In this study, we will be presenting LUMPAC (LUMinescence PACkage), which was developed with the objective of making possible the theoretical study of lanthanide-based luminescent systems. This is the first software that allows the study of luminescent properties of lanthanide-based systems. Besides being a computationally efficient software, LUMPAC is user friendly and can be used by researchers who have no previous experience in theoretical chemistry. With this new tool, we hope to enable research groups to use theoretical tools on projects involving systems that contain lanthanide ions.

In this work, we report a theoretical and experimental investigation of the energy transfer mechanism in two isotypical 2D coordination polymers, ∞ [(Tb 1−x Eu x )(DPA)(HDPA)], where H 2 DPA is pyridine 2,6-dicarboxylic acid and x = 0.05 or 0.50. Emission spectra of ∞ [(Tb 0.95 Eu 0.05 )(DPA)(HDPA)] and ∞ [(Tb 0.5 Eu 0.5 )(DPA)-(HDPA)], (1) and (2), show that the high quenching effect on Tb 3+ emission caused by Eu 3+ ion indicates an efficient Tb 3+ →Eu 3+ energy transfer (ET). The k ET of Tb 3+ → Eu 3+ ET and rise rates (k r ) of Eu 3+ as a function of temperature for (1) are on the same order of magnitude, indicating that the sensitization of the Eu 3+ 5 D 0 level is highly fed by ET from the 5 D 4 level of Tb 3+ ion. The η ET and R 0 values vary in the 67− 79% and 7.15 to 7.93 Å ranges. Hence, Tb 3+ is enabled to transfer efficiently to Eu 3+ that can occupy the possible sites at 6.32 and 6.75 Å. For (2), the ET processes occur on average with η ET and R 0 of 97% and 31 Å, respectively. Consequently, Tb 3+ ion is enabled to transfer energy to Eu 3+ localized at different layers. The theoretical model developed by Malta was implemented aiming to insert more insights about the dominant mechanisms involved in the ET between lanthanides ions. Calculated single Tb 3+ → Eu 3+ ETs are three orders of magnitude inferior to those experimentally; however, it can be explained by the theoretical model that does not consider the role of phonon assistance in the Ln 3+ → Ln 3+ ET processes. In addition, the Tb 3+ → Eu 3+ ET processes are predominantly governed by dipole−dipole (d−d) and dipole−quadrupole (d−q) mechanisms.

The recently published Parametric Method number 7, PM7, is the first semiempirical method to be successfully tested by modeling crystal structures and heats of formation of solids. PM7 is thus also capable of producing results of useful accuracy for materials science, and constitutes a great improvement over its predecessor, PM6. In this article, we present Sparkle Model parameters to be used with PM7 that allow the prediction of geometries of metal complexes and materials which contain lanthanide trications. Accordingly, we considered the geometries of 224 high-quality crystallographic structures of complexes for the parameterization set and 395 more for the validation of the parameterization for the whole lanthanide series, from La(III) to Lu(III). The average unsigned error for Sparkle/PM7 for the distances between the metal ion and its coordinating atoms is 0.063Å for all lanthanides, ranging from a minimum of 0.052Å for Tb(III) to 0.088Å for Ce(III), comparable to the equivalent errors in the distances predicted by PM7 for other metals. These distance deviations follow a gamma distribution within a 95% level of confidence, signifying that they appear to be random around a mean, confirming that Sparkle/PM7 is a well-tempered method. We conclude by carrying out a Sparkle/PM7 full geometry optimization of two spatial groups of the same thulium-containing metal organic framework, with unit cells accommodating 376 atoms, of which 16 are Tm(III) cations; the optimized geometries were in good agreement with the crystallographic ones. These results emphasize the capability of the use of the Sparkle Model for the prediction of geometries of compounds containing lanthanide trications within the PM7 semiempirical model, as well as the usefulness of such semiempirical calculations for materials modeling. Sparkle/PM7 is available in the software package MOPAC2012, at no cost for academics and can be obtained from http://openmopac.net.

In this article, we present Sparkle Model parameters to be used with RM1, presently one of the most accurate and widely used semiempirical molecular orbital models based exclusively on monoatomic parameters, for systems containing H, C, N, O, P, S, F, Cl, Br, and I. Accordingly, we used the geometries of 169 high quality crystallographic structures of complexes for the training set, and 435 more for the validation of the parameterization for the whole lanthanide series, from La(III) to Lu(III). The distance deviations appear to be random around a mean for all lanthanides. The average unsigned error for Sparkle/RM1 for the distances between the metal ion and its coordinating atoms is 0.065 Å for all lanthanides, ranging from a minimum of 0.056 Å for Pm(III) to 0.074 Å for Ce(III), making Sparkle/RM1 a balanced method across the lanthanide series. Moreover, a detailed analysis of all results indicates that Sparkle/RM1 is particularly accurate in the prediction of lanthanide cation-coordinating atom distances, making it a suitable method for the design of luminescent lanthanide complexes. We illustrate the potential of Sparkle/RM1 by carrying out a Sparkle/RM1 full geometry optimization of a tetramer complex of europium with 181 atoms. Sparkle/RM1 may be used for the prediction of geometries of large complexes, metal-organic frameworks, etc., to useful accuracy.

[Eu(btfa)3DPEPO] and [Eu(nta)3DPEPO] are bright, red emitting complexes. They have been incorporated into single and double emitting layer electroluminescent devices.