基于钌配合物荧光猝灭原理的新型氟化有机改性溶胶-凝胶氧传感膜的研究

选用3,3,3-三氟丙基三甲氧基硅烷为前驱体,制备氧光化学传感膜材料.利用4,7-二苯基-1,10-邻菲咯啉钌(Ⅱ)([Ru(dpp)3(ClO4)2])为氧荧光猝灭指示剂,通过优化制备条件获得对氧浓度变化具有敏感响应的传感膜.研究结果表明:所制备的氧传感膜对水体中的溶解氧的线性响应范围为0.5～16.0 mg/L,最...     

Direct observation of triplet state emission of single molecules: single molecule phosphorescence quenching of metalloporphyrin and organometallic complexes by molecular oxygen and their quenching rate distributions

Single molecules are detected through the phosphorescence emission of their triplet states. Emission of the triplet states of single molecules of Pt octabutoxycarbonyl porphyrin (PtOBCP) and ruthenium(II)-tris-4,7-diphenyl-1,10-phenanthroline dichloride (Ru(dpp)(3)Cl(2)) is reported. The single molecule phosphorescence is very sensitive to molecular oxygen. Each molecule has its own characteristic quenching rate by oxygen, and the distribution of these rates is measured for (Ru(dpp)(3)Cl(2)) on a quartz surface. The large variance of this distribution is presumed to be caused by fluctuations in the pseudobimolecular rate coefficient and the local oxygen concentration. The possibility of creating a quantitative single oxygen molecule sensor is suggested.     

3D inverted opal hydrogel scaffolds with oxygen sensing capability

The measurement of local oxygen level in 3D cell culture is desired but remains as a challenge problem. We developed a 3D cell scaffold with luminescence-based oxygen sensing capability that opens the possibility of 3D mapping of oxygen level during cell growth. Hydrogel inverted opal scaffold was prepared by photo-polymerization of poly(2-hydroxyethyl methacrylate (pHEMA) and poly(methacryloyloxy)ethyl-trimethylammonium chloride (pMEATAC) monomer using close-packed bead assembly as template. Tris(4,7-diphenyl-1,10-phenanthroline)ruthenium chloride (Ru(dpp)(3)), was coated on the pHEMA-pMEATAC 3D scaffolds by layer-by-layer (LBL) assembly. pHEMA-pMEATAC copolymer was coated on top of the Ru(dpp)(3) layer as a protection layer. The fluorescence emission of Ru(dpp)(3) can be dynamically quenched by oxygen. By measuring the emission intensity of the scaffold, the local oxygen level can be monitored. The hydrogel scaffolds are transparent, and thus 3D fluorescence intensity can be mapped by confocal microscopy. Human bone marrow stromal cells HS-5 were successfully cultured on the oxygen sensing scaffold, and the observed Ru(dpp)(3) emission intensity from the scaffold was stronger in cell rich area, which indicates a lower oxygen level due to the consumption of the cells.     

Structurally integrated organic light emitting device-based sensors for gas phase and dissolved oxygen

A compact photoluminescence (PL)-based O2 sensor utilizing an organic light emitting device (OLED) as the light source is described. The sensor device is structurally integrated. That is, the sensing element and the light source, both typically thin films that are fabricated on separate glass substrates, are attached back-to-back. The sensing elements are based on the oxygen-sensitive dyes Pt- or Pd-octaethylporphyrin (PtOEP or PdOEP, respectively), which are embedded in a polystyrene (PS) matrix, or dissolved in solution. Their performance is compared to that of a sensing element based on tris(4,7-diphenyl-l,10-phenanthroline) Ru II (Ru(dpp)) embedded in a sol-gel film. A green OLED light source, based on tris(8-hydroxy quinoline Al (Alq3), was used to excite the porphyrin dyes; a blue OLED, based on 4,4'-bis(2,2'-diphenylviny1)-1,1'-biphenyl, was used to excite the Ru(dpp)-based sensing element. The O2 level was monitored in the gas phase and in water, ethanol, and toluene solutions by measuring changes in the PL lifetime tau of the O2-sensitive dyes. The sensor performance was evaluated in terms of the detection sensitivity, dynamic range, gas flow rate, and temperature effect, including the temperature dependence of tau in pure Ar and O2 atmospheres. The dependence of the sensitivity on the preparation procedure of the sensing film and on the PS and dye concentrations in the sensing element, whether a solid matrix or solution, were also evaluated. Typical values of the detection sensitivity in the gas phase, S(g) identical with tau(0% O2)/tau(100% O2), at 23 degrees C, were approximately 35 to approximately 50 for the [Alq3 OLED[/[PtOEP dye] pair; S(g) exceeded 200 for the Alq3/PdOEP sensor. For dissolved oxygen (DO) in water and ethanol, S(DO) (defined as the ratio of tau in de-oxygenated and oxygen-saturated solutions) was approximately 9.5 and approximately 11, respectively, using the PtOEP-based film sensor. The oxygen level in toluene was measured with PtOEP dissolved directly in the solution. That sensor exhibited a high sensitivity, but a limited dynamic range. Effects of aggregation of dye molecules, sensing film porosity, and the use of the OLED-based sensor arrays for O2 and multianalyte detection are also discussed.     

