Photophysical studies of hydrophobically functionalized polyionene systems in aqueous solutions

1995 ◽  
Vol 73 (11) ◽  
pp. 2041-2046 ◽  
Author(s):  
P. Uznanski ◽  
J. Pecherz ◽  
M. Kryszewski
Keyword(s):  
Energy Transfer ◽  
Conformational Changes ◽  
Hydrophobic Interaction ◽  
Polymer Chains ◽  
Anionic Dyes ◽  
Fluorescence Studies ◽  
Surfactant Aggregates ◽  
Modified Polymers ◽  
Characteristic Behaviour ◽  
Polymer Surfactant

Complexes of polyionene and anionic dyes and surfactant were prepared by exchange reaction of counterions in the parent polymer. Fluorescence studies were conducted to observe some characteristic behaviour of these complexes in water Polyionenes with aromatic hydrocarbons adopt an open conformation and there is no evidence for interpolymer interactions. On the contrary, polyionenes with long aliphatic counterions easily form microdomains in aqueous solution due to hydrophobic interaction as evidenced by an increase in excimer emission. Microdomains have an interpolymer nature, as confirmed by measurements of energy transfer from naphthalene to pyrene moieties. Polyionenes with SDS counterions interact with external surfactant molecules and form polymer–surfactant aggregates. Electrostatic repulsions between aggregates dominate on hydrophobic interaction between polymer chains and are responsible for conformational changes. Keywords: hydrophobically modified polymers, surfactants, complexation, fluorescence, nonradiative energy transfer

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.

Covalently Linked Tetraphenylporphyrin Trimers and Tetramers and their Coordination Behaviour

1997 ◽  
Vol 01 (01) ◽  
pp. 17-28 ◽  
Author(s):  
G. VAIJAYANTHIMALA ◽  
V. KRISHNAN
Keyword(s):  
Energy Transfer ◽  
Conformational Changes ◽  
Photophysical Properties ◽  
Molecular Mechanics Calculations ◽  
Efficient Energy Transfer ◽  
Time Resolved ◽  
Fluorescence Studies ◽  
H Nmr ◽  
Coordination Behaviour ◽  
Covalently Linked

Several covalently linked tetraphenyl porphyrin trimers and tetramers bearing ethylene oxide bridges originating from the m and p positions of adjacent and/or opposite meso-aryl groups have been synthesized and characterized by fast atom bombardment mass spectroscopy, 1 H NMR, optical absorption and emission spectroscopies. The fully and partially metallated zinc(II) and copper(II) derivatives have been prepared and their photophysical properties are outlined. The steady-state and time-resolved fluorescence studies of the heterotrimers indicate efficient energy transfer from the ZnP to the H 2 P unit. The efficiency and rate of energy transfer are dependent on the number of free-base units in the hetero-oligomers and the geometrical position of the porphyrin units. The heterotrimers consisting of one, two and three zinc(II) centres bind 4,4″-bipyridyl in different modes as revealed by the nature of binding curves. The bipyridyl ligand functions as a chelate in the complexes of biszinc(II) porphyrin trimers while two bipyridyls bind to trizinc(II) porphyrin trimers with one ligand functioning as a chelate and another exhibiting monodentate coordination behaviour. The folding of two ZnP units is clearly seen in the complexes of bis and triszinc(II) trimers with bipyridyl, which is substantiated by molecular mechanics calculations. Axial ligation studies with trimers show that the preorganization of porphyrin hosts is necessary for recognition of the guest. The binding of bipyridyl to the trimers is followed by global conformational changes and this behaviour is analogous to activated complex binding in induced-fit enzymes.

