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Metal enhanced fluorescence

Mohammad Shakir, Summaiya Hanif, Md Fazle Alam, Hina Younus
Novel bio-relevant monometallic Schiff base complexes of the type, [Cu(L(1))2] (1), [Zn(L(1))2]·2H2O (2), [Cu(L(2))2]·2H2O (3) and [Zn(L(2))2]·H2O (4) [L(1)(E)-3-(((3-chloro-4-hydroxyphenyl)imino)methyl)naphthalen-2-ol and L(2)(E)-2-chloro-4-((1-(5-chloro-2-hydroxyphenyl)ethylidene)amino)phenol] were synthesized and characterized. A comparative account of analytical, spectroscopic (FT-IR, (1)H and (13)C NMR, Mass, UV-vis and EPR), thermal (TGA/DTA), XRD and SEM studies revealed a correlation between the structure and function of these biologically active molecular entities...
October 11, 2016: Journal of Photochemistry and Photobiology. B, Biology
Varsha B Gujar, Divya Ottoor
Behavior of Amiloride (AMI) as a metal ion sensor in anionic surfactant assemblies of varying concentrations at different pH is depicted in this work. From a non-sensor fluorophore, AMI has been transformed in to a tunable fluorosensor for Cu(2+) ions in various SDS concentrations. At premicellar concentration of SDS, ion-pair complex is expected to be formed between AMI and SDS due to electrostatic interactions between them. However at CMC concentrations of SDS, fluorescence intensity of AMI is greatly enhanced with red shift in emission, due to the incorporation of AMI molecule in the hydrophobic micellar interface...
October 18, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Zhenglong Zhang, Yurui Fang, Wenhui Wang, Li Chen, Mengtao Sun
Plasmonics is a well-established field, exploiting the interaction of light and metals at the nanoscale; with the help of surface plasmon polaritons, remote-excitation can also be observed by using silver or gold plasmonic waveguides. Recently, plasmonic catalysis was established as a new exciting platform for heterogeneous catalytic reactions. Recent reports present remote-excitation surface catalytic reactions as a route to enhance the rate of chemical reactions, and offer a pathway to control surface catalytic reactions...
January 2016: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
Subhadip Goswami, Lin Ma, Alex B F Martinson, Michael R Wasielewski, Omar K Farha, Joseph T Hupp
Owing to their ability to act as light-harvesting scaffolds, porphyrin-containing metal-organic frameworks (MOFs) are in the forefront of research on the application of highly ordered molecular materials to problems in solar-energy conversion. In this work, solvent assisted linker exchange (SALE) is performed on a pillared paddlewheel porphyrin containing MOF thin film to collapse a 3D-framework to a 2D-framework. The change in dimensionality of the framework is confirmed by a decrease in the film thickness, the magnitude of which is in agreement with crystallographic parameters for related bulk materials...
October 21, 2016: ACS Applied Materials & Interfaces
Jangsun Hwang, Mintai P Hwang, Moonhyun Choi, Youngmin Seo, Yeonho Jo, Jaewoo Son, Jinkee Hong, Jonghoon Choi
Heavy metal pollution has been a problem since the advent of modern transportation, which despite efforts to curb emissions, continues to play a critical role in environmental pollution. Copper ions (Cu(2+)), in particular, are one of the more prevalent metals that have widespread detrimental ramifications. From this perspective, a simple and inexpensive method of detecting Cu(2+) at the micromolar level would be highly desirable. In this study, we use porous silicon nanoparticles (NPs), obtained via anodic etching of Si wafers, as a basis for undecylenic acid (UDA)- or acrylic acid (AA)-mediated hydrosilylation...
October 18, 2016: Scientific Reports
Keiko Tawa, Shohei Yamamura, Chisato Sasakawa, Izumi Shibata, Masatoshi Kataoka
Plasmonic chip was applied to the live cancer cell imaging. The epithelial cell adhesion molecule (EpCAM) is a surface marker that can be used to classify breast cancer cell lines into distinct differentiation states. EpCAM and the nuclei of two kinds of living breast cancer cells, MDA-MB231 and MCF-7, were stained with allophycocyanin (APC)-labeled anti-EpCAM antibody and 4,6-diamidino-2-phenylindole (DAPI), respectively, and the cells were scattered on either a plasmonic chip (metal-coated wavelength-scale grating substrate) or a control glass slide...
October 18, 2016: ACS Applied Materials & Interfaces
Azadeh Kheirolomoom, Elizabeth S Ingham, Joel Commisso, Neveen Abushaban, Katherine W Ferrara
We previously developed a pH-responsive copper-doxorubicin (CuDox) cargo in lysolipid-based temperature-sensitive liposomes (LTSLs). The CuDox complex is released from the particle by elevated temperature; however, full release of doxorubicin from CuDox requires a reduced pH, such as that expected in lysosomes. The primary goal of this study is to evaluate the cellular uptake and intracellular trafficking of the drug-metal complex in comparison with intact liposomes and free drug. We found that the CuDox complex was efficiently internalized by mammary carcinoma cells after release from LTSLs...
