Carbohydrate-Appended Tumor Targeting Iron(III) Complexes Showing Photocytotoxicity in Red Light

Glucose-appended photocytotoxic iron(III) complexes of a tridentate Schiff base phenolate ligand Fe(bpyag) (L)] (NO3) (1-3), where bpyag is N,N-bis(2- pyridylmethyl)-2-aminoethyl-beta-D-glucopyranoside and H2L is 3-(2-hydroxyphenylimino)-1-phenylbutan-1-one (H(2)phap) in 1, 3-(2-hydroxyphenylimino)-9-anthrylbutan-1-one (H(2)anap) 2, and 3- (2-hydroxyphenylimino)-1-pyrenylbutan-1-one (H(2)pyap) in 3, were synthesized and characterized. The complex Fe(dpma)(anapn(NO3) (4), having bis-(2-pyridylmethyl)benzylamine (dpma), in which the glucose moiety of bpyag is substituted by a phenyl group, was used as a control, and the complex Fe(dpma)(anap)](PF6) (4a) was structurally characterized by X-ray crystallography. The structure shows a FeN4O2 core in a distorted octahedral geometry. The high-spin iron(III) complexes with magnetic moment value of similar to 5.9 mu(B) showed a low-energy phenolate-to-Fe(III) charge-transfer (CT) absorption band as a shoulder near 500 nm with a tail extending to 700 nm and an irreversible Fe(III)-Fe(II) redox couple near -0.6 V versus saturated calomel electrode. The complexes are avid binders to calf thymus DNA and showed photocleavage of supercoiled pUC19 DNA in red (647 nm) and green (532 nm) light. Complexes 2 and 3 displayed significant photocytotoxicity in red light, with an IC50 value of similar to 20 mu M in HeLa and HaCaT cells, and no significant toxicity in dark. The cell death is via an apoptotic pathway, by generation of reactive oxygen species. Preferential internalization of the carbohydrate-appended complexes 2 and 3 was evidenced in HeLa cells as compared to the control complex 4. A 5-fold increase in the cellular uptake was observed for the active complexes in HeLa cells. The photophysical properties of the complexes are rationalized from the density functional theory calculations.

Hetero-tri-spin 2p-3d-4f] Chain Compounds Based on Nitronyl Nitroxide Lanthanide Metallo-Ligands: Synthesis, Structure, and Magnetic Properties

Employing nitronyl nitroxide lanthanide(III) complexes as metallo-ligands allowed the efficient and highly selective preparation of three series of unprecedented heterotri-spin (Cu Ln-radical) one-dimensional compounds. These 2p-3d-4f spin systems, namely Ln(3)Cu(hfac)II(NitPhOAII)41 (Ln(III)=Gd 1(Gd), Tb 1(Tb), Dy 1(Dy); NitPhOAII=2-(4'-allyloxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3- oxide), Ln(3)Cu(hfac)II(NitPhOPO4] (1-nrn=Gd 2Gd, Tb 2Tb, Dy 2(Dy), Ho 2HOf Yb 2yb; NitPhOPr= 2-(4'-propoxyphenyI)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) and Ln3Cu(hfac)II(NitPhOB441 (LnIm=Gd 3Gd, Tb 3Tb, Dy 3(Dy); NitPhOBz=2-(4'-benzyloxy- phenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) involve O-bound nitronyl nitroxide radicals as bridging ligands in chain structures with a Cu-Nit-Ln-Nit-Ln-Nit-Ln-Nit] repeating unit. The dc magnetic studies show that ferromagnetic metal radical interactions take place in these heterotri-spin chain complexes, these and the next-neighbor interactions have been quantified for the Gd derivatives. Complexes 1Tb and 2Tb exhibit frequency dependence of ac magnetic susceptibilities, indicating single-chain magnet behavior.

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.

