scholarly journals Tuning Photophysical Properties of Donor/Acceptor Hybrid Thin- Film via Addition of SiO2/TiO2 Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 611
Author(s):  
Bandar Ali Al-Asbahi ◽  
Mohammad Hafizuddin Hj. Jumali ◽  
M. S. AlSalhi ◽  
Saif M. H. Qaid ◽  
Amanullah Fatehmulla ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Photophysical Properties ◽  
Critical Concentration ◽  
Radiative Energy ◽  
Conjugation Length ◽  
Quenching Rate ◽  
Efficient Energy Transfer ◽  
Time Resolved ◽  
Hybrid Thin Film ◽  
Hybrid Thin Films

The influence of SiO2/TiO2 nanocomposites (STNCs) content on non-radiative energy transfer (Förster-type) from poly (9,9′-dioctylfluorene-2,7-diyl) (PFO) to poly [2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) using steady-state and time-resolved photoluminescence spectroscopies was investigated at room temperature. The improved energy transfer from PFO to MEH-PPV upon an increment of the STNCs was achieved by examining absorbance, emission (PL) and photoluminescence excitation (PLE) spectra. The shorter values of the quantum yield (φDA) and lifetime (τDA) of the PFO in the hybrid thin films compared with the pure PFO, indicating efficient energy transfer from PFO to MEH-PPV with the increment of STNCs in the hybrid. The energy transfer parameters can be tuned by increment of the STNCs in the hybrid of PFO/MEH-PPV. The Stern–Volmer value (kSV), quenching rate value (kq), Förster radius (R0), distance between the molecules of PFO and MEH-PPV (RDA), energy transfer lifetime (τET), energy transfer rate (kET), total decay rate of the donor (TDR), critical concentration (Ao), and conjugation length (Aπ) were calculated. The gradually increasing donor lifetime and decreasing acceptor lifetime, upon increasing the STNCs content, prove the increase in conjugation length and meanwhile enhance in the energy transfer.

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.

Synthesis and Photophysical Properties of a Conformationally Flexible Mixed Porphyrin Star-Pentamer

2009 ◽  
Vol 62 (7) ◽  
pp. 692 ◽  
Author(s):  
Toby D. M. Bell ◽  
Sheshanath V. Bhosale ◽  
Kenneth P. Ghiggino ◽  
Steven J. Langford ◽  
Clint P. Woodward
Keyword(s):  
Energy Transfer ◽  
Photophysical Properties ◽  
Fluorescence Decay ◽  
High Yield ◽  
Free Base ◽  
Time Resolved ◽  
Zinc Porphyrin ◽  
Relative Contribution ◽  
Synthetic Strategy ◽  
Decay Times

The synthesis of a porphyrin star-pentamer bearing a free-base porphyrin core and four zinc(ii) metalloporphyrins, which are tethered by a conformationally flexible linker about the central porphyrin’s antipody, is described. The synthetic strategy is highlighted by the use of olefin cross metathesis to link the five chromophores together in a directed fashion in high yield. Photoexcitation into the Soret absorption band of the zinc porphyrin chromophores at 425 nm leads to a substantial enhancement of central free-base porphyrin fluorescence, indicating energy transfer from the photoexcited zinc porphyrin (outer periphery) to central free-base porphyrin. Time-resolved fluorescence decay profiles required three exponential decay components for satisfactory fitting. These are attributed to emission from the central free-base porphyrin and to two different rates of energy transfer from the zinc porphyrins to the free-base porphyrin. The faster of these decay components equates to an energy-transfer rate constant of 3.7 × 109 s–1 and an efficiency of 83%, whereas the other is essentially unquenched with respect to reported values for zinc porphyrin fluorescence decay times. The relative contribution of these two components to the initial fluorescence decay is ~3:2, similar to the 5:4 ratio of cis and trans geometric isomers present in the pentamer.