Luminescence Quenching Behavior of Oxygen Sensing ORMOSIL Films Based on Ruthenium Complex

An organically modified silicate(ORMOSIL) based optical sensor response to gaseous O2 or O2 dissolved in water is presented. The oxygen sensing film mechanism is based on the principle of fluorescence quenching of tris(4,7-diphenyl-l , 10-phenanthroline) ruthenium ( ) ([Ru(dpp)3]2+), which has been entrapped in a porous ORMOSIL film. In order to establish optimum film-processing parameters, comprehensive investigations, including the effects of the polarity and the hydrophobicity of the sensing film on oxygen quenching response and response time, were carried out. The film hydrophobicity increased as a function of dimethyl-dimethoxysilane (DiMe-DMOS) content, which is correlated with enhanced oxygen sensor performance. The sensor developed in the present work exhibits the advantages of fast response time and good reversibility. The detection limits are 0. 5 % and 0. 3 g/mL for O2 in the gaseous and the aqueous phases, respectively.     

A Water-Soluble Luminescence Oxygen Sensor

We developed a water-soluble luminescent probe for dissolved oxygen. This probe is based on (Ru[dpp(SO₃Na)₂]₃) Cl₂, which is a sulfonated analogue of the well-known oxygen probe (Ru[dpp]₃)Cl₂. The compound dpp is 4,7-diphenyl-1,10-phenanthroline and dpp(SO₃Na)₂ is a disulfonated derivative of the same ligand. In aqueous solution in the absence of oxygen (Ru[dpp(SO₃Na)₂]₃)Cl₂ displays a lifetime of 3.7 μs that decreases to 930 ns on equilibrium with air and 227 ns on equilibrium with 100% oxygen. The Stern–Vohner quenching constant is 11330 M⁻¹. This high oxygen-quenching constant means that the photoluminescence of Ru(dpp[SO₃Na]₂)₃Cl₂ is 10% quenched at an oxygen concentration of 8.8 x 10⁻⁶ M , or equilibration with 5.4 torr of oxygen. The oxygen probe dissolved in water displays minimal interactions with lipid vesicles composed of dipalmityl-L-α-phosphatidyl glycerol but does appear to interact with human serum albumin. The absorption maximum near 480 nm, long lifetime and large Stokes'shift allow this probe to be used with simple instrumentation based on a light-emitting diode light source, allowing low-cost oxygen sensing in aqueous solutions. To the best of our knowledge this is the first practical water-soluble oxygen sensor.     

Electrochemical and luminescent properties of new mononuclear ruthenium(II) and binuclear iridium(III)-ruthenium(II) terpyridine complexes.

Hexafluorophosphate salts of mononuclear complexes [Ru(II)Cl(L)(terpy)]+ (L = dmbpy (1); dpbpy (2), sambpy (3), and dpp (7), and binuclear complexes [Ru(II)2Cl2(dpp)(terpy)2]2+ (8) and [Ir(III)Ru(II)Cl2(dpp)(terpy)2]3+ (9) were prepared and characterized. Abbreviations of the ligands are bpy = 2,2'-bipyridine, dmbpy = 4,4'-dimethyl-2,2'-bipyridine, dpbpy = 4,4'-diphenyl-2,2'-bipyridine, dpp = 2,3-bis(2-pyridyl)pyrazine, sambpy = 4,4'-bis((S)-(+)-alpha-1-phenylethylamido)-2,2'-bipyridine, and terpy = 2,2':6',2'-terpyridine. The absorption spectra of 8 and 9 are dominated by ligand-centered bands in the UV region and by metal-to-ligand charge-transfer bands in the visible region. The details of their spectroscopic and electrochemical properties were investigated. In both binuclear complexes, it has been found that the HOMO is based on the Ru metal, and LUMO is dpp-based. [Ir(III)Ru(II)Cl2(dpp)(terpy)2]3+, indicating intense emission at room temperature, and a lifetime of 154 ns. The long lifetime of this bimetallic chromophore makes it a useful component in the design of supramolecular complexes.     

