scholarly journals Synthesis and Photophysical Properties of Some Conjugated Polymers Functionalized with Ruthenium Polypyridine Complexes

1997 ◽  
Vol 488 ◽  
Author(s):  
Po King Ng ◽  
Wai Yue Ng ◽  
Xiong Gong ◽  
Wai Kin Chan
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Conjugated Polymers ◽  
Conjugated Polymer ◽  
Photophysical Properties ◽  
Polymer Systems ◽  
Ligand Charge Transfer ◽  
Palladium Catalyzed ◽  
Polypyridine Complexes ◽  
Ruthenium Polypyridine

AbstractA series of conjugated polymers functionalized with different ruthenium polypyridine metal complexes were synthesized by the palladium catalyzed reaction. Two conjugated polymer systems have been studied: 1. poly(phenylenevinylene) with bis(2,2':6',2”-terpyridine) ruthenium (II) on the mainchain and 2. quinoxaline based polymers with tris(2,2'-bipyridine) ruthenium (II). The ruthenium polypyridine complexes exhibit a long-lived metal to ligand charge transfer excited state which can enhance the photosensitivity of the resulting polymers. Different physical properties such as the photoconductivity and charge mobility in these polymers are also studied.

Temperature dependence of photophysical properties of a dinuclear C^N-cyclometalated Pt(ii) complex with an intimate Pt–Pt contact. Zero-field splitting and sub-state decay rates of the lowest triplet

2018 ◽  
Vol 20 (38) ◽  
pp. 25096-25104 ◽  
Author(s):  
Joseph C. Deaton ◽  
Arnab Chakraborty ◽  
Rafal Czerwieniec ◽  
Hartmut Yersin ◽  
Felix N. Castellano
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Photophysical Properties ◽  
Decay Rates ◽  
Zero Field ◽  
Triplet Excited State ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
Ligand Charge Transfer ◽  
Metal Metal

A dinuclear Pt(ii) complexes exhibits an unusually large zero field splitting in its metal–metal-to-ligand charge transfer triplet excited state.

scholarly journals Light driven isomerization of coordinated ligand and modulation offac-[Re(CO)3(phen)(trans-bpe)]PF6photoluminescence in rigid media

2001 ◽  
Vol 3 (3) ◽  
pp. 143-164 ◽  
Author(s):  
Melina Kayoko Itokazu ◽  
André Sarto Polo ◽  
Neyde Yukie Murakami Iha
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Photophysical Properties ◽  
Acetonitrile Solution ◽  
Solid Films ◽  
Spectral Changes ◽  
Rhenium Complex ◽  
Photostationary State ◽  
Ligand Charge Transfer ◽  
Enhanced Luminescence

The excited state reactivity and photophysical properties offac-[Re(CO)3(phen)(L)]PF6(phen = 1,10-phenanthroline, L =trans- orcis-1,2-bis(4-pyridyl)ethylene, bpe) in PMMA (poly(methyl methacrylate)) films have been investigated and compared with those in acetonitrile solution.313 or 365 nm irradiation of the rhenium complex in PMMA leads to UV-vis spectral changes due to thetrans→cisisomerization of the coordinated bpe ligand. Thefac-[Re(CO)3(phen)(cis-bpe)]+product presents a markedly enhanced luminescence due to a lower lying metal-to-ligand charge transfer (MLCT) excited state in thecisisomer. This emitting property can be conveniently applied as a probe or sensor.Thecisis omer ratio in the photostationary state (PSS) is substantially smaller in solid films than in solution. The photochemical behavior of the freetrans-1,2-bis(4-pyridyl)ethylene in PMMA is also reported to establish comparisons with the investigation carried out in acetonitrile solution as well as with the behavior of the coordinated ligand.

Synthesis and Photophysical Properties of New Three-Coordinate N-Heterocyclic Carbene Copper Complex

2016 ◽  
Vol 878 ◽  
pp. 18-21
Author(s):  
Shao Bo Liu ◽  
Cheng Yi ◽  
Hong Ying Xia ◽  
Feng Zhao
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Absorption Band ◽  
Energy Absorption ◽  
Copper Complex ◽  
Room Temperature ◽  
Photophysical Properties ◽  
Emission Spectrometry ◽  
Emission Maximum ◽  
Ligand Charge Transfer

A three-coordinateopper (I) complex supported by N-heterocyclic carbene (NHC) ligand and bis [2-(diphenylphosphino) phenyl] ether (POP) ligand were successfully reported and characterized. The corresponding photophysical properties were investigated using UV-vis and emission spectrometry. The lowest-energy absorption band at 343 nm was assigned to metal-to-ligand charge transfer (MLCT) transtion. The emission maximum located at 470 nm upon excitation at 290 nm in PMMA films at room temperature originates from the typical 3MLCT excited state.