In situ Raman Spectroscopic Observation of Polymer Chains in Semi-Crystalline Polyethylene Solids

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Yusuke Hiejima ◽  
Takumitsu Kida ◽  
Koh-hei Nitta
Keyword(s):  
Conformational Changes ◽  
Tensile Elongation ◽  
Spectroscopic Observation ◽  
Polymer Chains ◽  
Trans Conformation ◽  
Raman Spectroscopic ◽  
Higher Temperature ◽  
Microscopic Origin ◽  
Crystalline Polyethylene

AbstractIn situ Raman spectroscopy is applied for polyethylene solid under various environments to elucidate the morphological and conformational changes. The trans conformation retains up to higher temperature for high-density polyethylene, reflecting higher stability of the orthorhombic crystals composed of stacked trans chains. It is suggested that the conversion of the non-crystalline trans chains to the crystalline phase is the microscopic origin of thermal history in the crystallinity, whereas the transformation between the trans and gauche conformers is practically in thermal equilibrium. Microscopic and dynamic mechanism of deformation during uniaxial stretching is investigated for the molecular orientation and the microscopic load sharing on the crystalline and amorphous chains. Lower crystallinity results in smoother and higher orientation toward the stretching direction, as well as higher load on the amorphous chains, during tensile elongation.

scholarly journals Quaternization of Poly(2-diethyl aminoethyl methacrylate) Brush-Grafted Magnetic Mesoporous Nanoparticles Using 2-Iodoethanol for Removing Anionic Dyes

2021 ◽  
Vol 11 (21) ◽  
pp. 10451
Author(s):  
Khalid Mohammed Alotaibi ◽  
Abdurrahman A. Almethen ◽  
Abeer M. Beagan ◽  
Hassan M. Al-Swaidan ◽  
Ashfaq Ahmad ◽  
...  
Keyword(s):  
Mesoporous Silica Nanoparticles ◽  
High Surface ◽  
High Surface Area ◽  
Polymer Chains ◽  
Sunset Yellow ◽  
Anionic Dyes ◽  
Solution Ph ◽  
Effects Of Ph ◽  
Weak Adsorption ◽  
Ph Level

Magnetic mesoporous silica nanoparticles (Fe3O4-MSNs) were successfully synthesized with a relatively high surface area of 568 m2g−1. Fe3O4-MSNs were then modified with poly(2-diethyl aminoethyl methacrylate) (PDEAEMA) brushes using surface-initiated ARGET atom transfer radical polymerization (ATRP) (Fe3O4@MSN-PDMAEMA). Since the charge of PDEAEMA is externally regulated by solution pH, tertiary amines in the polymer chains were quaternized using 2-iodoethanol to obtain cationic polymer chains with a permanent positive charge (Fe3O4@MSN-QPDMAEMA). The intensity of the C−O peak in the C1s X-ray photoelectron spectrum increased after reaction with 2-iodoethanol, suggesting that the quaternization process was successful. The applicability of the synthesized materials on the removal of methyl orange (MO), and sunset yellow (E110) dyes from an aqueous solution was examined. The effects of pH, contact time, and initial dyes concentrations on the removal performance were investigated by batch experiments. The results showed that the Fe3O4@MSN-PDMAEMA sample exhibited a weak adsorption performance toward both MO and E110, compared with Fe3O4@MSN-QPDMAEMA at a pH level above 5. The maximum adsorption capacities of MO and E110 using Fe3O4@MSN-QPDMAEMA were 294 mg g−1 and 194.8 mg g−1, respectively.

Energy transfer in and fluorescence studies of the Eu-Tb doped BPA-phen system

2019 ◽  
Vol 66 (8) ◽  
pp. 879-885 ◽  
Author(s):  
Guangbo Xie ◽  
Haibang Zhang ◽  
Zijun Zhang ◽  
Juntong Liu ◽  
Jingjing Zhang ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Fluorescence Studies ◽  
The Eu

Fluorescence Studies of Ligand-Induced Conformational Changes of the Na+/Glucose Cotransporter†

Biochemistry ◽  
2002 ◽  
Vol 41 (4) ◽  
pp. 1250-1258 ◽  
Author(s):  
Anne-Kristine Meinild ◽  
Bruce A. Hirayama ◽  
Ernest M. Wright ◽  
Donald D. F. Loo
Keyword(s):  
Conformational Changes ◽  
Fluorescence Studies
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