scholarly journals Energy transfer processes along a supramolecular chain of π-conjugated molecules

2012 ◽  
Vol 370 (1972) ◽  
pp. 3787-3801 ◽  
Author(s):  
S. A. Schmid ◽  
R. Abbel ◽  
A. P. H. J. Schenning ◽  
E. W. Meijer ◽  
L. M. Herz
Keyword(s):  
Wave Function ◽  
Energy Transfer ◽  
Main Chain ◽  
Polymer Chains ◽  
Linear Polymer ◽  
Exciton Migration ◽  
Energy Donor ◽  
Donor And Acceptor ◽  
Initial Excitation ◽  
Quadruple Hydrogen Bonding

We have investigated the energy transfer dynamics in a supramolecular linear polymer chain comprising oligofluorene (OF) energy donor units linked by quadruple hydrogen-bonding groups, and oligophenylene (OPV) chain ends that act as energy acceptors. Using femtosecond spectroscopy, we followed the dynamics of energy transfer from the main chain of OF units to the OPV chain ends and simulated these data taking a Monte Carlo approach that included different extents of electronic wave function delocalization for the energy donor and acceptor. Best correlations between experimental and theoretical results were obtained for the assumption of electronic coupling occurring between a localized donor dipole moment and a delocalized acceptor moment. These findings emphasize that geometric relaxation following initial excitation of the donor needs to be taken into account, as it leads to a localization of the donor's excited state wave function prior to energy transfer. In addition, our simulations show that the energy transfer from the main chain to the ends is dominated by an interplay between slow and spatially limited exciton migration along the OF segments comprising the main chain and the comparatively faster hetero-transfer to the end-cap acceptors from directly adjoining OF segments. These results clearly support the description of host–guest energy transfer in linear polymer chains as a two-step mechanism with exciton diffusion in the host being a prerequisite to energy transfer to the guest.

Shape-persistent poly-porphyrins assembled by a central truxene: synthesis, structure, and singlet energy transfer behaviors

2013 ◽  
Vol 17 (01n02) ◽  
pp. 44-55 ◽  
Author(s):  
Hai-Jun Xu ◽  
Bin Du ◽  
Claude P. Gros ◽  
Philippe Richard ◽  
Jean-Michel Barbe ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Fluorescence Lifetime ◽  
Time Scale ◽  
Selective Excitation ◽  
Methyl Groups ◽  
Flexible Systems ◽  
Relative Rigidity ◽  
Energy Donor ◽  
Donor And Acceptor

Four dyad systems composed of a central truxene and either one or three β-substituted zinc(II) porphyrins (ZnP: TruZnP (7) and TruTriZnP (9)) or free-bases (H2P: TruP (6) and TruTriP (8)) have been prepared. The presence of β-methyl groups minimizes π-conjugation through the quasi right angle made by the porphyrin and the truxene planes, and renders these dyads relatively rigid. The position of the absorption and emission 0–0 peaks confirms the role of the truxene and porphyrin as the energy donor and acceptor, respectively. Selective excitation of the truxene results in an efficient singlet energy transfer (S1 ET) from the truxene to the porphyrin unit. The rates for S1 ET (k ET ) are extracted from the change in the fluorescence lifetime of truxene in the presence and absence of the acceptor, and are temperature independent, (TruP (6), TruTriP (8), TruZnP (7) and TruTriZnP (9) are 5.0, 1.4, 1.0 and 1.4 at 298 K and 5.9, 1.3, 2.6, and 0.86 (ns)-1 at 77 K, respectively), consistent with their relative rigidity. These k ET 's are similar to other related but more flexible systems reported by one of us (Inorg. Chem.2011, 50, 11493–11505). The k ET 's time scale was assumed, based on modeling, to be related with hindered rotations about the truxene-porphyrin C–C bonds due to steric hexyl–hexyl interactions. This work confirms this earlier conclusion was correct.

scholarly journals Conformational Transitions of Polymer Chains in Solutions Characterized by Fluorescence Resonance Energy Transfer

Polymers ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1007 ◽  
Author(s):  
Linlin Qin ◽  
Linling Li ◽  
Ye Sha ◽  
Ziyu Wang ◽  
Dongshan Zhou ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Fluorescence Resonance Energy Transfer ◽  
Conformational Changes ◽  
Conformational Transition ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Polymer Chains ◽  
Donor And Acceptor ◽  
Transition Concentration ◽  
Fluorescence Resonance