Electrochemiluminescent metallopolymers: Tuning the emission wavelength by energy transfer between two bound centres

The electrochemical and photonic properties of a metallopolymer in which both [Ru(dpp)₂Cl]⁺ (N5Cl) and [Ru(dpp)₂]²⁺ (N6) moieties are coordinated to a poly(4-vinylpyridine) backbone are described, dpp is 4,7-diphenyl-1,10-phenanthroline. Cyclic voltammetry and luminescence studies indicate that approximately 2% of centres are bis-coordinated to the PVP backbone, i.e., 2% are [Ru(dpp)₂]²⁺. When dissolved in ethanol or acetonitrile, two photoluminescence peaks are observed, at 620 and 720 nm corresponding to the N6 and N5Cl moieties, respectively. This dual emission indicates that the two centres communicate weakly in solution. In contrast, in aqueous solution or in thin films, a single emission band at 720 nm is observed suggesting efficient energy transfer to the N5Cl moiety. Polymer films generate electrochemiluminescence in the presence of oxalate as a co-reactant with an emission maximum at 730 nm corresponding to emission from the N5Cl centres alone.     

trans-[Ru(II)(dpp)Cl2]: a convenient reagent for the preparation of heteroleptic Ru(dpp) complexes, where dpp is 2,9-di(pyrid-2'-yl)-1,10-phenanthroline

The reaction of 2,9-di(pyrid-2'-yl)-1,10-phenanthroline (dpp) with [RuCl(3)·3H(2)O] or [Ru(DMSO)(4)Cl(2)] provides the reagent trans-[Ru(II)(dpp)Cl(2)] in yields of 98 and 89%, respectively. This reagent reacts with monodentate ligands L to replace the two axial chlorides, affording reasonable yields of a ruthenium(II) complex with dpp bound tetradentate in the equatorial plane. The photophysical and electrochemical properties of the tetradentate complexes are strongly influenced by the axial ligands with electron-donating character to stabilize the ruthenium(III) state, shifting the metal-to-ligand charge-transfer absorption to lower energy and decreasing the oxidation potential. When the precursor trans-[Ru(II)(dpp)Cl(2)] reacts with a bidentate (2,2'-bipyridine), tridentate (2,2';6,2'-terpyridine), or tetradentate (itself) ligand, a peripheral pyridine on dpp is displaced such that dpp binds as a tridentate. This situation is illustrated by an X-ray analysis of [Ru(dpp)(bpy)Cl](PF(6)).     

Mixed-metal supramolecular complexes coupling phosphine-containing Ru(II) light absorbers to a reactive Pt(II) through polyazine bridging ligands

