skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Manipulating charge transfer excited state relaxation and spin crossover in iron coordination complexes with ligand substitution

Journal Article · · Chemical Science
DOI:https://doi.org/10.1039/C6SC03070J· OSTI ID:1335920
 [1];  [2];  [1];  [1];  [1];  [3];  [4];  [5];  [3];  [5];  [6];  [1];  [1];  [3];  [7];  [3];  [1];  [5];  [1];  [1] more »;  [7];  [1];  [1];  [3];  [3];  [1] « less
  1. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  2. SLAC National Accelerator Lab., Menlo Park, CA (United States); Lund Univ., Lund (Sweden); Technical Univ. of Denmark, Lyngby (Denmark)
  3. Lund Univ., Lund (Sweden)
  4. Stanford Univ., Stanford, CA (United States)
  5. SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States)
  6. Max Planck Institute for Biophysical Chemistry, Gottingen (Germany)
  7. Technical Univ. of Denmark, Lyngby (Denmark)
+ Show Author Affiliations

Developing light-harvesting and photocatalytic molecules made with iron could provide a cost effective, scalable, and environmentally benign path for solar energy conversion. To date these developments have been limited by the sub-picosecond metal-to-ligand charge transfer (MLCT) electronic excited state lifetime of iron based complexes due to spin crossover – the extremely fast intersystem crossing and internal conversion to high spin metal-centered excited states. We revitalize a 30 year old synthetic strategy for extending the MLCT excited state lifetimes of iron complexes by making mixed ligand iron complexes with four cyanide (CN–) ligands and one 2,2'-bipyridine (bpy) ligand. This enables MLCT excited state and metal-centered excited state energies to be manipulated with partial independence and provides a path to suppressing spin crossover. We have combined X-ray Free-Electron Laser (XFEL) Kβ hard X-ray fluorescence spectroscopy with femtosecond time-resolved UV-visible absorption spectroscopy to characterize the electronic excited state dynamics initiated by MLCT excitation of [Fe(CN)4(bpy)]2–. The two experimental techniques are highly complementary; the time-resolved UV-visible measurement probes allowed electronic transitions between valence states making it sensitive to ligand-centered electronic states such as MLCT states, whereas the Kβ fluorescence spectroscopy provides a sensitive measure of changes in the Fe spin state characteristic of metal-centered excited states. Here, we conclude that the MLCT excited state of [Fe(CN)4(bpy)]2– decays with roughly a 20 ps lifetime without undergoing spin crossover, exceeding the MLCT excited state lifetime of [Fe(2,2'-bipyridine)3]2+ by more than two orders of magnitude.

Research Organization:
SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
AC02-76SF00515; CHE-0948211; 226136-VISCHEM; KR3611/2-1
OSTI ID:
1335920
Journal Information:
Chemical Science, Journal Name: Chemical Science; ISSN 2041-6520
Publisher:
Royal Society of ChemistryCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 85 works
Citation information provided by
Web of Science

References (57)

