A Luminescent Rhenium(I) Metallacycle with Oxygen and Nitrogen Donor Atoms: Photophysical and Theoretical Studies

Abstract

A new N,O-bischelator-bridged dirhenium(I) metallacycle, [Re 2 (CO) 6 (μ-η 4 -mpdo)(μ-4,4Ј-tmdp)] (1, H 2 mpdo = 2-methylpyrimidine-4,6-diol, 4,4Ј-tmdp = 4,4Ј-trimethylenedipyridine) has been self-assembled in a one-pot reaction in p-xylene at 140°C. Compound 1 displays unusual multiple phosphorescence emissions at room temperature; an emission quan-

Self‐Assembly of Oxamidato‐Chelated ReI‐ and MnI‐Based Flexible Dinuclear Horse‐Stirrup‐Like Metallacycles

“…The UV/Vis absorption spectra of 1 – 3 in CH 2 Cl 2 showed two intraligand transitions at λ max = 230 and 283–311 nm, and the metal‐to‐ligand charge‐transfer (MLCT) transitions appeared in the region λ max = 361–374 nm. Similarly, the rhenium analogues 4 – 6 displayed two higher‐energy absorption bands at λ max = 228 and 266 nm for ligand‐centered transitions, and the lower‐energy bands at λ max = 309–316 nm were due to MLCT transitions 28,29,46. On excitation of the MLCT region, 1 displayed multiple broad emissions between λ max = 404 and 460 nm.…”

“…On excitation of the MLCT region, 1 displayed multiple broad emissions between λ max = 404 and 460 nm. On the other hand, the rhenium‐based 4 exhibited two emissions at λ max = 392 and 508 nm on excitation at 317 nm, whereas 5 and 6 displayed multiple emissions in the range λ max = 406–458 nm 28,29. The 1 H NMR spectrum of 1 displayed two signals at δ = 8.25 and 7.34 ppm, which were assigned to the H 2 py , and H 3 py protons of bpe, respectively.…”

“…On the other hand, the rhenium-based 4 exhibited two emissions at λ max = 392 and 508 nm on excitation at 317 nm, whereas 5 and 6 displayed multiple emissions in the range λ max = 406-458 nm. [28,29] The 1 H NMR spectrum of 1 displayed two signals at δ = 8.25 and 7.34 ppm, which were assigned to the H The rhenium analogues 4-6 also displayed similar patterns for the pyridyl and aromatic protons. In 1-6, two diastereotopic methylene protons adjacent to the nitrogen atom of the oxamidato bridge appeared as two doublets in the region δ = 5.33-3.13 ppm.…”

“…Similarly, the rhenium analogues 4-6 displayed two higher-energy absorption bands at λ max = 228 and 266 nm for ligand-centered transitions, and the lowerenergy bands at λ max = 309-316 nm were due to MLCT transitions. [28,29,46] On excitation of the MLCT region, 1 displayed multiple broad emissions between λ max = 404 and 460 nm. On the other hand, the rhenium-based 4 exhibited two emissions at λ max = 392 and 508 nm on excitation at 317 nm, whereas 5 and 6 displayed multiple emissions in the range λ max = 406-458 nm.…”

“…[15,[27][28][29][30][31] For the construction of such dirhenium metallacycles, bis(chelating) organic clips are usually utilized in combination with flexible dipyridyl linkers. [27,30] Owing to their efficacy in different fields such as luminescent sensors, imaging, and photocatalytic CO 2 reduction, Re I -based complexes continue to attract considerable interest for various modern applications.…”