Theoretical investigation of plasmonic enhancement of silica-coated gold nanorod on molecular fluorescence

The plasmonic enhancement or quenching effects of a silica-coated gold nanorod (GNR@SiO₂) on the fluorescence of a molecule doped in the silica layer are studied using the multiple multipole method. The enhancement factors (EF) of a GNR with a typical aspect ratio of 3 coated by a 13 nm silica layer upon the fluorescence of a molecule embedded at different locations with various orientations irradiated by a plane wave are analyzed, particularly at the longitudinal surface plasmon resonance (SPR) of GNR. The numerical results show that the EF of a GNR@SiO₂ on the fluorescence is sensitive to the molecular location and orientation. Furthermore, an effective EF (EEF), which is an average of EF over all possible orientations at a specific location, is calculated. According to EEF, the proximities of the end-caps of a GNR are strong enhancing zones. In contrast, the waist area is the weak zone. Moreover, a bigger GNR (a=10 nm) possesses a higher EEF than a smaller one (a=7 nm) for the same aspect ratio and the molecular relative location. Hence, a strong enhancement on the fluorescence is obtained using bigger GNR, if the molecule is near the end-cup and the dipole orientation is along the long axis. On the contrary, the consequence could be quenching, if the molecule is near the waist of a small GNR. The Stokes shift of fluorescence can also affect the EF, except the excitation wavelength.     

Nitric oxide turn-on fluorescent probe based on deamination of aromatic primary monoamines

The stable, water-soluble, and nonfluorescent FA-OMe can sense nitric oxide (NO) and form the intensely fluorescent product dA-FA-OMe via reductive deamination of the aromatic primary amine. The reaction is accompanied by a notable increase of the fluorescent quantum yield from 1.5 to 88.8%. The deamination mechanism of FA-OMe with NO was proposed in this study. The turn-on fluorescence signals were performed by suppression of photoinduced electron transfer (PeT), which was demonstrated by density functional theory (DFT) calculations of the components forming FA-OMe and dA-FA-OMe. Furthermore, FA-OMe showed water solubility and good stability at physiological pHs. Moreover, the selectivity study indicated that FA-OMe had high specificity for NO over other reactive oxygen/nitrogen species. In an endogenously generated NO detection study, increasing the incubation time of FA-OMe with lipopolysaccharide (LPS) pretreated Raw 264.7 murine macrophages could cause an enhanced fluorescence intensity image. In addition, a diffusion/localization cell imaging study showed that FA-OMe could be trapped in Raw 264.7 cells. These cell imaging results demonstrated that FA-OMe could be used as a turn-on fluorescent sensor for the detection of endogenously generated NO.     

Insight into the dinuclear {Fe(NO)2}10{Fe(NO)2}10 and mononuclear {Fe(NO)2}10 dinitrosyliron complexes