Supramolecular bimetallic Ru(II)/Pt(II) complexes [(tpy)Ru(PEt(2)Ph)(BL)PtCl(2)](2+) and their synthons [(tpy)Ru(L)(BL)](n)()(+) (where L = Cl(-), CH(3)CN, or PEt(2)Ph; tpy = 2,2':6',2'-terpyridine; and BL = 2,2'-bipyrimidine (bpm) or 2,3-bis(2-pyridyl)pyrazine (dpp)) have been synthesized and studied by cyclic voltammetry, electronic absorption spectroscopy, mass spectral analysis, and (31)P NMR. The mixed-metal bimetallic complexes couple phosphine-containing Ru chromophores to a reactive Pt site. These complexes show how substitution of the monodentate ligand on the [(tpy)RuCl(BL)](+) synthons can tune the properties of these light absorbers (LA) and incorporate a (31)P NMR tag by addition of the PEt(2)Ph ligand. The redox potentials for the Ru(III/II) couples occur at values greater than 1.00 V versus the Ag/AgCl reference electrode and can be tuned to more positive potentials on going from Cl(-) to CH(3)CN or PEt(2)Ph (E(1/2) = 1.01, 1.55, and 1.56 V, respectively, for BL = bpm). The BL(0/-) couple at -1.03 (bpm) and -1.05 V (dpp) for [(tpy)Ru(PEt(2)Ph)(BL)](2+) shifts dramatically to more positive potentials upon the addition of the PtCl(2) moiety to -0.34 (bpm) and -0.50 V (dpp) for the [(tpy)Ru(PEt(2)Ph)(BL)PtCl(2)](2+) bridged complex. The lowest energy electronic absorption for these complexes is assigned as the Ru(d pi) --> BL(pi*) metal-to-ligand charge transfer (MLCT) transition. These MLCT transitions are tuned to higher energy in the monometallic synthons when Cl(-) is replaced by CH(3)CN or PEt(2)Ph (516, 452, and 450 nm, for BL = bpm, respectively) and to lower energy when Pt(II)Cl(2) is coordinated to the bridging ligand (560 and 506 nm for BL = bpm or dpp). This MLCT state displays a broad emission at room temperature for all the dpp systems with the [(tpy)Ru(PEt(2)Ph)(dpp)PtCl(2)](2+) system exhibiting an emission centered at 750 nm with a lifetime of 56 ns. These supramolecular complexes [(tpy)Ru(PEt(2)Ph)(BL)PtCl(2)](2+) represent the covalent linkage of TAG-LA-BL-RM assembly (TAG = NMR active tag, RM = Pt(II) reactive metal).     

Entrapment of ionic tris(2,2'-bipyridyl) ruthenium(II) in hydrophobic siliceous zeolite: O2 sensing in biological environments

Synthesis of the ionic dye, tris(2,2'-bipyridyl) ruthenium(II) chloride (Ru(bpy) 3 2+.2Cl (-)) within the supercages of a highly hydrophobic zeolite Y is reported. Use of the neutral precursor Ru(bpy)Cl 2(CO) 2 allowed for high loading levels of Ru(bpy) 3 2+ (1 per 7 and 25 supercages). The emission quenching of the Ru(bpy) 3 2+-zeolite crystals dispersed in polydimethoxysiloxane (PDMS) films by dissolved oxygen in water was examined. The quenching data as a function of oxygen concentration was fit to a linear Stern-Volmer plot ( R2 = 0.98). Using the Stern-Volmer plot as calibration, changes in concentration of dissolved oxygen due to reaction with glucose in the presence of glucose oxidase was monitored. Human monocyte-derived macrophages internalized the submicron-sized Ru(bpy) 3 2+-zeolite crystals, and intracellular oxygen concentrations initiated by zymosan-mediated oxidative burst could be monitored by measuring the emission from Ru(bpy) 3 2+ by confocal fluorescence microscopy.     

改性SiO2载体对邻菲咯啉钌荧光特性及氧敏感荧光膜性能的影响

为提高极性荧光指示剂Ru(dpp)₃Cl₂在非极性硅橡胶中的分散性,以沉淀白炭黑、气相白炭黑和甲基MQ树脂,载负荧光指示剂Ru(dpp)₃Cl₂,再填充到二甲基硅橡胶(PDMS)中,制备氧敏感荧光膜.以分光光度计和荧光光谱仪,研究载体种类对Ru(dpp)₃Cl₂的吸附性、荧光特性及氧敏感荧光膜性能的影响.白炭黑载负Ru(dpp)₃Cl₂的荧光发射光谱相对其稀溶液约红移20 nm.载体表面的甲基可减弱SiO₂载体对Ru(dpp)₃Cl₂分子的吸附性和相互作用,减少荧光发射光谱的红移12 nm,提高荧光强度近10倍.白炭黑有助改善Ru(dpp)₃Cl₂在PDMS中的分散性和氧敏感荧光膜的荧光输出和猝灭比,尤以MQ树脂的效果最为显著.     

