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In this work, four different bis(imidazole) ligands, namely 1,4-bis(1-imidazolyl)benzene (bib), 4,4′-bis(1-imidazolyl)biphenyl (bibp), 1,4-bis (imidazol-1-ylmethylene)benzene) (bimb) and 4,4′-bis(imidazol-1-yl)diphenyl ether (bidpe), were used as the second ligand to give rise to the structural diversity of a coordination polymer based on the cobalt-miipa (H2miipa = 5-(2-methylimidazol-1-yl) isophthalic acid) system. In compound 1, miipa2− coordinates to Co(II) atoms to form the Co-miipa 3D network. On introducing linear bis(imidazole) ligands with different lengths and rigidities into the Co(II)-miipa system, the obtained compounds 2–4 form similar three-fold interpenetrating 3D MOFs constructed from the Co(II)-miipa layers pillared by bis(imidazole) ligands. While introducing the V-shaped half-flexible bis(imidazole) ligands, the obtained compound 5 exhibits a 2D double-layered network built from the Co(II)-miipa 1D quadrangular prism linked by the bis(imidazole) ligand. Each 2D double layer is further interlocked with two neighboring ones to produce an interesting 3D framework. Significantly, CoNC-5 derived from a mixture of dicyandiamide (DCD) and compound 5 with a low void volume shows a superior electrocatalytic performance for the oxygen reduction reaction. The Eonset (0.974 V) and E1/2 (0.830 V) of CoNC-5 in O2-saturated 0.1 M KOH at 1600 rpm and 5 mV s−1 are superior to those of Pt/C (0.968 and 0.799 V). The JL value of CoNC-5 (JL = 5.29 mA cm−2) is higher than that of Pt/C (5.09 mA cm−2). [ABSTRACT FROM AUTHOR]

The urothermal reactions of Co(II)/Zn(II) salts with the diverse carboxylic acid and 1,3,5,-tris(1-imidazolyl)benzene(tib) ligands afforded three novel MOFs, namely, [Co3(tib)2(abdc)2(ox)]2·6H2O (1), [Co3O(tib)(abdc)2(DMI)]·2DMI·2H2O (2) and [Zn3I2(tib)2(napdc)2]·2DMI·2H2O (3), (H2abdc = 5-amino-1,3-benzenedicarboxylate, H2napdc = 1,4-naphthalene dicarboxylic acid and DMI = 1,3-dimethyl-2-imidazolidinone). In compounds 1 and 2, the Co(II) atoms are connected by polycarboxylate ligands to form two-dimensional (2D) layers that are pillared by tib ligands leading to the formation of 3D porous frameworks. In compound 3, the Zn(II) atoms are linked by tib ligands to form one-dimensional ribbon-like chains which are further connected by polycarboxylate ligands, making a 3D framework possible. Compound 1 can selectively adsorb unsaturated hydrocarbon molecules (C2H2 and C2H4) and saturated hydrocarbon molecules (C2H6 and CH4). Specifically, compound 1 has high IAST selectivity for acetylene and methane (0.50 : 0.50, v/v) at 273 K and 1 bar. DFT calculations reveal that the π-conjugated hexagonal carbon ring may be the primary adsorption site because there are π–π interactions between the unsaturated hydrocarbon molecules (C2H2 and C2H4) and the π-conjugated hexagonal carbon ring in the framework of compound 1. [ABSTRACT FROM AUTHOR]

The urothermal reactions of Co(II)/Zn(II) salts with the diverse carboxylic acid and 1,3,5,-tris(1-imidazolyl)benzene(tib) ligands afforded three novel MOFs, namely, [Co3(tib)2(abdc)2(ox)]2·6H2O (1), [Co3O(tib)(abdc)2(DMI)]·2DMI·2H2O (2) and [Zn3I2(tib)2(napdc)2]·2DMI·2H2O (3), (H2abdc = 5-amino-1,3-benzenedicarboxylate, H2napdc = 1,4-naphthalene dicarboxylic acid and DMI = 1,3-dimethyl-2-imidazolidinone). In compounds 1 and 2, the Co(II) atoms are connected by polycarboxylate ligands to form two-dimensional (2D) layers that are pillared by tib ligands leading to the formation of 3D porous frameworks. In compound 3, the Zn(II) atoms are linked by tib ligands to form one-dimensional ribbon-like chains which are further connected by polycarboxylate ligands, making a 3D framework possible. Compound 1 can selectively adsorb unsaturated hydrocarbon molecules (C2H2 and C2H4) and saturated hydrocarbon molecules (C2H6 and CH4). Specifically, compound 1 has high IAST selectivity for acetylene and methane (0.50 : 0.50, v/v) at 273 K and 1 bar. DFT calculations reveal that the π-conjugated hexagonal carbon ring may be the primary adsorption site because there are π–π interactions between the unsaturated hydrocarbon molecules (C2H2 and C2H4) and the π-conjugated hexagonal carbon ring in the framework of compound 1. [ABSTRACT FROM AUTHOR]

