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Abstract: A series of gold(I) iodide complexes 1–11 have been prepared from di‐, tri‐, and tetraphosphane ligands. Crystallographic studies reveal that the di‐ (1–7) and tetrametallic (11) compounds feature linearly coordinated gold(I) ions with short aurophilic contacts. Their luminescence behavior is determined by the combined influence of the phosphane properties, metal–metal interaction, and intermolecular lattice‐defined interactions. The proposed variable contribution of 3(X+M)‐centered (X=halogen; M=metal) and 3XLCT (halogen to ligand charge transfer) electronic transitions into the lowest lying excited state, which is influenced by supramolecular packing, is presumably responsible for the alteration of room‐temperature emission color from green (λ=545 nm, for 11) to near‐IR (λ=698 nm, for 2). Dinuclear compounds 6 and 7 exhibit distinct luminescence thermochromism with a blueshift up to 5750 cm−1 upon cooling. Such dramatic change of emission energy is assigned to the presence of two coupled triplet excited states of 3ππ* and 3(X+M)C/3XLCT nature, the presence of which depends on both molecular structure and the crystal lattice arrangement. [ABSTRACT FROM AUTHOR]

Abstract: The series of cyanide‐bridged coordination polymers [(P2)CuCN]n (1), [(P2)Cu{M(CN)2}]n (M=Cu 3, Ag 4, Au 5) and molecular tetrametallic clusters [{(P4)MM'(CN)}2]2+ (MM′=Cu26, Ag27, AgCu 8, AuCu 9, AuAg 10) were obtained using the bidentate P2 and tetradentate P4 phosphane ligands (P2=1,2‐bis(diphenylphosphino)benzene; P4=tris(2‐diphenylphosphinophenyl)phosphane). All title complexes were crystallographically characterized to reveal a zig‐zag chain arrangement for 1 and 3–5, whereas 6–10 possess metallocyclic frameworks with different degree of metal‐metal bonding. The d10–d10 interactions were evaluated by the quantum theory of atoms in molecules (QTAIM) computational approach. The photophysical properties of 1–10 were investigated in the solid state and supported by theoretical analysis. The emission of compounds 1 and 3–5, dominated by metal‐to‐ligand charge transfer (MLCT) transitions located within {CuP2} motifs, is compatible with thermally activated delayed fluorescence (TADF) behaviour and a small energy gap between the T1 and S1 excited states. The luminescence characteristics of 6–10 are strongly dependent on the composition of the metal core; the emission band maxima vary in the range 484–650 nm with quantum efficiency reaching 0.56 (6). The origin of the emission for 6–8 and 10 at room temperature is assigned to delayed fluorescence. AuCu cluster 9, however, exhibits only phosphorescence that corresponds to theoretically predicted large value ΔE(S1−T1). DFT simulation highlights a crucial impact of metallophilic bonding on the nature and energy of the observed emission, the effect being greatly enhanced in the excited state. [ABSTRACT FROM AUTHOR]

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]

The Schiff base NNO ligand 1‐(furan‐2‐yl)‐N‐[(2‐methyl‐1H‐imidazol‐4‐yl)methylene]methanamine was synthesized and structurally characterized by XRD crystallography, mass spectrometry, and NMR spectroscopy. Quantum‐chemical calculations revealed conformational flexibility of the ligand backbone to give two different conformations with nearly equal ground‐state energies. The orientation of two nitrogen atoms and the oxygen atom in one conformation is a good fit for the NNO tridentate coordination mode, whereas the other would allow the NN coordination mode only. Two lanthanide complexes [Ln(tta)3(NNO)] (Ln = EuIII and LuIII; tta = thenoyltrifluoroacetone) were prepared and studied spectroscopically. The structures of the complexes were optimized by the DFT approach. The NNO ligand in the Eu complex displays tridentate NNO coordination, whereas the ligand is only NN‐coordinated in the Lu complex. The Eu complex shows bright red metal‐centered phosphorescence under excitation into the ligand (π–π*) absorption bands with a quantum yield of ca. 80 % and a lifetime of 580 μs. A mechanism for energy transfer between the ligands and metal centers was suggested and confirmed by DFT and time‐dependent DFT (TDDFT) studies. An organic light‐emitting diode (OLED) device based on the Eu complex incorporated into a poly(9‐vinylcarbazole) (PVK) matrix was prepared. A study of the characteristics of the device revealed electrochromism of the system owing to variations in the efficacy of metal‐centered and matrix emission at different strengths of applied electric field.Neutral EuIII and LuIII diketonate complexes with a Schiff base NNO ligand are studied spectroscopically. The Eu complex shows red metal‐centered phosphorescence with a quantum yield of ca. 80 %. An organic light‐emitting device (OLED) with the Eu complex in a poly(9‐vinylcarbazole) (PVK) matrix reveals electrochromism owing to variations in the efficacy of the metal‐centered and matrix emission. [ABSTRACT FROM AUTHOR]

