Highlights•Three new 2-phenyl-5-nitropyridyl-containing iridium(III) complexes are presented.•Electron-withdrawing nitro groups are introduced to the pyridyl of ppy.•The crystal structures of the complexes are determined.•Electrochemistry and photophysical properties of the complexes are investigated.•These Ir(III) complexes show narrow HOMO–LUMO energy gaps.The reactions of [Ir(5-NO2-ppy)2(PPh3)Cl] (5-NO2-ppy = 2-phenyl-5-nitropyridyl, PPh3 = triphenylphosphine, 1) with pseudohalides, replacing the weak π donor Cl− with strong σ donors and π acceptors, lead to three new iridium(III) cyclometalated complexes [Ir(5-NO2-ppy)2(PPh3)(L)] (L = NCO−, 2; NCS−, 3; N3−, 4) based on 2-phenylpyridyl (ppy) derivative, PPh3 and different pseudohalogen strong-field ancillary ligands. 2–4 are unambiguously characterized and their crystal structures are also determined by X-ray crystallography. The HOMO–LUMO electronic energy gaps of 1–4 estimated from the cyclic voltammetry measurements are comparable with those calculated from the UV–Vis absorption spectra, which are both in the order of 3 > 1 > 2 > 4. Furthermore, the electrochemical and photophysical properties of 1–4 show that the introduction of the electron-withdrawing nitro group to the pyridyl ring of the ppy backbone narrows the HOMO–LUMO electronic energy gaps, compared with those of corresponding ppy-containing iridium(III) complexes.Graphical abstractA series of new iridium(III) complexes [Ir(5-NO2-ppy)2(PPh3)(L)] (5-NO2-ppy = 2-phenyl-5-nitropyridyl, PPh3 = triphenylphosphine, L = NCO−; NCS−; N3−) are presented. The introduction of electron-withdrawing groups to the pyridyl rings of the ppy backbones narrows the HOMO–LUMO energy gaps of the complexes.

•Two 1D metallomacrocycle-containing coordination polymers 1 and 2 are presented.•The crystal structures of 1 and 2 are determined.•The conductivities of 1 and 2 at r.t. are 1.52 × 10− 8 and 1.18 × 10− 5 S cm− 1.•Protonic conduction makes 2 exhibit greatly higher electrical conductivity.•1 and 2 show outstanding thermal stability.Two one-dimensional (1D) germanium(IV) coordination polymers (CPs) containing macrocyclic tetraaza[14]annulene, [Ge(tmtaa)(L)]n [tmtaa = tetraaza[14]annulene, L = 1,4-benezedicarboxylate 1; 2,5-dihydroxyl-1,4-benezedicarboxylate, 2], are synthesized and characterized. The temperature dependence of the electrical conductivity (σ) for 1 or 2 indicates region of rising dσ/dT (the conductivity increases with increasing temperature), suggesting semiconductor-like charge transport in the stacking direction. The room temperature electrical conductivities for 1 and 2 are 1.52 × 10− 8 S cm− 1 and 1.18 × 10− 5 S cm− 1, respectively, which are obviously higher than those of most 1D metallophthalocyanine- and metalloporphyrine-containing CPs. Though the crystal structures of 1 and 2 are similar, 2 exhibits better electrical conductivity which is about three orders higher than that of 1. This may be due to the protonic conduction existing in 2. Furthermore, 1 and 2 show outstanding thermal stability. These results suggest the potential applications of 1 and 2 as semiconductive materials.Two 1D Ge(IV) coordination polymers containing macrocyclic tetraaza[14]annulene, 1 and 2, show notable semiconducting property. Though the structures of 1 and 2 are similar, 2 exhibits better electrical conductivity which is about three orders higher than that of 1. This may be due to the protonic conduction existing in 2.

A series of new 2-phenyl-5-nitropyridyl containing iridium(III) cyclometalated complexes ([Ir(5-NO2-ppy)2Cl]2 (1, 5-NO2-ppy = 2-phenyl-5-nitropyridyl), Ir(5-NO2-ppy)2(PPh3)Cl (2, PPh3 = triphenylphosphine), Ir(5-NO2-ppy)2(pic) (3, pic = picolinic acid)) have been synthesized and unambiguously characterized. The crystal structures of 2 and 3 have been determined by X-ray diffraction analyses. The HOMO–LUMO energy gaps of 1–3 estimated by the cyclic voltammetry (CV) show values in the order of 2 > 3 > 1. The UV–vis absorption and the solid photoluminescence (PL) spectra of 1–3 have also been measured, exhibiting the changing orders being consistent with that of the HOMO–LUMO energy gaps. Moreover, the UV–vis absorption spectra of 1–3 show obvious red-shifts compared with those of the corresponding 2-phenylpyridyl (ppy) containing Ir(III) complexes ([Ir(ppy)2Cl]2, Ir(ppy)2(PPh3)Cl and Ir(ppy)2(pic)) in which no strongly electron-withdrawing nitro groups are introduced to the pyridyl rings of the ppy ligands. Thus, the HOMO–LUMO energy gaps of 1–3 should be narrower than those of [Ir(ppy)2Cl]2, Ir(ppy)2(PPh3)Cl and Ir(ppy)2(pic).A series of new iridium(III) complexes ([Ir(5-NO2-ppy)2Cl]2 (1, 5-NO2-ppy = 2-phenyl-5-nitropyridyl), Ir(5-NO2-ppy)2(PPh3)Cl (2) and Ir(5-NO2-ppy)2(pic) (3)) in which the strongly electron-withdrawing nitro groups are introduced to the pyridyl rings of the 2-phenylpyridyl (ppy) ligands have been synthesized and characterized, showing narrower HOMO–LOMO energy gaps compared with the corresponding ppy containing complexes.Highlights► A series of 2-phenyl-5-nitropyridyl containing iridium(III) complexes are presented. ► Electron-withdrawing nitro groups are introduced to the pyridyl of the complexes. ► The crystal structures of two new Ir(III) complexes are determined. ► Electrochemistry and photophysical properties of the complexes are investigated. ► These new Ir(III) complexes show narrow HOMO–LUMO energy gaps.