Iron(III) Complexes of a Pyridoxal Schiff Base for Enhanced Cellular Uptake with Selectivity and Remarkable Photocytotoxicity

Iron(III) complexes of pyridoxal (vitamin B6, VB6) or salicylaldehyde Schiff bases and modified dipicolylamines, namely, Fe(B)(L)](NO3) (15), where B is phenyl-N,N-bis((pyridin-2-yl)methyl)methanamine (phbpa in 1), (anthracen-9-yl)-N,N-bis((pyridin-2-yl)methyl)methanamine (anbpa in 2, 4) and (pyren-1-yl)-N,N-bis((pyridin-2-yl)methyl)methanamine (pybpa in 3, 5) (H2L1 is 3-hydroxy-5-(hydroxymethyl)-4-(((2-hydroxyphenyl)imino)methyl)-2-methylp yridine (13) and H2L2 is 2-(2-hydroxyphenyl-imino)methyl]phenol), were prepared and their uptake in cancer cells and photocytotoxicity were studied. Complexes 4 and 5, having a non-pyridoxal Schiff base, were prepared to probe the role of the pyridoxal group in tumor targeting and cellular uptake. The PF6 salt (1a) of complex 1 is structurally characterized. The complexes have a distorted six-coordinate FeN4O2 core where the metal is in the +3 oxidation state with five unpaired electrons. The complexes display a ligand to metal charge transfer band near 520 and 420 nm from phenolate to the iron(III) center. The photophysical properties of the complexes are explained from the time dependent density functional theory calculations. The redox active complexes show a quasi-reversible Fe(III)/Fe(II) response near -0.3 V vs saturated calomel electrode. Complexes 2 and 3 exhibit remarkable photocytotoxicity in various cancer cells with IC50 values ranging from 0.4 to 5 mu M with 10-fold lower dark toxicity. The cell death proceeded by the apoptotic pathway due to generation of reactive oxygen species upon light exposure. The nonvitamin complexes 4 and 5 display 3-fold lower photocytotoxicity compared to their VB6 analogues, possibly due to preferential and faster uptake of the vitamin complexes in the cancer cells. Complexes 2 and 3 show significant uptake in the endoplasmic reticulum, while complexes 4 and 5 are distributed throughout the cells without any specific localization pattern.

Highly enantioselective resolution of terminal epoxides with cross-linked polymeric salen-Co(III) complexes

Crosslinked polymeric salen-Co(III) complexes derived from a novel dialdehyde and a trialdehyde were synthesized and employed in the hydrolytic kinetic resolution (HKR) of terminal epoxides. Up to 99%, ee were obtained with only 0.16-0.02 mol%,, of catalyst (based on catalytic unit). (C) 2003 Elsevier Ltd. All rights reserved.

Ternary lanthanide (Er3+, Nd3+, Yb3+, Sm3+, Pr3+) complex-functionalized mesoporous SBA-15 materials that emit in the near-infrared range

The tertiary lanthanide complexes [Ln(hfth)(3)phen] (Ln=Er, Nd, Yb, Sm) and [Pr(tfnb)(3)phen] have been Successfully covalently attached in the ordered SBA-15 mesoporous materials via a functionalized 1,10-phenanthroline group 5-(N,N-bis-3-(triethoxysilyl)propyl)ureyl-1,10-phenanthroline (Phen-Si). The derivative materials [denoted as Ln(hfth)(3)phen-S15 and Pr(tfnb)(3)phen-S15; Ln=Er, Yb, Nd, Sm; hfth=4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)hexane-1,3-dionate; tfnb=4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedionate] were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and N-2 adsorption/desorption.

Synthesis, structural characterization, and ethylene polymerization behavior of the vanadium(III) complexes bearing salicylaldiminato ligands

Vanadium(III) complexes bearing salicylaldiminato ligands (2a-k) [RN=CH(Ar0)]VCl2(THF)2 (Ar C61714, R = Ph, 2a; p-CF3Ph, 2b; p-CH3Ph, 2c; 2,6-Me2Ph, 2d; 2,6-iPr2Ph, 2e; cyclohexyl, 2f; Ar = C6H3tBu(2), R = Ph, 2g; 2,6-iPr2Ph, 2h; Ar = C6H2tBU2(2,4), R = Ph, 2i; 2,6-iPr2Ph, 2j; Ar = C6H2Br2, R = Ph, 2k) were prepared from VC13(THF)3 by treating with 1.0 equiv of (RN=CH)ArOH in tetrahydrofuran (THF) in the presence of excess triethylamine (TEA).