The critical overlap concentration C* is an important concept in polymer solutions and is defined as the boundary between dilute and semidilute regimes. In this study, the chain conformational changes of polystyrene (PS) with both high (Mn = 200,000 Da) and low (Mn = 13,000 Da) molecular weights in cis-decalin were compared by intrachain fluorescence resonance energy transfer (FRET). The random labeling of donor and acceptor chromophores strategy was employed for long PS chains, whereas chain-end labeling was used for short PS chains. By monitoring the spectroscopic intensity ratio between acceptor and donor, the concentration dependence on chain conformation from dilute to semidilute solutions was determined. Both long and short chains exhibit a conformational transition concentration, above which the polymer chains begin to collapse with concentration significantly. Interestingly, for randomly labeled polymer long chains, such concentration is consistent with C* determined from the viscosity result, below which only slight conformational change of polymer chain takes place. However, for the chain-end labeled short chain, the conformational transition concentration takes place earlier than C*, below which no significant polymer conformation change is observed.

Chemiluminescent self-reported unfolding of single-chain nanoparticles

2021 ◽  
Author(s):  
Fabian R. Bloesser ◽  
Sarah L. Walden ◽  
Ishrath M. Irshadeen ◽  
Lewis C. Chambers ◽  
Christopher Barner-Kowollik
Keyword(s):  
Polymer Chains ◽  
Linear Polymer ◽  
Single Chain

We demonstrate the light-induced, crosslinker mediated collapse of linear polymer chains into single-chain nanoparticles (SCNPs) capable of self-reporting their unfolding.

scholarly journals Responsive Polyesters with Alkene and Carboxylic Acid Side-Groups for Tissue Engineering Applications

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1636
Author(s):  
Stella Afroditi Mountaki ◽  
Maria Kaliva ◽  
Konstantinos Loukelis ◽  
Maria Chatzinikolaidou ◽  
Maria Vamvakaki
Keyword(s):  
Carboxylic Acid ◽  
Chain Length ◽  
Main Chain ◽  
Alkyl Chain ◽  
Click Reaction ◽  
Irradiation Time ◽  
Alkyl Chain Length ◽  
Polymer Chains ◽  
Condensation Polymerization ◽  
L929 Fibroblast

Main chain polyesters have been extensively used in the biomedical field. Despite their many advantages, including biocompatibility, biodegradability, and others, these materials are rather inert and lack specific functionalities which will endow them with additional biological and responsive properties. In this work, novel pH-responsive main chain polyesters have been prepared by a conventional condensation polymerization of a vinyl functionalized diol with a diacid chloride, followed by a photo-induced thiol-ene click reaction to attach functional carboxylic acid side-groups along the polymer chains. Two different mercaptocarboxylic acids were employed, allowing to vary the alkyl chain length of the polymer pendant groups. Moreover, the degree of modification, and as a result, the carboxylic acid content of the polymers, was easily tuned by varying the irradiation time during the click reaction. Both these parameters, were shown to strongly influence the responsive behavior of the polyesters, which presented adjustable pKα values and water solubilities. Finally, the difunctional polyesters bearing the alkene and carboxylic acid functionalities enabled the preparation of cross-linked polyester films by chemically linking the pendant vinyl bonds on the polymer side groups. The biocompatibility of the cross-linked polymers films was assessed in L929 fibroblast cultures and showed that the cell viability, proliferation, and attachment were greatly promoted on the polyester surface, bearing the shorter alkyl chain length side groups and the higher fraction of carboxylic acid functionalities.

Control of Förster energy transfer in the vicinity of metallic surfaces and hyperbolic metamaterials

2015 ◽  
Vol 178 ◽  
pp. 395-412 ◽  
Author(s):  
T. U. Tumkur ◽  
J. K. Kitur ◽  
C. E. Bonner ◽  
A. N. Poddubny ◽  
E. E. Narimanov ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Spontaneous Emission ◽  
Practical Importance ◽  
Index Of Refraction ◽  
Metallic Surfaces ◽  
Dielectric Media ◽  
Plasmonic Structures ◽  
Donor And Acceptor ◽  
Förster Energy Transfer ◽  
Photonic States

