The competition between conformational dynamics and electron transfer within a series of phenothiazine-(phenyl)n-pyrene (n = 0, 1) donor−acceptor dyads potential use in organic light emitting diodes was examined using femtosecond transient absorption spectroscopy. molecular structures these permit only torsional motions around the single bonds joining each aromatic subunit. redox properties molecules are nearly independent phenyl bridging group, whereas spectroelectrochemistry shows that...

The driving force dependence of photoinduced electron-transfer dynamics in duplex DNA has been investigated for 16 synthetic hairpins which an acceptor chromophore serves as a linker connecting two complementary oligonucleotide arms containing single donor nucleobase located either adjacent to the or separated from by unreactive base pairs. rate constants both charge separation and recombination processes have determined means subpicosecond time-resolved transient absorption spectroscopy...

We have prepared a green chromophore, 1,7-bis(pyrrolidin-1-yl)-3,4:9,10-perylene-bis(dicarboximide) (5PDI), that exhibits photophysical and redox properties similar to those of chlorophyll (Chl a), yet unlike Chl a, it can be easily functionalized incorporated into wide variety biomimetic electron donor−acceptor systems. The N,N'-dicyclohexyl derivative (5PDI) absorbs strongly (ε = 46 000 M-1 cm-1) at 686 nm in toluene fluoresces 721 with 35% quantum yield. Additionally, 5PDI is both...

The dynamics of photoinduced charge separation and recombination in synthetic DNA hairpins have been investigated by means femtosecond nanosecond transient spectroscopy. consist a stilbene linker connecting two complementary 6-mer or 7-mer oligonucleotide strands. Base pairing between these strands results formation which the is approximately parallel to adjacent base pair. singlet selectively quenched guanine, but not other nucleobases, via an electron-transfer mechanism state electron...

Summary. The international MRI expert subgroup of the International Prophylaxis Study Group (IPSG) has developed a consensus for magnetic resonance imaging (MRI) scales assessment haemophilic arthropathy. A scoring scheme including 10 step progressive scale and 20 additive with identical definitions mutual steps is presented. Using scale, effusion/haemarthrosis can correspond to scores 1, 2, or 3, synovial hypertrophy and/or haemosiderin deposition 4, 5, 6. score be 7 8 if there are...

During the last decade, saliva has emerged as a potentially ideal diagnostic biofluid for noninvasive testing. In this paper, we present an automated, integrated platform useable by minimally trained personnel in field diagnosis of respiratory diseases using human sample specimen. platform, is loaded onto disposable microfluidic chip containing all necessary reagents and components required analysis. The then inserted into automated analyzer, SDReader, where multiple potential protein...

Gallium antimonide single crystals have been prepared from melts ranging in composition nearly stoichiometric to Sb/Ga atom ratios of about 3/1. P‐type and, by suitable impurity additions, produced with superior electrical properties. The residual acceptor concentration has reduced the order growth antimony‐rich melts. Hole mobilities at 78°K 6000 cm2/volt‐sec and electron over 10,000 realized.

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationStructure and Photoinduced Electron Transfer in Exceptionally Stable Synthetic DNA Hairpins with Stilbenediether LinkersFrederick D. Lewis, Xiaoyang Liu, Yangsheng Wu, Scott E. Miller, Michael R. Wasielewski, Robert L. Letsinger, Ruslan Sanishvili, Andrzej Joachimiak, Valentina Tereshko, Martin EgliView Author Information Department of Chemistry, Northwestern University Evanston, Illinois 60208-3113 Structural Biology Center, Biosciences Division...

The branched donor−acceptor triad 4 and tetrad 5 were synthesized to study the possibility of controlling direction electron transfer in a divergent array acceptors using ultrafast laser pulses. Compounds employ 1,3,5-triaminobenzene as central branch point. In 4, 4-(N-piperidinyl)-1,8-naphthaleneimide donor (ANI) was attached 1 position two acceptors, 1,8:4,5-naphthalenediimide, NI, pyromellitimide, PI, 3 positions benzene ring. 5, terminal end PI acceptor is functionalized with an...

A comparison of the structure, spectroscopy, and oxygen atom-transfer reactivity cofacial bisporphyrins anchored by xanthene (DPX) dibenzofuran (DPD) pillars is presented. The synthesis characterization dicopper(II) dinickel(II) complexes DPD completes a homologous series homobimetallic zinc(II), copper(II), nickel(II) for both platforms. X-ray crystallographic analysis parent free-base porphyrins H4DPX (1) H4DPD (5) confirms face-to-face arrangement two porphyrin macrocycles with large...

