Novel D-A-D Fluorescent Dyes Based on 9-(p-Tolyl)-2,3,4,4a,9,9a-hexahydro-1H-carbazole as a Donor Unit for Solution-Processed Organic Light-Emitting-Diodes.

New fluorescent D-A-D dyes containing 9-(p-tolyl)-2,3,4,4a,9,9a-hexahydro-1H-carbazole as a donor unit and 2,1,3-benzochalcogenadiazoles as an electron-withdrawing group were synthesized. The photoluminescent and electroluminescent properties of novel dyes for fluorescent OLED application were investigated. It was demonstrated that the replacement of lightweight heteroatoms by heavier ones enables the fine tuning of the maximum emission without significantly reducing the luminescence quantum yield. The maximum quantum yield value of 62.6% for derivatives based on 2,1,3-benzoxadiazole (1a) in cyclohexane was achieved. Two devices with the architecture of glass/ITO/PEDOT-PSS/poly-TPD/EML/TPBi/LiF/Al (EML = emitting layer) were fabricated to check the suitability of the synthesized compounds as a single active emission layer in OLED. These OLEDs exhibited clear red electroluminescence of the dyes with the maximum current efficiency of 0.85 Cd/A.

DFT Study of Molecular and Electronic Structure of Ca(II) and Zn(II) Complexes with Porphyrazine and tetrakis(1,2,5-thiadiazole)porphyrazine.

Electronic and geometric structures of Ca(II) and Zn(II) complexes with porphyrazine (Pz) and tetrakis(1,2,5-thiadiazole)porphyrazine (TTDPz) were investigated by density functional theory (DFT) calculations and compared. The perimeter of the coordination cavity was found to be practically independent on the nature of a metal and a ligand. According to the results of the natural bond orbital (NBO) analysis and quantum theory of atoms in molecules (QTAIM) calculations, Ca-N bonds possess larger ionic contributions as compared to Zn-N. The model electronic absorption spectra obtained with the use of time-dependent density functional theory (TDDFT) calculations indicate a strong bathochromic shift (~70 nm) of the Q-band with a change of Pz ligand by TTDPz for both Ca and Zn complexes. Additionally, CaTTDPz was synthesized and its electronic absorption spectrum was recorded in pyridine and acetone.

Photoactive Hexanuclear Molybdenum Nanoclusters Embedded in Molecular Organogels.

Hexanuclear molybdenum clusters are attractive species because of their outstanding photonic properties, and in the past they have been attached to a variety of supports such as organic polymers and inorganic nanoparticles, as described in the recent literature. Here, a cluster of the formula TBA2[Mo6I8Ac6] (TBA = tetrabutylammonium; Ac = acetate) has been supported on molecular organogels for the first time, resulting in a new soft material with remarkable photoactivity. Electron and confocal microscopic analyses showed the alignment of the nanoclusters to 1D self-assembled fibers formed by the organic gelator, and emission spectroscopy corroborated the interaction of the emissive clusters with such fibrillary structures. The new hybrid system is a deep-red emissive material (phosphorescence maximum at ca. 680 nm), with chromatic coordinates x = 0.725 and y = 0.274, capable of efficiently generating singlet oxygen (1O2) upon illumination with white light, as demonstrated by the photooxygenation of 9,10-dimethylanthracene and 1,5-dihydroxynaphthalene. The organogels can been made in dichloromethane and toluene and in both solvents display phosphorescence emission and photocatalytic properties.

Synthetic Tuning of Redox, Spectroscopic, and Photophysical Properties of {Mo6I8}(4+) Core Cluster Complexes by Terminal Carboxylate Ligands.

The reactions between the tetra-n-butylammonium salt of [{Mo6I8}I6](2-) and silver carboxylates RCOOAg (R = CH3 (1), C(CH3)3 (2), α-C4H3O (3), C6H5 (4), α-C10H7 (5), or C2F5 (6)) in CH2Cl2 afforded new carboxylate complexes [{Mo6I8}(RCOO)6](2-). The complexes were characterized by X-ray single-crystal diffraction and elemental analysis, cyclic/differential pulse voltammetry, and IR, NMR, and UV-visible spectroscopies. The emission properties of the complexes 1-6, and those of the earlier reported complexes with R = CF3 (7) and n-C3F7 (8), were studied both in acetonitrile solution and in the solid state. In deaerated CH3CN at 298 K, all of the complexes 1-8 exhibit intense and long-lived emission with the quantum yield and lifetime being 0.48-0.73 and 283-359 µs, respectively. The oxidation (Eox)/reduction (Ered) potentials of the complexes correlate linearly with the pKa value of the terminal carboxylate ligands L = RCOO (pKa(L)). Reflecting the pKa(L) dependences of Eox/Ered, the emission energy (νem) of the complexes was also shown to correlate with pKa(L). The present study successfully demonstrates synthetic tuning of the redox, spectroscopic, and photophysical characteristics of a {Mo6I8}(4+)-based cluster complex with pKa(L).