Optical cavities, plasmonic structures, photonic band crystals and interfaces, as well as, generally speaking, any photonic media with homogeneous or spatially inhomogeneous dielectric permittivity (including metamaterials) have local densities of photonic states, which are different from that in vacuum. These modified density of states environments are known to control both the rate and the angular distribution of spontaneous emission. In the present study, we question whether the proximity to metallic and metamaterial surfaces can affect other physical phenomena of fundamental and practical importance. We show that the same substrates and the same nonlocal dielectric environments that boost spontaneous emission, also inhibit Förster energy transfer between donor and acceptor molecules doped into a thin polymeric film. This finding correlates with the fact that in dielectric media, the rate of spontaneous emission is proportional to the index of refractionn, while the rate of the donor–acceptor energy transfer (in solid solutions with a random distribution of acceptors) is proportional ton−1.5. This heuristic correspondence suggests that other classical and quantum phenomena, which in regular dielectric media depend onn, can also be controlled with custom-tailored metamaterials, plasmonic structures, and cavities.

Conjugated alternating copolymers containing both donor and acceptor moieties in the main chain

2007 ◽  
pp. 1704-1706 ◽  
Author(s):  
Ming Zhang ◽  
Changduk Yang ◽  
Ashok K. Mishra ◽  
Wojciech Pisula ◽  
Gang Zhou ◽  
...  
Keyword(s):  
Main Chain ◽  
Alternating Copolymers ◽  
Donor And Acceptor

scholarly journals Horizontal versus vertical charge and energy transfer in hybrid assemblies of semiconductor nanoparticles

2012 ◽  
Vol 3 ◽  
pp. 629-636 ◽  
Author(s):  
Gilad Gotesman ◽  
Rahamim Guliamov ◽  
Ron Naaman
Keyword(s):  
Energy Transfer ◽  
Charge Transfer ◽  
Horizontal Plane ◽  
Quartz Substrate ◽  
Vertical Direction ◽  
Time Resolved ◽  
Transfer Processes ◽  
Donor And Acceptor ◽  
Hybrid Assemblies ◽  
Time Resolved Photoluminescence

We studied the photoluminescence and time-resolved photoluminescence from self-assembled bilayers of donor and acceptor nanoparticles (NPs) adsorbed on a quartz substrate through organic linkers. Charge and energy transfer processes within the assemblies were investigated as a function of the length of the dithiolated linker (DT) between the donors and acceptors. We found an unusual linker-length-dependency in the emission of the donors. This dependency may be explained by charge and energy transfer processes in the vertical direction (from the donors to the acceptors) that depend strongly on charge transfer processes occurring in the horizontal plane (within the monolayer of the acceptor), namely, parallel to the substrate.

scholarly journals Distribution of a Glycosylphosphatidylinositol-anchored Protein at the Apical Surface of MDCK Cells Examined at a Resolution of <100 Å Using Imaging Fluorescence Resonance Energy Transfer

1998 ◽  
Vol 142 (1) ◽  
pp. 69-84 ◽  
Author(s):  
A.K. Kenworthy ◽  
M. Edidin
Keyword(s):  
Energy Transfer ◽  
Lipid Rafts ◽  
Fluorescence Resonance Energy Transfer ◽  
Mdck Cells ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Membrane Microdomains ◽  
Apical Surface ◽  
Donor And Acceptor ◽  
Fluorescence Resonance

Membrane microdomains (“lipid rafts”) enriched in glycosylphosphatidylinositol (GPI)-anchored proteins, glycosphingolipids, and cholesterol have been implicated in events ranging from membrane trafficking to signal transduction. Although there is biochemical evidence for such membrane microdomains, they have not been visualized by light or electron microscopy. To probe for microdomains enriched in GPI- anchored proteins in intact cell membranes, we used a novel form of digital microscopy, imaging fluorescence resonance energy transfer (FRET), which extends the resolution of fluorescence microscopy to the molecular level (&lt;100 Å). We detected significant energy transfer between donor- and acceptor-labeled antibodies against the GPI-anchored protein 5′ nucleotidase (5′ NT) at the apical membrane of MDCK cells. The efficiency of energy transfer correlated strongly with the surface density of the acceptor-labeled antibody. The FRET data conformed to theoretical predictions for two-dimensional FRET between randomly distributed molecules and were inconsistent with a model in which 5′ NT is constitutively clustered. Though we cannot completely exclude the possibility that some 5′ NT is in clusters, the data imply that most 5′ NT molecules are randomly distributed across the apical surface of MDCK cells. These findings constrain current models for lipid rafts and the membrane organization of GPI-anchored proteins.

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