An Isolated Molecule of Iron(II) Phthalocyanin Exhibits Quintet Ground-State: A Nexus between Theory and Experiment

0494028 - ÚOCHB 2019 RIV DE eng J - Journal Article
Nachtigallová, Dana - Antalík, Andrej - Lo, Rabindranath - Sedlák, Robert - Manna, Debashree - Tuček, J. - Ugolotti, J. - Veis, Libor - Legeza, Ö. - Pittner, Jiří - Zbořil, R. - Hobza, Pavel
An Isolated Molecule of Iron(II) Phthalocyanin Exhibits Quintet Ground-State: A Nexus between Theory and Experiment.
Chemistry - A European Journal. Roč. 24, č. 51 (2018), s. 13413-13417. ISSN 0947-6539. E-ISSN 1521-3765
R&D Projects: GA MŠMT(CZ) LM2015073; GA ČR(CZ) GA16-16959S; GA ČR GA16-12052S; GA ČR(CZ) GJ18-18940Y; GA ČR(CZ) GA18-24563S
Institutional support: RVO:61388963 ; RVO:61388955
Keywords : density functional calculations * iron * magnetism * Mössbauer spectroscopy * SQUID measurements
OECD category: Physical chemistry; Physical chemistry (UFCH-W)
Impact factor: 5.160, year: 2018

Iron(II) phthalocyanine (FePc) is an important member of the phthalocyanines family with potential applications in the fields of electrocatalysis, magnetic switching, electrochemical sensing, and phototheranostics. Despite the importance of electronic properties of FePc in these applications, a reliable determination of its ground-state is still challenging. Here we present combined state of the art computational methods and experimental approaches, that is, Mossbauer spectroscopy and Superconducting Quantum Interference Device (SQUID) magnetic measurements to identify the ground state of FePc. While the nature of the ground state obtained with density functional theory (DFT) depends on the functional, giving mostly the triplet state, multi-reference complete active space second-order perturbation theory (CASPT2) and density matrix renormalization group (DMRG) methods assign quintet as the FePc ground-state in gas-phase. This has been confirmed by the hyperfine parameters obtained from Fe-57 Mossbauer spectroscopy performed in frozen monochlorobenzene. The use of monochlorobenzene guarantees an isolated nature of the FePc as indicated by a zero Weiss temperature. The results open doors for exploring the ground state of other metal porphyrin molecules and their controlled spin transitions via external stimuli.
Permanent Link: http://hdl.handle.net/11104/0287272