Synthesis, crystal structures, photophysical, electrochemical studies, DFT and TD-DFT calculations and Hirshfeld analysis of new 2, 2′:6′, 2′′-terpyridine ligands with pendant 4′-(trimethoxyphenyl) groups and their homoleptic ruthenium complexes. (25th June 2020)

• Record Type: Journal Article
• Authors: Ramesh, Golla; P., Raghavendra Kumar; Pillegowda, Manohar; Periyasamy, Ganga; Suchetan, P. A.; Butcher, R. J.; Foro, Sabine; Nagaraju, G.
• Is Part Of: New journal of chemistry. Volume 44:Number 27(2020)
• Page Start: 11471
• Page End: 11489
• Publication Date: 2020-06-25
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/d0nj00046a
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : [Ru(L 1 )2 ](PF6 )2 (1 ) and [Ru(L 2 )2 ](PF6 )2 (2 ): X-ray structures, CH⋯F/O, OH⋯F/N, CH⋯O/π, π⋯π interactions, absorption and emission spectra, DFT/TD-DFT, Hirshfeld analysis. Abstract : Two new ligands, 4′-(2, 3, 4-trimethoxyphenyl)-2, 2′:6′, 2′′-terpyridine (L 1 ) and 4′(2, 4, 5-trimethoxyphenyl)-2, 2′:6′, 2′′-terpyridine (L 2 ), and their homoleptic ruthenium(ii ) complexes, [Ru(L 1 )2 ](PF6 )2 (1 ) and [Ru(L 2 )2 ](PF6 )2 (2 ), were synthesized and characterized by elemental analysis, 1 H and 13 C{ 1 H} NMR spectroscopy, FT-IR spectroscopy and single crystal X-ray diffraction. The crystals of these compounds contain CH⋯F, OH⋯F, CH⋯O, CH⋯π and/or π⋯π intermolecular secondary interactions, resulting in supramolecular architectures. Hirshfeld surface analysis of all four compounds was also carried out to determine the intermolecular interactions. We investigated the photophysical properties of L 1, L 2, 1 and 2 by UV-Visible absorption and fluorescence emission spectroscopy and studied their electrochemical properties by cyclic voltammetry. In addition to n–π* and π–π* bands in the UV-Visible spectra of both ligands and complexes, a fairly strong and relatively broad 1 MLCT band appeared at λ max ∼ 500 nm in complexes 1 and 2 . The emission bands in ligands L 1 and L 2 appeared at λ em 429 and 426 nm, respectively, whereas in the complexes 1 and 2, these bands showed red-shifts of 34 and 82 nm, respectively. Both L 1 and L 2 showed two oxidation peaks; however, only L 2 showed a significant reduction peak. Complexes 1 and 2 showed two oxidation peaks and two reduction peaks. The effects of increasing scan rate (100 to 1000 mV s −1 ) on the electrochemical behaviour of complexes 1 and 2 were also investigated. The experimentally observed structural and photophysical properties were supported by DFT and TD-DFT calculations.