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The bifunctional aminopyridine ligands H2N-(CH2) n-4-C5H4N ( n=0, L1; 1, L2; 2, L3) have been utilized for the preparation of the rhenium complexes [Re(phen)(CO)3( L1- L3)]+ ( 1- 3; phen=phenanthroline). Complexes 2 and 3 with NH2-coordinated L2 and L3, respectively, were coupled with cycloplatinated motifs {Pt(ppy)Cl} and {Pt(dpyb)}+ (ppy=2-phenylpyridine, dpyb=dipyridylbenzene) to give the bimetallic species [Re(phen)(CO)3(μ- L2/ L3)Pt(ppy)Cl]+ ( 4, 6) and [Re(phen)(CO)3(μ- L2/ L3)Pt(dpyb)]2+ ( 5, 7). In solution, complexes 4 and 6 show 3MLCT {Re}-based emission at 298 K, which changes to the 3IL(ppy) state at 77 K. The photophysical properties of compounds 5 and 7 display a pronounced concentration dependence, presumably due to the formation of bimolecular aggregates. Analysis of the spectroscopic data, combined with TD-DFT simulations, suggest that unconventional heteroleptic {Re(phen)}⋅⋅⋅{Pt(dpyb)} π-π stacking operates as the driving force for ground-state association. The latter, together with intra- and intermolecular energy-transfer processes, determines the appearance of multiple emission bands and results in nonlinear relaxation kinetics of the excited states. [ABSTRACT FROM AUTHOR]

Reactions of the [(tppm)Au3Cl3] [tppm = tris(diphenylphosphanyl)methane] precursor and CuI ions with a stoichiometric amount of the corresponding linear mono- [HC2(C6H4) nC6H5; n = 1, 2] and diacetylenes [HC2(C6H4) nC2H; n = 1-3] that contain extended polyaryl moieties afford a series of luminescent heterometallic complexes with a common structural motif based on the {(AuC2)3Cu} cluster core. The complexes obtained were characterized by using X-ray crystallography and NMR spectroscopy. All compounds studied display dual singlet and triplet luminescence, the former component of which can be completely suppressed in concentrated solution by a self-absorption phenomenon. The results of the photophysical measurements together with the quantum chemical calculations (PBE0-DFT level of theory) indicate that singlet emission originates mainly from copper-perturbed intraligand transitions, whereas the phosphorescence can be assigned to the {(AuC2)3Cu} core-centered transitions. Due to the low contribution of the gold atoms to the orbitals responsible for the singlet and triplet emission, the emissive excited states are very weakly coupled, thereby resulting in a negligible energy transfer between these excited states. [ABSTRACT FROM AUTHOR]

Coordination of P,N indolyl-phosphine ligands to AuI, AgIand CuImetal ions under weakly basic conditions results in easy deprotonation of the indolyl N–H function and effective formation of a family of homo- and heterobimetallic complexes MM′(PPh2C9H7N)2(M = M′ = Au (2), Ag (5); M = Au, M′ = Cu (3), Ag (4)). The latter (4) exists as an inseparable mixture of four different complexes, which are in equilibrium driven by slow dynamics. The reaction of silver(i) and copper(i) ions with PPh2(C9H8N) affords a rare tetranuclear Z-shaped cluster Ag2Cu2(PPh2C9H7N)4(6), which exhibits red luminescence in solid state (650 nm) and a weak dual emission in solution with the main component in the near-IR region (746 nm). [ABSTRACT FROM AUTHOR]

A family of triphosphine gold–copperclusters bearing aliphaticand hydroxyaliphatic alkynyl ligands of general formula [HC(PPh2)3Au3Cu(C2R)3]+(R = cyclohexyl (1), cyclopentyl (2), But(3), cyclohexanolyl (4), cyclopentanolyl (5), 2,6-dimethylheptanolyl (6), 2-methylbutanolyl (7), diphenylmethanolyl(8)) was synthesized via a self-assembly protocol, whichinvolves treatment of the (AuC2R)nacetylides with the (PPh2)3CH ligandin the presence of Cu+ions and NEt3. Additionof Cl–or Br–anions to complex 8results in coordination of the halides to the copper atomsto give neutral HC(PPh2)3Au3CuHal(C2COHPh2)3derivatives (Hal = Cl (9), Br (10)). The title compounds were characterizedby NMR and ESI-MS spectroscopy, and the structures of 1, 4, 7, and 8were determinedby single-crystal X-ray diffraction analysis. The photophysical behaviorof all of the complexes has been studied to reveal moderate to weakphosphorescence in solution and intense emission in the solid statewith a maximum quantum yield of 80%. Exposure of the solvent-freeX-ray amorphous samples 8–10(R =diphenylmethanolyl) to vapors of the polar solvents (methanol, THF,acetone) switches luminescence with a visible hypsochromic shift ofemission of 50–70 nm. The vapochromism observed is tentativelyascribed to the formation of a structurally ordered phase upon absorptionof organic molecules by the amorphous solids. [ABSTRACT FROM AUTHOR]