title: Understanding the quenching effects of aromatic C-H- and C-D-oscillators in near-IR lanthanoid luminescence.
abstract: Several series of selectively deuterated 2,2'-bipyridine-based cryptates with the near-IR emissive lanthanoids Pr, Nd, Er, and Yb are reported. The structural and luminescence properties of these complexes have been comprehensively investigated. A combination of experimental techniques (X-ray crystallography, lanthanoid-induced NMR shift analysis, luminescence, vibrational near-IR absorption) and theoretical concepts has been applied with a focus on nonradiative deactivation through multiphonon relaxation of lanthanoid excited states by aromatic, high-energy C-(H/D) oscillators. It is shown that the characteristics for the overtones of these vibrational modes deviate substantially from harmonic oscillators and that anharmonicity within a local-mode Morse model is an essential parameter for any accurate description. The spectral overlap integrals (SOIs) of lanthanoid electronic states with aromatic C-(H/D) overtones are evaluated quantitatively for different lanthanoid/oscillator combinations and the implications for luminescence enhancement through deuteration is discussed. Simple Gaussian functions are proposed as appropriate mathematical forms for the empirical approximation of SOIs.
authors.affiliation: Inorganic Chemistry I, Department of Chemistry and Biochemistry, Ruhr-University Bochum, 44780 Bochum, Germany.
authors.forename: Christine
authors.initials: C
authors.lastname: Doffek
authors.forename: Nicola
authors.initials: N
authors.lastname: Alzakhem
authors.forename: Caroline
authors.initials: C
authors.lastname: Bischof
authors.forename: Jessica
authors.initials: J
authors.lastname: Wahsner
authors.forename: Tuba
authors.initials: T
authors.lastname: Güden-Silber
authors.forename: Joachim
authors.initials: J
authors.lastname: Lügger
authors.forename: Carlos
authors.initials: C
authors.lastname: Platas-Iglesias
authors.forename: Michael
authors.initials: M
authors.lastname: Seitz