Universität zu Köln

Eskelinen, Toni, Buss, Stefan, Petrovskii, Stanislav K., Grachova, Elena, V, Krause, Maren, Kletsch, Lukas, Klein, Axel, Strassert, Cristian A., Koshevoy, Igor O. and Hirva, Pipsa (2021). Photophysics and Excited State Dynamics of Cyclometalated [M(Phbpy)(CN)] (M = Ni, Pd, Pt) Complexes: A Theoretical and Experimental Study. Inorg. Chem., 60 (12). S. 8777 - 8790. WASHINGTON: AMER CHEMICAL SOC. ISSN 1520-510X

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Abstract

Cyclometalated complexes [M(Phbpy)(CN)] (HPhbpy = 6-phenyl-2,2'-bipyridine) of the group 10 metals (Ni, Pd, and Pt) bearing a carbanionic C-<^>N<^>N pincer ligand were synthesized and studied in a combined experimental and computational DFT approach. All three complexes were crystallographically characterized showing closely packed dimers with head-to-tail stacking and short metal-metal contacts in the solid state. The computational models for geometries, excited states, and electronic transitions addressed both monomeric (Ni-mono, Pd-mono, and Pt-mono) and dimeric (Ni-dim, Pd-dim, and Pt-dim) entities. Photophysical properties and excited state dynamics of all title complexes were investigated in solution and in the solid at 298 and 77 K. [Ni(Phbpy)(CN)] and [Pd(Phbpy)(CN)] are virtually nonemissive in solution at 298 K, whereas [Pt(Phbpy)(CN)] shows phosphorescence in CH2Cl2 (DCM) solution (lambda(em) = 562 nm) stemming from a mixed (MLCT)-M-3/ILCT (metal-to-ligand charge transfer/intraligand charge transfer) state. At 77 K in a glassy frozen DCM:MeOH matrix, [Pd(Phbpy)(CN)] shows a remarkable emission (lambda(em) = 571 nm) with a photoluminescence quantum yield reaching almost unity, whereas [Ni(Phbpy)(CN)] is again nonemissive. Calculations on the monomeric models M-mono show that low-lying metal-centered states (MC, i.e., d-d* configuration) with dissociative character quench the photoluminescence. In the solid state, the complexes [M(Phbpy)(CN)] show defined photoluminescence bands (lambda(em) = 561 nm for Pd and 701 nm for Pt). Calculations on the dimeric models M-dim shows that the axial M center dot center dot center dot M interactions alter the photophysical properties of Pd-dim and Pt-dim toward MMLCT (metal-metal-to-ligand charge transfer) excited states with Pd-dim showing temperature-dependent emission lifetimes, suggesting thermally activated delayed fluorescence, whereas Pt-dim displayed phosphorescence with excimeric character. The metal-metal interactions were analyzed in detail with the quantum theory of atoms in molecules approach.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Eskelinen, Toni UNSPECIFIED UNSPECIFIED UNSPECIFIED Buss, Stefan UNSPECIFIED UNSPECIFIED UNSPECIFIED Petrovskii, Stanislav K. UNSPECIFIED UNSPECIFIED UNSPECIFIED Grachova, Elena, V UNSPECIFIED UNSPECIFIED UNSPECIFIED Krause, Maren UNSPECIFIED UNSPECIFIED UNSPECIFIED Kletsch, Lukas UNSPECIFIED UNSPECIFIED UNSPECIFIED Klein, Axel UNSPECIFIED UNSPECIFIED UNSPECIFIED Strassert, Cristian A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Koshevoy, Igor O. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hirva, Pipsa UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-586390
DOI:	10.1021/acs.inorgchem.1c00680
Journal or Publication Title:	Inorg. Chem.
Volume:	60
Number:	12
Page Range:	S. 8777 - 8790
Date:	2021
Publisher:	AMER CHEMICAL SOC
Place of Publication:	WASHINGTON
ISSN:	1520-510X
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language METAL-COMPLEXES; MOLECULES; ENERGIES; SPECTRA; PT(II); DFT; PHOSPHORESCENCE; LUMINESCENCE; SIMULATION Multiple languages Chemistry, Inorganic & Nuclear Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/58639