Exploring the Promotion of Synthons of Choice: Halogen Bonding in Molecular Lanthanide Complexes Characterized via X-ray Diffraction, Luminescence Spectroscopy, and Magnetic Measurements
Promotion of a synthon of choice for the non-covalent assembly of lanthanide tectons represents both a noteworthy challenge and opportunity within Ln(III) hybrid materials. We have developed a system wherein some control can be exercised over supramolecular assembly and, as part of continued efforts to improve this process we have generated a family of ten new lanthanide (Ln = Sm 3+ -Lu 3+ )-2,4,6-trichlorobenzoic acid-1,10- phenanthroline molecular complexes. Delineation of criteria for promoting assembly via halogen based interactions was introduced previously and is refined herein based on the characterization of complexes 1-10 via single crystal X-ray diffraction. Direct comparison of means of supramolecular assembly for 1-10 with isostructural Ln-pchlorobenzoic acid-1,10-phenathroline analogues verifies that increasing the number of halogens at the periphery of a tecton is one route that increases the frequency of halogen bonding interactions. Additionally, solid-state visible and near-IR photoluminescence and luminescent lifetime data were collected for complexes 1 (Sm 3+ ), 2 (Eu 3+ ), 4 (Tb 3+ ), 5 (Dy 3+ ), 6 (Ho 3+ ), 7 (Er 3+ ), and 9 (Yb 3+ ) and characteristic emission was observed for all complexes except 6. Further, direct current magnetic susceptibility measurements were carried out for complexes 5 (Dy 3+ ) and 7 (Er 3+ ), and two slow magnetic relaxation processes were characterized using alternating current magnetic susceptibility measurements for 5.