October 13, 2016: Journal of Controlled Release: Official Journal of the Controlled Release Society
Bhaskar Sen, Sanjoy Kumar Sheet, Romita Thounaojam, Ramen Jamatia, Amarta Kumar Pal, Kripamoy Aguan, Snehadrinarayan Khatua
A new coumarin based Schiff base compound, CSB-1 has been synthesized to detect metal ion based on the chelation enhanced fluorescence (CHEF). The cation binding properties of CSB-1 was thoroughly examined in UV-vis and fluorescence spectroscopy. In fluorescence spectroscopy the compound showed high selectivity toward Al(3+) ion and the Al(3+) can be quantified in mixed aqueous buffer solution (MeOH: 0.01M HEPES Buffer; 9:1; v/v) at pH7.4 as well as in BSA media. The fluorescence intensity of CSB-1 was enhanced by ~24 fold after addition of only five equivalents of Al(3+)...
October 11, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Manik Lal Saha, Xuzhou Yan, Peter J Stang
Over the past couple of decades, coordination-driven self-assembly has evolved as a broad multidisciplinary domain that not only covers the syntheses of aesthetically pleasing supramolecular architectures but also emerges as a method to form new optical materials, chemical sensors, theranostic agents, and compounds with light-harvesting and emissive properties. The majority of these applications depend upon investigations that reveal the photophysical nature and electronic structure of supramolecular coordination complexes (SCCs), including two-dimensional (2D) metallacycles and three-dimensional (3D) metallacages...
October 13, 2016: Accounts of Chemical Research
Caixia Niu, Quanwei Song, Gen He, Na Na, Jin Ouyang
Optical antennas with anisotropic metal nanostructures are widely used in the field of fluorescence enhancement based on localized surface plasmons (LSPs). They overcome the intrinsic defects of low brightness of near-infrared (NIR) dyes and can be used to develop sensitive NIR sensors for bioapplications. Here, we demonstrate a novel NIR plasmon-enhanced fluorescence (PEF) system consisting of elongated gold nanobipyramids (Au NBPs) antennas, silica, and NIR dyes. Silica was chosen as the rigid spacer to regulate the distance between the metal nanostructures and dyes...
October 13, 2016: Analytical Chemistry
Hong-Yan Zhuo, Hai-Feng Su, Zhao-Zhen Cao, Wei Liu, Shu-Ao Wang, Lei Feng, Gui-Lin Zhuang, Shui-Chao Lin, Mohamedally Kurmoo, Chen-Ho Tung, Di Sun, Lan-Sun Zheng
Cu(CF3 COO)2 reacts with tert-butylacetylene (tBuC≡CH) in methanol in the presence of metallic copper powder to give two air-stable clusters, [Cu(I)15 (tBuC≡C)10 (CF3 COO)5 ]⋅tBuC≡CH (1) and [Cu(I)16 (tBuC≡C)12 (CF3 COO)4 (CH3 OH)2 ] (2). The assembly process involves in situ comproportionation reaction between Cu(2+) and Cu(0) and the formation of two different clusters is controlled by reactants concentration. The clusters consist of Cu15 and Cu16 cores co-stabilized by strong by σ- and π-bonded tert-butylethynide and CF3 COO(-) (together with methanol molecule in 2)...
October 12, 2016: Chemistry: a European Journal
Soumen K Samanta, Damien Moncelet, Volker Briken, Lyle Isaacs
Self-assembly of ligand 1 and Pd(NO3)2 delivers Fujita-type metal organic polyhedron (MOP) 3 which bears 24 covalently attached methyl viologen units on its external surface as evidenced by 1H NMR, DOSY NMR, electrospray mass spectrometry, TEM, and AFM measurements. MOP 3 undergoes non-covalent complexation with cucurbit[n]urils to yield MOPs 4 - 6 with diameter ≈ 5-6 nm. MOP 5 can be fully loaded with doxorubicin prodrug 2 via hetero ternary complex formation to yield 7. The MOPs exhibit excellent stability toward neutral to slightly acidic pH in 10 mM sodium phosphate buffer mitigating the concern of disassembly during circulation...
October 10, 2016: Journal of the American Chemical Society
Amit Kumar, Sungi Kim, Jwa-Min Nam
The localized surface plasmon resonance of metal nanopar-ticles is the collective oscillation of electrons on particle surface, and is a particle composition, morphology and cou-pling-dependent property. Plasmonic engineering deals with highly precise formation of the targeted nanostructures with targeted plasmonic properties (e.g., electromagnetic field distribution and enhancement) via controlled synthetic, assembling and atomic/molecular tuning strategies. These plasmonically engineered nanostructures (PENs) have a variety of unique and beneficial physical, chemical and bio-logical properties including optical signal enhancement, catalytic property and local temperature-tuning photother-mal property...