Fiber-optic fluorescence sensor for dissolved oxygen detection based on fluorinated xerogel immobilized with ruthenium (II) complex

A fiber-optic sensor based on fluorescence quenching was designed for dissolved oxygen (DO) detection. The fluorinated xerogel-based sensing film of the present sensor was prepared from 3, 3, 3-trifluoropropyltrimethoxysilane (TFP–TriMOS). Oxygen-sensitive fluorophores of tris (2, 2′- bipyridine) ruthenium (II) (Ru(bpy)₃²⁺) were immobilized in the sensing film and the emission fluorescence was quenched by dissolved oxygen. In the sensor fabrication, a two-fiber probe was employed to obtain the best fluorescence collection efficiency and the sensing film was attached to the probe end. Scanning electron microscope (SEM), UV–Vis absorption spectroscopy (UV–Vis) and fourier transform infrared spectroscopy (FTIR) measurements have been used to characterize the sensing film. The sensor sensitivity is quantified by I _deoxy/I _oxy, where I _deoxy and I _oxy represented the detected fluorescence intensities in fully deoxygenated and fully oxygenated environments, respectively. Compared with tetramethoxysilane (TMOS) and methyltriethoxysilane (MTMS)-derived sensing films, TFP–TriMOS-based sensor exhibited excellent performances in dissolved oxygen detection with short response time of 4 s, low limit of detection (LOD) of 0.04 ppm (R.S.D. = 2.5%), linear Stern–Volmer calibration plot from 0 to 40 ppm and long-term stability during the past 10 months. The reasons for the preferable performances of TFP–TriMOS-based sensing film were discussed.     

光学氧传感器的研制

本文根据氧分子能有效地猝灭金属有机络合物的荧光的原理，研制了一种氧传感器。     

Photobiological impact of [{(bpy)2Ru(dpp)}2RhCl2]Cl5 and [{(bpy)2Os(dpp)}2RhCl2]Cl5 [bpy=2,2'-bipyridine; dpp=2,3-Bis(2-pyridyl)pyrazine] on vero cells

The in vitro photobiology of the supramolecular complexes [{(bpy)2Ru(dpp)}2RhCl2]Cl5 and [{(bpy)2Os(dpp)}2RhCl2]Cl5 [bpy=2,2'-bipyridine; dpp=2,3-bis(2-pyridyl)pyrazine] with African green monkey kidney epithelial (Vero) cells was investigated. Previously, the complexes have been shown to photocleave DNA in the presence or absence of O2. Vero cell replication was uninhibited for cells exposed to the metal complex but protected from light. Vero cells that were exposed to metal complex, rinsed, and illuminated with >460 nm light showed a replication response that was metal complex concentration-dependent. Vero cells exposed to 3.0-120 microM [{(bpy)2Ru(dpp)}2RhCl2]Cl5 and illuminated showed inhibition of cell growth, with evidence of cell death seen for complex concentrations>or=10 microM. Cells exposed to [{(bpy)2Os(dpp)}2RhCl2]Cl5 at concentrations of 5.5-110 microM, rinsed, and illuminated showed only inhibition of cell growth. The impact of [{(bpy)2Ru(dpp)}2RhCl2]Cl5 and [{(bpy)2Os(dpp)}2RhCl2]Cl5 on cell growth following illumination shows the promise of this new structural motif as a photodynamic therapy agent.     

A new Os,Rh bimetallic with O2 independent DNA cleavage and DNA photobinding with red therapeutic light excitation

Many Ru and Os systems display photoactive (3)MLCT states. Systems activated by therapeutic window light in the absence of O(2) remain elusive. [(bpy)(2)Os(dpp)RhCl(2)(phen)](3+) photobinds and photocleaves DNA under red light in an oxygen independent manner, due to molecular design involving one Os chromophore coupled to a photoactive cis-Rh(III)Cl(2) moiety.     

Ruthenium(II)-polyazine light absorbers bridged to reactive cis-dichlororhodium(III) centers in a bimetallic molecular architecture

