Metal-to-Ligand Charge Transfer Excited States in π-Conjugated Systems

2001 ◽  
Vol 665 ◽  
Author(s):  
Yiting Li ◽  
C. Ed Whittle ◽  
Keith A. Walters ◽  
Kevin D. Ley ◽  
Kirk S. Schanze
Keyword(s):  
Optical Properties ◽  
Charge Transfer ◽  
Excited States ◽  
Transition Metal Complexes ◽  
Transient Absorption ◽  
Photophysical Properties ◽  
Transient Absorption Spectroscopy ◽  
Conjugated Oligomers ◽  
Conjugated Systems ◽  
Ligand Charge Transfer

ABSTRACTThis paper overviews recent work that examined the optical properties of mono-disperse, PPE-based π-conjugated oligomers that contain a 2,2-bipyridine-5,5'-diyl metal coordinating unit. The photophysical properties of the free oligomers and metallated oligomers that contain the -Ru(bpy)22+ and -Re(CO)3Cl transition metal complexes coordinated to the bpy-diyl unit have been characterized by absorption, photoluminescence and transient absorption spectroscopy. In addition, we report the photophysics of a novel organometallic “square” that features “sides” consisting of a PPE-type π-conjugated oligomer and “corners” that consist of (dbubpy)PtII(acetylide)2 units (where dbubpy = 4,4'-di-tert-butyl-2,2'-bipyridine).

Coherence in Metal−Metal-to-Ligand-Charge-Transfer Excited States of a Dimetallic Complex Investigated by Ultrafast Transient Absorption Anisotropy

2011 ◽  
Vol 115 (16) ◽  
pp. 3990-3996 ◽  
Author(s):  
Sung Cho ◽  
Michael W. Mara ◽  
Xianghuai Wang ◽  
Jenny V. Lockard ◽  
Aaron A. Rachford ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Excited States ◽  
Transient Absorption ◽  
Ultrafast Transient Absorption ◽  
Ligand Charge Transfer ◽  
Metal Metal

Ligand-to-ligand charge transfer in heteroleptic Ir-complexes: comprehensive investigations of its fast dynamics and mechanism

2016 ◽  
Vol 18 (22) ◽  
pp. 15162-15169 ◽  
Author(s):  
Yang-Jin Cho ◽  
So-Yoen Kim ◽  
Minji Cho ◽  
Kyung-Ryang Wee ◽  
Ho-Jin Son ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Ancillary Ligands ◽  
Femtosecond Transient Absorption ◽  
Ligand Charge Transfer ◽  
Femtosecond Transient Absorption Spectroscopy ◽  
Charge Transfer Dynamics

The ligand-to-ligand charge transfer dynamics from cyclometalating ligand to ancillary ligands was probed using femtosecond transient absorption spectroscopy after the selective excitations.

Comparative Charge Transfer Studies of Porphyrin-Fullerene Dyads: Substituents Effect

2020 ◽  
Vol 20 (6) ◽  
pp. 3437-3447 ◽  
Author(s):  
Neha Gupta ◽  
Samya Naqvi ◽  
Nikita Vasistha ◽  
Mahesh Kumar ◽  
Rachana Kumar
Keyword(s):  
Charge Transfer ◽  
Transient Absorption ◽  
Separation Efficiency ◽  
Photophysical Properties ◽  
Conductivity Measurement ◽  
Transient Absorption Spectroscopy ◽  
Electrical Conductivity Measurement ◽  
Conductivity Enhancement ◽  
Quenching Efficiency ◽  
Electron Donating Groups

