- Fluorescent gelators for detection of explosives
-
Carbazole-, quinoline-, benzothiazole-, and stilbene-containing fluorescent gelators are synthesized by connecting gelationdriving segments, and their gelation abilities are studied with 13 solvents. Fibrous thin-layer films are prepared on quartz plates
- Hanabusa, Kenji,Takata, Shingo,Fujisaki, Masafumi,Nomura, Yasushi,Suzuki, Masahiro
-
-
Read Online
- STUDY OF THE TRANS->CIS PHOTOISOMERIZATION OF 4-NITRO-4'-DIMETHYLAMINOSTILBENE IN TOLUENE SOLUTIONS
-
The direct trans->cis photoisomerization of 4-nitro-4'-dimethylaminostilbene (NDMAS) in toluene solutions and the role of triplet states have been studied by standard techniques and laser flash photolysis, respectively.The quantum yields of trans->cis photoisomerization (Φt->c), of fluorescence (Φf) and of triplet formation (ΦT) as well as the triplet lifetime (τ) have been measured as functions of temperature (-80 to 100 deg C).Different activation energies, obtained from Φf and Φt->c measurements, indicate the presence of two consecutive thermally activated steps.None of the hitherto published mechanisms for trans->cis photoisomerization account for this result.The trans->cis photoisomerization pathway is tentatively assigned to the sequence 1t*->ΔA*->Δp*->1p->(1-β)1c.The steps marked with Δ are thermally activated steps, A* is an excited trans state and p* is an excited twisted state which decays to the twisted ground state (1p) which in turn deactivates to the cis and trans forms.
- Goerner, Helmut,Schulte-Frohlinde, Dietrich
-
-
Read Online
- SEMICONDUCTIVITY OF ORGANIC SUBSTANCES-15
-
Part 15 treats compounds related to stilbene. Dark conductivity in diphenylbutadiene and four analogs of stilbene has been examined. The compounds were chosen to reveal the possible effects of a donor and an acceptor group attached to opposite ends of the
- ELEY DD,NEWMAN OMG
-
-
Read Online
- Evaluating two new Schiff bases synthesized on the inhibition of corrosion of copper in NaCl solutions
-
Two kinds of new Schiff base derivatives, 2-((4-(4-(dimethylamino)styryl)phenylimino)methyl) (DSM) and its intermediate 4-(4-aminostyryl)-N,N-dimethylaniline (AND), form self-assembled monolayers (SAMs) on copper surfaces. The SAMs have been examined by a series of techniques, including contact angle (CA), atomic force microscope (AFM), scanning electronic microscope (SEM), and electrochemical measurements. The results suggest that the two derivatives adsorb onto the copper surface and generate corresponding hydrophobic films, which play an important role in the anticorrosion of copper in 3% NaCl solution. Quantum chemical calculations and molecular dynamics (MD) simulation are also used for further insight into the adsorption mechanism.
- Zhou, Yang,Xu, Shenying,Guo, Lei,Zhang, Shengtao,Lu, Hao,Gong, Yulong,Gao, Fang
-
-
Read Online
- Charge neutral rhenium tricarbonyl complexes of tridentate N-heterocyclic carbene ligands that bind to amyloid plaques of Alzheimer's disease
-
Two tridentate ligand systems bearing N-heterocyclic carbene (NHC), amine and carboxylate donor groups coupled to benzothiazole- or stilbene-based amyloid binding moieties were synthesised. Reaction of the imidazolium salt containing pro-ligands with Re(CO)5Cl yielded the corresponding rhenium metal complexes which were characterised by NMR, and X-ray crystallography. These ligands are of interest for the potential preparation of technetium-99m imaging agents for Alzheimer's disease and the capacity of these rhenium complexes bind to amyloid fibrils composed of amyloid-β peptide and amyloid plaques in human frontal cortex brain tissue was evaluated using fluorescence microscopy. These studies show that the complexes bound efficiently to amyloid-β fibrils and some evidence of binding to amyloid-β plaques.
