(Bis(1,2,4-triazol-1-yl)methane)silver(I) phosphino complexes: structures and spectroscopic properties of mixed-ligand coordination polymers

Adducts of the ligand bis(1,2,4-triazol-1-yl)methane (tz(2)(CH(2))) of the form AgX:tz(2)(CH(2)):ER(3):MeCN (1:1:1:x) (X = NO(3), R = Ph, E = P, As, or Sb, x = 1 or 2; X = NO(2), ClO(4), O(3)SCF(3), E = P, R = Ph, x = 0, 1 or 2; X = NO(3), ClO(4), E = P, R = cy, x = 1; X = ClO(4), E = As, R = Ph, x = 2) and AgNO(3):tz(2)(CH(2)):P(o-tolyl)(3) (2:2:1) have been synthesized and characterized in the solid state and in solution by analyses, spectral (IR, far-IR, (1)H and (13)C NMR, ESI MS data) data, and conductivity measurements. In the one-dimensional polymers (characterized by X-ray studies) AgNO(3):tz(2)(CH(2)):PPh(3):CH(3)CN (1:1:1:1), AgClO(4):tz(2)(CH(2)):PPh(3):CH(3)CN (1:1:1:2), AgNO(3):tz(2)(CH(2)):AsPh(3): CH(3)CN (1:1:1:2), and AgNO(3):tz(2)(CH(2)):SbPh(3):CH(3)CN (1:1:1:2), the silver atom can be regarded as four-coordinate, the tz(2)(CH(2)) ligands behaving as bridging groups rather than chelates, with no pair of ligands being dominant, quasi-trans, in their interactions. The AgNO(3):tz(2)(CH(2)):P(o-tolyl)(3) (2:2:1) adduct is a two-dimensional polymer containing two independent silver atoms, one four-coordinated unsymmetrically by a pair of triazolyl rings, one P(o-tolyl)(3), and a unidentate nitrate and the second by a quasi-symmetrical O(2)NO chelate and a pair of equivalent triazolyl rings.     

Analysis of the Temperature and Composition Dependence of Viscosimetric Properties of 2-Butanone <Emphasis Type="Bold">+</Emphasis> 2-Butanol Solvent Mixtures

Kinematic viscosities were measured for 2-butanone + 2-butanol binary liquid mixtures with a capillary Ubbelohde routine viscometer in the temperature range from 273.15 to 353.15 K at atmospheric pressure, and covering the whole miscibility field (0x_i1). Experimental data have been correlated by means of different empirical or semiempirical relationships, such as =(T), =(x_i), and =(T, x_i). Viscosity deviations, , from ideal behavior are negative at all experimental conditions, confirming that structure breaking effects prevail in the liquids. Furthermore, the thermodynamics of viscous flow and excess Gibbs energy of activation of viscous flow, G*^E, have been calculated. As an alternative and complementary approach to such investigations, the fluidity () of this binary system has been analyzed by the modified—Batschinski theory. The results are discussed in terms of the specific molecular interactions between the mixture components.     

Determination of phenolic compounds and authentication of PDO Lambrusco wines by HPLC-DAD and chemometric techniques

This work proposes a fast and simple method for detection and quantification of phenolic compounds in PDO Lambrusco wines using HPLC-DAD and chemometric techniques. Samples belonging to three different varieties of Lambrusco (Grasparossa, Salamino and Sorbara) were analyzed to provide a methodology appropriate for routine analysis. Given the high complexity of the sample and the coelution among chromatographic peaks, the use of chemometric techniques to extract the information of the individual eluting compounds was needed. Multivariate curve resolution-alternating least squares (MCR-ALS) allowed the resolution of the chromatographic peaks obtained and the use of this information for the quantification of the phenolic analytes in the presence of interferences. Use of multiset analysis and local rank/selectivity information was proven to be crucial for the correct resolution and quantification of compounds. The quantitative data provided by MCR-ALS about the phenolic targets and additional compounds present in the samples analyzed provided wine composition profiles, which were afterwards used to distinguish among wine varieties. Principal component analysis applied to the wine profiles allowed characterizing the wines according to their varieties.     

