Influence of upper rim dibromo-substitution in bis-1, 3-diketone calix[4]arenes on spectral properties of ligands and their lanthanide complexes. Issue 36 (7th September 2017)

• Record Type: Journal Article
• Authors: Podyachev, Sergey N.; Gimazetdinova, Gulnaz Sh.; Sudakova, Svetlana N.; Shamsutdinova, Nataliya A.; Lapaev, Dmitry V.; Syakaev, Victor V.; Gubaidullin, Aidar T.; Nagimov, Rinas N.; Mustafina, Asiya R.
• Is Part Of: Tetrahedron. Volume 73:Issue 36(2017)
• Page Start: 5397
• Page End: 5407
• Publication Date: 2017-09-07
• Subjects: Calixarenes -- Ketones -- Luminescence -- Chelates -- Lanthanides; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tet.2017.07.043
• Languages: English
• ISSNs: 0040-4020

Abstract

Abstract: The present work introduces the synthesis and characterization of upper rim dibromo-substituted bis-1, 3-diketone calix[4]arenes with hydroxy and propyloxy groups at the lower rim as ligands for Gd 3+ and Tb 3+ complexes. The dibromo-substitution does not affect 1:1 complex formation with the lanthanide ions arising from their coordination via two 1, 3-diketonate groups incorporated at the upper rim of the calix[4]arene. The analysis of the time-resolved luminescence spectra of the Gd 3+ complexes clearly demonstrates the notable enhancement of the decay time of the ligand triplet state, while the energy of the triplet state for the new dibromo-bis-1, 3-diketones remains practically unchanged versus its non-substituted analogues. The latter tendency points to the heavy-atom effect on the energy transfer from the excited state to vibration levels of the dibromo-substituted ligand resulting in a decreased radiationless decay contribution. Measurements of Tb 3+ -centered luminescence indicate a better antenna effect (∼1.7) of dibromo-calix[4]arenes compared with its non-substituted counterpart. Graphical abstract: New bis -1, 3-diketone calix[4]arene derivatives adopting cone conformation with dibromo-substituted upper rim of calix[4]arene backbone are introduced as ligands for lanthanide ions with improved sensitization of Tb 3+ -centered luminescence due to heavy-atom effect.