A series of heteroleptic cyclometalated Ir (III) complexes, which are used for OLED application, were investigated by DFT and TD-DFT method. The frontier molecular orbital character and charge transfer character shown that they have the advantages of low efficiency roll-off properties, which is a "stumbling block" in the process of OLED solid-lighting's development. Namely, means the materials will play an important role in the journey development of OLED. [Display omitted] • Cyclometalated iridium (III) complexes have received special attention as dopants for harvesting the otherwise nonemissive triplet states formed in OLEDs, but now, most of them cannot satisfy to be used for the applications, especially for Bright blue and Near-infrared , since that a fast reduction in efficiency known as roll-off, however, occurs when the drive current increases, this leads to a much lower luminance and more power consumption. • Thus in this paper, in order to find a kind of Bright blue and Near-infrared OLED materials with low efficiency roll-off properties, we theoretical design and investigate a series of Iridium complexes. • The geometries, electronic structures, the lowest-lying singlet absorptions, triplet emissions properties and the application value for organic light emitting devices were all analyzed by theory in this article. A series metal iridium complexes were calculated using the method of DFT and TD-DFT under Gaussian 09 software. H atoms on the N counter in 2-(4-fluorophenyl)pyridine were replaced with methyl and nitro groups, respectively, to obtain two main ligands CFM(2-(4-fluorobrobenyl)-4-methylpyridine) and CFN(2-(4-fluorobrobenyl)-4-nitropyridine), then we obtained six complexes: (CFM) 2 Ir(acac), (CFM) 2 Ir(tpip), (CFM) 3 Ir, (CFN) 2 Ir(acac), (CFN) 2 Ir(tpip) and (CFN) 3 Ir, Where acac is represented as pentane-2, 4-dione, tpip as tetraphenylimido-diphosphinate. The electronic structure, the lowest singlet absorption, the triple excited states as well as the emission spectrum are also theoretically studied. [ABSTRACT FROM AUTHOR]

[Display omitted] • Six 5,5′-(1,2-phenylenebis(methoxy))diisophthalate coordination polymers were prepared. • The tetracarboxylic acid displays seven types of coordination modes. • These complexes exhibit 2D networks and 3D porous MOFs. • Mn(II) complexes 1 and 2 have antiferromagnetic couplings. Mn(II)/Cd(II) nitrates react with 5,5′-(1,2-phenylenebis(methoxy))diisophthalic acid (H 4 L) and four dipyridyl-typed N -donor ligands to afford six coordination polymers, {[Mn 2 (L)(bpee) 2 ]·DMF} n (1), {[Mn 3 (H 2 L) 3 (bpmp)(H 2 O) 2 ]·2DMF·2H 2 O} n (2), {[(CH 3) 2 NH 2 ] 2 [Cd(L)]·2H 2 O} n (3), [Cd 2 (L)(H 2 O) 2 (DMF)] n (4), {[Cd(L) 0.5 (bpdb)]·DMF} n (5) and [Cd(H 2 L)(bpp)(H 2 O)] n (6) [bpee = 1,2-bis(4-pyridyl)ethylene, bpmp = 1,4-bis(4-pyridylmethyl)piperazine, bpdb = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, bpp = 1,3-bis(4-pyridyl)propane]. These complexes were characterized by elemental analyses, IR spectra, PXRD, thermogravimetry and X-ray structural analysis. H 4 L displays seven types of coordination modes in them. Four complexes are 3D coordination polymers, except 2D wave-like network of complex 3 and 1D double-chain polymer of complex 6. Cd(II) complexes 3 , 4 and 6 display strong blue luminescence. Complex 1 exhibits weak antiferromagnetic coupling in [Mn 2 (μ 2 -COO) 2 (COO) 2 ] dimer, while complex 2 shows antiferromagnetic coupling in [Mn 3 (μ 2 -COO) 6 ] trinuclear cluster. [ABSTRACT FROM AUTHOR]