Fluorescence emission modulation of alkynyl-functionalized iron(II) spin-crossover complexes

Open AccessCCS ChemistryRESEARCH ARTICLES20 Aug 2024Fluorescence emission modulation of alkynyl-functionalized iron(II) spin-crossover complexes Yang Qu, Rong Sun, Bing-Wu Wang and Song Gao Yang Qu , Rong Sun , Bing-Wu Wang and Song Gao Cite this: CCS Chemistry. 2024;0:1–23https://doi.org/10.31635/ccschem.024.202404670 SectionsSupplemental MaterialAboutPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail Combining the spin crossover (SCO) and fluorescence properties could respond to multiple physical stimulus and is meaningful for the development of switches and imaging tools. In this work, we present a new family of neutral mononuclear iron(II) complexes, denoted as Fe( L1–3)2 and Fe( L3)2·CH2Cl2 with N4O2 donor sets. These complexes were synthesized employing a series of tridentate Schiff base ligands, which contain an ethynyl group (H L1–3 = 3-ethynyl-N′-((4-methylpyridin-2-yl)methylene)benzohydrazide ( 4MePAH-3EyBHZ, H L1), 3-ethynyl-N′-((4-methoxylpyridin-2-yl)methylene)benzohydrazide ( 4OMePAH-3EyBHZ, H L2), 3-ethynyl-N′-((5-methylpyridin-2-yl)methylene)benzohydrazide ( 5MePAH-3EyBHZ, H L3)). Variable-temperature magnetic susceptibility measurements revealed that Fe( L1)2 exhibits an abrupt and complete SCO with characteristic temperature T1/2↓ = 176 K and T1/2↑ = 178 K; Fe( L2)2 exhibits an abrupt and complete SCO with T1/2↓ = 214 K and T1/2↑ = 219 K; Fe( L3)2 exhibits an abrupt and complete SCO with T1/2↓ = 218 K andT1/2↑ = 226 K. The partial conformational inversion is observed between high spin and low spin state of Fe( L2)2 evidenced by the variable-temperature single-crystal X-ray diffraction analysis. An unusual increase of emission intensity was observed in the fluorescence spectra of Fe( L1)2 and Fe( L2)2 during the heating SCO process. These findings are both valuable in the study of spin-fluorescence interaction and synthesis of new multifunctional SCO complexes. Download figure Download PowerPoint Previous articleNext article FiguresReferencesRelatedDetails Issue AssignmentNot Yet AssignedSupporting Information Copyright & Permissions© 2024 Chinese Chemical Society Downloaded 37 times PDF downloadLoading ...