Polyacetylenes Bearing Chiral-Substituted Fluorene and Terfluorene Pendant Groups: Synthesis and Properties

The synthesis of the first polyacetylenes bearing chiral fluorene-based pendant groups is described. Poly{9,9-bis[(S)-3,7-dimethyloctyl]fluoren-2-ylacetylene} (PFA1), poly{9,9-bis[(S)-2-methylbutyl]- fluoren-2-ylacetylene} (PFA2), and poly{9,9,9′,9′,9′′,9′′-hexakis[(S)-2-methylbutyl]-7,2′;7′,2′′-terfluoren- 2-ylacetylene} (PFA3) have been obtained by Rh(I)-catalyzed polymerization of the corresponding terminal acetylene monomers 2-ethynyl-9,9-bis[(S)-3,7-dimethyloctyl]fluorene (2a), 2-ethynyl-9,9-bis[(S)-2-methylbutyl]fluorene (2b), and 2-ethynyl-9,9,9′,9′,9′′,9′′-hexakis[(S)-2-methylbutyl]-7,2′;7′,2′′-terfluorene (10). The effect of the alkyl chain length at the C-9 position of fluorene on the structural and conformational aspects of the polymers PFA1 and PFA2 as well as on their chiroptical properties was studied by XRD, DSC, TGA, GPC, UV-vis, and CD. A more planar conformation of the polyenic backbone of PFA1 with respect to PFA2 can be inferred by a red shift of the ð-ð* transition in the UV-vis spectra. Their photoluminescence properties are those typical of fluorene systems. CD measurements evidenced Cotton effects of opposite signs in correspondence of the backbone absorption region, ascribable to an excess of a screw sense of the helical conformations assumed by the two polymers. PFA3 revealed an amorphous structure and exhibited peculiar thermal stability features (as indicated by TGA and DSC). Its emission spectra interest the violet-blue region and do not show any substantial red shift passing from solution to solid state, thus pointing out an aggregation prevention of terfluorene groups by means of the polyacetylene backbone

CaCO3 as an environmentally friendly renewable material for drug delivery systems: Uptake of HSA-CaCO3 nanocrystals conjugates in cancer cell lines

Chemical and biochemical functionalization of nanoparticles (NPs) can lead to an active cellular uptake enhancing their efficacy thanks to the targeted localization in tumors. In the present study calcium carbonate nano-crystals (CCNs), stabilized by an alcohol dehydration method, were successfully modified by grafting human serum albumin (HSA) on the surface to obtain a pure protein corona. Two types of CCNs were used: naked CaCO3 and the (3-aminopropyl)triethoxysilane (APTES) modified CaCO3-NH2. The HSA conjugation with naked CCN and amino-functionalized CCN (CCN-NH2) was established through the investigation of modification in size, zeta potential, and morphology by Transmission Electron Microscopy (TEM). The amount of HSA coating on the CCNs surface was assessed by spectrophotometry. Thermogravimetric analysis (TGA) and Differential scanning calorimetry (DSC) confirmed the grafting of APTES to the surface and successive adsorption of HSA. Furthermore, to evaluate the effect of protein complexation of CCNs on cellular behavior, bioavailability, and biological responses, three human model cancer cell lines, breast cancer (MCF7), cervical cancer (HeLa), and colon carcinoma (Caco-2) were selected to characterize the internalization kinetics, localization, and bio-interaction of the protein-enclosed CCNs. To monitor internalization of the various conjugates, chemical modification with fluorescein-isothiocyanate (FITC) was performed, and their stability over time was measured. Confocal microscopy was used to probe the uptake and confirm localization in the perinuclear region of the cancer cells. Flow cytometry assays confirmed that the bio-functionalization influence cellular uptake and the CCNs behavior depends on both cell line and surface features

Uranium and thorium in lamprophyres of the Altai-Sayan folded region

The work is devoted to the study of lamprophyres of the Altai-Sayan region. According to X-ray phase analysis, these rocks have a complex mineral composition. According to the TAS diagram, the petrochemical composition varies from alkaline picrites to trachytes. As the INAA shows, the studied samples are significantly enriched with thorium and uranium. Combining the method of electron microscopy and fission radiography (f-radiography), the occurrence forms of thorium and uranium were studied, therefore concentrating minerals were identified

Synthesis and optical behaviour of monodispersed oligo(fluorenylidene)s

The synthesis of the first series of monodispersed oligo(fluorenylidene)s is reported. The synthetic sequence envisages as key steps the obtainment (a) of a bis-pinacolboronate fluorenylidene dimer by a Ni(cod)2 promoted homocoupling of the suitable 7-bromo-fluorenylidene boronic ester and (b) of the bis-pinacolboronate fluorenylidene trimer and tetramer by a Ni(cod)2 promoted coupling of a 7-bromo-fluorenylidene boronic ester with 0.5 equiv of the corresponding 2,7-dibromofluorenylidene derivative. The optical properties of the obtained oligomers were studied. In the case of OF3 the optical behaviour was compared to that of a suitably synthesized fluorenone-containing model compound

Chemical analysis of cesium lead-halide perovskite nanocrystals by total-reflection X-ray fluorescence spectroscopy

Cesiumlead-halide perovskite nanocrystals are an emerging class of materials which potentially have different applications due to the several physical properties they exhibit. These properties are strongly dependent on the elemental composition of the nanocrystals and, to date, only few methods are available for their chemical analysis, such as scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX). The present work aims at establishing a new, fast and simple method for the elemental analysis of cesium lead-halide perovskite nanocrystals exploiting total-reflection x-ray fluorescence (TXRF) spectroscopy. The method was validated using a synthetized set of samples and comparing the TXRF results with SEM-EDX data. The sample preparation consisted in suspending the perovskites in 2.0 ml of hexane and sampling 10 μl of the suspension for deposition on a preheated quartz carrier. The element recovery ranged between 82% and 118% for mixed-halide perovskites, while for single halide perovskites it improved to 86%–105%. The present method can be implemented and used also for the elemental characterization of other types of perovskite nanocrystals

Heterogeneous optochemical VOC sensing layers selected by esi-mass spectrometry

Spin-coated films of 29H,31H-tetra-4-(2,4-di-tert-amylphenoxy)phthalocyanine (H2Pc) and [P,-S-(dppeS)Pt(CH3)]2[BF4]2 have been used as sensing layers deposited in thin film form for the detection of VOCs. The sensing behaviour of the blend was predicted on the basis of mass spectrometric determinations performed on H2Pc/Pt-complex solutions, by monitoring the formation of gas-phase ions at the electrospray interface. The addition of small amounts of acetonitrile produced a [M+ 41]+ peak whereas the addition of similar amounts of methanol, ethanol and isopropyl alcohol did not give the corresponding [M+ROH]+ species. These results were confirmed by sensing tests. A pure phthalocyanine optosensing element did not show relevant selectivity. Conversely, the heterogeneous sensing layer obtained by spin-coating deposition of a Pt-complex/H2Pc blend allowed the sensing of acetonitrile vapours with respect to the above mentioned alcohols