36425
2012
2012
eng
103
109
7
1
10
article
Royal Society of Chemistry
Cambridge
1
--
--
--
Barton radical reactions of 2-C-branched carbohydrates
Barton esters have been introduced into the side chain of carbohydrates with high yields in only a few steps from easily available glycals. Their radical reactions afford 2-C-methyl and 2-C-bromomethyl hexoses, pentoses and disaccharides in good yields in analytically pure form. Since the Barton esters have been synthesized by an oxidative radical addition and their transformations by reductive radical processes, our results demonstrate the power of such reactions in carbohydrate chemistry.
Organic & biomolecular chemistry : an international journal of synthetic, physical and biomolecular organic chemistry
10.1039/c1ob06370g
1477-0520
wos:2011-2013
WOS:000297589900018
Linker, T (reprint author), Univ Potsdam, Dept Chem, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany., linker@uni-potsdam.de
University of Potsdam
Tukaram M. Pimpalpalle
Jian Yin
Torsten Linker
Institut für Chemie
Referiert
36417
2012
2012
eng
75
86
12
733
article
Springer
Dordrecht
1
--
--
--
Semiconductor quantum dots as FRET acceptors for multiplexed diagnostics and molecular ruler application
Applications based on Forster resonance energy transfer (FRET) play an important role for the determination of concentrations and distances within nanometer-scale systems in vitro and in vivo in many fields of biotechnology. Semiconductor nanocrystals (Quantum dots - QDs) possess ideal properties for their application as FRET acceptors when the donors have long excited state lifetimes and when direct excitation of QDs can be efficiently suppressed. Therefore, luminescent terbium complexes (LTCs) with excited state lifetimes of more than 2 ms are ideal FRET donor candidates for QD-acceptors. This chapter will give a short overview of theoretical and practical background of FRET, QDs and LTCs, and present some recent applications of LTC-QD FRET pairs for multiplexed ultra-sensitive in vitro diagnostics and nanometer-resolution molecular distance measurements.
Advances in Experimental Medicine and Biology
10.1007/978-94-007-2555-3_8
978-94-007-2554-6
0065-2598
978-94-007-2555-3
wos:2011-2013
47th Oholo Conference on Novel Approaches in Nano Bio-Technology for Biomedical and Diagnostics Research
DEC, 2010
WOS:000339176500008
Eilat, ISRAEL
Hildebrandt, N (reprint author), Univ Paris 11, Inst Elect Fondamentale, F-91405 Orsay, France., niko.hildebrandt@u-psud.fr
European Commission [NANOGNOSTICS-HEALTH-F5-2009-242264]
Niko Hildebrandt
Daniel Geissler
eng
uncontrolled
Diagnostics
eng
uncontrolled
FRET
eng
uncontrolled
Imaging
eng
uncontrolled
Quantum dots
eng
uncontrolled
Terbium
Institut für Chemie
Referiert
36395
2012
2012
eng
108
118
11
1
50
article
Wiley-Blackwell
Malden
1
--
--
--
Radical addition fragmentation chain transfer (RAFT) polymerization of ferrocenyl (meth)acrylates
We report on the controlled free radical homopolymerization of 1-ferrocenylethyl acrylate as well as of three new ferrocene bearing monomers, namely 4-ferrocenylbutyl acrylate, 2-ferrocenylamido-2-methylpropyl acrylate, and 4-ferrocenylbutyl methacrylate, by the RAFT technique. For comparison, the latter monomer was polymerized using ATRP, too. The ferrocene containing monomers were found to be less reactive than their analogues free of ferrocene. The reasons for the low polymerizability are not entirely clear. As the addition of free ferrocene to the reaction mixture did not notably affect the polymerizations, sterical hindrance by the bulky ferrocene moiety fixed on the monomers seems to be the most probable explanation. Molar masses found for 1-ferrocenylethyl acrylate did not exceed 10,000 g mol(-1), while for 4-ferrocenylbutyl (meth) acrylate molar masses of 15,000 g mol(-1) could be obtained. With PDIs as low as 1.3 in RAFT polymerization of the monomers, good control over the polymerization was achieved.
