A Synthetically Tunable System To Control MLCT Excited-State Lifetimes and Spin States in Iron(II) Polypyridines
| Autor: | Robert F. Higgins, Matthew P. Shores, Steven M. Fatur, Samuel G. Shepard, Niels H. Damrauer |
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| Rok vydání: | 2017 |
| Předmět: |
Spin states
010405 organic chemistry Chemistry Relaxation (NMR) General Chemistry 010402 general chemistry Photochemistry 01 natural sciences Biochemistry Catalysis 0104 chemical sciences Colloid and Surface Chemistry Spin crossover Excited state Intramolecular force Physical chemistry Singlet state Ground state Excitation |
| Zdroj: | Journal of the American Chemical Society. 139(12) |
| ISSN: | 1520-5126 |
| Popis: | 2,2′:6′,2″-Terpyridyl (tpy) ligands modified by fluorine (dftpy), chlorine (dctpy), or bromine (dbtpy) substitution at the 6- and 6″-positions are used to synthesize a series of bis-homoleptic Fe(II) complexes. Two of these species, [Fe(dctpy)2]2+ and [Fe(dbtpy)2]2+, which incorporate the larger dctpy and dbtpy ligands, assume a high-spin quintet ground state due to substituent-induced intramolecular strain. The smaller fluorine atoms in [Fe(dftpy)2]2+ enable spin crossover with a T1/2 of 220 K and a mixture of low-spin (singlet) and high-spin (quintet) populations at room temperature. Taking advantage of this equilibrium, dynamics originating from either the singlet or quintet manifold can be explored using variable wavelength laser excitation. Pumping at 530 nm leads to ultrafast nonradiative relaxation from the singlet metal-to-ligand charge transfer (1MLCT) excited state into a quintet metal centered state (5MC) as has been observed for prototypical low-spin Fe(II) polypyridine complexes such as [Fe(t... |
| Databáze: | OpenAIRE |
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