From ruthenium(II) to iridium(III): 15 years of triads based on bis-terpyridine complexes

In order to mimic the photosynthetic reaction centre and better understand photoinduced electron transfer processes, a family of compounds has been studied for the past 15 years. These are transition metal complexes, M(tpy)(2) where tpy is a 2,2':6',2" terpyridine based ligand, bearing on one side a donor group and on the other side an acceptor group. The resulting triad molecules or their two-component reference compounds (donor-M(tpy)(2) and M(tpy)(2-acceptor) can contain Ru, Os, Rh or Ir as the metal centre and both visible-light non absorbing groups and porphyrins as donor and acceptor groups. This tutorial review will briefly present the different systems studied and the reasons that led to the preparation of new systems with improved performances.     

Porous silicon-based optical biosensors and biochips

Porous silicon multilayered microstructures have unique optical and morphological properties that can be exploited in chemical and biological sensing. The large specific surface of nanostructured porous silicon can be chemically modified to link different molecular probes (DNA strands, enzymes, proteins and so on), which recognize the target analytes, in order to enhance the selectivity and specificity of the sensor device. We designed fabricated and characterized several photonic porous silicon-based structures, which were used in sensing some specific molecular interactions. The next step is the integration of the porous silicon-based optical transducer in biochip devices: at this aim, we have tested an innovative anodic bonding process between porous silicon and glass, and its compatibility with the biological probes.     

Quadrupole moments of 81+ states in 92,94Mo

The ratio of the quadrupole moments of the 8₁⁺ states in ${}^{\mathrm{92,94}}\text{Mo}$ has been measured as $\text{Q(}{}^{94}\text{)}\text{Mo}\text{Q(}{}^{92}\text{Mo}\text{)}\text{= 1.48 ± 0.12}$ by means of the TD PAD method following the ${}^{\mathrm{90,92}}\text{Zr}\text{(α, 2}\text{n}\text{)}{}^{\mathrm{92,94}}\text{Mo}$ reactions on enriched Zr metal foils. This ratio is consistent with the effective charge ratio for the 8⁺ → 6⁺E2 transitions which demonstrates a prediction of the effective charge concept.     

Efficient charge storage in photoexcited TiO2 nanorod-noble metal nanoparticle composite systems

Following UV-illumination, TiO2 nanorod-stabilized noble metal (Ag, Au) nanoparticles dispersed in deaerated organic mixtures can sustain a higher degree of conduction band electron accumulation than that achievable with pristine titania.     

Variable strategy toward carbasugars and relatives. 4. Viable access to (4a-carbapentofuranosyl)amines, (5a-carbahexopyranosyl)amines,and amino acids thereof

A chiral, divergent synthesis of two carbafuranosylamines, 1 and 2, two carbapyranosylamines, 3 and 4, two carbafuranosylamino acids, 5 and 6, and two carbapyranosylamino acids, 7 and 8, has been achieved. Highlights of the procedure include the following: a diastereoselective crossed vinylogous Mukaiyama aldol coupling between N-(tert-butoxycarbonyl)-2-[(tert-butyldimethylsilyl)oxy]pyrrole (TBSOP, 9) and 2,3-O-isopropylidene-D-glyceraldehyde (10) for the assembly of the target compound carbon backbone; a high-yielding silylative cycloaldolization that gives the cyclopentanoid and cyclohexanoid motifs; and a reductive or hydrolytic breakage of the lactam C(O)-N link to liberate the carbasugar and install the desired pseudo-anomeric amine and the hydroxymethyl or carboxyl functionalities. The sequences leading to trans-configured carbafuranosyl compounds 1 and 5 and carbapyranosyl compounds 3 and 7 were 12- and 13-step processes, with overall yields of 34%, 35%, 17%, and 16%. Cis-configured isomers 2, 4, 6, and 8 were obtained only in minor yields.     

Photoinduced electron transfer in bisporphyrin-diimide complexes

The bisporphyrin host ZnH was synthesized, and its complexation with two aromatic diimide guest molecules, bis(pyridyl)naphthalenediimide NIN and bis(pyridyl)phenyldiimide PIN, was investigated by (1)H NMR and UV/Vis spectroscopy. The diimide guests were complexed simultaneously with both metalloporphyrins of the host, with association constants on the order of 10(8)M(-1). The processes occurring in the complex after excitation of the porphyrinic host were studied by steady-state and time-resolved emission and transient absorption spectroscopy. Complexation alters the photophysical properties of the host ZnH; the luminescence bands shift to the red by 30 nm in the complexed forms, while the emission quantum yield and the lifetime decrease. Comparison of a complex between ZnH and a model guest unable to undergo photoinduced processes allowed us to establish that, in the diimide complexes, quenching of the porphyrinic luminescence occurs with a rate of 1.1 x 10(10)s(-1). The process is identified as an electron transfer from the excited singlet of the porphyrinic host to the imide guest, which yields charge-separated states with a lifetime of 710 ps for ZnH(+)-NIN(-) and 260 ps for ZnH(+)-PIN(-).     

Conversion of carbamates to amidosulfones and amides. Synthesis of the [14C]-labeled antiobesity agent Ro23-7637

[reaction: see text] Carbamates of primary and secondary amines react with the dianion of methyl phenyl sulfone to yield amidosulfones. Alylation of the amidosulfone followed by reductive removal of the sulfonyl residue gives an amide.