Effect of secondary ligands' size on energy transfer and electroluminescent efficiencies for a series of europium(III) complexes, a density functional theory study

In this paper, a quantum chemistry method was used to investigate the effect of different sizes of substituted phenanthrolines on absorption, energy transfer, and the electroluminescent performance of a series of Eu(TTA)(3)L (L = [1,10] phenanthroline (Phen), Pyrazino[2,3-f][1,10]phenanthroline (PyPhen), 2-methylprrazino[2,3-f][1,10] phenanthroline(MPP), dipyrido[3,2-a:2',3'-c]phenazine(DPPz), 11-methyldipyrido[3,2-a:2',3'c]phenazine(MDPz), 11.12-dimethyldipyrido[3,2-a:2',3'-c]phenazine(DDPz), and benzo[i]dipyrido[3,2-a:2',3'-c]phenazine (BDPz)) complexes. Absorption spectra calculations show that different sizes of secondary ligands have different effects on transition characters, intensities, and absorption peak positions.

Synthesis, Structural Characterization, and Olefin Polymerization Behavior of Vanadium(III) Complexes Bearing Tridentate Schiff Base Ligands

Vanadium(III) complexes bearing tridentate salicylaldiminato ligands (2a-f) [OC6H4CH=NL]VCl2(THF) (L = CH2CH2OMe, 2a; CH2CH2NMe2, 2b; CH2C5H4N, 2c; 8-C9H6N (quinoline), 2d; 2-MeSC6H4, 2e; 2-Ph2PC6H4, 2f) and tridentate beta-enaminoketonato ligands [OC6H8CH=N-2-Ph2PC6H4]VCl2(THF) (2g) and [O(Ph)C=CHCH=N-2-Ph2PC6H4]VCl2(THF) (2h) were prepared from VCl3(THF)(3) by treating with 1.0 equiv of the deprotonated ligands in tetrahydrofuran (THF). These complexes were characterized by FTIR and mass spectrometry as well as elemental analysis. Structures of complexes 2e, 2f, and 2h were further confirmed by X-ray crystallographic analysis. These complexes were investigated as catalysts for olefin polymerization in the presence of organoaluminum compounds. On activation with Et2AlCl, complexes 2a-h exhibited high catalytic activities toward ethylene polymerization (up to 20.64 kg PE/mmol(v) center dot h center dot bar) even at high temperature, suggesting these catalysts possess high thermal stability.

Novel vanadium(III) complexes with bidentate N,N-chelating iminopyrrolide ligands: synthesis, characterization and catalytic behaviour of ethylene polymerization and copolymerization with 10-undecen-1-ol

A series of novel vanadium(III) complexes bearing iminopyrrolide chelating ligands [2-(RN=CH)C4H3N]V(THF)(2)Cl-2 (2a: R = cyclohexyl; 2b: R = Ph; 2c: R = 2,6-iPr(2)C(6)H(3); 2d: R = p-CF3C6H4; 2e: R = C6F5) have been synthesized and characterized. Single-crystal X-ray diffraction revealed that complexes 2a, 2c and 2e adopt an octahedral geometry around the vanadium center. In the presence of Et2AlCl as a co-catalyst, these complexes displayed high catalytic activities up to 48.6 kg PE mmol(V)(-1) h(-1) bar(-1) for ethylene polymerization, and produced high molecular weight polymers. 2a-e/Et2AlCl catalytic systems were tolerant to elevated temperature (70 degrees C) and yielded unimodal polyethylenes, indicating the single site behaviour of these catalysts. By pre-treating with equimolar amounts of alkylaluminums, functional alpha-olefin 10-undecen-1-ol can be efficiently incorporated into polyethylene chains. 10-Undecen-1-ol incorporation can easily reach 15.8 mol% under the mild conditions.

