Photodynamics and Luminescence of Mono‐ and Tri‐Nuclear Lanthanide Complexes in the Gas Phase and in Solution

Abstract

Lanthanide ions (Dy , Eu ) are stabilized by coordination with two Schiff base ligands in compounds [Dy{H L} ](NO )(EtOH)(H O) (1) and [Eu{H L} ](NO )(H O) (3) (H L, 2,2'-{[(2-aminoethyl)imino]bis[2,1-ethanediyl-nitriloethylidyne]}bis-2-hydroxy-benzoic acid). The latter is reported here for the first time. Both luminescence and ultrafast photodynamics after photoexcitation via a ligand absorption band (∼400 nm) have been studied. In solution, only the [Eu{H L} ] ([3] ) complex displays the typical lanthanide emission lines, whereas in gas phase both, [Dy{H L} ] ([1] ) and [3] , show their corresponding transitions depending on excitation energy. The ultrafast excited state dynamics, obtained in gas phase and in solution, are assigned to excited state intramolecular proton transfer processes in the ligands. The antenna ligand moiety of these complexes provides pockets for stabilization of two Mn ions so that we additionally investigated the photophysical behavior of the corresponding tri-nuclear (NHEt ) [Ln{MnL} ](ClO )(H O) (Ln=Dy , Eu ) compounds (2, 4). Interestingly, the related complexes do not show lanthanide emission, neither in solution nor in gas phase. Transient data in solution and gas phase suggests an efficient quenching of the ligand's electronically excited state by strong interaction with the Mn ions. This effect could possibly be developed further into a design principle for luminescence-based sensing devices for metal cations.

A new setup for low-temperature gas-phase ion fluorescence spectroscopy

“…Dispersed fluorescence spectra of many ions have been reported (see Refs. [12][13][14], and even excited-state lifetimes can be obtained from time-resolved fluorescence experiments as beautifully demonstrated by Nagy et al 15 For measurements of electronic transition energies of molecular ions in vacuo, one significant advantage of fluorescence spectroscopy is that there is no limitation on the size of the molecular ion. In contrast, a frequently encountered obstacle for photoinduced dissociation (PID) action spectroscopy is insufficient dissociation on the time scale of the experiment (microseconds to tens of milliseconds).…”

The combination of laser photodissociation, action spectroscopy, and mass spectrometry to identify and separate isomers

“…Other groups have deployed femtosecond or picosecond pump-probe laser configurations combined with photodissociation mass-spectrometry to interrogate excited-state lifetimes of ions in tandem time-of-flight mass spectrometers, [133][134][135] triple-quadrupole mass spectrometers, 136 ion storage rings, 137,138 custom built ion traps at room temperature, [139][140][141] custom built ion traps that are cryogenically cooled, 81,85,132,142 and commercial ion traps. 87,[143][144][145][146] There are also setups using electronic delays for pump-probe photodissociation on the nanosecond to millisecond timescale. 117,132,[146][147][148][149][150][151] The excited 63 This journal is © The Royal Society of Chemistry 2022 state dynamics of few gas-phase ions has been investigated experimentally or computationally, especially relative to solution-phase species.…”

Advancing Inorganic Coordination Chemistry by Spectroscopy of Isolated Molecules: Methods and Applications

“…Along the same lines: analogous investigations of isolated oligonuclear TM complexes often yield surprising results, such as for example the quenching of well characterized and understood lanthanide luminescence upon embedding into a larger scaffold together with Mn II cations. [125] Gaseous ion PD spectroscopy, often in combination with messenger tagging, has also been used extensively to study the electronic spectroscopy of various coinage metal cluster systems. An intriguing recent example of PD spectroscopy in the UV-vis spectral range was obtained for the isolated Au 2 + cation.…”

“…Along the same lines: analogous investigations of isolated oligonuclear TM complexes often yield surprising results, such as for example the quenching of well characterized and understood lanthanide luminescence upon embedding into a larger scaffold together with Mn II cations. [125] …”