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

Figure S1. The synthetic route of 2,2′:6′,2′′-terpyridine, 2,6-di(thiazol-2-yl)pyridine and 2,6-di(pyrazin-2-yl)pyridine derivatives.

Figure S2. IR spectra of complexes 1-6.

Figure S3. Aromatic region of ¹H NMR spectra of ligand L⁴ and complex 4 in d⁶-DMSO, showing clear differentiation between proton signals from outer 2-pyridyl rings of coordinated ligand.

Figure S4. ¹H NMR spectra of ligands L¹-L⁶ in CDCl₃.

Figure S5. ¹³C NMR spectra of ligands L¹-L⁶ in CDCl₃.

Figure S6. ¹H NMR spectra of compounds 1-6 (1, 3, 4, 6 in DMSO-d⁶, 2 and 5 in acetone-d⁶).

Figure S7. ¹³C NMR spectra of compounds 1, 3 and 4 in DMSO-d⁶.

Figure S8. MS spectra of complexes 1-6.

Figure S9. A perspective views of showing the molecular structures of 1–3 with the atom numbering. Displacement ellipsoids are drawn at the 50% probability level.

Figure S10. Hirshfeld surface mapped with d_norm along (a), and 2D fingerprint plots (b) for 1–6, together with the relative contributions of various intermolecular interactions to the Hirshfeld surfaces

Table S1. Experimental and theoretical bond lengths [Å] and angles [°] for 1–6.

Table S2. Short intra- and intermolecular contacts detected in the structures of the rhenium(I) complexes.

Table S3. Short π•••π interactions

Table S4. Crystal data and structure refinement of 1–6.

Table S5. Thermal properties of studied compounds.

Figure S11. DSC curves of ligand L⁵ and its complex 5, registered for first and second heating scan.

Table S6. The electrochemical properties of free ligands L¹–L⁶ and Re(I) complexes (1-6).

Figure S12. UV-Vis spectra of L¹-L⁶ in MeCN (a) and CHCl₃ with photoluminescence spectrum of PVK:PBD matrix (b).

Figure S13. UV-Vis spectra of 1-6 in MeCN (a) and CHCl₃ with photoluminescence spectrum of PVK:PBD matrix (b).

Figure S14. UV-vis spectra of ligands L¹ and L⁴ and its complexes 1 and 6 as thin films on glass substrate together with PL spectrum of PVK:PBD matrix.

Table S7. The absorption maxima and molar extinction coefficient values for the free ligands (L¹-L⁶) and complexes [ReCl(CO)₃(Lⁿ-κ²N)] (1-6).)

Figure S15. Luminescent properties of L¹-L⁶ ligands and 1-6 complexes in solid state, low temperature glass matrix (EtOH:MeOH, 4:1 v/v), acetonitrile and chloroform solutions.

Figure S16. Chromaticity plots for compounds L¹-L⁶ and complexes 1-6 in solution (a – MeCN, b – CHCl₃) and solid state(c).

Table S8. Summary of photoluminescent properties of ligands L¹-L⁶.

Table S9. Summary of photoluminescent properties of Re(I) complexes (1-6)

Table S10. Calculated Onsager cavity radius (a).

Figure S17. PL spectra of selected compounds in the form of a layer on glass under different excitation wavelengths (a) of L¹ and L⁴ and (b) of 1 and 4 and (c) the energy diagram of ligands and complexes.

Figure S18. Comparison of PL spectra of ligand L¹ and L⁶ in film, solution and in blend together with emission of PVK:PBD matrix a),b); comparison of PL spectra of complexes 1 and 6 in film, solution and in blend c), d).

Figure S19. Emission spectra of complexes 1-6 in EtOH:MeOH (4:1) glass matrix in 77K.

Figure S20. EL spectra of diodes based on ligands L¹-L⁴ and L⁶ and complexes 1-5.

Figure S21. Normalized emission spectra of complexes 1-6 in solid state.

Figure S22. Experimental (black line) absorption spectra and calculated transitions (red) of ligands L¹-L⁶.

Figure S23. Experimental (black line) absorption spectra and calculated transitions (red) of complexes 1-6.

Table S11. The energies and characters of the selected spin-allowed electronic transitions for L¹ calculated with the TDDFT/PBE1PBE method, together with assignment to the experimental absorption bands.

Table S12. The energies and characters of the selected spin-allowed electronic transitions for L2 calculated with the TDDFT/PBE1PBE method, together with assignment to the experimental absorption bands.

Table S13. The energies and characters of the selected spin-allowed electronic transitions for L³ calculated with the TDDFT/PBE1PBE method, together with assignment to the experimental absorption bands.

Table S14. The energies and characters of the selected spin-allowed electronic transitions for L⁴ calculated with the TDDFT/PBE1PBE method, together with assignment to the experimental absorption bands.

Table S15. The energies and characters of the selected spin-allowed electronic transitions for L⁵ calculated with the TDDFT/PBE1PBE method, together with assignment to the experimental absorption bands.

Table S16. The energies and characters of the selected spin-allowed electronic transitions for L⁶ calculated with the TDDFT/PBE1PBE method, together with assignment to the experimental absorption bands.

Table S17. The energies and characters of the selected spin-allowed electronic transitions for 1 calculated with the TDDFT/PBE1PBE method, together with assignment to the experimental absorption bands.

Table S18. The energies and characters of the selected spin-allowed electronic transitions for 2 calculated with the TDDFT/PBE1PBE method, together with assignment to the experimental absorption bands.

Table S19. The energies and characters of the selected spin-allowed electronic transitions for 3 calculated with the TDDFT/PBE1PBE method, together with assignment to the experimental absorption bands.

Table S20. The energies and characters of the selected spin-allowed electronic transitions for 4 calculated with the TDDFT/PBE1PBE method, together with assignment to the experimental absorption bands.

Table S21. The energies and characters of the selected spin-allowed electronic transitions for 5 calculated with the TDDFT/PBE1PBE method, together with assignment to the experimental absorption bands.

Table S22. The energies and characters of the selected spin-allowed electronic transitions for 6 calculated with the TDDFT/PBE1PBE method, together with assignment to the experimental absorption bands.

Figure S24. TD-DFT and MS-CASPT2 values of excitations energy for S₂ electronic state of L⁴. The black dotted line corresponds to the energy (3.70 eV) for the maximum of lowest band in the experimental absorption spectrum.

Table S23. Parameter Λ, oscillator strength, composition and transition character for ten low-lying TDDFT electronic singlet states of L¹ and L⁴ ligands. Results based on the PBE1PBE/def2-TZVP calculations with use PCM solvent model.

Table S24. MS-CASPT2 electronic states for L¹ ligand.

Table S25. MS-CASPT2 electronic states for L⁴ ligand.

Table S26. Calculated phosphorescence emission energies (DFT/PBE1PBE/DEF2-TZVPD/DEF2-TZVP) of 1–6, compared to the experimental values recorded in acetonitrile solution.

Figure S25. Active space CAS(12,12) used in CAS/MS-CASPT2 calculations for L¹ ligand.

Figure S26. Active space CAS(12,12) used in CAS/MS-CASPT2 calculations for L⁴ ligand.

Figure S27. Frontier molecular orbitals of complexes 1-6.

Figure S28. Isodensity surface plots of the LSOMO and HSOMO for the complexes 1–6 at their T₁ TD-DFT state geometry. Blue and grey colours show regions of positive and negative spin density values, respectively.

Figure S29. Isodensity surface plots of the LSOMO and HSOMO for the complexes 1 and 4 at their T₁ TD-DFT state geometry. Blue and grey colours show regions of positive and negative spin density values, respectively.