Construction Of Anthracenecarboxylic Acid-based Complexes And Their Photochromic And Photomagnetic Response

Photochromic and photomagnetic materials exhibit important application prospects in the fields of optical switching,sensing,encryption and intelligent information storage.However,it is still a challenge to realize the synergistic response of photochromism and photomagnetism at room temperature.This paper aims to develop electron transfer photochromic materials with room temperature photomagnetic properties,and synthesizes novel photochromic molecular magnets via assembly of self-photochromic anthracene carboxylic acid with transition metal ions.Through the changes of magnetic couplings between metal centers and photogenerated radicals,the regulation of photomagnetic properties will be realized after room temperature light irradiation.The specific works are as follows:Firstly,9-anthracene carboxylic acid（9-AC）ligand was found to show radical-induced self-photochromic behavior.Due to the difference in intermolecular hydrogen bonding interactions,the two configurations of 9-AC exhibited different photochromic efficiencies.A reported single-chain complex[Mn（9-AC）₂（H₂O）₂]·H₂O（1）was synthesized and its photochromic properties were tested.Compound 1 showed radical-induced photochromism under room temperature illumination,confirming that 9-AC can be used as a photoactive ligand to construct electron transfer photochromic materials.By assembling 9-AC with paramagnetic metal ions,one single-nuclear compound{[Ni（TEA）₂]（9-AC）₂}（2）was constructed.Compound 2 undergone intramolecular electron transfer after irradiation,generateing stable radicals and producing observably photochromic phenomenon.Furthermore,accompanied with the reduction of magnetic susceptibilities,room temperature photomagnetic response was realized in 2 after light irradiation.Secondly,9,10-anthracenedicarboxylic acid（H₂ADC）exhibited self-photochromic property in the crystal state.Two compounds,Cd₂（ADC）₂（DMF）₂（H₂O）（3）and Zn（ADC）（H₂O）·DMA·H₂O（4）were constructed by coordinating H₂ADC ligands with diamagnetic metal ions.The photochromic behavior in both compounds was investigated and different coordination modes in metal centers could affect the photochromic rate.A series of one-dimensional chain structures M（ADC）（H₂O）₂（DMF）₂（5,M=Mn;6,M=Zn;7,M=Ni;8,M=Co）were also obtained by assembly of H₂ADC transition metal ions.Compounds 5 and 6 exhibited photochromic behavior with photogenerated stable radicals after light irradiation.For 5,via the variations of magnetic couplings between photogenerated radicals and Mn²⁺ions,magnetic bistability with huge thermal hysteresis was realized for the first time in the radical-actuated photochromic materials.