A Heteroleptic Ferrous Complex with Mesoionic Bis(1,2,3-triazol-5-ylidene) Ligands: Taming the MLCT Excited State of Iron(II) journal December 2014
Femtosecond X-ray Absorption Spectroscopy at a Hard X-ray Free Electron Laser: Application to Spin Crossover Dynamics journal January 2013
Probing the 3d Spin Momentum with X-ray Emission Spectroscopy:  The Case of Molecular-Spin Transitions journal June 2006
Lifetimes, spectra, and quenching of the excited states of polypyridine complexes of iron(II), ruthenium(II), and osmium(II) journal February 1980
Study of the Light-Induced Spin Crossover Process of the [Fe II (bpy) 3 ] 2+ Complex journal April 2010
Fe(II)-Polypyridines as Chromophores in Dye-Sensitized Solar Cells: A Computational Perspective journal April 2015
Femtosecond XANES Study of the Light-Induced Spin Crossover Dynamics in an Iron(II) Complex journal January 2009
Picosecond X-ray Absorption Spectroscopy of a Photoinduced Iron(II) Spin Crossover Reaction in Solution journal January 2006
On the interplay between charge, spin and structural dynamics in transition metal complexes journal January 2012
Tracking excited-state charge and spin dynamics in iron coordination complexes journal May 2014
New Photosensitizers Based upon [Fe(L) 2 (CN) 2 ] and [Fe(L) 3 ] (L = Substituted 2,2‘-Bipyridine):  Yields for the Photosensitization of TiO 2 and Effects on the Band Selectivity journal April 2000
Iron sensitizer converts light to electrons with 92% yield journal October 2015
High resolution 1s core hole X-ray spectroscopy in 3d transition metal complexes—electronic and structural information journal January 2005
[8] Singular value decomposition: Application to analysis of experimental data book January 1992
Guest–Host Interactions Investigated by Time-Resolved X-ray Spectroscopies and Scattering at MHz Rates: Solvation Dynamics and Photoinduced Spin Transition in Aqueous Fe(bipy) 3 2+ journal October 2012
Spin-state studies with XES and RIXS: From static to ultrafast journal June 2013
Dual Pathways for TiO 2 Sensitization by Na 2 [Fe(bpy)(CN) 4 ] journal August 2000
Photo-Induced Spin-State Conversion in Solvated Transition Metal Complexes Probed via Time-Resolved Soft X-ray Spectroscopy journal May 2010
Femtosecond Excited-State Dynamics of an Iron(II) Polypyridyl Solar Cell Sensitizer Model journal May 2000
Femtosecond Soft X-ray Spectroscopy of Solvated Transition-Metal Complexes: Deciphering the Interplay of Electronic and Structural Dynamics journal March 2011
Ultrafast Electron Transfer Dynamics from Molecular Adsorbates to Semiconductor Nanocrystalline Thin Films journal May 2001
Solvent tuning of the excited-state properties of (2,2'-bipyridine)tetracyanoferrate(II): direct observation of a metal-to-ligand charge-transfer excited state of iron(II) journal May 1987
High-Resolution X-ray Emission and X-ray Absorption Spectroscopy journal June 2001
Spectroscopic studies of preferential and asymmetric solvation in substituted cyanoiron(II) complexes journal August 1983
Towards longer-lived metal-to-ligand charge transfer states of iron(ii) complexes: an N-heterocyclic carbene approach journal January 2013
Hydrogen Produced from Hydrohalic Acid Solutions by a Two-Electron Mixed-Valence Photocatalyst journal August 2001
Femtosecond Time-Resolved Optical and Raman Spectroscopy of Photoinduced Spin Crossover: Temporal Resolution of Low-to-High Spin Optical Switching journal October 2008
Light-induced spin crossover in Fe(II)-based complexes: The full photocycle unraveled by ultrafast optical and X-ray spectroscopies journal November 2010
Homogeneous catalysis of the photoreduction of water by visible light. Mediation by a tris(2,2'-bipyridine)ruthenium(II)-cobalt(II) macrocycle system journal February 1979
Ultrafast Nonadiabatic Dynamics of [Fe II (bpy) 3 ] 2+ in Solution journal July 2007
Molecular and Interfacial Calculations of Iron(II) Light Harvesters journal March 2016
Influence of Solvent on the Spectroscopic Properties of Cyano Complexes of Ruthenium(II) journal January 1996
Probing Valence Orbital Composition with Iron Kβ X-ray Emission Spectroscopy journal July 2010
A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films journal October 1991
Spectroelectrochemical identification of charge-transfer excited states in transition metal-based polypyridyl complexes journal January 2014
Vibrational Coherences and Relaxation in the High-Spin State of Aqueous [Fe II (bpy) 3 ] 2+   journal September 2009
Lifetimes and spectra of the excited states of cis-dicyanobis(2,2'-bipyridine)iron(II) and -ruthenium(II) in solution journal January 1987
Subpicosecond 1MLCT .fwdarw. 5T2 intersystem crossing of low-spin polypyridyl ferrous complexes journal January 1993
Photosensitization of TiO 2 by [Fe II (2,2‘-bipyridine-4,4‘-dicarboxylic acid) 2 (CN) 2 ]:  Band Selective Electron Injection from Ultra-Short-Lived Excited States journal February 1998
Exceptional Excited-State Lifetime of an Iron(II)– N -Heterocyclic Carbene Complex Explained journal May 2014
Kβ Mainline X-ray Emission Spectroscopy as an Experimental Probe of Metal–Ligand Covalency
  • Pollock, Christopher J.; Delgado-Jaime, Mario Ulises; Atanasov, Mihail
  • Journal of the American Chemical Society, Vol. 136, Issue 26 https://doi.org/10.1021/ja504182n
journal June 2014
Atomic-Scale Perspective of Ultrafast Charge Transfer at a Dye–Semiconductor Interface journal July 2014
Sub-50-fs photoinduced spin crossover in [Fe(bpy)3]2+ journal July 2015
On the role of the metal-to-ligand charge transfer states in the light-induced spin crossover in FeII (bpy)3 journal February 2011
Ultrafast Deactivation Mechanism of the Excited Singlet in the Light-Induced Spin Crossover of [Fe(2,2′-bipyridine) 3 ] 2+ journal November 2013
Intersystem crossing in the [Fe(ptz) 6 ](BF 4 ) 2 spin crossover system (ptz=1‐propyltetrazole) journal February 1991
The X-ray Pump–Probe instrument at the Linac Coherent Light Source journal April 2015
Theoretical Investigation of the Electronic Structure of Fe(II) Complexes at Spin-State Transitions journal December 2012
Picosecond Time-Resolved X-Ray Emission Spectroscopy: Ultrafast Spin-State Determination in an Iron Complex journal July 2010
Photoinduced Magnetization of a Cobalt-Iron Cyanide journal May 1996
An Iron-Based Photosensitizer with Extended Excited-State Lifetime: Photophysical and Photovoltaic Properties: An Iron-Based Photosensitizer with Extended Excited-State Lifetime journal April 2015
Direct Probing of Spin State Dynamics Coupled with Electronic and Structural Modifications by Picosecond Time-Resolved XAFS journal January 2010
Charge-Transfer Studies of Iron Cyano Compounds Bound to Nanocrystalline TiO 2 Surfaces journal March 2002
Solar Chemistry of Metal Complexes journal December 1981
Picosecond Time-Resolved X-Ray Emission Spectroscopy: Ultrafast Spin-State Determination in an Iron Complex journal July 2010
Vibrational Coherences and Relaxation in the High-Spin State of Aqueous [Fe II (bpy) 3 ] 2+   journal September 2009
Molecular and Interfacial Calculations of Iron(II) Light Harvesters journal March 2016