Journal of polymer science : A, Polymer chemistry
10.1002/pola.24994
0887-624X
wos:2011-2013
WOS:000298478300012
Barner-Kowollik, C (reprint author), Karlsruhe Inst Technol, Inst Tech Chem & Polymerchem, Engesserstr 18, D-76128 Karlsruhe, Germany., christopher.barner-kowollik@kit.edu; laschews@rz.uni-potsdam.de
Karlsruhe Institute of Technology (KIT) within Excellence Initiative for
leading German universities; German Research Council (DFG) [LA611/7];
Ministry of Arts and Science of the State of Baden-Wurttemberg; Fonds
der Chemischen Industrie (FCI)
Christoph Herfurth
Dominik Voll
Jens Buller
Jan Weiss
Christopher Barner-Kowollik
André Laschewsky
eng
uncontrolled
ferrocene
eng
uncontrolled
living radical polymerization (LRP)
eng
uncontrolled
monomers
eng
uncontrolled
radical addition fragmentation chain transfer (RAFT)
eng
uncontrolled
radical polymerization
eng
uncontrolled
redox polymers
eng
uncontrolled
synthesis
Institut für Chemie
Referiert
36385
2012
2012
eng
409
414
6
2
3
article
Royal Society of Chemistry
Cambridge
1
--
--
--
Alkyne-azide coupling of tailored poly(vinylidene fluoride) and polystyrene for the synthesis of block copolymers
The synthesis of block copolymers consisting of poly(vinylidene fluoride) (PVDF) and polystyrene (PS) is reported. Firstly, a propargyl-functionalized alkoxyamine initiator (PgOTIPNO) was prepared and subsequently used for the preparation of a propargyl-terminated PS homopolymer of different chain lengths with low dispersities via nitroxide-mediated radical polymerization. A tailored PVDF homopolymer with iodine end groups originating from iodine transfer polymerization was transformed to PVDF with azide end group. Then, alkyne-terminated PS with different molecular weights and azide-terminated PVDF were joined together via copper-catalyzed alkyne-azide coupling. The block copolymers were characterized using H-1-NMR, F-19-NMR, IR, SEC, and DSC.
Polymer Chemistry
10.1039/c1py00427a
1759-9954
wos:2011-2013
WOS:000298991200023
Beuermann, S (reprint author), Univ Potsdam, Inst Chem, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany., sabine.beuermann@uni-potsdam.de
University of Potsdam
Radovan Vukicevic
Ulrike Schwadtke
Simon Schmuecker
Philipp Schaefer
Dirk Kuckling
Sabine Beuermann
Institut für Chemie
Referiert
36384
2012
2012
eng
352
361
10
2
3
article
Royal Society of Chemistry
Cambridge
1
--
--
--
Water-soluble random and alternating copolymers of styrene monomers with adjustable lower critical solution temperature
Random copolymers of 4-vinylbenzyl tri(oxyethylene) and tetra(oxyethylene) ethers, as well as alternating copolymers of 4-vinylbenzyl methoxytetra(oxyethylene) ether and a series of N-substituted maleimides, were synthesised by conventional free radical polymerisation, reversible addition fragmentation chain transfer (RAFT) and atom transfer radical polymerisation (ATRP). Their thermosensitive behaviour in aqueous solution was studied by turbidimetry and dynamic light scattering. Depending on the copolymer composition, a LCST type phase transition was observed in water. The transition temperature of the obtained random as well as alternating copolymers could be varied within a broad temperature window. In the case of the random copolymers, transition temperatures could be easily fine-tuned, as they showed a linear dependence on the copolymer composition, and were additionally modified by the nature of the polymer end-groups. Alternating copolymers were extremely versatile for implementing a broad range of variations of the phase transition temperatures. Further, while alternating copolymers derived from 4-vinylbenzyl methoxytetra(oxyethylene) ether and maleimides with small hydrophobic side chains underwent macroscopic phase separation when dissolved in water and heated above their cloud point, the incorporation of maleimides bearing larger hydrophobic substituents resulted in the formation of mesoglobules above the phase transition temperature, with hydrodynamic diameters of less than 100 nm.
Polymer Chemistry
10.1039/c1py00422k
1759-9954
wos:2011-2013
WOS:000298991200016
Laschewsky, A (reprint author), Univ Potsdam, Dept Chem, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany., laschews@rz.uni-potsdam.de
German Research Council (Deutsche Forschungsgemeinschaft DFG) [LA611/4];
Fonds der Chemischen Industrie (FCI)
Jan Weiss
Ang Li
Erik Wischerhoff
André Laschewsky
Institut für Chemie
Referiert
36379
2012
2012
eng
250
256
7
1
27
article
Elsevier
Oxford
1
--
--
--
Diffusion, degradation or on-site stabilisation - identifying causes of kinetic processes involved in metal-humate complexation
The applicability of equilibrium models for humic-bound transport of toxic or radioactive metals is affected by kinetic processes leading to an increasing inertness of metal-humic complexes. The chemical background is not yet understood. It is widely believed that bound metals undergo an in-diffusion process within the humic colloids, changing from weaker to stronger binding sites. This work is focussed on the competition effect of Al(III) on complexation of Tb(III) or Eu(III) as analogues of trivalent actinides. By using ion exchange and spectroscopic methods, their bound fractions were determined for solutions of Al and humic acid that had been pre-equilibrated for different periods of time. Whilst the amount of bound Al remained unchanged, its blocking effect was found to increase over a time frame of 2 days, which corresponds to the kinetics of the increase in complex inertness reported in most pertinent studies. Thus, the derived "diffusion theory'' turned out to be inapplicable, since it cannot explain an increase in competition for the "initial'' sites. A delayed degradation of polynuclear species (as found for Fe) does not occur. Consequently, the temporal changes must be based on structural rearrangements in the vicinity of bound Al, complicating the exchange or access. Time-dependent studies by laser fluorescence spectroscopy (steady-state and time-resolved) yielded evidence of substantial alterations, which were, however, immediately induced and did not show any significant trend on the time scale of interest, suggesting that the stabilisation process is based on comparatively moderate changes.
Applied geochemistry : journal of the International Association of Geochemistry and Cosmochemistry
10.1016/j.apgeochem.2011.11.001
0883-2927
wos:2011-2013
WOS:000299109600024
Lippold, H (reprint author), Helmholtz Ctr Dresden Rossendorf, Inst Radiochem, Res Site Leipzig,Permoserstr 15, D-04318 Leipzig, Germany., h.lippold@hzdr.de
German Federal Ministry of Economics and Technology (BMWi) [02 E 10176]
Holger Lippold
Sascha Eidner
Michael Uwe Kumke
Johanna Lippmann-Pipke
Institut für Chemie
Referiert
36375
2012
2012
eng
83
90
8
1
25
article
Wiley-Blackwell
Hoboken
1
--
--
--
Conformational analysis of 4,4-dimethyl-1-(trifluoromethylsulfonyl)-1,4-azasilinane and 2,2,6,6-tetramethyl-4-(trifluoromethylsulfonyl)-1,4,2,6-oxazadisilinane
4,4-Dimethyl-1-(trifluoromethylsulfonyl)-1,4-azasilinane 1 and 2,2,6,6-tetramethyl-4-(trifluoromethylsulfonyl)-1,4,2,6-oxazadisilinane 2 were studied by variable temperature dynamic 1H, 13C, 19F NMR spectroscopy and theoretical calculations at the DFT (density functional theory) and MP2 (Moller-Plesset 2) levels of theory. Both kinetic (barriers to ring inversion) and thermodynamic data (frozen conformational equilibria) could be obtained for the two compounds. The computations revealed two minima on the potential energy surface for molecules 1 and 2 corresponding to the rotamers with the CF3SO2 group directed inward and outward the ring, the latter being 0.20.4 kcal/mol (for 1) and 1.1 kcal/mol (for 2) more stable than the former. The vibrational calculations at the DFT and MP2 levels of theory give the values of the free energy difference Delta G degrees for the 'inward' reversible arrow 'outward' equilibrium consistent with those determined from the experimentally measured ratio of the rotamers. The structure of crystalline compound 2 was ascertained by X-ray diffraction analysis.
Journal of physical organic chemistry
10.1002/poc.1882
0894-3230
wos:2011-2013
WOS:000298385200012
Shainyan, BA (reprint author), Russian Acad Sci, Siberian Div, AE Favorsky Irkutsk Inst Chem, 1 Favorsky St, Irkutsk 664033, Russia., bagrat@irioch.irk.ru
Russian Foundation for Basic Research; Deutsche Forschungsgemeinschaft
[11-03-91334]
Bagrat A. Shainyan
Elena N. Suslova
Erich Kleinpeter
eng
uncontrolled
conformational analysis
eng
uncontrolled
dynamic NMR
eng
uncontrolled
quantum chemical calculations
eng
uncontrolled
2
eng
uncontrolled
6-disilamorpholines
eng
uncontrolled
4-silapiperidines
Institut für Chemie
Referiert
36367
2012
2012
eng
370
376
7
1
18
article
Wiley-Blackwell
Malden
1
--
--
--
Is the conventional interpretation of the anisotropic effects of C=C double bonds and aromatic rings in NMR spectra in terms of the p-electron shielding/deshielding contributions correct?
Based on the nucleus-independent chemical shift (NICS) concept, isotropic magnetic shielding values have been computed along the three Cartesian axes for ethene, cyclobutadiene, benzene, naphthalene, and benzocyclobutadiene, starting from the molecular/ring center up to 10 angstrom away. These through-space NMR spectroscopic shielding (TSNMRS) values, which reflect the anisotropic effects, have been broken down into contributions from localized- and canonical molecular orbitals (LMOs and CMOs); these contributions revealed that the proton NMR spectroscopic chemical shifts of nuclei that are spatially close to the C?C double bond or the aromatic ring should not be explained in terms of the conventionally accepted p-electron shielding/deshielding effects. In fact, these effects followed the predictions only for the antiaromatic cyclobutadiene ring.
Chemistry - a European journal
10.1002/chem.201101882
0947-6539
wos:2011-2013
WOS:000298547800044
Baranac-Stojanovic, M (reprint author), Univ Belgrade, Fac Chem, Studentski Trg 16,POB 158, Belgrade 11000, Serbia., mbaranac@chem.bg.ac.rs
Ministry of Science of the Republic of Serbia; Deutscher Akademischer
Austauschdienst (DAAD) [ID: 504 252 70]
Marija Baranac-Stojanovic
Andreas Koch
Erich Kleinpeter
eng
uncontrolled
ab initio calculations
eng
uncontrolled
anisotropic effects
eng
uncontrolled
NMR spectroscopy
eng
uncontrolled
nucleus-independent chemical shift
eng
uncontrolled
pi interactions
Institut für Chemie
Referiert
36360
2012
2012
eng
2788
2797
10
9
41
article
Royal Society of Chemistry
Cambridge
1
--
--
--
Mono- and dinuclear ruthenium(II) 1,6,7,12-tetraazaperylene complexes
We report the synthesis of free 1,6,7,12-tetraazaperylene (tape). Tape was obtained from 1,1'-bis-2,7-naphthyridine by potassium promoted cyclization followed by oxidation with air. Mono-and dinuclear ruthenium(II) 1,6,7,12-tetraazaperylene complexes of the general formulas [Ru(L-L)(2)(tape)](PF6)(2), [1] (PF6)(2)-[5](PF6)(2), and [{Ru(L-L)(2)}(2)(mu-tape)](PF6)(4), [6](PF6)(4)-[10](PF6)(4), with{L-L = phen, bpy, dmbpy (4,4'-dimethyl-2,2'-bipyridine), dtbbpy (4,4'-ditertbutyl-2,2'-bipyridine) and tmbpy (4,4' 5,5'-tetramethyl-2,2'- bipyridine)}, respectively, were synthesized. The X-ray structures of tape center dot 2CHCl(3) and the mononuclear complexes [Ru(bpy)(2)(tape)](PF6)(2)center dot 0.5CH(3)CN center dot 0.5toluene, [Ru(dmbpy)(2)(tape)] (PF6)(2)center dot 2toluene and [Ru(dtbbpy)(2)(tape)](PF6)(2) center dot 3acetone center dot 0.5H(2)O were solved. The UV-vis absorption spectra and the electrochemical behavior of the ruthenium(II) tape complexes were explored and compared with the data of the analogous dibenzoeilatin (dbneil), 2,2'-bipyrimidine (bpym) and tetrapyrido [3,2-a:2',3'-c:3 '',2''-h:2''',3'''-j] phenazin (tpphz) species.
