Tetrabutylammonium decatungstate (TBADT) accelerated the addition of C-H bonds to the N═N double bond of diisopropyl azodicarboxylate (DIAD) under irradiation conditions. The photoinduced three-component coupling between cyclic alkanes, CO, and DIAD was also achieved to give the corresponding acyl hydrazides.

Excited tetrabutylammonium decatungstate (TBADT), known to activate a variety of compounds via hydrogen atom transfer (HAT), has now been applied as a photoredox catalyst for the effective oxidative cleavage of benzyl silanes and radical benzylation of reducible olefins occurring in isolated yields from poor to excellent.

Atorvastatin calcium (ATV) is one of the most frequently prescribed drugs worldwide. Among the adverse effects observed for this lipid-lowering agent, clinical cases of cutaneous adverse reactions have been reported and associated with photosensitivity disorders. Previous work dealing with ATV photochemistry has shown that exposure to natural sunlight in aqueous solution leads to photoproducts resulting from oxidation of the pyrrole ring and from cyclization to a phenanthrene derivative. Laser flash photolysis of ATV, at both 266 and 308 nm, led to a transient spectrum with two maxima at lambda= 360 and lambda= 580 nm (tau= 41 micro), which was assigned to the primary intermediate of the stilbene-like photocyclization. On the basis of the absence of a triplet-triplet absorption, the role of the parent drug as singlet oxygen photosensitizer can be discarded. By contrast, a stable phenanthrene-like photoproduct would be a good candidate to play this role. Laser flash photolysis of this compound showed a triplet-triplet transient absorption at lambdamax = 460 nm with a lifetime of 26 micro, which was efficiently quenched by oxygen (kq = 3 (+/-0.2) x 10(9) M(-1) s(-1)). Its potential to photosensitize formation of singlet oxygen was confirmed by spin trapping experiments, through conversion of TEMP to the stable free radical TEMPO. The photoreactivity of the phenanthrene-like photoproduct was investigated using Trp as a marker. The disappearance of the amino acid fluorescence (lambdamax = 340 nm) after increasing irradiation times at 355 nm was taken as a measurement of photodynamic oxidation. To confirm the involvement of a type II mechanism, the same experiment was also performed in D2O; this resulted in a significant enhancement of the reaction rate. On the basis of the obtained photophysical and photochemical results, the phototoxicity of atorvastatin can be attributed to singlet oxygen formation with the phenanthrene-like photoproduct as a photosensitizer.

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A mechanism for triflusal‐induced photoallergy involving complexation of 2‐hydroxy‐4‐trifluoromethylbenzoic acid with site I of human serum albumin and subsequent formation of a covalent adduct by photoreaction between a metabolite and a neighboring lysine residue is proposed. This is supported by the observed photobinding to poly‐L‐lysine. Thereby, a photoantigen is generated, which is a likely trigger of the immune response. The goal of the work presented herein is to gain deeper insight into the molecular basis of photoallergy mediated by triflusal through its active metabolite, 2‐hydroxy‐4‐trifluoromethylbenzoic acid (HTB). For this purpose, the interaction between HTB and human serum albumin (HSA) was investigated by fluorescence and laser flash photolysis to monitor inclusion into the protein binding sites through variation in the excited‐state properties. A remarkable lengthening of HTB triplet lifetime in the presence of HSA was observed. The use of oleic acid as a displacement probe clearly suggests the preference for dark binding in site I. The mechanism of photobinding was studied by irradiation of HTB in the presence of amino acids, and, in the case of lysine, a photoadduct was detected that arises from nucleophilic attack by the ε‐amino group to the trifluoromethyl substituent of HTB. Accordingly, photobinding of the metabolite to poly‐L‐lysine was also observed. Overall, these results are consistent with a mechanism for triflusal photoallergy involving complexation of HTB to site I of HSA and subsequent formation of a covalent photoadduct with one neighboring lysine residue.

A straightforward PEGylation of SWCNTs has been performed by photomediated addition of various PEG derivatives onto the nanotube surfaces. The reaction was promoted both by UV and by solar light and took place under very mild conditions using commercial PEGs as PEGylating agents. The process relies on the formation of α‐oxy radicals directly from PEGs by a photochemical hydrogen abstraction reaction mediated by a decatungstate salt. Actually, low‐molecular‐weight PEGs (e.g. PEG 200) added more efficiently than those having long polyethylene glycol chains (e.g. PEG 600). Interestingly, the functionalization caused a partial dissolution of the resulting CNTs in the reaction medium.

Radical conjugate addition onto vinyl sulfones was achieved by means of a convenient, tinfree procedure. This was based on the photocatalyzed C À H bond activation in aldehydes, amides, ethers and even cycloalkanes by using tetrabutylammonium decatungstate (TBADT). The reaction was likewise effective for the functionalization of b-substituted vinyl sulfones. The products are useful building blocks and were obtained in satisfactory yields both under artificial UV light and under sunlight, so demonstrating the "green" potential of the process.

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