Synthesis, Characterization and Photophysical Properties of Rhenium(I) Complexes Containing 4,5-Diazafluorene Ligan

2011 ◽  
Vol 239-242 ◽  
pp. 2612-2615
Author(s):  
Jie Xiu Wang ◽  
Feng Zhao
Keyword(s):  
Charge Transfer ◽  
Fluorescence Spectra ◽  
Photophysical Properties ◽  
Absorption And Fluorescence Spectra ◽  
Rhenium Complexes ◽  
H Nmr ◽  
Ligand Charge Transfer

Two related tricarbonyl rhenium complexes with the formula of [Re(CO)3(L)Cl], where L=4,5-diazafluoren-9-one (Dafo-Re) and 9-(phenylamino)-4,5-diazafluoren (PADF-Re) were successfully synthesized with the aim to explore the effect of the geometry of Dafo on Rhenium(I) coordination, and characterized by1H NMR. Photophysical behaviors are investigated by UV–vis absorption and Fluorescence spectra. The two complexes Dafo-Re and PADF-Re show metal-to-ligand charge transfer absorptions at ca.391nm, ca.394 nm and emissions at ca.492nm, ca.470nm, respectively.

scholarly journals Conjugated Polymer Donor-Molecular Acceptor Nanohybrids for Photocatalytic Hydrogen Evolution

2019 ◽  
Author(s):  
Haofan Yang ◽  
Xiaobo Li ◽  
Reiner Sebastian Sprick ◽  
Andrew I. Cooper
Keyword(s):  
Photocatalytic Activity ◽  
Charge Transfer ◽  
Conjugated Polymers ◽  
Hydrogen Evolution ◽  
Conjugated Polymer ◽  
Apparent Quantum Yield ◽  
High Hydrogen ◽  
Photocatalytic Hydrogen Evolution ◽  
Efficient Charge ◽  
Donor Acceptor

A library of 237 organic binary/ternary nanohybrids consisting of conjugated polymers donors and both fullerene and non-fullerene molecular acceptors was prepared and screened for sacrificial photocatalytic hydrogen evolution. These donor-acceptor nanohybrids (DANHs) showed significantly enhanced hydrogen evolution rates compared with the parent donor or acceptor compounds. DANHs of <a></a><a>a polycarbazole</a>-based donor combined with a methanofullerene acceptor (PCDTBT/PC<sub>60</sub>BM) showed a high hydrogen evolution rate of 105.2 mmol g<sup>-1</sup> h<sup>-1</sup> under visible light (λ > 420 nm). This DANH photocatalyst produced 5.9 times more hydrogen than a sulfone-containing polymer (P10) under the same conditions, which is one of the most efficient organic photocatalysts reported so far. An apparent quantum yield of hydrogen evolution of 3.0 % at 595 nm was measured for this DANH. The photocatalytic activity of the DANHs, which in optimized cases reached 179.0 mmol g<sup>-1</sup> h<sup>-1</sup>, is attributed to efficient charge transfer at the polymer donor/molecular acceptor interface. We also show that ternary donor<sub>A</sub>-donor<sub>B</sub>-acceptor nanohybrids can give higher activities than binary donor-acceptor hybrids in some cases.

scholarly journals Towards Iron(II) Complexes with Octahedral Geometry: Synthesis, Structure and Photophysical Properties

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5991
Author(s):  
Mohamed Darari ◽  
Antonio Francés-Monerris ◽  
Bogdan Marekha ◽  
Abdelatif Doudouh ◽  
Emmanuel Wenger ◽  
...  
Keyword(s):  
Excited States ◽  
Photophysical Properties ◽  
Octahedral Geometry ◽  
Ligand Field ◽  
Unexpected Result ◽  
Quintet State ◽  
Dft Modeling ◽  
Ligand Charge Transfer ◽  
Td Dft ◽  
Polypyridine Complexes

The control of ligand-field splitting in iron (II) complexes is critical to slow down the metal-to-ligand charge transfer (MLCT)-excited states deactivation pathways. The gap between the metal-centered states is maximal when the coordination sphere of the complex approaches an ideal octahedral geometry. Two new iron(II) complexes (C1 and C2), prepared from pyridylNHC and pyridylquinoline type ligands, respectively, have a near-perfect octahedral coordination of the metal. The photophysics of the complexes have been further investigated by means of ultrafast spectroscopy and TD-DFT modeling. For C1, it is shown that—despite the geometrical improvement—the excited state deactivation is faster than for the parent pseudo-octahedral C0 complex. This unexpected result is due to the increased ligand flexibility in C1 that lowers the energetic barrier for the relaxation of 3MLCT into the 3MC state. For C2, the effect of the increased ligand field is not strong enough to close the prominent deactivation channel into the metal-centered quintet state, as for other Fe-polypyridine complexes.

