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Reaction of [Au(tht)2](ClO4) (tht = tetrahydrothiophene), [Cu(CH3CN)4](ClO4), 3,6-di-tert-butyl-1,8-diethynyl-9H-carbazole (H3decz), and bis(2-diphenylphosphinophenyl)ether (POP) in the presence of triethylamine (NEt3) gave the cluster complex Au4Cu2(decz)2(POP)2 as yellow crystals. As revealed by X-ray crystallography, the Au4Cu2 cluster exhibits scissor-like structure sustained by two decz and two POP ligands and stabilized by Au-Cu and Au-Au interactions. The Au4Cu2 cluster shows bright yellow to orange photoluminescence upon irradiation at >300 nm, arising from 3[π (decz)→5d (Au)] 3LMCT (ligand-to-metal charge transfer) and 3[π→π* (decz)] 3IL (intraligand) triplet states as revealed by theoretical and computational studies. When it is mechanically ground, reversible phosphorescence conversion from yellow to red is observed owing to more compact molecular packing and thus stronger intermetallic interaction. Variable-temperature luminescence studies reveal that it displays distinct red-shifts of the emission whether the temperature is elevated or lowered from ambient temperature, suggestive of exceptional thermochromic phosphorescence characteristics. [ABSTRACT FROM AUTHOR]

Three quinoline-based zinc(ii)–Schiff base complexes were synthesized and characterized by X-ray crystallography. They exhibit remarkable aggregation-induced emission enhancement (AIEE) in acetonitrile/diethyl ether mixtures due to the conversion of weak luminescence in homogeneous solution into strong emission in the nano-aggregated phase after increasing the fractions of diethyl ether. Interestingly, the AIEE performance can be significantly promoted by joining the two quinoline units through an alkoxy chain. Moreover, they show reversible mechanochromic luminescence behavior between dark and bright states during the grinding–fuming cycles, due to the modulation of morphologies between amorphous and crystalline states. Introducing an electron donating group in the para-position of aniline significantly improves the mechanochromic luminescence effect with a more accessible and distinct emission colour contrast. The molecular packing in the crystalline phase and time-dependent density functional theory (TD-DFT) calculations demonstrate that multiple intermolecular C–H…π and π–π interactions significantly strengthen the molecular rigidity and enhance the intramolecular charge-transfer (ICT) characteristics, leading to the effective emission enhancement in crystalline/nano-aggregated states. The novel AIEE and reversible mechanochromic luminescence properties point to the promising potential applications of these complexes in smart fluorescent materials. [ABSTRACT FROM AUTHOR]

The planar platinum(ii) complex [Pt(Me3SiC≡CbpyC≡CSiMe3)(C≡CC6H4Et-4)2] (1) with 5,5-bis(trimethylsilylethynyl)-2,2′-bipyridine was prepared and characterized. Solid-state 1 exhibits unusual, selective and reversible luminescence vapochromism to CH3CN and ClCH2CN vapors, which is useful for the detection of these hazardous vapors. A vapochromic cycle was monitored by dynamic variations in emission spectra and X-ray diffraction (XRD) patterns. Both X-ray crystallographic and density functional theory studies suggest that the vapochromic and vapoluminescent behavior of 1 are induced by the variation in the intermolecular Pt–Pt interactions. [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 copper(II) complexes of disubstituted 2,2'-bipyridine (bpy = 2, 2'-bipyridine) with tetraalkylammonium groups, [Cu(L1)2Br](ClO4)5·2H2O (1) and [Cu(L2)2Br](ClO4)5·H2O (2) (L1 = [4, 4'-(Et3NCH2)2-bpy]2+, L2 = [4, 4'-((n-Bu)3NCH2)2-bpy]2+), have been synthesized and characterized. X-ray crystallographic study of 1 indicates that Cu(II) is a distorted trigonal bipyramidal or square pyramid. DNA binding of both complexes was studied by UV spectroscopic titration. In the presence of reducing reagents, the cleavage of plasmid pBR322 DNA mediated by both complexes was investigated and efficient oxidative cleavage of DNA was observed. Mechanistic study with reactive oxygen scavengers indicates that hydrogen peroxide and singlet oxygen participate in DNA cleavage. [ABSTRACT FROM AUTHOR]

Heterotetranuclear geometrical (Er2Yb2/Yb2Er2) and configuational (EuTb3/Eu3Tb) isomeric lanthanide(III) complexes havebeen synthesizedand characterized by spectroscopy as well as X-ray crystallography.The geometric Er2Yb2/Yb2Er2isomers exhibit dual emissions from both erbium(III) and ytterbium(III)ions. For the EuTb3/Eu3Tb configurational isomers,the TbIIIsubunits transfer energy to the EuIIIcenters in the EuTb3complex, whereas the TbIIIion in the TbEu3complex serves mainly as a structuralstabilizer. [ABSTRACT FROM AUTHOR]