October 10, 2016: Journal of the American Chemical Society
Yang Yuan, H Enis Karahan, Cansu Yıldırım, Li Wei, Özgür Birer, Shengli Zhai, Raymond Lau, Yuan Chen
The chirality-selective synthesis of relatively large (diameter > 1 nm) single-walled carbon nanotubes (SWCNTs) is of great interest for a variety of practical applications, but only a few catalysts are available so far. Previous studies suggested that S (compounds) can enhance the chirality-selectivity of Co catalysts in SWCNT synthesis, however, the mechanism behind is not fully understood, and no tailorable methodology has yet been developed. Here, we demonstrate a facile approach to achieve the chirality-selective synthesis of SWCNTs by the sulfidation-based poisoning of silica-supported Co catalysts using a mixture of H2S and H2...
October 14, 2016: Nanoscale
Leena Mandal, Samit Majumder, Sasankasekhar Mohanta
The work in the present investigation reports the syntheses, crystal structures, ESI-MS (positive) and steady state and time resolved photophysical properties of a tetraaminodiphenol macrocyclic ligand H2L (saturated analogue of a tetraiminodiphenol macrocycle obtained on 2 + 2 condensation of 4-ethyl-2,6-diformylphenol and 2,2-dimethyl-1,3-diaminopropane) and its three dinuclear d(10) metal ion (Zn(II), Cd(II) and Hg(II)) complexes having compositions [ZnLCl2]·2CH3OH (1), [CdL(μ-H2O)(H2O)2](NO3)2·4H2O (2) and [HgLCl2] (3)...
October 10, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Christos Tserkezis, Nikolaos Stefanou, Martijn Wubs, N Asger Mortensen
Molecular spontaneous emission and fluorescence depend strongly on the emitter local environment. Plasmonic nanoparticles provide excellent templates for tailoring fluorophore emission, as they exhibit potential for both fluorescence enhancement and quenching, depending on emitter positioning in the nanoparticle vicinity. Here we explore the influence of hitherto disregarded nonclassical effects on the description of emitter-plasmon hybrids, focusing on the roles of the metal nonlocal response and especially size-dependent plasmon damping...
October 14, 2016: Nanoscale
S A James, R Burke, D L Howard, K M Spiers, D J Paterson, S Murphy, G Ramm, R Kirkham, C G Ryan, M D de Jonge
Coordination chemistry underlies the structure/function of biological metal complexes. Contextualising this chemical information within an organism's physiology is critical for enhancing the understanding of bioinorganic chemistry but few high-fidelity probes are available. Here we develop fluorescence X-ray absorption near-edge structure tomography as a means for studying the spatial arrangement of biological coordination chemistry within intact organisms, and demonstrate the approach by mapping the distribution of cuprous and cupric complexes within Drosophila melanogaster...
September 27, 2016: Chemical Communications: Chem Comm
Jinfeng Zhang, Wencheng Chen, Rui Chen, Xiao-Ke Liu, Yuan Xiong, Stephen V Kershaw, Andrey L Rogach, Chihaya Adachi, Xiaohong Zhang, Chun-Sing Lee
We applied organic nanostructures based on thermally activated delayed fluorescent (TADF) emitters for singlet oxygen generation. Due to the extremely small energy gaps between the excited singlet states (S1) and triplet states (T1) of these heavy-metal-free organic nanostructures, intersystem conversion between S1 and T1 can occur easily. This strategy also works well for exciplex-type TADF emitters prepared by mixing suitable donors and acceptors which have no TADF characteristics themselves.
September 27, 2016: Chemical Communications: Chem Comm
Jingjing Deng, Guoyue Shi, Tianshu Zhou
This study demonstrates a new strategy for colorimetric detection of alcoholic strength (AS) in spirit samples based on dual-responsive lanthanide infinite coordination polymer (Ln-ICP) particles with ratiometric fluorescence. The ICP used in this study are composed of two components: one is the supramolecular Ln-ICP network formed by the coordination between the ligand 2,2'-thiodiacetic acid (TDA) and central metal ion Eu(3+); and the other is a fluorescent dye, i.e., coumarin 343 (C343), both as the cofactor ligand and as the sensitizer, doped into the Ln-ICP network through self-adaptive chemistry...
October 26, 2016: Analytica Chimica Acta
Yang Song, Ruiqing Fan, Jizhuang Fan, Kai Xing, Xi Du, Ping Wang, Yulin Yang
Three novel metal-organic assemblies (MOAs), namely, [Ag(2,4'-Hpdc)(4,4'-bpy)]n (1), [Ag(2,2'-Hpdc)(4,4'-bpy)0.5]n (2), and [Cu(2,2'-Hpdc)2(1,4-bib)]n (3) [2,4'-H2pdc = 2,4'-biphenyldicarboxylic acid; 2,2'-H2pdc = 2,2'-biphenyldicarboxylic acid; 4,4'-bpy = 4,4'-bipyridine; 1,4-bib = 1,4-bis(1-imidazolyl)benzene] have been hydrothermally synthesized by using mixed ligands and characterized by single crystal X-ray diffraction, infrared (IR), elemental analysis and thermogravimetric analysis (TGA). The crystal structures of the three compounds indicate that the hydrogen bonding (C-HO and C-Hπ) and ππ stacking interactions play critical roles in the formation of an extended supramolecular array...
October 18, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
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