Dalton transactions : a journal of inorganic chemistry, including bioinorganic, organometallic, and solid-state chemistry
10.1039/c2dt11805j
1477-9226
wos:2011-2013
WOS:000300314700030
Holdt, HJ (reprint author), Univ Potsdam, Inst Chem, Karl Liebknecht Str 24-25, D-14476 Golm, Germany., Holdt@Chem.Uni-Potsdam.de
Thomas Martin Brietzke
Wulfhard Mickler
Alexandra Kelling
Hans-Jürgen Holdt
Institut für Chemie
Referiert
36358
2012
2012
eng
27
43
17
1-2
58
article
Elsevier
Amsterdam
1
--
--
--
A conformational analysis and vibrational spectroscopic investigation on 1,2-bis(o-carboxyphenoxy) ethane molecule
The minima on the potential energy surface of 1,2-bis(o-carboxyphenoxy)ethane (CPE) molecule in its electronic ground state were searched by a molecular dynamics simulation performed with MM2 force field. For each of the found minimum-energy conformers, the corresponding equilibrium geometry, charge distribution, HOMO-LUMO energy gap, force field, vibrational normal modes and associated IR and Raman spectral data were determined by means of the density functional theory (DFT) based electronic structure calculations carried out by using B3LYP method and various Pople-style basis sets. The obtained theoretical data confirmed the significant effects of the intra- and inter-molecular hydrogen bonding interactions on the conformational structure, force field, and group vibrations of the molecule. The same data have also revealed that two of the determined stable conformers, both of which exhibit pseudo-crown structure, are considerably more favorable in energy to the others and accordingly provide the major contribution to the experimental spectra of CPE. In the light of the improved vibrational spectral data obtained within the "SQM FF" methodology and "Dual Scale Factors" approach for the monomer and dimer forms of these two conformers, a reliable assignment of the fundamental bands observed in the experimental room-temperature IR and Raman spectra of the molecule was given, and the sensitivities of its group vibrations to conformation, substitution and dimerization were discussed.
Vibrational spectroscopy : an international journal devoted to applications of infrared and raman spectroscopy
10.1016/j.vibspec.2011.11.011
0924-2031
wos:2011-2013
WOS:000300600500004
Balci, K (reprint author), Istanbul Univ, Dept Phys, Fac Sci, TR-34134 Istanbul, Turkey., kbalci@istanbul.edu.tr
Scientific and Technology Research Council of Turkey (TUBITAK)
[104T079]; The Scientific Research Projects Coordination Unit of
Istanbul University [BYP-2459/15052008]
Kubilay Balci
G. Yapar
Y. Akkaya
S. Akyuz
Andreas Koch
Erich Kleinpeter
eng
uncontrolled
Glycol podands
eng
uncontrolled
Salicylic acid
eng
uncontrolled
IR and Raman spectra
eng
uncontrolled
SQM FF
eng
uncontrolled
Dual Scale Factors
Institut für Chemie
Referiert