A comprehensive study of a series four monodisperse, metal-organic pi-conjugated oligomers varying length is reported. The are based on the aryleneethynylene architecture, and they contain 2,2'-bipyridine-5,5'-diyl (bpy) metal binding unit. photophysical properties free their complexes with (L)Re(I)(CO)(3)X chromophore (where L = bpy-oligomer X Cl or NCCH(3)) were explored by variety methods including electrochemistry, UV-visible absorption, variable temperature photoluminescence (PL),...

The dynamics of electron injection has been investigated in DNA hairpins possessing a stilbenediether donor linker by means femtosecond transient absorption spectroscopy. Ultrafast and charge recombination are observed with neighboring cytosine or thymine bases; however, guanine-guanine base pairs not reduced, permitting the investigation distance dependence injection.

Summary. We tested the reliability and construct validity of Compatible magnetic resonance imaging (MRI) scale for evaluation haemophilic knees ankles compared diagnostic performance MRI plain film radiographs. Sagittal coronal gradient‐echo 1.5‐T MR images ( n = 22) 23) were obtained from boys (age range 4–16 years; mean 11 years) in two centres (Toronto, 26; Europe, 19). The independently read by four blinded radiologists on occasions. Number previous joint bleedings laboratory level...

Cofacial palladium(II) bisporphyrins anchored by xanthene [Pd2(DPX)] and dibenzofuran [Pd2(DPD)] pillars were prepared, the dynamics of their triplet excited states investigated. The phosphorescence quantum yield [Φp = 4.59(121) × 10-3 in CH2Cl2] lifetime [τp 18.2(2) μs Pd2(DPD) are significantly attenuated compared to those its Pd2(DPX) congener 29.4(5) τp 102(3) CH2Cl2]. Electronic absorption emission spectroscopy electrochemical measurements establish that porphyrin rings DPX cofacial...

Summary. Effective treatment of haemophilic arthropathy requires a detailed evaluation joint integrity. Methodological assessment magnetic resonance imaging (MRI) scores are needed to assure reproducibility measurements when comparing results clinical trials conducted in different centres. We compared the reliability two MRI scoring systems for arthropathy: one progressive system that displays most severe change and additive depicts osteochondral soft tissue‐related changes. A total 47 1.5 T...

A series of rodlike donor−bridge−acceptor (D−B−A) molecules was synthesized to study the role bridge energy levels on electron transfer (ET) rates. In these compounds, a 4-aminonaphthalene-1,8-imide (ANI) donor is linked 1,8:4,5-naphthalenediimide acceptor (NI) via 1,4 positions phenyl bridge. The substituted at 2 and 5 with methyl or methoxy groups yield ANI-diMe-NI ANI-diMeO-NI. These differ only in molecular orbitals. Other parameters affecting ET rates such as donor−acceptor distance,...

Summary. We assessed the reliability and construct validity of Compatible MRI scale for evaluation elbows, compared diagnostic performance radiographs assessment these joints. Twenty‐nine MR examinations elbows from 27 boys with haemophilia A B [age range, 5–17 years (mean, 11.5)] were independently read by four blinded radiologists on two occasions. Three centres participated in study: (Toronto, n = 24 examinations; Atlanta, 3; Cuiaba, 2). The number previous joint bleeds severity reference...

Direct numerical simulation of nanoparticle coagulation in a planar jet is performed. The particle field represented using sectional method to approximate the aerosol general dynamic equation. methodology advantageous that there are no priori assumptions regarding size distribution and coupled with an unsteady Navier-Stokes solver, it provides spatio-temporal evolution accurate manner. consists incompressible fluid containing particles 1 nm diameter issuing into particle-free coflowing...

The dynamics of charge separation and recombination in synthetic DNA hairpins possessing diphenylacetylene-4,4'-dicarboxamide linkers have been investigated by means femtosecond time-resolved transient absorption spectroscopy. lowest excited singlet state the linker is capable oxidizing nearest neighbor adenine as well guanine. A large wavelength shift spectrum accompanies conversion to its anion radical, facilitating investigation electron-transfer dynamics. rate constants for are dependent...

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTElectronic Interactions between π-Stacked DNA Base Pairs and Diphenylacetylene-4,4'-dicarboxamide in Hairpin DNAFrederick D. Lewis, Xiaoyang Liu, Scott E. Miller, Michael R. WasielewskiView Author Information Department of Chemistry, Northwestern University Evanston, Illinois 60208 Cite this: J. Am. Chem. Soc. 1999, 121, 41, 9746–9747Publication Date (Web):October 4, 1999Publication History Received15 July 1999Revised7 September 1999Published...

A composite piezolaminated shallow thin shell theory has been developed in which the individual laminae are capable of electromechanical transduction. Utilizing a first order shear deformation approximation and assuming that an electrical field may be applied only across thickness given lamina, resulting shows piezolaminae exciting sensing bending, torsion, inplane shearing, stretching. Piezolaminae shown to incapable transverse unless three-dimensional is applied. Inplane shearing torsion...