Reversible SC‐SC Transformation involving [4+4] Cycloaddition of Anthracene: A Single‐Ion to Single‐Molecule Magnet and Yellow‐Green to Blue‐White Emission

• Published in: Angewandte Chemie International Edition Vol. 57; no. 28; pp. 8577 - 8581
• Main Authors: Huang, Xin‐Da, Xu, Yan, Fan, Kun, Bao, Song‐Song, Kurmoo, Mohamedally, Zheng, Li‐Min
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 09.07.2018
• Edition: International ed. in English
• Subjects: Anthracene; Clean energy; Cycloaddition; Dimerization; dysprosium; Dysprosium compounds; Emission; Gadolinium; Magnetic properties; Molecular chains; Optical materials; Phosphonates; photocycloaddition; single-molecule magnets; Smart materials; Switches; white light; anthracene; photocycloaddition; dysprosium; white light; single-molecule magnets
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201804102

In search of magneto‐optic materials, the mononuclear compounds LnIII(depma)(NO3)3(hmpa)2 (Ln=Dy, Gd) were synthesized. The anthracene moieties undergo [4+4] dimerization when irradiated at 365 nm without loss of crystallinity. The Dy compound switches from a single‐ion to a single‐molecule magnet with doubling of the spin reversal barrier energy and from yellow‐green to blue‐white emission. The dimerization is reversed by heating at 100 °C or partially on light irradiating at 254 nm. The results suggest that lanthanide phosphonates with anthracene are promising smart materials displaying synergistic magneto‐optic property. Pairing up: The mononuclear compound DyIII(depma)(NO3)3(hmpa)2 (depma= 9‐diethylphosphono‐methylanthracene, hmpa=hexamethylphosphoramide) undergoes reversible [4+4] photodimerization in a single‐crystal‐to‐single‐crystal manner. This process is accompanied by a change from a single‐ion to a single‐molecule magnet and from yellow‐green to blue‐white emission.