Bimetallic complexes of the form [(bpy)(2)Ru(BL)RhCl(2)(phen)](PF(6))(3), where bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline, and BL = 2,3-bis(2-pyridyl)pyrazine (dpp) or 2,2'-bipyrimidine (bpm), were synthesized, characterized, and compared to the [{(bpy)(2)Ru(BL)}(2)RhCl(2)](PF(6))(5) trimetallic analogues. The new complexes were synthesized via the building block method, exploiting the known coordination chemistry of Rh(III) polyazine complexes. In contrast to [{(bpy)(2)Ru(dpp)}(2)RhCl(2)](PF(6))(5) and [{(bpy)(2)Ru(bpm)}(2)RhCl(2)](PF(6))(5), [(bpy)(2)Ru(dpp)RhCl(2)(phen)](PF(6))(3) and [(bpy)(2)Ru(bpm)RhCl(2)(phen)](PF(6))(3) have a single visible light absorber subunit coupled to the cis-Rh(III)Cl(2) moiety, an unexplored molecular architecture. The electrochemistry of [(bpy)(2)Ru(dpp)RhCl(2)(phen)](PF(6))(3) showed a reversible oxidation at 1.61 V (vs Ag/AgCl) (Ru(III/II)), quasi-reversible reductions at -0.39 V, -0.74, and -0.98 V. The first two reductive couples corresponded to two electrons, consistent with Rh reduction. The electrochemistry of [(bpy)(2)Ru(bpm)RhCl(2)(phen)](PF(6))(3) exhibited a reversible oxidation at 1.76 V (Ru(III/II)). A reversible reduction at -0.14 V (bpm(0/-)), and quasi-reversible reductions at -0.77 and -0.91 V each corresponded to a one electron process, bpm(0/-), Rh(III/II), and Rh(II/I). The dpp bridged bimetallic and trimetallic display Ru(dpi)-->dpp(pi*) metal-to-ligand charge transfer (MLCT) transitions at 509 nm (14,700 M(-1) cm(-1)) and 518 nm (26,100 M(-1) cm(-1)), respectively. The bpm bridged bimetallic and trimetallic display Ru(dpi)-->bpm(pi*) charge transfer (CT) transitions at 581 nm (4,000 M(-1) cm(-1)) and 594 nm (9,900 M(-1) cm(-1)), respectively. The heteronuclear complexes [(bpy)(2)Ru(dpp)RhCl(2)(phen)](PF(6))(3) and [{(bpy)(2)Ru(dpp)}(2)RhCl(2)](PF(6))(5) had (3)MLCT emissions that are Ru(dpi)-->dpp(pi*) CT in nature but were red-shifted and lower intensity than [(bpy)(2)Ru(dpp)Ru(bpy)(2)](PF(6))(4). The lifetimes of the (3)MLCT state of [(bpy)(2)Ru(dpp)RhCl(2)(phen)](PF(6))(3) at room temperature (30 ns) was shorter than [(bpy)(2)Ru(dpp)Ru(bpy)(2)](PF(6))(4), consistent with favorable electron transfer to Rh(III) to generate a metal-to-metal charge-transfer ((3)MMCT) state. The reported synthetic methods provide means to a new molecular architecture coupling a single Ru light absorber to the Rh(III) center while retaining the interesting cis-Rh(III)Cl(2) moiety.     

Characteristics and properties of metal-to-ligand charge-transfer excited states in 2,3-bis(2-pyridyl)pyrazine and 2,2'-bypyridine ruthenium complexes. Perturbation-theory-based correlations of optical absorption and emission parameters with electrochemistry and thermal kinetics and related Ab initio calculations

The absorption, emission, and infrared spectra, metal (Ru) and ligand (PP) half-wave potentials, and ab initio calculations on the ligands (PP) are compared for several [L(n)()Ru(PP)](2+) and [[L(n)Ru]dpp[RuL'(n)]](4+) complexes, where L(n) and L'(n) = (bpy)(2) or (NH(3))(4) and PP = 2,2'-bipyridine (bpy), 2,3-bis(2-pyridyl)pyrazine (dpp), 2,3-bis(2-pyridyl)quinoxaline (dpq), or 2,3-bis(2pyridyl)benzoquinoxaline (dpb). The energy of the metal-to-ligand charge-transfer (MLCT) absorption maximum (hnu(max)) varies in nearly direct proportion to the difference between Ru(III)/Ru(II) and (PP)/(PP)(-) half-wave potentials, DeltaE(1/2), for the monometallic complexes but not for the bimetallic complexes. The MLCT spectra of [(NH(3))(4)Ru(dpp)](2+) exhibit three prominent visible-near-UV absorptions, compared to two for [(NH(3))(4)Ru(bpy)](2+), and are not easily reconciled with the MLCT spectra of [[(NH(3))(4)Ru]dpp[RuL(n)]](4+). The ab initio calculations indicate that the two lowest energy pi orbitals are not much different in energy in the PP ligands (they correlate with the degenerate pi orbitals of benzene) and that both contribute to the observed MLCT transitions. The LUMO energies calculated for the monometallic complexes correlate strongly with the observed hnu(max) (corrected for variations in metal contribution). The LUMO computed for dpp correlates with LUMO + 1 of pyrazine. This inversion of the order of the two lowest energy pi orbitals is unique to dpp in this series of ligands. Configurational mixing of the ground and MLCT excited states is treated as a small perturbation of the overall energies of the metal complexes, resulting in a contribution epsilon(s) to the ground-state energy. The fraction of charge delocalized, alpha(DA)(2), is expected to attenuate the reorganizational energy, chi(reorg), by a factor of approximately (1 - 4alpha(DA)(2) + alpha(DA)(4)), relative to the limit where there is no charge delocalization. This appears to be a substantial effect for these complexes (alpha(DA)(2) congruent with 0.1 for Ru(II)/bpy), and it leads to smaller reorganizational energies for emission than for absorption. Reorganizational energies are inferred from the bandwidths found in Gaussian analyses of the emission and/or absorption spectra. Exchange energies are estimated from the Stokes shifts combined with perturbation--theory-based relationship between the reorganizational energies for absorption and emission values. The results indicate that epsilon(s) is dominated by terms that contribute to electron delocalization between metal and PP ligand. This inference is supported by the large shifts in the N-H stretching frequency of coordinated NH(3) as the number of PP ligands is increased. The measured properties of the bpy and dpp ligands seem to be very similar, but electron delocalization appears to be slightly larger (10-40%) and the exchange energy contributions appear to be comparable (e.g., approximately 1.7 x 10(3) cm(-1) in [Ru(bpy)(2)dpp](2+) compared to approximately 1.3 x 10(3) cm(-1) in the bpy analogue).     

