Strong, low-energy two-photon absorption in extended amine-terminated cyano-substituted phenylenevinylene oligomers

Three quadrupolar oligophenylenevinylenes with five rings in the conjugated backbone, terminal donor groups, and various acceptors and/or donors along the backbone were synthesized and their two-photon spectroscopic properties investigated. These chromophores exhibit large two-photon absorption cross sections over a wide wavelength range and two distinct peaks, the strongest of which (deltamax > 3600 GM) is observed at 960-970 nm, a wavelength close to twice the value of the linear absorption maximum (2lambda(1)max). The findings on these chromophores are compared with those for analogous molecules with shorter conjugation length, for which the main two-photon band is at significantly shorter wavelength than 2lambda(1)max.     

Synthesis,spectroscopic characterization (IR, 1H, 13C and 119Sn NMR,electrospray mass spectrometry) and toxicity of new organotin(IV) complexes with N,N′,O‐ and N,N′,S‐scorpionate ligands

New organotin(IV) derivatives containing the anionic ligands bis(3,5‐dimethylpyrazol‐1‐yl)dithioacetate [LCS₂]⁻ and bis(3,5‐dimethylpyrazol‐1‐yl)acetate [LCO₂]⁻ have been synthesized from reaction between (CH₃)₂SnCl₂ and lithium salts of the ligands. Mononuclear complexes of the type {[LCX₂](CH₃)₂SnCl} (X = S or O) have been obtained and fully characterized by elemental analyses and FT‐IR in the solid state and by NMR (¹H, ¹³C and ¹¹⁹Sn) spectroscopy, conductivity measurements and electrospray ionization mass spectrometry in solution. The acute toxicity of new organotin(IV) derivatives on rat was studied, comparing their effect with those of dimethyltin chloride (CH₃)₂SnCl₂. The comparison of LD₅₀ of organotin(IV) complexes and (CH₃)₂SnCl₂ administered intraperitoneally, as a single dose, evaluated in vivo on rats, showed that toxicity decreases as follows: (CH₃)₂SnCl₂ > LCO₂ > LCS₂. The effect of these organotin(IV) complexes on DNA was evaluated in vitro and in vivo on rats treated with different doses of these compounds (1/20 LD₅₀ and 1/100 LD₅₀). The lymphocyte DNA status was assessed by the comet assay, a rapid and sensitive single‐cell electrophoresis technique, used to detect primary DNA damage in individual cells. After 36 h from the start of treatment the two new organotin(IV) derivatives induced a significant rise in comet assay parameters, indicating an increasing presence of damaged DNA. Copyright © 2005 John Wiley & Sons, Ltd.     

Influence of crystal polymorphism on mechanical and barrier properties of poly(l-lactic acid)

The effect of crystal polymorphism on barrier and mechanical properties of PLLA is detailed in this contribution. PLLA films containing different amounts of α and α′ crystal forms were prepared by annealing quenched PLLA at different temperatures. The polymorphic structure of the films was analyzed by X-ray diffraction. Mechanical properties and permeability to water vapor were investigated as a function of degree of crystallinity (w_C) and related to crystal polymorphism developed during annealing. The polymorphic structure of PLLA significantly affects mechanical and barrier properties. The α crystal modification provides a better barrier to water vapor and a higher Young’s modulus, compared to films containing the α′ modification, but a lower elongation at break. The varied barrier and mechanical properties were correlated to the different packing of PLLA chains in the two analyzed polymorphs. The conformational disorder of the α′ form makes this structure a mesophase (condis crystal), with remarkable effects on material properties.     

Synthesis of poly(urethane urea) by in situ polymerization inside stone

The first synthesis of poly(urethane urea) by in situ polymerization inside stone was successfully carried out. Poly(propylene glycol), isophorondiisocyanate, and a catalyst [tin(II) ethyl hexanoate, aluminum acetylacetonate, or zirconium acetylacetonate] were mixed with acetone in petri dishes, and tuff samples were placed in the dishes at room temperature. The effects of the comonomer ratio, catalyst, and catalyst concentration on the chemical structure of the synthesized poly(urethane urea) were investigated. The poly(urethane urea) distribution inside the tuff and the related morphology were also analyzed, as well as the reversibility of the performed treatments. Finally, the effects of the in situ polymerization polymer on the properties of the stone, such as water capillary absorption and permeability to water vapor, were assessed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 542–552, 2005     

Fluorescent Nitric Oxide Photodonors Based on BODIPY and Rhodamine Antennae

Two novel NO photodonors (NOPDs) based on BODIPY and Rhodamine antennae activatable with the highly biocompatible green light are reported. Both NOPDs exhibit considerable fluorescence emission and release NO with remarkable quantum efficiencies. The combination of the photoreleasing and emissive performance for both compounds is superior to those exhibited by other NOPDs based on similar light-harvesting centres, making them very intriguing for image-guided phototherapeutic applications. Preliminary biological data prove their easy visualization in cell environment due to the intense green and orange-red fluorescence and their photodynamic action on cancer cells due to the NO photo-liberated.     