Synthesis and evaluation of a new non-fluorescent quencher in fluorogenic oligonucleotide probes for real-time PCR

A non-fluorescent quencher, based on the diaminoanthraquinone Disperse Blue 3, has been incorporated into oligonucleotides at the 5'-end, the 3'-end and internally as a thymidine derivative. Fluorimetry and fluorogenic real-time PCR experiments demonstrate that the quencher is effective with a wide range of fluorescent dyes. The anthraquinone moiety increases the melting temperature of DNA duplexes, thus allowing shorter, more discriminatory probes to be used. The quencher has been used in Scorpion primers and TaqMan probes for human DNA sequence recognition and mutation detection.     

Gold Catalysis: In Situ EXAFS Study of Homogeneous Oxidative Esterification

Gold complexes were prepared and investigated as catalysts for the oxidative esterification of aldehydes. Stabilisation by pyridine ligands gave good conversions and the in situ extended X‐ray absorption fine structure (EXAFS) study of the reactions indicated that the reaction mixtures contained only mononuclear gold species. Thus, this is the first proof for a homogeneous gold‐catalysed oxidation reaction; the presence of nanoparticles could be excluded experimentally.     

Photochemistry in Photonic Crystal Fiber Nanoreactors

We report the use of a liquid‐filled hollow‐core photonic crystal fiber (PCF) as a highly controlled photochemical reactor. Hollow‐core PCFs have several major advantages over conventional sample cells: the sample volume per optical path length is very small (2.8 nL cm^?1 in the fiber used), long optical path lengths are possible as a result of very low intrinsic waveguide loss, and furthermore the light travels in a diffractionless single mode with a constant transverse intensity profile. As a proof of principle, the (very low) quantum yield of the photochemical conversion of vitamin B₁₂, cyanocobalamin (CNCbl) to hydroxocobalamin ([H₂OCbl]⁺) in aqueous solution was measured for several pH values from 2.5 to 7.5. The dynamics of the actively induced reaction were monitored in real‐time by broadband absorption spectroscopy. The PCF nanoreactor required ten thousand times less sample volume compared to conventional techniques. Furthermore, the enhanced sensitivity and optical pump intensity implied that even systems with very small quantum yields can be measured very quickly—in our experiments one thousand times faster than in a conventional cuvette.     

Halo-carbonyl complexes of palladium,platinum and gold

In this review we summarize some recent literature data concerning synthetic procedures, properties, structure, reactivity and applications of halo-carbonyl complexes of palladium, platinum and gold, taking into consideration that the organometallic chemistry of these metals, with a particular attention to the halo-carbonyls, has been reviewed 20 years ago [F. Calderazzo, J. Organomet. Chem. 400 (1990) 303]. A brief overview of the early studies is provided.     

A solid-phase approach to the synthesis of N-1-alkyl analogues of cyclic inosine-diphosphate-ribose (cIDPR)

We report here an efficient solid-phase synthesis of N-1-alkyl-substituted analogues of cyclic inosine-diphosphate-ribose (cIDPR), a mimic of cyclic ADP-ribose (cADPR). Our synthetic strategy makes use of a polystyrene support to which inosine was bonded through a 2′,3′-acetal linkage. Insertion of a ω-hydroxy-polymethylene chain of variable length on N-1, followed by conversion into N-1-alkylinosine-bis-phosphate derivatives and cyclization, allowed to obtain analogues of cIDPR of various ring size. The cyclization step was carried out both in solid-phase and in solution by pyrophosphate bond formation. The effect of the N-1-polymethylene chain length on the cyclization yields as well as the reaction conditions, which led to the solid-phase pyrophosphate bond formation, were thoroughly investigated.