Alkynyl complexes of high-valence clusters. synthesis and luminescence properties of [Mo6I8(C≡CC(O)OMe)6]2-, the first complex with exclusively organometallic outer ligands in the family of octahedral {M6X8} clusters.

The reaction of [Mo6I14](2-) with methyl propiolate HC≡CC(O)OMe in the presence of Ag(+) and Et3N yielded the new luminescent complex [Mo6I8(C≡CC(O)OMe)6](2-), the first fully organometallic complex in the family of octahedral {M6X8} clusters. The cluster was crystallized as tetraphenylphosphonium salt and characterized by X-ray single-crystal diffraction and elemental analyses, mass spectrometry, (13)C NMR, UV-vis, and luminescence spectroscopies.

Structure impact on photodynamic therapy and cellular contrasting functions of colloids constructed from dimeric Au(I) complex and hexamolybdenum clusters.

Electrostatically driven self-assembly of [Au2L2]2+ (L is cyclic PNNP ligand) with [{Mo6I8}(L')6]2- (L' = I-, CH3COO-) in aqueous solutions is introduced as facile route for combination of therapeutic and cellular contrasting functions within heterometallic colloids (Mo6-Au2). The nature of L' affects the size and aggregation behavior of crystalline Mo6-Au2 aggregates, which in turn affect the luminescence of the cluster units incorporated into Mo6-Au2 colloids. The spin trap facilitated electron spin resonance spectroscopy technique indicates that the level of ROS generated by Mo6-Au2 colloids is also affected by their size. Both (L' = I-, CH3COO-) Mo6-Au2 colloids undergo cell internalization, which is enhanced by their assembly with poly-DL-lysine (PL) for L' = CH3COO-, but remains unchanged for L' = I-. The colloids PL-Mo6-Au2 (L' = CH3COO-) are visualized as huge crystalline aggregates both outside and inside the cell cytoplasm by confocal microscopy imaging of the incubated cells, while the smaller sized (30-50 nm) PL-Mo6-Au2 (L' = I-) efficiently stain the cell nuclei. Quantitative colocalization analysis of PL-Mo6-Au2 (L' = CH3COO-) in lysosomal compartments points to the fast endo-lysosomal escape of the colloids followed by their intracellular aggregation. The cytotoxicity of PL-Mo6-Au2 differs from that of Mo6 and Au2 blocks, predominantly acting through apoptotic pathway. The photodynamic therapeutic effect of the PL-Mo6-Au2 colloids on the cancer cells correlates with their intracellular trafficking and aggregation.

Superior performance of macroporous over gel type polystyrene as a support for the development of photo-bactericidal materials.

A hexanuclear molybdenum cluster [Mo6I8Ac6]2- (1) has been ionically bound onto macroporous (Pmp) and gel-type (Pgel) resins and their performance as materials for the photodynamic inactivation of microorganisms has been studied. It has been found that 1@Pmp in combination with light is able to reduce 99.999999% of the population of Gram-positive Staphylococcus aureus whereas the activity of 1@Pgel is limited to a 99.99% reduction at the same light dose. The same trend is observed with Gram-negative Pseudomonas aeruginosa. A comprehensive study of both materials has been performed using confocal laser scanning microscopy, thermogravimetric analysis, nitrogen porosimetry, steady state and time resolved fluorometries and diffuse reflectance spectroscopy. The photochemical generation of singlet oxygen (1O2) has been assessed using 9,10-dimethylanthracene as a trap for this reactive oxygen species. It can be concluded that the nature of the polymeric support is of paramount importance for the development of surfaces with bactericidal properties.

A photobleaching resistant polymer supported hexanuclear molybdenum iodide cluster for photocatalytic oxygenations and photodynamic inactivation of Staphylococcus aureus.

The ability of a hexanuclear molybdenum cluster, [Mo6I8(CH3COO)6]2-, to carry out, upon irradiation, singlet oxygen mediated photocatalytic oxygenation reactions has been tested. This complex has been also supported on a solid polymeric matrix, yielding an immobilized photosensitizer with remarkable photostability and recyclability. Preliminary studies of antibacterial photoinactivation of Staphylococcus aureus have been conducted, with positive results.