Adjustable and fixed interest rates mortgage markets modelling

Due to recent developments in credit markets, the interdependencies among fixed rate mortgages (FRMs) and adjustable rate mortgages (ARMs) markets are analysed in the study of the interactions within credit markets since it appears very suitable and interesting. A meaningful and complete database of information on Financial Institutions in Italy (1997:q1–2011:q4) hold by the Banca d’Italia shows that the relative importance of these markets recently displayed significant fluctuations since in 2005 fixed interest rate mortgage loans were about 10 % while in 2009 they raised up to 70 %. In the context of the FRMs and ARMs characteristics in Italian markets as well as the available database, among the proposed models for the study of interconnected markets (see Brock and Hommes in Econometrica 65(5):1059–1095, 1997, J Econ Dyn Control 22:1235–1274, 1998; Dieci and Westerhoff in Appl Math Comput 215:2011–2023, 2009; J Econ Behav Organ 75(3):461–481, 2010 and related literature cited therein), the models recently developed by Casellina et al. (Comput Econ 38:221–239, 2011) is applied to test its capacity to capture the dynamics of the observed data. It is worth stressing that the involved real data (volume of contracts and average interest rate in the FRMs and ARMs markets) are not sample information but they are evaluated on the entire population. The obtained findings point out the good level to fit the interest rates dynamics. Moreover, the model captures the switching mechanism and it catches the structural breaks when they occurs.     

Visible-Light-Induced Insertion of Sulfur Dioxide Mediated by Electron Donor–Acceptor Complex: Synthesis and Photophysical Properties of 3-Sulfonyl Indolizines

This work investigates a light-driven 3-component sulfonylation reaction of indolizines without needing any external photocatalyst. The mechanistic investigations support the formation of an electron donor–acceptor (EDA) complex in situ. This transformation offers a mild and sustainable approach with high functional group tolerance for the synthesis of 3-sulfonylated indolizines. This compound class has valuable photophysical properties and represents promising candidates in various applications related to fluorescence.     

Novel silver/polyurethane nanocomposite by in situ reduction: Effects of the silver nanoparticles on phase and viscoelastic behavior

A novel silver/poly(carbonate urethane) nanocomposite was prepared through in situ reduction of a silver salt (AgNO₃) added to a solution consisting of a commercial poly(carbonate urethane) dissolved in N,N‐dimethylformamide (DMF). In this system, the presence of the poly(carbonate urethane) was proved to protect the silver nanoparticles, whose formation was confirmed by means of UV–vis spectroscopy, from aggregation phenomena. The silver morphology developed in the solid state after DMF casting was imaged by FESEM. Homogeneous dispersion of silver nanoprisms in the poly(carbonate urethane) matrix was clearly observed. The effects of dispersion of silver nanoparticles within the poly(carbonate urethane) matrix were investigated by means of ATR‐FTIR and multifrequency dynamic mechanical thermal analyses. The obtained results revealed that the presence of silver nanoparticles modifies both the phase and the viscoelastic behaviors of poly(carbonate urethane). As a matter of fact, the hydrogen bond formation in the hard and soft segments was found to be hindered and the molecular motions of the soft segments were restricted, because a comparatively higher activation energy was required for the related α‐relaxation process. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 344–350, 2008     

Molecular organization in liquids consisting of anisometric molecules: Monte Carlo simulations and comparison with theories

Monte Carlo computer simulations of systems of rigid anisometric molecules with axial ratio x 3, 4 and 5 have been performed at densities comparable to those of the mesogenic groups in liquid crystalline materials. The agreement between computer experiments and Flory-Ronca-Irvine theory is quite good. In particular, the nematic-isotropic transition temperatures found in the simulations are within 20 K of those predicted by the theory in all cases examined with x 3 and 4, and only slightly higher when x 5. Furthermore, the orientational distributions of the molecular long axes with respect to the nematic director are always nearly coincident with those evaluated according to the FRI theory, provided that the order parameter is the same. However, the order parameters at the transition points are smaller than expected on the basis of the theory, and closer to experimental values. Calculations performed by changing the size of the simulated systems prove that the reported results are size independent, while size dependent results are obtained with smaller systems.     

α‐Mannosyl‐Functionalized Cationic Nanohydrogel Particles for Targeted Gene Knockdown in Immunosuppressive Macrophages

Immunosuppressive M2 macrophages govern the immunophathogenic micromilieu in many severe diseases including cancer or fibrosis, thus, their re‐polarization through RNA interference is a promising concept to support combinatorial therapies. For targeted siRNA delivery, however, safe and stable carriers are required that manage cell specific transport to M2 macrophages. Here, siRNA‐loaded cationic nanogels are reported with α‐mannosyl decorated surfaces that target and modify M2 macrophages selectively. Via amphiphilic precursor block copolymers bearing one single α‐mannosyl moiety at their chain end mannosylated cationic nanohydrogel particles (ManNP) were obtained of 20 nm diameter determined by dynamic light scattering and cryogenic electron transmission microscopy. α‐Mannosyl surface modification is confirmed by agglutination with concanavalin A. SiRNA‐loaded ManNP preferentially targets the overexpressed mannose receptor CD206 on M2 macrophages, as shown by in vitro cell uptake studies in M2 polarized primary macrophages. This specificity is confirmed, since ManNP uptake could be reduced by blocking of CD206 with mannan. Effective ManNP‐guided siRNA delivery is confirmed by sequence‐specific gene knockdown of CSF‐1R in M2‐type macrophages exclusively, while the expression levels in M1‐polarized macrophages is not affected. In conclusion, α‐mannosyl‐functionalized ManNPs are promising universal siRNA carriers for targeted immunomodulatory treatment of immunosuppressive macrophages.