The novel heterobimetallic Au(i)–M(i) (M = Cu, Ag) alkynyl-diphosphine clusters were effectively prepared using a family of dialkynyl-based diphosphines, PPh2–C2–(C6H4)n–C2–PPh2(n= 0–2). These compounds consist of [AuxMy(C2C6H4R)2x]y−xclusters (x= (n+ 2)(n+ 3)/2; y= (n+ 1)(n+ 2)) “wrapped” in gold–diphosphine “belts” (M = Cu, n= 0, R = H (4); n= 1, R = H (6), OMe (8), NMe2(9). M = Ag, n= 0, 1, 2, R = H (5, 7, 10). The solid-state structures of 5and 6have been determined by X-ray crystallographic studies, other complexes were characterized by NMR spectroscopy and ESI-MS measurements. The luminescence behavior of these compounds has been studied both in the solid state and solution, and intense room-temperature emission in fluid medium with maximum quantum yield of 0.5 (6) was detected. Computational studies have been carried out and the theoretical results obtained are in good agreement with the experimental data. The calculations provided additional information on the structural and electronic properties of the aggregates under investigation and allowed for the rationalization of the difference in their photophysical behavior. [ABSTRACT FROM AUTHOR]

The noncovalent intermolecular interactions (π-π stacking, metallophilic bonding) of the cyclometalated complexes [Pt(NCN)L]+X- (NCN = dipyridylbenzene, L = pyridine (1), acetonitrile (2)) are determined by the steric properties of the ancillary ligands L in the solid state and in solution, while the nature of the counterion X- (X- = PF6 -, ClO4 -, CF3SO3 -) affects the molecular arrangement of 2·X in the crystal medium. According to the variable-temperature X-ray diffraction measurements, the extensive Pt···Pt interactions and π-stacking in 2·X are significantly temperature-dependent. The variable concentration ¹H and diffusion coefficients NMR measurements reveal that 2·X exists in the monomeric form in dilute solutions at 298 K, while upon increase in concentration [Pt(NCN)(NCMe)]+ cations undergo the formation of the ground-state oligomeric aggregates with an average aggregation number of ∼3. The photoluminescent characteristics of 1 and 2·X are largely determined by the intermolecular aggregation. For the discrete molecules the emission properties are assigned to metal perturbed IL charge transfer mixed with some MLCT contribution. In the case of oligomers 2·X the luminescence is significantly red-shifted with respect to 1 and originates mainly from the ³MMLCT excited states. The emission energies depend on the structural arrangement in the crystal and on the complex concentration in solution, variation of which allows for the modulation of the emission color from greenish to deep red. In the solid state the lability of the ligands L leads to vapor-induced reversible transformation 1 ↔ 2 that is accompanied by the molecular reorganization and, consequently, dramatic change of the photophysical properties. Time-dependent density functional theory calculations adequately support the models proposed for the rationalization of the experimental observations. [ABSTRACT FROM AUTHOR]

Two-photon microscopy reveals several advantages over conventional one since it provides higher spatial resolution as well as deeper penetration into the sample under study. The development of suitable two-photon probes is one of the most challenging tasks in this area. Here we present phosphorescent non-covalent adduct of human serum albumin and Au-Ag alkynyl-diphosphine complex, [Au 14 Ag 4 (C 2 Ph) 12 (PPh 2 C 6 H 4 PPh 2 ) 6 ][PF 6 ] 4 , which exhibits high cross section of two-photon-induced luminescence ( δ TPE ) within large near-infrared excitation wavelength region (700–800 nm) with maximum δ TPE about 38 GM at 740 nm. This feature makes it a promising probe for multiphoton bioimaging as demonstrated by successful visualization of glioma C6 cells and various tissues by two-photon confocal microscopy both in planar and z -stacking modes. Additionally, the broad excitation region enables optimization of the signal-to-background auto-fluorescence ratio via variation of excitation wavelength. [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]