Laboratoire de Photophysique et Photochimie Supramoléculaires et Macromoléculaires

In recent years, the flexibility of porous organic polymers has demonstrated very unique properties during their applications. This paper reports a novel soluble porous polymer (named BIT-POP-75 and BIT-POP-75-OH) with 1,2-diketone and 1,2-diol subunits in the flexible polymer chain using contorted subunits. The solubility of the porous polymer and the flexible chelating 1,2-diol moiety facilitates the high loading and uniform dispersion of Pd nanoparticles to give the catalyst Pd@BIT-POP-75-OH, which shows high efficiency (kapp = 0.965 min-1) for the catalytic reduction of 4-nitrophenol with good recyclability (10 cycles).

The Uden–Slabroek cemetery yielded one of the richest Early Iron Age burials found in the Netherlands: an inhumation grave of a person wearing elaborate bronze and iron ornaments (ca. 8th century BC). Exceptionally mineralised fragments of wool textiles were found inside the corrosion layer of the bronze anklets and bracelets. Advanced multidisciplinary analysis of these textiles identified them as the remains of the oldest garment of the Netherlands, made from a bright red and blue wool twill fabric woven in a shepherd’s check pattern. Advanced mass spectrometry analysis provided direct identification of dyes, including cochineal — the earliest evidence of a red dye for the entire region (especially the precious insect dye variant). Virtual synchrotron-based 3D analysis of the fragments documented the textile weave types and the morphometry of surface and buried layers. The correlation of the two approaches makes it possible to recover an entire, now-vanished, colour pattern from highly altered fabrics.

Looting and plough damage to the eighth–fifth centuries BC tumulus of Creney-le-Paradis, France, hinders interpretation of this potentially significant site. Nevertheless, application of novel microtomographic techniques in combination with optical and scanning electron microscopy allows the first detailed examination of 99 textile fragments recovered from the central pit. The authors argue that the diversity of textiles revealed—at least 16 different items—and the quality of weaving involved confirm earlier interpretations of the high status of this burial, which is comparable, at least in terms of textiles and metal urns, with other ‘aristocratic’ tombs of the European Iron Age.

Molecular photoswitches capable of reversible photoswitching in aqueous media are highly demanded for various biological applications and photopharmacology. Carbohydrates, as natural and abundant raw materials, provide opportunity to make photoswitches water-soluble through linking sugar to the photoswitching molecules. We have developed a one-pot synthesis method to prepare water-soluble glycosyl azobenzenes through DMC (2-chloro-1,3-dimethylimidazolinium chloride)-mediated glycosylation between sugar and dihydroxyazobenzenes (DHABs) in aqueous media. The scope of the method has been investigated with different mono- and disaccharides, as well as with p,p'- and o,o'-DHAB, with excellent 1,2-trans stereoselectivity. Diglycosylation products can also be obtained with an excess amount of monosaccharides in one step. We have also demonstrated the possibility of further functionalization on the azobenzene moiety of glycosyl azobenzene. Both mono- and diglycosyl azobenzenes showed excellent photoswitching properties in water with high fatigue resistance and good thermostability for the Z-isomers. Excellent E → Z photoisomerization of both mono- and diglycosylated azobenzenes (Z/E = 99/1) is observed under illumination at 365 nm, while back Z → E photoisomerization can be achieved with blue light (with E/Z = 80/20 at PSS485 for the diglycosyl derivative).

We report the first intramolecular excimer photoswitching induced by molecular motion within a dithienylethene (DTE) molecule without destructive readout. The photochromic compound DTE bears two pyrene chromophores, judiciously positioned to face each other in the DTE's open form. The close proximity of the pyrenes in the open form is confirmed by NMR experiments and geometry optimization. Intense pyrene excimer luminescence is recorded, upon both one- and two-photon excitation (OPE and TPE). The photocyclization reaction of the DTE core induces a molecular motion of one pyrene moiety which thus prevents the possibility of formation of an excimer. Our DTE-based pyrene is stable upon TPE irradiation and shows a high photocyclization quantum yield. Such property specifications allow us to report the original nondestructive readout fluorescence by alternating exposure to OPE and TPE.