Novel, highly efficient blue-emitting heteroleptic iridium(III) complexes based on fluorinated 1,3,4-oxadiazole: tuning to blue by dithiolate ancillary ligands

Novel blue-emitting phosphorescent iridium(III) complexes with fluorinated 1,3,4-oxadiazole derivatives as cyclometalated ligands and dithiolates as ancillary ligands have been synthesized and fully characterized; highly efficient OLEDs have been achieved using these complexes in the light-blue to blueemitting region.

Supramolecular architectures, photophysics, and electroluminescence of 1,3,4-oxadiazole-based iridium(III) complexes: From mu-dichloro bridged dimer to mononuclear complexes

One mu-dichloro bridged diiridium complex and three mononuclear iridium(III) complexes based on the 1,3,4-oxadiazole derivatives as cyclometalated ligands and acetylacetonate (acac) or dithiolates O,O'-diethyldithiophosphate (Et(2)dtp) or N,N'-diethyldithiocarbamate (Et(2)dtc) as ancillary ligands have been synthesized and systematically studied by X-ray diffraction analysis. The results reveal that three mononuclear complexes all adopt distorted octahedral coordination geometry around the iridium center by two chelating ligands with cis-C-C and trans-N-N dispositions, which have the same coordination mode as the diiridium dimer. The dinuclear complex crystallizes in the monoclinic system and space group C2/c, whereas three mononuclear iridium complexes are all triclinic system and space group P(1) over bar. In the stacking structure of the dimer, one-dimensional tape-like chains along the b-axis are formed by hydrogen bondings, which are strengthened by pi stacking interactions between phenyl rings of 1,3,4-oxadiazole ligands. Then these chains assemble a three-dimensional alternating peak and valley fused wave-shape structure. In each stacking structure of three mononuclear complexes, two molecules form a dimer by the C-H center dot center dot center dot O hydrogen bondings, and these dimers are connected by pi stacking interactions along the b-axis, constructing a zigzag chain.

Achiral lanthanide alkyl complexes bearing N,O multidentate ligands. Synthesis and catalysis of highly heteroselective ring-opening polymerization of rac-lactide

Alkane elimination reactions of amino-amino-bis(phenols) H2L1-4, Salan H2L5, and methoxy-beta-diimines HL6,7 with lanthanide tris(alkyl) s, Ln(CH2SiMe3)(3)(THF)(2) (Ln = Y, Lu), respectively, afforded a series of lanthanide alkyl complexes 1-8 with the release of tetramethylsilane. Complexes 1-6 are THF-solvated mono( alkyl) s stabilized by O, N, N, O-tetradentate ligands. Complexes 1-3 and 5 adopt twisted octahedral geometry, whereas 4 contains a tetragonal bipyramidal core. Bearing a monoanionic moiety L-6 (L-7), complex 7 ( 8) is a THF-free bis(alkyl). In complex 7, the O, N, N-tridentate ligand combined with two alkyl species forms a tetrahedral coordination core. Complexes 1, 2, and 3 displayed modest activity but high stereoselectivity for the polymerization of rac-lactide to give heterotactic polylactide with the racemic enchainment of monomer units P-r ranging from 0.95 to 0.99, the highest value reached to date. Complex 5 exhibited almost the same level of activity albeit with relatively low selectivity. In contrast, dramatic decreases in activity and stereoselectivity were found for complex 4. The Salan yttrium alkyl complex 6 was active but nonselective. Bis(alkyl) complexes 7 and 8 were more active than 1-3 toward polymerization of rac-LA, however, to afford atactic polylactides due to di-active sites. The ligand framework, especially the "bridge" between the two nitrogen atoms, played a significant role in governing the selectivity of the corresponding complexes via changing the geometry of the metal center.