Cited By (20)

Kovalenzgetriebene Erhaltung lokaler Ladungsdichten in einem durch Metall‐Ligand‐Ladungstransfer angeregten Eisenphotosensibilisator journal July 2019
Hot Branching Dynamics in a Light‐Harvesting Iron Carbene Complex Revealed by Ultrafast X‐ray Emission Spectroscopy journal October 2019
Covalency-Driven Preservation of Local Charge Densities in a Metal-to-Ligand Charge-Transfer Excited Iron Photosensitizer journal July 2019
Hot Branching Dynamics in a Light‐Harvesting Iron Carbene Complex Revealed by Ultrafast X‐ray Emission Spectroscopy journal January 2020
Boosting Vis/NIR Charge-Transfer Absorptions of Iron(II) Complexes by N-Alkylation and N-Deprotonation in the Ligand Backbone journal May 2017
Toward Luminescent Iron Complexes: Unravelling the Photophysics by Computing Potential Energy Surfaces journal May 2019
UV-vis absorption spectra of Sn(IV)tetrakis(4-pyridyl) porphyrins on the basis of axial ligation and pyridine protonation journal September 2019
Recent advances in structure design for enhancing photocatalysis journal February 2019
Core-level nonlinear spectroscopy triggered by stochastic X-ray pulses journal October 2019
Designing air-stable cyclometalated Fe( ii ) complexes: stabilization via electrostatic effects journal January 2019
Theoretical study on the excited state decay properties of iron( ii ) polypyridine complexes substituted by bromine and chlorine journal January 2019
Ligand manipulation of charge transfer excited state relaxation and spin crossover in [Fe(2,2′-bipyridine) 2 (CN) 2 ] journal July 2017
Elucidation of the photoaquation reaction mechanism in ferrous hexacyanide using synchrotron x-rays with sub-pulse-duration sensitivity journal October 2019
Chemical interactions and dynamics with femtosecond X-ray spectroscopy and the role of X-ray free-electron lasers journal April 2019
Scientific instrument Femtosecond X-ray Experiments (FXE): instrumentation and baseline experimental capabilities journal August 2019
Improving the Light-Induced Spin Transition Efficiency in Ni(II)-Based Macrocyclic-Ligand Complexes journal November 2019
Fingerprints of electronic, spin and structural dynamics from resonant inelastic soft X-ray scattering in transient photo-chemical species text January 2019
Chemical interactions and dynamics with femtosecond X-ray spectroscopy and the role of X-ray free-electron lasers text January 2019
Hot Branching Dynamics in a Light‐Harvesting Iron Carbene Complex Revealed by Ultrafast X‐ray Emission Spectroscopy text January 2020
Covalency-Driven Preservation of Local Charge Densities in a Metal-to-Ligand Charge-Transfer Excited Iron Photosensitizer other January 2019

Similar Records

Ligand manipulation of charge transfer excited state relaxation and spin crossover in [Fe(2,2'-bipyridine)2(CN)2]
Journal Article · Thu Jul 06 00:00:00 EDT 2017 · Structural Dynamics · OSTI ID:1335920
+21 more
Solvent control of charge transfer excited state relaxation pathways in [Fe(2,2'-bipyridine)(CN)4]2-
Journal Article · Fri Jan 19 00:00:00 EST 2018 · Physical Chemistry Chemical Physics. PCCP · OSTI ID:1335920
+34 more
Chemical control of competing electron transfer pathways in iron tetracyano-polypyridyl photosensitizers
Journal Article · Thu Apr 16 00:00:00 EDT 2020 · Chemical Science · OSTI ID:1335920
+15 more

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY