Halogen-Bonded Self-Assembly of Mononuclear Lanthanide (III) Complexes: Variable Temperature Photoluminescence Study and Sensing of Nitro Aromatics

Abstract

A series of lanthanide complexes, [LnL2][Et3NH]·H2O [where Ln = Dy (1), Sm (2) and Gd (3), [H2L = 2-bis (2-hydroxy-3,5-dibromo benzyl)aminomethyl]pyridine] have been synthesized and characterized through various spectroscopic techniques, including UV-Vis, infrared, mass spectroscopy, and single-crystal X-ray diffraction. The supramolecular interaction of the complexes was analysed through a computational study. The photoluminescent properties of 1 and 2 complexes have been investigated, showcasing the characteristic colourful emissions perceivable by the human visual system (yellow and orange, respectively). Correlated colour temperature study shows that 1 is almost invariant, ranging from 3400-3500 K and for 2 the values range from 7000-8000 K over the temperature range 10-300 K. These emissive species are appropriate for the development of the colour point of the white light, and this could be useful for improvement of the brightness of display devices. Furthermore, the practical applicability of 1 was investigated as a fluorescence sensor for the sensitive detection of picric acid in a methanolic medium. Such complexes have potential applications in light-emitting devices, sensing of molecular materials, and research contributes to the growing interest in lanthanide-based materials for various technological applications, providing insights into their structural and photophysical properties.