The reversible redox transformations [(NO)(2)Fe(S(t)Bu)(2)](-) ? [Fe(μ-S(t)Bu)(NO)(2)](2)(2-) ? [Fe(μ-S(t)Bu)(NO)(2)](2)(-) ? [Fe(μ-S(t)Bu)(NO)(2)](2) and [cation][(NO)(2)Fe(SEt)(2)] ? [cation](2)[(NO)(2)Fe(SEt)(2)] (cation = K(+)-18-crown-6 ether) are demonstrated. The countercation of the {Fe(NO)(2)}(9) dinitrosyliron complexes (DNICs) functions to control the formation of the {Fe(NO)(2)}(10){Fe(NO)(2)}(10) dianionic reduced Roussin's red ester (RRE) [PPN](2)[Fe(μ-SR)(NO)(2)](2) or the {Fe(NO)(2)}(10) dianionic reduced monomeric DNIC [K(+)-18-crown-6 ether](2)[(NO)(2)Fe(SR)(2)] upon reduction of the {Fe(NO)(2)}(9) DNICs [cation][(NO)(2)Fe(SR)(2)] (cation = PPN(+), K(+)-18-crown-6 ether; R = alkyl). The binding preference of ligands [OPh](-)/[SR](-) toward the {Fe(NO)(2)}(10){Fe(NO)(2)}(10) motif of dianionic reduced RRE follows the ligand-displacement series [SR](-) > [OPh](-). Compared to the Fe K-edge preedge energy falling within the range of 7113.6-7113.8 eV for the dinuclear {Fe(NO)(2)}(9){Fe(NO)(2)}(9) DNICs and 7113.4-7113.8 eV for the mononuclear {Fe(NO)(2)}(9) DNICs, the {Fe(NO)(2)}(10) dianionic reduced monomeric DNICs and the {Fe(NO)(2)}(10){Fe(NO)(2)}(10) dianionic reduced RREs containing S/O/N-ligation modes display the characteristic preedge energy 7113.1-7113.3 eV, which may be adopted to probe the formation of the EPR-silent {Fe(NO)(2)}(10)-{Fe(NO)(2)}(10) dianionic reduced RREs and {Fe(NO)(2)}(10) dianionic reduced monomeric DNICs in biology. In addition to the characteristic Fe/S K-edge preedge energy, the IR ν(NO) spectra may also be adopted to characterize and discriminate [(NO)(2)Fe(μ-S(t)Bu)](2) [IR ν(NO) 1809 vw, 1778 s, 1753 s cm(-1) (KBr)], [Fe(μ-S(t)Bu)(NO)(2)](2)(-) [IR ν(NO) 1674 s, 1651 s cm(-1) (KBr)], [Fe(μ-S(t)Bu)(NO)(2)](2)(2-) [IR ν(NO) 1637 m, 1613 s, 1578 s, 1567 s cm(-1) (KBr)], and [K-18-crown-6 ether](2)[(NO)(2)Fe(SEt)(2)] [IR ν(NO) 1604 s, 1560 s cm(-1) (KBr)].     

Synthesis and characterization of new soluble poly(amide‐imide)s derived from 2,2‐bis[4‐(4‐trimellitimidophenoxy)phenyl]hexafluoropropane

A series of new soluble poly(amide‐imide)s were prepared from the diimide‐dicarboxylic acid 2,2‐bis[4‐(4‐trimellitimidophenoxy)phenyl]hexafluoropropane with various diamines by direct polycondensation in N‐methyl‐2‐pyrrolidinone containing CaCl₂ with triphenyl phosphite and pyridine as condensing agents. All the polymers were obtained in quantitative yields with inherent viscosities of 0.52–0.86 dL · g^?1. The poly(amide‐imide)s showed an amorphous nature and were readily soluble in various solvents, such as N‐methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide, pyridine, and cyclohexanone. Tough and flexible films were obtained through casting from DMAc solutions. These polymer films had tensile strengths of 71–107 MPa and a tensile modulus range of 1.6–2.7 GPa. The glass‐transition temperatures of the polymers were determined by a differential scanning calorimetry method, and they ranged from 242 to 279 °C. These polymers were fairly stable up to a temperature around or above 400 °C, and they lost 10% of their weight from 480 to 536 °C and 486 to 537 °C in nitrogen and air, respectively. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3498–3504, 2001     

Chelating and Tellurolate Ligand‐Transfer Studies of the Complex fac‐[Fe(CO)3(TePh)3]−: Crystal Structures of Heterodinuclear (CO)3Mn(μ‐TePh)3Fe(CO)3 and CpNi(TePh)(PPh3)