Resonance energy transfer study of laser dyes LD 489 and LD 473 with rhodamine 6G

2014 ◽  
Vol 92 (4) ◽  
pp. 302-306 ◽  
Author(s):  
H.R. Deepa ◽  
J. Thipperudrappa ◽  
H.M. Suresh Kumar
Keyword(s):  
Energy Transfer ◽  
Rhodamine 6G ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Laser Dyes ◽  
Rate Parameter ◽  
Quenching Rate ◽  
Range Interaction ◽  
Time Resolved ◽  
Bimolecular Quenching

The energy transfer using two laser dyes 6,7,8,9-tetrahydro-6,8,9-trimethyl-4-(trifluoromethyl)-2H-pyrano[2,3-b][1,8]naphthyridin-2-one (LD-489) and 1,2,3,8-tetrahydro-1,2,3,3,8-pentamethyl-5-(trifluoromethyl)-7H-pyrrolo[3,2-g]quinolin-7-one (LD-473) as donors and rhodamine 6G (Rh6G) as acceptor was investigated in methanol using steady state and time resolved fluorescence spectroscopy. The bimolecular quenching rate parameter, kq, and the translation diffusion rate parameter, kd, were calculated and these values indicated that the diffusion process alone does not operate in energy transfer process. The mean diffusion length, d1, is found to be less than the Förster distance, R0, supporting the dominance of long-range interaction. The critical transfer distances determined from both the Förster equation and the half quenching concentration are close to one another, revealing that the Förster mechanism plays an important role in overall energy transfer of the donors.

Polypeptides with pendant porphyrins of defined sequence of chromophores: towards artificial photosynthetic systems

2008 ◽  
Vol 12 (12) ◽  
pp. 1232-1241 ◽  
Author(s):  
Farid Aziat ◽  
Régis Rein ◽  
Jorge Peón ◽  
Ernesto Rivera ◽  
Nathalie Solladié
Keyword(s):  
Energy Transfer ◽  
Excited State ◽  
Amino Acid ◽  
Fluorescence Spectroscopy ◽  
Photophysical Properties ◽  
Free Base ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Absorption And Fluorescence Spectroscopy ◽  
Artificial Photosynthetic

In this paper we now report our ongoing progress in the preparation of artificial photosynthetic systems through the preparation of light harvesting multi-porphyrins. A tetramer, constituted of a central dipeptide functionalized by two free-base porphyrins and surrounded by one amino-acid bearing a pendant Zn ( II ) porphyrin on each side, has been chosen. The optical and photophysical properties of this tetramer have been studied by absorption and fluorescence spectroscopy. In addition, the energy transfer phenomenon has been studied and monitored by femtosecond time-resolved fluorescence. Our results indicate that the excited state dynamics redounding in the excitation being localized in the inner free-base porphyrins takes place in the time scale of approximately 1 ps.

scholarly journals Investigation of Energy Transfer in Star-Shaped White Polymer Light-Emitting Devices via the Time-Resolved Photoluminescence

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1719 ◽  
Author(s):  
Hui He ◽  
Xiaoqing Liao ◽  
Jiang Cheng ◽  
Ying Li ◽  
Junsheng Yu ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Current Efficiency ◽  
Intermolecular Interactions ◽  
Efficient Energy Transfer ◽  
Time Resolved ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Efficient Energy ◽  
Polymer Light Emitting Devices ◽  
Time Resolved Photoluminescence

A series of white polymer light-emitting devices (WPLEDs) were fabricated by utilizing star-shaped white-emission copolymers containing tri[1-phenylisoquinolinato-C2,N]iridium (Ir(piq)3), fluorenone (FO) and poly(9,9-dioctylfluorene) (PFO) as red-, green- and blue-emitting (RGB) components, respectively. In these WPLEDs, a maximum current efficiency of 6.4 cd·A−1 at 20 mA·cm−2 and Commission Internationale d’Eclairage (CIE) coordinates of (0.33, 0.32) were achieved, and the current efficiency was still kept to 4.2 cd·A−1 at the current density of 200 mA·cm−2. To investigate energy transfer processes among the three different chromophores of the star-shaped copolymers in these WPLEDs, the time-resolved photoluminescence (PL) spectra were recorded. By comparing the fluorescence decay lifetimes of PFO chromophores in the four star-like white-emitting copolymers, the efficient energy transfer from PFO units to Ir(piq)3 and FO chromophores was confirmed. From time-resolved PL and the analysis of energy transfer process, the results as follows were proved. Owing to the star-like molecular structure and steric hindrance effect, intermolecular interactions and concentrations quenching in the electroluminescence (EL) process could also be sufficiently suppressed. The efficient energy transfer also reduced intermolecular interactions’ contribution to the enhanced device performances compared to the linear single-polymer white-light systems. Moreover, saturated stable white emission results from the joint of energy transfer and trap-assisted recombination. This improved performance is expected to provide the star-like white-emitting copolymers with promising applications for WPLEDs.