A density functional theory and spectroscopic study of intramolecular quenching of metal-to-ligand charge-transfer excited states in some mono-bipyridine ruthenium(II) complexes

2014 ◽  
Vol 92 (10) ◽  
pp. 996-1009 ◽  
Author(s):  
Shivnath Mazumder ◽  
Ryan A. Thomas ◽  
Richard L. Lord ◽  
H. Bernhard Schlegel ◽  
John F. Endicott
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Charge Transfer ◽  
Excited States ◽  
Lower Energy ◽  
Density Functional ◽  
Dimethyl Sulfide ◽  
Intramolecular Electron Transfer ◽  
Functional Theory ◽  
Ligand Charge Transfer

The complexes [Ru(NCCH3)4bpy]2+ and [Ru([14]aneS4)bpy]2+ ([14]aneS4 = 1,4,8,11-tetrathiacyclotetradecane, bpy = 2,2′-bipyridine) have similar absorption and emission spectra but the 77 K metal-to-ligand charge-transfer (MLCT) excited state emission lifetime of the latter is less than 0.3% that of the former. Density functional theory modeling of the lowest energy triplet excited states indicates that triplet metal centered (3MC) excited states are about 3500 cm−1 lower in energy than their 3MLCT excited states in both complexes. The differences in excited state lifetimes arise from a much larger coordination sphere distortion for [Ru(NCCH3)4bpy]2+ and the associated larger reorganizational barrier for intramolecular electron transfer. The smaller ruthenium ligand distortions of the [Ru([14]aneS4)bpy]2+ complex are apparently a consequence of stereochemical constraints imposed by the macrocyclic [14]aneS4 ligand, and the 3MC excited state calculated for the unconstrained [Ru(S(CH3)2)4bpy]2+ complex (S(CH3)2 = dimethyl sulfide) is distorted in a manner similar to that of [Ru(NCCH3)4bpy]2+. Despite the lower energy calculated for its 3MC than 3MLCT excited state, [Ru(NCCH3)4bpy]2+ emits strongly in 77 K glasses with an emission quantum yield of 0.47. The emission is biphasic with about a 1 μs lifetime for its dominant (86%) emission component. The 405 nm excitation used in these studies results in a significant amount of photodecomposition in the 77 K glasses. This is a temperature-dependent biphotonic process that most likely involves the bipyridine-radical anionic moiety of the 3MLCT excited state. A smaller than expected value found for the radiative rate constant is consistent with a lower energy 3MC than 3MLCT state.

Conjugated Polymers Containing Pendant Terpyridine Complexes as Photoactive Sensors

1997 ◽  
Vol 488 ◽  
Author(s):  
Biwang Jiang ◽  
Shailesh Sahay ◽  
Wayne E. Jones
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Conjugated Polymers ◽  
Conjugated Polymer ◽  
Polymer System ◽  
High Sensitivity ◽  
Transition Metal Ions ◽  
Ligand Charge Transfer ◽  
Mlct State ◽  
Trapping Sites

AbstractWe have synthesized a novel conjugated polymer containing terpyridine receptors. This conjugated, polymer-based fluorescent chemosensory system exhibits unusually high sensitivity toward transition metal ions (∼-10−9 M). The fluorescence quenching response of the terpyridine containing conjugated polymer to transition metal ions is related to a facile energy migration in which energy from absorption of a photon, can migrate through the conjugated polymer system and be quenched by trapping sites. Terpyridine receptors can readily bind to transition metal ions and create a low lying Metal to Ligand Charge Transfer (MLCT) state which can act as an excitation trap.

Ultrafast excited state dynamics of [Cr(CO)4(bpy)]: revealing the relaxation between triplet charge-transfer states

RSC Advances ◽  
2016 ◽  
Vol 6 (25) ◽  
pp. 20507-20515 ◽  
Author(s):  
Fei Ma ◽  
Martin Jarenmark ◽  
Svante Hedström ◽  
Petter Persson ◽  
Ebbe Nordlander ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Absorption Spectroscopy ◽  
Dft Calculation ◽  
Pump Probe ◽  
Excited State Dynamics ◽  
Mlct Transition ◽  
Ligand Charge Transfer ◽  
Probe Absorption

Ultrafast excited state dynamics of [Cr(CO)4(bpy)] upon metal-to-ligand charge-transfer (1MLCT) transition have been studied by pump-probe absorption spectroscopy and DFT calculation.

scholarly journals Sensitization of ultra-long-range excited-state electron transfer by energy transfer in a polymerized film

2012 ◽  
Vol 109 (38) ◽  
pp. 15132-15135 ◽  
Author(s):  
Akitaka Ito ◽  
David J. Stewart ◽  
Zhen Fang ◽  
M. Kyle Brennaman ◽  
Thomas J. Meyer
Keyword(s):  
Electron Transfer ◽  
Energy Transfer ◽  
Excited State ◽  
Charge Transfer ◽  
Long Range ◽  
Methyl Viologen ◽  
Polymer Network ◽  
Triplet Energy ◽  
Ligand Charge Transfer ◽  
Triplet Energy Transfer

Distance-dependent energy transfer occurs from the Metal-to-Ligand Charge Transfer (MLCT) excited state to an anthracene-acrylate derivative (Acr-An) incorporated into the polymer network of a semirigid poly(ethyleneglycol)dimethacrylate monolith. Following excitation, to Acr-An triplet energy transfer occurs followed by long-range, Acr-3An—Acr-An → Acr-An—Acr-3An, energy migration. With methyl viologen dication (MV2+) added as a trap, Acr-3An + MV2+ → Acr-An+ + MV+ electron transfer results in sensitized electron transfer quenching over a distance of approximately 90 Å.

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