A series of platinum(II) terpyridyl acetylide complexes, [Pt(trpy)(CtCR)]PF 6 (R ) C 6 H 5 , C 6 H 4 Cl-4, C 6 H 4 CH 3 -4, C 6 H 4 OCH 3 -4, C 6 H 4 NO 2 -4, benzo-15-crown-5, C 6 H 3 -(OCH 3 ) 2 -3,4), have been synthesized and characterized. Their luminescence and electrochemical behaviors have been studied. The ion-binding properties of [Pt(trpy)(CtC-benzo-15-crown-5)]PF 6 and the X-ray crystal structure of [Pt(trpy)(CtCC 6 H 5 )]PF 6 are also reported.

A series of mono-and multinuclear dicyclometalated platinum(II) complexes, namely, [Pt-(C ∧ N ∧ C)L 1 ] [HC ∧ N ∧ CH ) 2,6-diphenylpyridine; L 1 ) 4-tert-butylpyridine (1), 1-methyl-4,4′bipyridinium (MQ + ) hexafluorophosphate (2(PF 6 )), 2,6-dimethylphenylisocyanide (4), tricyclohexylphosphine (5), triphenylphosphine ( 7) pyrazine (pyr; 3), bis(dicyclohexylphosphino)methane (dcpm; 6), bis(diphenylphosphino)methane (dppm; 8)], and [Pt 3 (C ∧ N ∧ C) 3 (µ 3 -dpmp)] [dpmp ) bis(diphenylphosphinomethyl)phenylphosphine (9)], were synthesized from [Pt(C ∧ N ∧ C)dmso] (dmso ) dimethyl sulfoxide). The X-ray crystal structures of 1, 3‚CHCl 3 , 4, 6‚CHCl 3 ‚CH 3 OH‚4H 2 O, 7, 8 (yellow form), and 8‚CHCl 3 (orange form) have been determined. For complex 1, the Pt(C ∧ N ∧ C) units are oriented into pairs in a head-to-tail fashion with an interplanar separation of 3.40 Å. For complex 4, dimeric π-π overlap between Pt(C ∧ N ∧ C) and phenyl moieties in a head-to-tail manner is observed, with interplanar stacking at 3.39 Å. There are two crystal forms for complex 8. Only one intramolecular Pt(C ∧ N ∧ C)-phenyl π-π interaction (separation 3.381 Å) is apparent in the yellow form. For the orange form (8‚CHCl 3 ), there are two intramolecular Pt(C ∧ N ∧ C)-phenyl π-π contacts (separations 3.115 and 3.287 Å). For 3‚CHCl 3 , the dihedral angles between the pyrazine and the two Pt(C ∧ N ∧ C) planes are 124.0°and 130.5°, which allows the possibility for partial orbital interaction between the (5d)Pt and pπ*(pyrazine) orbitals. Complexes 1 and 4-9 display vibronically structured emission (λ max of most intense band ) 508-526 nm) in 77 K methanol/ethanol (1:5, v/v) glass, which are assigned to 3 IL excited states. For 1, 4-6, 8, and 9, the 77 K structureless emission at λ max 596-636 nm in methanol/ethanol glasses is assigned as ππ* excimeric in nature. These excimeric emissions are concentrationdependent for 1 and 4-6 and concentration-independent for 8 and 9. The 298 K solid emission spectra of 1, 4-6, 8, and 9 are characterized by a broad, unstructured band at λ max 566-633 nm, which red-shift in energy upon cooling to 77 K. These bands are comparable in energy to the 77 K glassy emissions and are similarly assigned. Complexes 2 and 3 show an intense absorption at λ max 410 (shoulder) and 456 nm, which are ascribed to the MLCT (5d)Pt f π*(1-methyl-4,4′-bipyridinium/pyrazine) transition, respectively. Likewise, the solid-state emissions of 2 and 3 at λ max 686 and 658 nm, respectively, are assigned as MLCT. The vapochromism of complex 8 has been investigated.

A spectroscopic and structural investigation of binuclear silver(I) complexes supported by aliphatic phosphine ligands, namely [Ag(PCy3)(O2CCF3)]2 (1), [Ag2(μ-dcpm)2]X2 (X = CF3SO3, 2; PF6, 3; dcpm = bis(dicyclohexylphosphino)methane), and [Ag2(μ-dcpm)(μ-O2CCF3)2] (4), is described. X-ray structural analyses of 1−4 reveal Ag−Ag separations of 3.095(1), 2.948 (av), 2.923 (av), and 2.8892(9) Å, respectively. Due to the optical transparency of the phosphine ligands, the UV−vis absorption band at 261 nm in CH3CN for 2 and 3 is assigned to a 4dσ* → 5pσ transition originating from Ag(I)−Ag(I) interactions. The argentophilic nature of this band is verified by the resonance Raman spectrum of 2 with 273.9 nm excitation, where virtually all of the Raman intensity appears in the Ag−Ag stretch fundamental (80 cm-1) and overtone bands. Complexes 2 and 3 exhibit photoluminescence in the solid state at room temperature.