Synthesis of unsymmetrical porphyrin triad containing three different porphyrin subunits assembled by covalent and non-covalent interactions

2008 ◽  
Vol 12 (09) ◽  
pp. 1030-1040 ◽  
Author(s):  
Sokkalingam Punidha ◽  
Smita Rai ◽  
Mangalampalli Ravikanth
Keyword(s):  
Building Block ◽  
Functional Group ◽  
Photophysical Properties ◽  
Time Resolved Fluorescence ◽  
Efficient Energy Transfer ◽  
Time Resolved ◽  
Fluorescence Studies ◽  
Efficient Energy ◽  
Non Covalent Interactions ◽  
Covalent Interactions

Cis-21,23-dithiaporphyrin building block containing one iodophenyl and one pyridyl functional group at meso positions was synthesized by condensing unsymmetrical thiophene diol and symmetrical 16-thiatripyrrin under refluxing propionic acid conditions. The 21,23-dithiaporphyrin building block was coupled with mono-functionalized 21-thiaporphyrin building block containing meso-phenylethyne functional group under mild Pd (0) coupling conditions. The steady-state and time-resolved fluorescence studies support an efficient energy transfer in the singlet excited state from N 3 S porphyrin subunit to N 2 S 2 porphyrin subunit in the dyad. The N 3 S - N 2 S 2 porphyrin dyad was then treated with RuTPP ( CO )( EtOH ) in toluene at refluxing temperature and purified by column chromatography to afford a porphyrin triad containing N 3 S , N 2 S 2 and RuN 4 porphyrin subunits assembled using both covalent and non-covalent interactions. The photophysical properties showed the fluorescence quenching of N 3 S and N 2 S 2 porphyrin subunits in triad due to heavy ruthenium ion which was coordinated to meso-pyridyl ' N ' of N 2 S 2 porphyrin subunit of porphyrin triad.

scholarly journals Effect of Ce3+ Co-doping on GdPO4:Tb3+ Nanoparticles: Photoluminescence and Energy Transfer Studies

2021 ◽  
Vol 33 (4) ◽  
pp. 903-908
Author(s):  
N. Yaiphaba
Keyword(s):  
Energy Transfer ◽  
Critical Concentration ◽  
Reaction Medium ◽  
Average Crystallite Size ◽  
Low Temperature Synthesis ◽  
Temperature Synthesis ◽  
Efficient Energy Transfer ◽  
Efficient Energy ◽  
Co Doping ◽  
Biological Labeling

Low temperature synthesis of Tb3+-doped GdPO4 nanoparticles sensitized with Ce3+ (Ce3+ = 0, 3, 5, 7 and 10 at.%) have been reported. Ethylene glycol was used as capping agent as well as reaction medium at 160 ºC. The as-prepared particles crystallized in a monoclinic structure with an average crystallite size of 25-46 nm. From the photoluminescence study, enhanced emission of Tb3+ with co-doping of Ce3+ was attributed to efficient energy transfer from the sensitizer to activator. The luminescence emission intensity increases upto 5 at.% of Ce3+ and then decreases. Less efficient energy transfer from sensitizer to the activator with increasing concentration of sensitizer may be attributed to critical concentration of Ce3+ with the host or dipole-quadrupole interaction amongst the Ce3+ ions. Moreover, presence of -OH group in the samples will make them a potential target for biological labeling and optical devices.

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