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An intense visible yellow-orange emission with long lifetime and enhanced quantum yield has been achieved for a metal-organic framework based on a highly light-harvesting dyclo-metalated iridium(III) unit, which shows effective detection of nitroaromatic explosives on the ppm scale.

Two cationic cyclometallated iridium(III) complexes with 2,2'-bipyridine-acylhydrazone were synthesized and characterized by spectroscopic and photophysical measurements. They exhibit remarkable aggregation-induced phosphorescent emission (AIPE) phenomenon which is caused by the restriction of rapid isomerization of the C=N bond in the acylhydrazone moiety and are supported by TD-DFT studies. They also act as a significant 'off-on' luminescent switch for Cu(2+) which works as both catalyzer and oxidant in the sensing process, resulting in hydrolysis and cyclization products which are highly emissive. The sensing properties of iridium(III) complexes are also investigated by ESI-MS spectrometry and (1)H NMR spectroscopy.

An iridium(III)-containing phosphorescent chemosensor Ir(ppy)(2)(L)(PF(6)) (1, ppy = 2-phenylpyridine) containing a 2,2'-bipyridyl ligand (L) functionalized with an alpha,beta-unsaturated ketone for selective detection of thiol was synthesized and characterized by spectroscopic and photophysical measurements. The structure of complex 1 was determined by X-ray crystallography. In order to get an insight into 1,4-addition reactions of thiol to complex 1, the adduct 2 from reaction of 1 with benzenethiol was successfully prepared and characterized. Complex 1 shows a lowest energy absorption at ca. 450 nm, primarily ascribable to an intraligand charge transfer (ILCT) transition from the HOMO (pi) resident on the fragment -C(O)C(6)H(4)N(C(2)H(5))(2) to the LUMO (pi*) localized on the 2,2'-bipyridyl moiety in the functionalized 2,2'-bipyridyl ligand as suggested from DFT computational studies. Complex 1 is weakly emissive at ca. 587 nm at ambient temperature, arising likely from the (3)ILCT excited state. Upon addition of thiol to a semi-aqueous solution of complex 1, the lowest energy absorption is obviously blue-shifted and the emission is remarkably enhanced due probably to a conversion from the primary ILCT state to the predominant [pi(ppy)-->pi*(L)] LLCT and the [5d(Ir)-->pi*(L)] MLCT state caused by the formation of the 1-thiol adduct. The sensing properties of 1 to thiol were also investigated by ESI-MS spectrometry and (1)H NMR spectroscopy.

We have synthesized four Ir(iii) metal complexes (1–4) bearing dual fluorine-free cyclometalates that are derived from 2′,6′-dimethoxy-4-t-butyl-2,3′-bipyridine (pypy)H or 2-(2,4-dimethoxypyrimidin-5-yl)-4-t-butylpyridine (pmpy)H and a third ancillary, e.g. 5-pyridin-2-yl-pyrazolate (Pz) or 5-pyridin-2-yl-pyrrolide (Pr), respectively. The Ir(iii) complexes 3 and 4 were examined by X-ray diffraction studies for providing the structural proofs. Photophysical properties were next measured in CH2Cl2 at RT, among which the pypy complexes 1 and 2 showed an identical structured emission with an E0-0 peak located at 458 nm, while the corresponding pmpy derivative 3 displayed the most blue-shifted E0-0 peak at 444 nm. Organic light-emitting diodes (OLEDs) were fabricated using multiple layered architecture and the aforementioned phosphor at 8 wt% doping level. The associated OLED performances, cf. max. E.Q.E. = 9.0%, 14.3%, 5.8% and 9.4% and CIEx,y coordinates at (0.16, 0.22), (0.16, 0.24), (0.16, 0.17) and (0.16, 0.20) at 100 cd m−2 for phosphors 1–4 in sequence, confirmed their potential to act as blue dopants for phosphorescent OLEDs. [ABSTRACT FROM AUTHOR]

Two cationic cyclometallated iridium(iii) complexes with 2,2′-bipyridine-acylhydrazone were synthesized and characterized by spectroscopic and photophysical measurements. They exhibit remarkable aggregation-induced phosphorescent emission (AIPE) phenomenon which is caused by the restriction of rapid isomerization of the C=N bond in the acylhydrazone moiety and are supported by TD-DFT studies. They also act as a significant ‘off–on’ luminescent switch for Cu2+ which works as both catalyzer and oxidant in the sensing process, resulting in hydrolysis and cyclization products which are highly emissive. The sensing properties of iridium(iii) complexes are also investigated by ESI-MS spectrometry and 1H NMR spectroscopy. [ABSTRACT FROM AUTHOR]