Complex fac‐[Fe(CO)₃(TePh)₃]^? was employed as a “metallo chelating” ligand to synthesize the neutral (CO)₃Mn(μ‐TePh)₃Fe(CO)₃ obtained in a one‐step synthesis by treating fac‐[Fe(CO)₃(TePh)₃]^? with fac‐[Mn‐(CO)₃(CH₃CN)₃]⁺. It seems reasonable to conclude that the d⁶ Fe(II) [(CO)₃Fe(TePh)₃]^? fragment is isolobal with the d⁶ Mn(I) [(CO)₃Mn(TePh)₃]^2? fragment in complex (CO)₃Mn(μ‐TePh)₃Fe(CO)₃. Addition of fac‐[Fe(CO)₃(TePh)₃]^? to the CpNi(I)(PPh₃) in THF resulted in formation of the neutral CpNi(TePh)(PPh₃) also obtained from reaction of CpNi(I)(PPh₃) and [Na][TePh] in MeOH. This investigation shows that fac‐[Fe(CO)₃(TePh)₃]^? serves as a tridentate metallo ligand and tellurolate ligand‐transfer reagent. The study also indicated that the fac‐[Fe(CO)₃(SePh)₃]^? may serve as a better tridentate metallo ligand and chalcogenolate ligand‐transfer reagent than fac‐[Fe(CO)₃(TePh)₃]^? in the syntheses of heterometallic chalcogenolate complexes.     

Polarization Control Technique to Reduce, Power Penalty in Tri-Directional, Transmission Systems

Polarization control is used in a tri-directional wavelength-reused system to reduce the power penalty caused by coherent mixing of the signal with Rayleigh backscattering noise. For a 25 + 25 km, 10 Gb/s tri-directional transmission system, the power penalty is 4.0 dB under the worst polarization control and could be reduced to 0.4 dB under optimal polarization control. The experimental results show that reusing the same wavelength is an efficient and promising method for tri-directional lightwave systems.     

Photophysical and viscometric properties of naphthalene-labeled acrylamide/N,N-dimethyl maleimido propyl ammonium propane sulfonate copolymer

 The synthesis, viscometric, and fluorescence properties of a water-soluble zwitterionic sulfobetaine copolymer, poly(ADMMAPS)/NA, are reported. When fluorescent hydrophobes (naphthyl group) are incorporated into the zwitterionic copolymer, the photophysical response may effectively probe solution behavior on the microscopic level. Experimental results indicate that I _E/I _M steadily increases with increases in polymer concentration. I _E/I _M in aqueous solution is greater than that in aqueous potassium chloride solution. Dynamic light scattering (QELS) measurements show that hydrodynamic diameters of the naphthalene-labeled zwitterionic sulfobetaine copolymer increase with an increasing salt concentration. Viscosity studies reveal that the polymer coil expanded as more salt is added. In fluorescence quenching study, the reduction in the quenching efficiency of Tl⁺ with salt addition can arise from enhanced compartmentalization of naphthalene labels as added electrolyte enhances intrapolymer micellization. The intrapolymer micelle is easily formed, indicating that the thallium ion has difficulty reacting with bound naphthalenes located in the polymer coil. The naphthalene-labeled zwitterionic sulfobetaine copolymer is depicted as a compacted polymer coil conformation in deionized water because of intra-and inter-associations. Consequently, salt addition breaks up the associations and enhances the intrapolymer micellization. The microscopic and macroscopic behaviors of zwitterionic sulfobetaine copolymer differ a lot from those of the corresponding cationic copolymer. Received: 4 February 1997 Accepted: 1 May 1997     

Versatility of dithiophosphates in the syntheses of copper(I) complexes with bis(diphenylphosphino)alkanes: abstraction of chloride from dichloromethane