Reactions of Pt(diimine)(tdt) (tdt = 3,4-toluenedithiolate) with [M2(dppm)2(MeCN)2]²+ (M = CuΙ or AgΙ, dppm = bis(diphenylphosphino)methane) gave heterotrinuclear complexes [PtCu2(tdt)(μ-SH)(dppm)3](CIO4)(1) and [PtCu2-(diimine)a(tdt)(dppm)2](CIO4)2 (diimine = 2,2′-byridine (bpy) 2; 4,4′-dimethyl-2,2′-bipyridine (dmbpy) 3; phenanthroline (phen) 4, 5-bromophenanthroline (Brphen) 5) for M - CuΙ, but [PtAg2(tdt)(μ-SH)(dppm)3](SbF6) (6) and [PtAg2(diimine)(tdt)(dppm)2](SbF6)2 (diimine = bpy 7; dmbpy 8; phen 9; Brphen 10) for M = AgΙ. While the complexes [PtAg2(diimine)(tdt)(dppm)2](SbF6)2 (7–10) result from linkage of Pt(diimine)(tdt) and [M2(dppm)2(MeCN)2]²+ by tdt sulfur donors, formation of [PtCu2(diimine)2(tdt)(dppm)2](ClO4)2 (2–5) is related to rupture of metal-ligand bonds in the metal components and recombination between the ligands and the metal atoms by self-assembly. The formation of 1 and 6 is involved not only in dissociation and recombination of the metal components, but also in disruption of C-S bonds in the dithiolate (tdt). The dithiolate tdt adopts a chelating and bridging coordination mode in anti conformation for [PtCu2(diimine)2(tdt)(dppm)2](CIO4)2 (2–5), whereas there is the syn conformation for other complexes. Compounds 1 and 6 represent sparse examples of μ-SH-bridged heterotrinuclear PtΙΙMΙ2 complexes, in which PtΙΙ-MΙ centers are bridged by dppm and sulfur donors of tdt, whereas MΙ-MΙ (M = Cu for 1; Ag for 6) centers are linked by dppm and the μ-SH donor. The 31P NMR spectra show typical platinum satellites (JPt-P = 1450–1570 Hz) for 1–6 and Ag-P coupling for PtΙΙ-AgΙ (JAg-P = 350–450 Hz) complexes 6–10. All of the complexes show intense emission in the solid state and in frozen glasses at 77 K. The complexes [PtAg2(diimine)(tdt)(dppm)2](SbF6)2 (7–10) also afford emission in fluid acetonitrile solutions at room temperature. Solid-state emission lifetimes at room temperature are in the microsecond range. It is revealed that emission energies of the trinuclear heterometallic complexes [PtAg2(diimine)(tdt)(dppm)2](SbF6)2 (7–10) exhibit a remarkable blue shift (0.10–0.35 eV) relative to those of the precursor compounds Pt(diimine)(tdt). The crystal structures of 1, 2, 4, 6, 8, and 9 were determined by X-ray crystallography. [ABSTRACT FROM AUTHOR]

Two new blue luminescent silver(I) complexes have been successfully synthesized from mixed-ligand of 2-diphenylphosphinopyridine and N(CN) 2 − or C(CN) 3 −. Both complexes exhibit strong blue emission with phosphorescent quantum yields of 13.4% and 39.2% in solid state. • Two stable silver(I) complexes were synthesized through a mixed-ligand strategy. • They display 0D or 1D structures depending on the geometry of bridging ligand. • They exhibit strong blue emission with high phosphorescent quantum yields. Two new silver(I) complexes 2-diphenylphosphinopyridine (dppy), {Ag 2 (dppy) 2 [N(CN) 2 } 2 μ -N(CN) 2 2 (1) and {Ag 2 (dppy) 2 μ -C(CN) 3 2 } n (2) linked by dicyanamide (N(CN) 2 −) or tricyanomethanide (C(CN) 3 −) were synthesized and characterized by X-ray crystallography. Complex 1 forms a tetranuclear structure with two binucleate moieties [Ag 2 (dppy) 2 + linked by two dicyanamide ligands. Interestingly, when bridging ligand is changed to tricyanomethanide, complex 2 displays one-dimensional infinite chain structure. Both complexes exhibit strong blue emission with phosphorescent quantum yields of 13.4% for 1 and 39.2% for 2 in solid state. [ABSTRACT FROM AUTHOR]