Fluorescent Metal Nanoshells: Lifetime-Tunable Molecular Probes in Fluorescent Cell Imaging

We reported the preparation of lifetime-tunable fluorescent metal nanoshells and used them as lifetime imaging agents for potential detection of multiple target molecules by a single cell imaging scan. These metal nanoshells were generated to have 40 nm silica cores and 10 nm silver shells. Three kinds of metal-ligand complexes tris(5-amino-1,10-phenanthroline)ruthenium(II) (Ru(NH(2)-Phen)(3) (2+)), tris(2,2'-bipyridine) ruthenium(II) (Ru(bpy)(3) (2+)), and tris(2,3-bis(2-pyridyl)pyrazine))ruthenium(II) (Ru(dpp)(3) (2+)) that have similar excitation and emission wavelengths but different lifetimes were respectively encapsulated in the cores of metal nanoshells for the purpose of fluorescence. Compared with the metal-free silica spheres, these metal nanoshells were found to display enhanced emission intensities and shortened lifetimes due to near-field interactions of Ru(II) complexes with the metal shells. The shortened lifetimes of these metal nanoshells were definitely unique relevant to the Ru(II) complexes: 10 ns for the Ru(Phen-NH(2))(3) (2+)-Ag nanoshells, 45 ns for the Ru(bpy)(3) (2+)-Ag nanoshells, and 200 ns for the Ru(dpp)(3) (2+)-Ag nanoshells. These lifetimes were longer than the lifetime of cellular autofluorescence (2 - 5 ns), so the emission signals of these metal nanoshells could be distinctly isolated from the cellular background on the lifetime cell images. Moreover, these lifetimes were also different from one another, resulting in the emission signals of three metal nanoshells could be distinguished from one another on the cell images. This feature may offer an opportunity to detect multiple target molecules in a single cell imaging scan when the metal nanoshells are bound with various targets in the cells.     

共价嫁接Ru(Ⅱ)配合物杂化材料的制备及氧气传感性能研究

利用十六烷基三甲基溴化铵制备了一种具有MSU型蠕虫状孔道结构, 同时共价嫁接了Ru(Ⅱ)配合物的介孔杂化功能材料, 并研究了其氧气传感性能. 双功能有机改性硅酸酯Bpy-Si不仅是配合物Ru(bpy)2Cl2·2H2O的一个配体, 而且通过与正硅酸乙酯的水解和共聚反应, 把Ru(bpy)2(bpy-Si)Cl2配合物通过Si—C共价键嫁接到二氧化硅的骨架上. 研究结果表明, Ru(Ⅱ)分子在杂化材料中的发光受氧气猝灭明显, 而且具有较快的响应时间, 所得材料具有作为性能优良的氧气传感材料研究的潜质. 由于介孔材料的独特孔道结构有利于氧气在载体中的扩散, 介孔样品表现出比无定形样品更高的灵敏度.