Reactions of [Cu(CH(3)CN)(4)]X (X = PF(6), BF(4)) with bis(diphenylphosphino)methane (dppm = Ph(2)PCH(2)PPh(2)) and ammonium dialkyldithiophosphates, (NH(4))[S(2)P(OR)(2)] (R = Et, (i)Pr), yield a series of novel Cu(I) polynuclear complexes, trinuclear [Cu(3)(mu-dppm)(3)(mu(3)-Cl){S(2)P(OEt)(2)}] (PF(6)) 1 and [Cu(3)(mu-dppm)(2){S(2)P(OR)(2)}(2)](PF(6)) (R = Et, 2; (i)Pr, 3), tetranuclear [Cu(4)(mu-dppm)(2) {S(2)P(OEt)(2)}(4)] 4, and hexanuclear [Cu(6)(mu-dppm)(2)(mu(4)-Cl){S(2)P(O(i)()Pr)(2)}(4)](BF(4)) 5. Similarly, the reaction of [Cu(2)(mu-L-L)(2)(CH(3)CN)(2)](PF(6))(2) (L-L, dppm, dppe = Ph(2)PCH(2)CH(2)PPh(2)) with (NH(4))[S(2)P(OR)(2)] yields dinuclear [Cu(2)(mu-dppm)(2){S(2)P(OR)(2)}(2)] 6 (R= (i)Pr, 6A; Et, 6B), trinuclear [Cu(3)(mu-dppe)(3)(mu-Cl)(2){S(2)P(O(i)Pr)(2)}] 9, and polymeric [Cu(mu(2)-dppe){S(2)P(OR)(2)}](n) (R = Et, 7; (i)Pr, 8) complexes. The formation of 1 and 5 involved the abstraction of chloride from dichloromethane when the Cu/S(2)P(OR)(2) ratio exceeded 1, but when ratio was 1:1, no Cl abstraction occurred, as in compound 4. Compound 9, however, was obtained as a 12% byproduct in the synthesis of 8 using a 1:1:1 ratio of Cu/dppe/S(2)P(O(i)Pr)(2). The chloride binds to Cu atoms in a mu(3)-Cl mode by capping one face of the Cu(3) triangle of cluster 1. A mu(4)-Cl caps a single tetragonal face of the trigonal prism of cluster 5, and in the cluster 9, two chlorides bond in mu(2)-Cl modes. Both clusters 2 and 3 exhibit the mu(3)-S mode of bonding for dtp ligands. Only cluster 5 exhibited close Cu...Cu contacts (2.997-3.0238 A). All of compounds were characterized by single-crystal X-ray diffraction and pertinent crystallographic data for 1, 5, and 9 are are follows: (1) C(79)H(76)ClCu(3)F(6)O(2)P(8)S(2), triclinic, P, a = 11.213(1) A, b = 14.142(1) A, c = 25.910(2) A, alpha = 95.328(2) degrees , beta = 99.594(2) degrees , gamma = 102.581(2) degrees , V = 3918.2(6) A(3), Z = 2; (5) C(74)H(100)BClCu(6)F(4)O(8)P(8)S(8), monoclinic, P2(1)/n, a = 25.198(4) A, b = 15.990(3) A, c = 25.421(4) A, beta = 106.027(3) degrees , V = 9845(3)A(3), Z = 4; (9) C(84)H(86)Cl(2)Cu(3)O(2)P(7)S(2), monoclinic, C2/c, with a = 24.965(3) A, b = 17.058(2) A, c = 20.253(2) A, beta = 95.351(4) degrees , V = 8587.4(17)A(3), Z = 4.     

TUMOR DESTRUCTION IN PHOTODYNAMIC THERAPY

Abstract The effects of photodynamic therapy (PDT) on the tumor microvasculature in the first few hours after treatment was studied at the light microscope (LM) and electron microscope (EM) levels in DBA/2Ha mice bearing SMT-F tumors. Animals received intraperitoneal injections of 10 mg kg⁻ of Photofrin II and 24 h later tumors were treated with 100 J cm⁻² of light (630 nm). Animals were sacrificed and their tumors removed at time 0, 30 min, 1, 2, 4, 8, 16 and 24 h after treatment. The results indicate that the effects of PDT are initially direct destruction of the microfibrils in the subendothelial zone of the tumor capillaries with subsequent tumor cell death secondary to hemorrhage and vascular collapse.