Experimental and computational exploration of photophysical and electroluminescent properties of modified 2,2′:6′,2″‐terpyridine, 2,6‐di(thiazol‐2‐yl)pyridine and 2,6‐di(pyrazin‐2‐yl)pyridine ligands and their Re(I) complexes

Abstract

H NMR (400 MHz, DMSO-d 6 , δ, ppm): 10.34 (s, 1H), 9.17 (d, J = 1.8 Hz, 1H), 9.11 (d, J = 1.2 Hz, 2H), 8.96 (d, J = 3.0 Hz, 1H), 8.90 (t, J = 2.2 Hz, 2H), 8.25 (d, J = 1.8 Hz, 1H), 8.18 (d, J = 9.0 Hz, 2H), 6.72 (d, J = 9.0 Hz, 2H), 3.38 (d, J = 6.5 Hz, 4H), 2.01 (t, J = 6.4 Hz, 4H).13C NMR not recorded due to insufficient complex solubility. HRMS (ESI): calcd for C 26 H 20 N 6 O 3 ReCl [M + Na] + 709.13 g mol −1 ; found 709.07 g mol −1 .

In-Depth Studies of Ground- and Excited-State Properties of Re(I) Carbonyl Complexes Bearing 2,2′:6′,2″-Terpyridine and 2,6-Bis(pyrazin-2-yl)pyridine Coupled with π-Conjugated Aryl Chromophores

“…In solution, the maximum emission energies of 1A – 3A are similar to each other and resemble those for [ReCl(CO) 3 (terpy-κ 2 N )] and [ReCl(CO) 3 (4′-Ph-terpy-κ 2 N )], 14 , 23 implying that the emitting state in these complexes is of the same origin, and it is only slightly affected by the aryl group attached to the terpy core ( Figure 3 a and Table 2 ). All of these complexes exhibit broad and structureless steady-state emission spectra with maxima in the narrow range 641–663 nm for CH 3 CN and 645–665 nm for CHCl 3 , with lifetimes in the nanosecond domain and rather low emission quantum yields.…”

“… 20 Prolonged lifetimes have also been confirmed for some Re(I) diamine carbonyls [ReX(CO) 3 (phen-TPA)] (X = Cl, Br; TPA = triphenylamine) with the emitting state of 3 ILCT nature, 21 and they have been supported for some other terpyridine Re(I) complexes [ReCl(CO) 3 (L n -κ 2 N )] incorporating strong electron-donating substituents by the Wang group 22 and our group. 14 , 16 , 23 …”

Tuning Optical Properties of Re(I) Carbonyl Complexes by Modifying Push–Pull Ligands Structure

“…10 Furthermore, to get better insight into the structure−property relationships, the electrochemical and photo-and electro-luminescent properties of 1−12 were discussed with reference to those reported for the parental compounds [ReCl(CO) 3 (4′-Ph-terpy-κ 2 N)], [ReCl(CO) 3 (4′-Ph-dtpy-κ 2 N)], and [ReCl(CO) 3 (4′-Ph-dppy-κ 2 N)] and related compound [ReCl(CO) 3 (L n -κ 2 N)]. 11 The character and energies of the electronic transitions that occur in these systems were investigated both experimentally (with electrochemistry and absorption and emission spectroscopy) and theoretically (using DFT calculations at the PBE1PBE/DEF2− TZVPD/DEF2-TZVP level). In addition, the capacity of obtained compounds for electroluminescence was examined.…”

“…11,14 As a result of the introduction of strong electron-donating amine group in the 4′-Ph-terpy/4′-Ph-dtpy/ 4′-Ph-dppy core, the HOMO orbital of 1−12 is expected to rise higher in energy, which leads to a reduction of the HOMO−LUMO energy gap, manifested as a red-shift of the lowest energy absorption band of 1−12 relative to the previously reported [ReCl(CO) 3 (4′-Ph-terpy-κ 2 N)], [ReCl-(CO) 3 (4′-Ph-dtpy-κ 2 N)], and [ReCl(CO) 3 (4′-Ph-dppyκ 2 N)]. 11 Consistent with contribution of ILCT transitions, the lowest energy absorption band of 1−12 demonstrates substantial increase in extinction coefficients in comparison to the parental complexes. 11 High-energy bands are primarily attributed to 1 π → π* transitions within the triimine ligand.…”

“…11 Consistent with contribution of ILCT transitions, the lowest energy absorption band of 1−12 demonstrates substantial increase in extinction coefficients in comparison to the parental complexes. 11 High-energy bands are primarily attributed to 1 π → π* transitions within the triimine ligand.…”