bonded to MCM-41.

Rational Design, Synthesis, and Optical Properties of Film-Forming, Near-Infrared Absorbing, and Fluorescent Chiromophores with Multidonors and Large Heterocyclic Acceptors

A new series of film-forming, low-bandgap chromophores (1a,b and 2a,b) were rationally designed with aid of a computational study., and then synthesized and characterized. To realize absorption and emission above the 1000 nm wavelength, the molecular design focuses on lowering the LUMO level by fusing common heterocyclic units into a large conjugated core that acts an electron acceptor and increasing the charge transfer by attaching the multiple electron-donating groups at the appropriate positions of the acceptor core. The chromophores have bandgap levels of 1.27-0.71 eV, and accordingly absorb at 746-1003 nm and emit at 1035-1290 nm in solution. By design, the relatively high molecular weight (up to 2400 g mol(-1)) and non-coplanar structure allow these near-infrared (NIR) chromophores to be readily spin-coated as uniform thin films and doped with other organic semiconductors for potential device applications. Doping with [6,6]-phenyl-C-61 butyric acid methyl ester leads to a red shift in the absorption on]), for la and 2a. An interesting NIR electrochromism was found for 2a, with absorption being turned on at 1034 nm when electrochemically switched (at 1000 mV) from its neutral state to a radical cation state. Furthermore, a large Stokes shift (256-318 nm) is also unique for this multidonor-acceptor type of chromophore.

Probing near-infrared photorelaxation pathways in eumelanins and pheomelanins.

Ultraviolet-visible spectroscopy readily discerns the two types of melanin pigments (eumelanin and pheomelanin), although fundamental details regarding the optical properties and pigment heterogeneity are more difficult to disentangle via analysis of the broad featureless absorption spectrum alone. We employed nonlinear transient absorption spectroscopy to study different melanin pigments at near-infrared wavelengths. Excited-state absorption, ground-state depletion, and stimulated emission signal contributions were distinguished for natural and synthetic eumelanins and pheomelanins. A starker contrast among the pigments is observed in the nonlinear excitation regime because they all exhibit distinct transient absorptive amplitudes, phase shifts, and nonexponential population dynamics spanning the femtosecond-nanosecond range. In this manner, different pigments within the pheomelanin subclass were distinguished in synthetic and human hair samples. These results highlight the potential of nonlinear spectroscopies to deliver an in situ analysis of natural melanins in tissue that are otherwise difficult to extract and purify.

Rare-earth complexes of ferrocene-containing ligands: Visible-light excitable luminescent materials

The ferrocene-derivatives bis(ferrocenyl-ethynyl)-1,10-phenanthroline (Fc(2)phen) and ferrocenoyltrifluoroacetone (Hfta) have been used to synthesize ferrocene-containing rare-earth beta-diketonate complexes. The complexes [Ln(tta)(3)(Fc(2)phen)] and [Ln(fta)(3)(phen)] (where Ln = La, Nd, Eu, Yb) show structural similarities to the tris(2-thenoyltrifluoroacetonate)(1,10-phenanthroline)lanthanide(III) complexes, [Ln(tta)(3)(phen)]. The coordination number of the lanthanide ion is 8, and the coordination sphere can be described as a distorted dodecahedron. However, the presence of the ferrocene moieties shifts the ligand absorption bands of the rare-earth complexes to longer wavelengths so that the complexes can be excited not only by ultraviolet radiation but also by visible light of wavelengths up to 420 nm. Red photoluminescence is observed for the europium(III) complexes and near-infrared photoluminescence for the neodymium(III) and ytterbium(III) complexes. The presence of the ferrocene groups makes the rare-earth complexes hydrophobic and well-soluble in apolar organic solvents.

Near infrared electroluminescence from neodymium complex-doped polymer light emitting diodes

Organic light emitting diode devices employing organometallic Nd(9-hydroxyphenalen-1-one)(3) complexes as near infrared emissive dopants dispersed within poly(N-vinylcarbazole) (PVK) host matrices have been fabricated by spin-casting layers of the doped polymer onto glass/indium tin oxide (ITO)/3,4-polyethylene-dioxythiophene-polystyrene sulfonate (PEDOT) substrates. Room temperature electroluminescence, centered at similar to 1065 nm. was observed from devices top contacted by evaporated aluminum or calcium metal cathodes and was assigned to transitions between the F-4(3/2) -> I-4(11/2) levels of the Nd3+ ions. In particular, a near infrared irradiance of 8.5 nW/mm(2) and an external quantum efficiency of 0.007% was achieved using glass/ITO/PEDOT/PVK:Nd(9-hydroxyphenalen-1-one)(3)/Ca/Al devices. (c) 2005 Elsevier B.V. All rights reserved.

Extensive optical and near-infrared observations of the nearby, narrow-lined type Ic SN 2007gr: days 5 to 415

We present photometric and spectroscopic observations at optical and near-infrared wavelengths of the nearby type Ic supernova 2007gr. These represent the most extensive data-set to date of any supernova of this sub-type, with frequent coverage from shortly after discovery to more than one year post-explosion. We deduce a rise time to B-band maximum of 11.5 +/- 2.7 d. We find a peak B-band magnitude of M-B = -16.8, and light curves which are remarkably similar to the so-called "hypernova" SN 2002ap. In contrast, the spectra of SNe 2007gr and 2002ap show marked differences, not least in their respective expansion velocities. We attribute these differences primarily to the density profiles of their progenitor stars at the time of explosion i.e. a more compact star for SN 2007gr compared to SN 2002ap. From the quasi-bolometric light curve of SN 2007gr, we estimate that 0.076 +/- 0.010 M-circle dot of Ni-56 was produced in the explosion. Our near-infrared (IR) spectra clearly show the onset and disappearance of the first overtone of carbon monoxide (CO) between similar to 70 to 175 d relative to B-band maximum. The detection of the CO molecule implies that ionised He was not microscopically mixed within the carbon/oxygen layers. From the optical spectra, near-IR light curves, and colour evolution, we find no evidence for dust condensation in the ejecta out to about +400 d. Given the combination of unprecedented temporal coverage, and high signal-to-noise data, we suggest that SN 2007gr could be used as a template object for supernovae of this sub-class.