The template reaction of o-phenylenediamine, 1-benzoylacetone and nickelous acetate tetrahydrate results in two structure isomers, 6,17-dimethyl-8,15-diphenyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecinatonickel (II) (2) and 6,15-dimethyl-8,17-diphenyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecinatonickel (II) (4). However, the latter has been neglected in the previous research because of its low yield in the template reaction. The mechanism of this template reaction is discussed. Though the steric hindrance between the phenyl ring and the benzo ring in 2 is greater than that in 4, the intermediate of the former shows better structural stability than that of the latter, leading to obviously higher final yield of 2 compared with that of 4. n-Butyl alcohol is used artfully to separate the crude product of the template reaction into almost pure 2 and a mixture of 2 and 4 in a mole ratio of 1:5. The free base of 2, 5,14-dihydro-6,17-dimethyl-8,15-diphenyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine (1), can be synthesized by demetalization of 2 with gaseous HCl. The same treatment to the mixture of 2 and 4 in a mole ratio of 1:5 leads to the free base of 4, 5,14-dihydro-6,15-dimethyl-8,17-diphenyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine (3). The neglected macrocyclic compounds 3 and 4 have been characterized unambiguously and their single-crystal structures have also been determined by X-ray diffraction analysis for the first time.A macrocyclic ligand 5,14-dihydro-6,15-dimethyl-8,17-diphenyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine and its nickel(II) complex, 6,15-dimethyl-8,17-diphenyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecinatonickel (II), have been synthesized and characterized unambiguously. Their single-crystal structures have also been determined by X-ray diffraction analysis for the first time.Highlights► A template reaction results in a mixture of (E)-Nidmdptaa and (Z)-Nidmdptaa. ► (E)-Nidmdptaa and (Z)-Nidmdptaa are macrocyclic structure isomers. ► (E)-Nidmdptaa is successfully separated from the mixture of isomers. ► (E)-H2dmdptaa, the free base of (E)-Nidmdptaa, is synthesized and characterized. ► The single-crystal structures of (E)-Nidmdptaa and (E)-H2dmdptaa are determined.

A new non-planar saddle shaped macrocyclic ligand 4,11-dihydro-5,7,12,14-tetramethyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine (H2tmtaa) containing a six-coordinate germanium(IV) complex, Ge(tmtaa)(OOCH)2 (1), in which two axial formate ligands are in the trans positions, has been synthesized. IR, UV, mass, NMR spectroscopic study and elemental analysis have been performed to characterize the complex. The single crystal X-ray diffraction analysis shows that in the solid state, molecules of 1 are connected through intermolecular hydrogen-bond weak interactions to form a one-dimensional supramolecular network. The temperature dependence of the electrical conductivity data (240–300 K) for 1 indicates a region of falling dσ/d(1/T), suggesting “semiconductor-like” charge transport in the stacking direction. The conductivity of 1 at room temperature is 6.1 × 10−8 S/cm.

Two new heteroleptic iridium(III) complexes [Ir(4,6-dfppy)2(PPh3)L] (4,6-dfppy = 2-(4,6-difluorophenyl)pyridyl, PPh3 = triphenylphosphine, L = NCS−, 1; NCO−, 2) have been synthesized and fully characterized. By introduction of electron-withdrawing groups such as fluorine atoms on the 4- and 6-positions of 2-phenylpyridyl (ppy) and using strong-field ligands for instance PPh3 and pseudohalogen as ancillary ligands, the HOMO–LUMO electronic energy gaps of 1 and 2 have been increased sufficiently. The photoluminescence (PL) spectra of 1 and 2 in solution show emission maxima at 456 and 458 nm, respectively, corresponding to efficient blue light-emitting. X-ray analyses show that intra- and intermolecular π–π interactions exist in the solid state of 1 and 2. The PL spectra of 1 and 2 in solid state exhibit about 30 nm spectral red shifts compared with those in solution.The PL spectra of high HOMO–LUMO energy gaps containing iridium(III) complexes [Ir(4,6-dfppy)2(PPh3)L] (L = NCS−, 1; NCO−, 2) in solution show emission maxima at 456 and 458 nm, respectively, corresponding to well blue light-emitting. The PL spectra of 1 and 2 in solid state exhibit 30 nm spectral red shifts.

A series of new neutral iridium(III) complexes containing strong-field ancillary ligands, [Ir(ppy)2(PPh3)L] (ppy = 2-phenylpyridine, PPh3 = triphenylphosphine, L = NCS−, 1; N3-, 2; NCO−, 3), have been synthesized and fully characterized by 1H NMR, IR, ESI mass spectral and elemental analysis. The crystal structure of 1 has been determined by X-ray analysis. The photoluminescence (PL) spectra of 1–3 show emission maxima at 477, 489 and 485 nm, respectively, corresponding to blue light-emitting of 1 and blue-green light-emitting of 2 and 3. PL quantum yields (PLQYs) of 1–3 are 0.39, 0.13 and 0.43, respectively.Neutral iridium(III) complexes Ir(ppy)2(PPh3)L (L = NCS−, 1; N3−, 2; NCO−, 3) have been synthesized and characterized. Crystal structure of 1 has been determined. The photoluminescence spectra of 1–3 show emission maxima at 477, 489 and 485 nm, respectively. Photoluminescence quantum yields of 1–3 are 0.39, 0.13 and 0.43, respectively.