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While photochemical transformations with sunlight almost exclusively utilize the UV-vis part of the solar spectrum, the majority of the photons emitted by the sun have frequencies in the near-infrared region. Phthalocyanines show high structural similarity to the naturally occurring light-harvesting porphyrins, chlorins, and mainly bacteriochlorins and are also known for being efficient and affordable near-infrared light absorbers as well as triplet sensitizers for the production of singlet oxygen. Although having been neglected for a long time in synthetic organic chemistry due to their low solubility and high tendency toward aggregation, their unique photophysical properties and chemical robustness make phthalocyanines attractive photocatalysts for the application in near-infrared-light-driven synthesis strategies. Herein, we report a cheap, simple, and efficient photocatalytic protocol, which is easily scalable under continuous-flow conditions. Various phthalocyanines were studied as near-infrared photosensitizers in oxidative cyanations of tertiary amines to generate α-aminonitriles, a synthetically versatile compound class.

Cr(ppy) 3 , a structural analog of the green phosphorescent Ir(ppy) 3 , emits even in solution at room temperature from a weakly distorted spin-flip state at 910 nm (Hppy = 2-phenylpyridine). The low energy arises from an enhanced covalence of the Cr-C bonds as compared to Cr-N bonds. Lower temperature reduces thermally activated decay increasing the emission intensity.

New cationic metallo ligands L1-L3 based on bis(terpyridine) ruthenium(II) complexes decorated with differently substituted 2,2'-bipyridines attached via amide groups (5-NHCO-bpy, 4-CONH-bpy, 5-CONH-bpy) were prepared. Coordination of Re(I)Cl(CO)(3) fragments to the bpy unit gives the corresponding bimetallic Ru~Re complexes 1-3. Hydrogen bonds of the bridging amide groups to [PF(6)](-) counterions or to water molecules are observed both in the solid state and in solution. The impact of the amide orientation, the connecting site, and the coordination of counterions on redox and photophysical properties is explored. Both the metallo ligands L1-L3 and the bimetallic complexes 1-3 are emissive at room temperature in fluid solution. The emission originates from (3)MLCT(Ru) states in all cases. Accordingly, the first oxidation of L1-L3 and 1-3 to [L1](+)-[L3](+) and [1](+)-[3](+) is assigned to the Ru(II/III) couple, while the first reduction to [L1](-)-[L3](-) and [1](-)-[3](-) occurs at the tpy-CO ligand as shown by UV/vis, IR, and EPR spectroscopy of the chemically generated radicals. Under rapid freezing conditions, radicals [2](-) and [3](-) are stabilized as different valence isomers with the odd electron localized at the [bpy-CO](•) bridging unit instead of the [tpy-CO](•). Furthermore, in radical [3](-) this valence equilibrium is shifted from [bpy-CO](•) to [tpy-CO](•) by coordination of [PF(6)](-) counterions to the bridging amide unit and back by replacing the [PF(6)](-) counterion with [BPh(4)](-). Photoinduced electron transfer (λ(exc) = 500 nm) to L1-L3 and to 1-3 is successful using triethanolamine (TEOA) as a reducing agent. Photocatalytic reduction of CO(2) by TEOA and 1-3 is hampered by the wrong site of electron localization in the one-electron reduced species [1](-)-[3](-).

Oligoferrocenes Fmoc-Fca(n)-OMe (n=3-5) are assembled in a stepwise precise manner from Fmoc-protected ferrocene amino acid Fmoc-Fca-OH (H-Fca-OH = 1-amino-1'-ferrocene carboxylic acid; Fmoc = 9-fluorenylmethyloxycarbonyl) via amide bonds on solid supports by sequential Fmoc deprotection, acid activation and coupling steps. The resulting well-defined oligomers form ordered zigzag structures in THF solution with characteristic hydrogen bonding patterns. Electrochemical experiments reveal sequential oxidations of the individual ferrocene units in these peptides giving mixed-valent cations. Optical intervalence electron transfer is detected by intervalence transitions in the near-IR., (© The Royal Society of Chemistry 2011)

A solid-phase synthesis approach for a class of molybdenum carbonyl complexes has been developed. The system can be used to perform metal-complexation, ligand substitution reactions and oxidative eliminations on the solid phase and to cleave the final complexes under mild and selective conditions. Comparison is made to corresponding soluble complexes and liquid-phase reactions.