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 .

Three pentacoordinate complexes of the type [Co­(pypz)­X2], where pypz is a tridentate ligand 2,6-bis­(pyrazol-1-yl)­pyridine and X = Cl– (1), NCS– (2), and NCO– (3), have been synthesized, and their structures have been determined by X-ray analysis. The DC magnetic data show a sizable magnetic anisotropy, which was confirmed by high-field high-frequency electron paramagnetic resonance (HF EPR) measurements. Well-resolved HF EPR spectra of high spin cobalt (II) were observed over the microwave frequency range 100–650 GHz. The experimental spectra of both complexes were simulated with axial g tensor components, a very large positive D value, and different E/D ratios. To determine the exact D value for 2 (38.4 cm–1) and 3 (40.92 cm–1), the far-infrared magnetic spectroscopy method was used. Knowledge of the zero field splitting parameters and their signs is crucial in interpreting the single-molecule magnet or single chain magnet behavior. The AC susceptibility data confirm that these complexes exhibit a slow magnetic relaxation under small applied DC field with two (1 and 3) or three (2) relaxation modes.

Several 2,2':6',2''-terpyridines substituted in the 4'-position were synthesized and their photophysical properties were investigated by absorption and photoluminescence spectroscopy in dilute solutions and solid state. The studies confirmed that the absorption and emission wavelengths, fluorescence quantum yields and lifetimes of 1-R(1-16) are strongly structure-related, demonstrating a decisive role of the nature of the substituent in determining the photophysical properties of 4'-functionalized terpyridines. Additionally, the density functional theory (DFT) calculations were performed for 1-R(1-16) to get insight into their electronic structure and spectroscopic properties.

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Three cobalt(ii) complexes of formulae [Co(dca)2(bim)4] (), [Co(dca)2(bim)2]n () and [Co(dca)2(bmim)2]n () [dca = dicyanamide, bim = 1-benzylimidazole and bmim = 1-benzyl-2-methylimidazole] were prepared and structurally analyzed by single-crystal X-ray crystallography. Compound is a mononuclear species where the cobalt(ii) ion is six-coordinate with four bim molecules in the equatorial positions [Co-Nbim = 2.1546(15) and 2.1489(15) Å] and two trans-positioned dca ligands [Co-Ndca = 2.1575(18) Å] in the axial sites of a somewhat distorted octahedral surrounding. The structures of and consist of two-dimensional grids of cobalt(ii) ions where each metal atom is linked to the other four metal centres by single dca bridges exhibiting the μ1,5-dca coordination mode [Co-Ndca = 2.190(3)-2.220(3) () and 2.127(3)-2.153(3) Å ()]. Two trans-coordinated bim ()/bmim () molecules achieve the six-coordination around each cobalt(ii) ion [Co-Nbim = 2.128(3)-2.134(4) Å () and Co-Nbmim = 2.156(3)-2.163(39) Å ()]. The values of the cobalt-cobalt separation through the single dca bridges are 8.927(2) and 8.968(2) Å in and 8.7110(5) and 8.7158(5) Å in . Magnetic susceptibility measurements for in the temperature range of 2.0-300 K reveal that these compounds behave as magnetically isolated high-spin cobalt(ii) ions with a significant orbital contribution to the magnetic moment. Alternating current (ac) magnetic susceptibility measurements for show a frequency dependence of out-of-phase susceptibility under static applied fields in the range of 500-2500 G, a feature which is characteristic of the single-ion magnet behaviour (SIM) of the Co(ii) ion in them. The values of the energy barrier for the magnetic relaxation (Ea) are 5.45-7.74 (), 4.53-9.24 () and 11.48-15.44 cm(-1) (). They compare well with those previously reported for the analogous dca-bridged 2D compound [Co(dca)2(atz)2]n () (Ea = 5.1 cm(-1) under an applied static field of 1000 G), which was the subject of a previous report.

Photophysics of [ReCl(CO)3(4′-R-terpy-κ2N)].

In this work, the structure–property relationship was investigated for a series of Re­(I) carbonyls [ReCl­(CO)3(R-terpy-κ2N)], [ReCl­(CO)3(R-dtpy-κ2N)], and [ReCl­(CO)3(R-dppy-κ2N)]. The studied compounds bear 2,2′:6′,2″-terpyridines (R-terpy), 2,6-di­(thiazol-2-yl)­pyridines (R-dtpy), and 2,6-di­(pyrazin-2-yl)­pyridines (R-dppy) functionalized with strongly electron-donating cyclic (piperidine and morpholine) and acyclic (dimethylamine, diphenylamine) amine donor attached to the central pyridine ring of the triimine skeleton via phenylene linkage. Their thermal properties were evaluated using DSC. The ground- and excited-state properties of these systems were elucidated with electrochemistry, absorption and emission spectroscopy, and density-functional theory (DFT)-based calculations. The terpy skeleton was found to efficiently stabilize the LUMO orbital, as manifested by the most negative reduction potentials for Re­(I) terpyridine complexes and significant blue-shift of the absorption and emission of [ReCl­(CO)3(R-terpy-κ2N)] in relation to those of Re­(I) carbonyls bearing dtpy- and dppy-based ligands. Substitution of the triimines with amine substituents resulted in participation of intraligand charge-transfer (ILCT) transitions, and it was found to be beneficial for hole-transport properties of the Re­(I) carbonyls. The constructed nondoped and doped single layer diodes based on Re­(I) complexes emitted red light with various intensity.

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