- Barnard, Peter J.,Donnelly, Paul S.,McLean, Catriona A.,Noor, Asif,Wiratpruk, Nuchareenat
-
supporting information
p. 4559 - 4569
(2020/04/17)
-
- New organic conjugated dye nano-aggregates exhibiting naked-eye fluorescence color switching
-
In this study, a variety of new conjugated containing strong electron-donating groups were prepared for formation of organic nano-scale aggregates. The properties and aggregation modes of these aggregates were investigated on basis of time dependent absorption, fluorescence emission spectra as well as scanning electron microscope images. The results show that nano organic aggregates could be yielded by the linear dyes in mixed DMF/H2O solvent through a simple re-precipitation method, while no aggregates of the branched dyes were produced. X-ray diffraction of single crystal and X-ray diffraction patterns of the powders results demonstrate that the linear dyes tend to show ordered molecular arrangements, while the armed dyes do not exhibit such a tendency. A remarkable fluorescence switching process under 365 nm lamp was observed for the target aggregates. This study successfully provides real examples of organic aggregates in mixed DMF/H2O solvent which have great capacity to show enhanced fluorescence color switching.
- Ding, Ge,Lu, Yao,Qin, Xiaozhuan,Su, Jihong,Zhang, Shengtao,Li, Hongru,Luo, Ziping,Chen, Lingyun,Gao, Fang
-
-
- Trans->Cis Photoisomerization, Fluorescence, and Relaxation Phenomena oxf trans-4-Nitro-4'-(dialkylamino)stilbenes and Analogues with a Nonrotatable Amino Group
-
The steady-state fluorescence properties of 4-nitro-4'-aminostilbenes (4-nitro-4'-aminostilbene (1); 4-nitro-4'-(dimethylamino)stilbene (2); 4-nitro-4'-(diethylamino)stilbene (3); 1-(4-nitrophenyl)-2-(2,3-dihydro-N-R-indol-5-yl)ethylene, R = H (4) and R = CH3 (5) were studied in various solvents and as a function of temperature.The quantum yield of fluorescence for trans isomer (Φf), the Stokes shift, and the quantum yield of trans->cis photoisomerization (Φt->c) depend markedly on the nature of the solvent.When the polarity is increased the Stokes shift increases, Φt->c decreases strongly, and Φf at first rises and then also decreases strongly.The five trans isomers show similar effects of solvent polarity and, generally, only small differences for a given solvent.This shows that the reduction in Φt->c in solvents of moderate and higher polarity is not caused by deactivation of the first excited trans singlet state (1t(excit)) via rotation of the dialkylamino group since in 4 and 5 it cannot rotate whereas in 1-3 it can.Activation energies in m-xylene, toluene, and dioxane, obtained from Φt->c (range: 7-13 kcal/mol) and from Φf measurements (3-4 kcal/mol), differ significantly.It is concluded that the substantial decrease of Φt->c on going from nonpolar to slightly polar solvents is due (i) to relaxation to the trans ground state of the transoid excited state (A(excit.)) that is not identical with the solvent-relaxed spectroscopic 1t(excit.) state and (ii) to the presence of an energy barrier along the pathway of trans->cis photoisomerization (following the step 1t(excit.) -> A(excit.)), which cannot be overcome in more polar solvents.
- Gruen, Henry,Goerner, Helmut
-
p. 7144 - 7152
(2007/10/02)
-
- Application of Phase-Transfer Catalysis to the Synthesis of Mono- and Bis-stilbenes and Styryls
-
A novel and convenient method has been developed for the synthesis of substituted stilbenes by the condensation of active methyl group in suitably substituted toluenes with aromatic aldehydes in aq. medium at room temperature using benzyltriethylammonium chloride as a phase-transfer catalyst.This method has also been applied for the preparation of heterocyclic styryls and extended to the synthesis of bis-stilbenes and bis-styryls using aromatic dialdehydes in place of monoaldehydes.A comparison of the results shows that the present method is superior to the conventional methods in many respects.
- Lokhande, S. B.,Rangnekar, D. W.
-
p. 485 - 488
(2007/10/02)
-