The designed synthesis of a sensitive phosphorescent chemosensor [Ir(ppy)2(L1)](PF6) (1) (Hppy = 2-phenylpyridine, L1 = 4′-methyl-2,2′-bipyridyl-4-carbaldehyde oxime) was carried out for selective detection of hypochlorite (ClO−). Complex 1is weakly emissive in solution at ambient temperature due likely to rapid isomerization of CN–OH as an effective non-radiative decay process. When 1reacts with ClO−, however, the emission is remarkably enhanced, in which the oxime in L1 is converted to a carboxylic acid in L2 (4′-methyl-2,2′-bipyridine-4-carboxylic acid). The produced complex [Ir(ppy)2(L2)](PF6) (2) exhibits bright orange-yellow luminescence originating from [5d(Ir) → π*(bpy)] 3MLCT and [π(ppy) → π*(bpy)] 3LLCT triplet excited states as suggested from the DFT computational studies. The selective and competitive experiments reveal that complex 1shows high sensing selectivity and sensitivity for ClO−over other reactive oxygen species (ROS) and metal ions. [ABSTRACT FROM AUTHOR]

An iridium(iii)-containing phosphorescent chemosensor Ir(ppy)2(L)(PF6) (1, ppy = 2-phenylpyridine) containing a 2,2′-bipyridyl ligand (L) functionalized with an α,β-unsaturated ketone for selective detection of thiol was synthesized and characterized by spectroscopic and photophysical measurements. The structure of complex 1was determined by X-ray crystallography. In order to get an insight into 1,4-addition reactions of thiol to complex 1, the adduct 2from reaction of 1with benzenethiol was successfully prepared and characterized. Complex 1shows a lowest energy absorption at ca.450 nm, primarily ascribable to an intraligand charge transfer (ILCT) transition from the HOMO (π) resident on the fragment -C(O)C6H4N(C2H5)2to the LUMO (π*) localized on the 2,2′-bipyridyl moiety in the functionalized 2,2′-bipyridyl ligand as suggested from DFT computational studies. Complex 1is weakly emissive at ca.587 nm at ambient temperature, arising likely from the 3ILCT excited state. Upon addition of thiol to a semi-aqueous solution of complex 1, the lowest energy absorption is obviously blue-shifted and the emission is remarkably enhanced due probably to a conversion from the primary ILCT state to the predominant [π(ppy)→π*(L)] LLCT and the [5d(Ir)→π*(L)] MLCT state caused by the formation of the 1-thiol adduct. The sensing properties of 1to thiol were also investigated by ESI-MS spectrometry and 1H NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Two cationic cyclometallated iridium(iii) complexes with 2,2′-bipyridine-acylhydrazone were synthesized and characterized by spectroscopic and photophysical measurements. They exhibit remarkable aggregation-induced phosphorescent emission (AIPE) phenomenon which is caused by the restriction of rapid isomerization of the C=N bond in the acylhydrazone moiety and are supported by TD-DFT studies. They also act as a significant ‘off–on’ luminescent switch for Cu2+ which works as both catalyzer and oxidant in the sensing process, resulting in hydrolysis and cyclization products which are highly emissive. The sensing properties of iridium(iii) complexes are also investigated by ESI-MS spectrometry and 1H NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract: A series of cyclometallated iridium(III) acetylide complexes Ir(ppy)2(PPh3)(C:hsp sp="0.12" />=C6H5 3, C6H4But-4 4, C6F5 5, C6H4COMe-4 6, SiMe3 7) were synthesized by substitution of coordination chloride in precursor Ir(ppy)2(PPh3)Cl (2, ppy=2-phenylpyridine) with an acetylide ligand. These complexes are brightly luminescent in fluid dichloromethane at ambient temperature, originating from 3MLCT/3LLCT/3IL states as supported by TD-DFT studies. It is demonstrated that substitution of coordination chloride in precursor 2 (λ em =456 and 485nm, Φ em =1.6%) with an acetylide ligand results in obvious red-shift of the emission as well as significant enhancement of the luminescence efficiency in 3–7 (λ em =480–510nm, Φ em =9.5%–19%) since the energy level of non-emissive d–d transition is highly raised and thus d–d state deactivation is significantly suppressed. [Copyright &y& Elsevier]

Abstract: Reaction of cyclometallated iridium(III) complex Ir(ppy)2(PPh3)Cl (2, ppy=2-phenylpyridine) with dicyanamide or tricyanomethanide gave neutral mononuclear complexes Ir(ppy)2(PPh3)N(CN)2 (3a) or Ir(ppy)2(PPh3)C(CN)3 (3b), and dicyanamide/tricyanomethanide-linked binuclear iridium(III) complexes [{Ir(ppy)2(PPh3)}2N(CN)2]+ (4a) or [{Ir(ppy)2(PPh3)}2C(CN)3]+ (4b). Substitution of coordinated chloride in the precursor 2 with dicyanamide or tricyanomethanide improved significantly the luminescence properties of 3a–4b. Compared with that in the precursor 2 (1.6%), 2.2 to 9.3-fold enhancement of emission quantum yields was detected in 3a–4b. [Copyright &y& Elsevier]