The present study deals with the study of charge transfer and photophysical properties of synthesized non-metallated fullerene-porphyrin dyad-III (H2P3-C60) via Prato reaction. The porphyrin has been substituted with electron donating groups (3,5-di-tert-butylbenzene) at meso positions facilitating the effective charge transfer for the formation of long lived charge-separated states in dyad molecule. The photophysical and thermal activated conducting properties of dyad was comprehensively studied to establish the effect of substituents and also by comparing with our reported dyad II having only meso-phenyl groups. The charge separation efficiency in dyad III has been calculated in solution as well as in films showing 62% and ˜99% quenching efficiency respectively suggesting faster photoinduced charge transfer from porphyrin to fullerene moiety. Transient absorption spectroscopy (TAS) showed formation of longer lived charge separated states in solution as well as in films compared to dyad-II. The thermal activated electrical conductivity measurement of dyad-III showed conductivity enhancement on increasing temperature. The activation energy for conduction was also found lower than dyad-II suggesting a substantial effect of electron-donating groups present on porphyrin ring in conducting behavior of dyad-III. Through this study with a very simple dyad structure we established that the presence of electron donating groups in dayds, highly influence photophysical and electronic properties. This special characteristic further makes them potential material to be used in various opto-electronic applications.

scholarly journals Revealing excited states dynamics in cross-linked covalent hybrids of graphene and diketopyrrolopyrrole oligomers via ultrafast transient absorption spectroscopy

2020 ◽  
Vol 238 ◽  
pp. 07007
Author(s):  
Aaron M. Ross ◽  
Meng Zheng ◽  
Michele Maggini ◽  
Fabio Marangi ◽  
Giulio Cerullo ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Charge Transfer ◽  
Excited States ◽  
Absorption Spectroscopy ◽  
Transient Response ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Ultrafast Dynamics ◽  
Charge Energy ◽  
Ultrafast Charge Transfer

We report on ultrafast dynamics in cross-linked covalent hybrids of graphene and diketopyrrolopyrrole (TDPP) oligomers. Comparisons between non-polymerizing (EXG-TDPP) and polymerizing (c-EXG-TDPP) hybrids show that charge/energy transfer occurs faster than 50 ps in EXGTDPP, while the c-EXG-TDPP system shows quenching within 18 ps. The transient response of c-EXGTDPP is completely quenched (>99%), while in EXG-TDPP full quenching occurs after 1.39 ns. Photocurrent studies of c-EXG-TDPP films show IPCE > 2%, indicating ultrafast charge transfer between TDPP and graphene.

Synthesis and Photochemical Properties of Re(I) Tricarbonyl Complexes Bound to Thione and Thiazole-2-ylidene Ligands

2020 ◽  
Author(s):  
Matthew Stout ◽  
Brian Skelton ◽  
Alexandre N. Sobolev ◽  
Paolo Raiteri ◽  
Massimiliano Massi ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Excited States ◽  
Ligand Exchange ◽  
Ligand Substitution ◽  
Bidentate Ligand ◽  
The Other ◽  
Ligand Exchange Reaction ◽  
Multiple Products ◽  
Ligand Charge Transfer ◽  
Photochemical Properties

<p>Three Re(I) tricarbonyl complexes, with general formulation Re(N^L)(CO)<sub>3</sub>X (where N^L is a bidentate ligand containing a pyridine functionalized in the position 2 with a thione or a thiazol-2-ylidene group and X is either chloro or bromo) were synthesized and their reactivity explored in terms of solvent-dependent ligand substitution, both in the ground and excited states. When dissolved in acetonitrile, the complexes bound to the thione ligand underwent ligand exchange with the solvent resulting in the formation of Re(NCMe)<sub>2</sub>(CO)<sub>3</sub>X. The exchange was found to be reversible, and the starting complex was reformed upon removal of the solvent. On the other hand, the complexes appeared inert in dichloromethane or acetone. Conversely, the complex bound to the thiazole-2-ylidene ligand did not display any ligand exchange reaction in the dark, but underwent photoactivated ligand substitution when excited to its lowest metal-to-ligand charge transfer manifold. Photolysis of this complex in acetonitrile generated multiple products, including Re(I) tricarbonyl and dicarbonyl solvato-complexes as well as free thiazole-2-ylidene ligand.</p>

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