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We present the synthesis and photophysical and electroluminescent properties for a series of platinum(II) alpha-diimine bis(arylacetylide) complexes. The molecular structures of five derivatives have been elucidated by X-ray crystallography. Intermolecular pi-pi interactions (between aromatic diimine and phenylacetylide moieties) are apparent in the crystal lattices of two of these. All bis(phenylacetylide) derivatives exhibit intense triplet metal-to-ligand charge transfer (MLCT) photoluminescence in the solid state and in fluid solutions at room temperature. The impact of different solvents, substituents on the diimine ligands, and complex concentrations upon their emissive behavior have been examined and demonstrates that their emission energies can be systematically modified. Application of the 3MLCT excited state of the [Pt(alpha-diimine) (C(triple bond)CPh)2] materials in single- and double-layer organic light-emitting devices are described. The bis(butadiynyl) complex [Pt(4,4'-dtbpy)(C(triple bond)C-C(triple bond)CPh)2] (dtbpy = 4,4'-di-tert-butyl-2,2'-bipyridine) displays strong solid-state and solution phosphorescence at 77 and 298 K; the associated excited state is proposed to arise from both acetylenic 3pi pi*(C(triple bond)C-C(triple bond)CPh) and 3MLCT [Pt --> pi*(diimine)] transitions.

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A series of luminescent mononuclear [(C ∧ N ∧ N)Pt(CtNR)]X (HC ∧ N ∧ N ) 6-phenyl-2,2′bipyridine; R ) t Bu (1), n Bu (2), i Pr (3), cyclohexyl (Cy, 4), X ) ClO 4 ; R ) 2,6-Me 2 C 6 H 3 (Ar′, 5), X ) PF 6 ) and [(C ∧ N ∧ N)Pt(CO)]CF 3 SO 3 (6(CF 3 SO 3 )) and binuclear [{(C ∧ N ∧ N)Pt} 2 (µ-Ct N(CH 2 ) 3 NtC)](PF 6 ) 2 (7(PF 6 ) 2 ) complexes were synthesized, and their spectroscopic and photophysical properties have been investigated. The crystal lattices of 1(ClO 4 ) and 5(PF 6 ) reveal close [C ∧ N ∧ N] π-π intermolecular contacts (3.4-3.6 Å). Additional metal-metal interactions are evident in 5(PF 6 ) with intermolecular Pt-Pt distances of 3.3831(9) Å. At complex concentration greater than 5 × 10 -3 mol dm -3 , the UV-vis absorption spectrum of 2 displays a weak shoulder at 511 nm ( ) 120 dm 3 mol -1 cm -1 ), which does not obey Beer's law. A metal-metal-to-ligand charge transfer (MMLCTThe room-temperature emission spectrum of 4 for complex concentrations g 7 × 10 -3 mol dm -3 shows a low-energy band at 710 nm originating from a 3 MMLCT excited state. A corresponding well-defined low-energy absorption at 500 nm in the excitation spectrum of 4 (λ em 710 nm) is assigned to the 1 MMLCT transition. The 77 K emissions of complexes 1-6 in glassy solutions are sensitive to complex concentration. Upon increasing concentrations from 5 × 10 -5 to 2 × 10 -3 mol dm -3 for 1-4, red emissions at 600-625 nm ascribed to π-π excimeric excited states develop at the expense of the vibronic 3 MLCT emissions at λ max ∼502 nm. Complexes 2 and 4 show additional low-energy emissions at 739 and 710 nm, respectively, attributable to 3 MMLCT states. Concentrated 77 K glassy solutions of complexes 5-7 exhibit 3 MMLCT emissions (λ max 711-744 nm). The broad structureless solid-state luminescence of 2(ClO 4 ), 3(ClO 4 ), 5(PF 6 ), 6(CF 3 SO 3 ), and 7(PF 6 ) 2 at 298 K (λ max 701-748 nm) and 77 K (λ max 744-813 nm) are assigned to 3 MMLCT excited states arising from intermolecular stacking interactions in the solid state. The spectroscopic properties of the related [(C ∧ N ∧ C)Pt(L)] (HC ∧ N ∧ CH ) 2,6-diphenylpyridine; L ) CO and CtNAr′) solids are compared, and no MMLCT emission is evident.

The synthesis of a series of mono- and binuclear cyclometalated gold(III) complexes containing the tridentate C∧N∧C ligand (HC∧N∧CH = 2,6-diphenylpyridine) was developed using K[AuCl4] and the organomercury(II) compound Hg(C∧N∧CH)Cl as precursors. The molecular structures of [Au(C∧N∧C)(Spy-2)] (Spy-2 = 2-mercaptopyridine), [Au(C∧N∧C)PPh3]ClO4, [Au2(C∧N∧C)2(μ-dppm)](ClO4)2, and [Au2(C∧N∧C)2(μ-dppe)](ClO4)2 have been determined by X-ray crystallography. In the crystal lattice of [Au2(C∧N∧C)2(μ-dppm)](ClO4)2 and [Au2(C∧N∧C)2(μ-dppe)](ClO4)2, interplanar separations of 3.4 Å are observed between the intramolecular [Au(C∧N∧C)] moieties, which imply the presence of weak π−π interactions. The torsion angle between the two [Au(C∧N∧C)] units in the former is 8.7°, while a larger angle (34.2°) is observed in the latter. In the absorption spectra, the binuclear complexes show a red shift for the absorption band in the near-visible region compared to the mononuclear analogues. This is attributed to π−π interactions between the intramolecular C∧N∧C ligands in solution. The new complexes are emissive at low temperatures (77 K) in acetonitrile.