LIVIVO - The Search Portal for Life Sciences

zur deutschen Oberfläche wechseln
Advanced search

Search results

Result 1 - 10 of total 21

Search options

  1. Article ; Online: Regioselectivity Control in Spirobifluorene Nitration under Mild Conditions: Explaining the Crivello's Reagent Mechanism.

    Yousif, Dawod / Vaghi, Luca / Daniliuc, Constantin G / Po, Riccardo / Papagni, Antonio / Rizzo, Fabio

    The Journal of organic chemistry

    2023  Volume 88, Issue 9, Page(s) 5285–5290

    Abstract: The regioselective nitration of 9,9'-spirobifluorene under mild conditions is reported for the first time by operating under Menke's and Crivello's conditions. The optimized protocol allows obtaining 2-nitro and 2,2'-dinitro-9,9'-spirobifluorene in ... ...

    Abstract The regioselective nitration of 9,9'-spirobifluorene under mild conditions is reported for the first time by operating under Menke's and Crivello's conditions. The optimized protocol allows obtaining 2-nitro and 2,2'-dinitro-9,9'-spirobifluorene in yields of 79 and 95% and, for the first time, 2,2',7-trinitro-9,9'-spirobifluorene with 66% yield. Besides, the role of dinitrate salt in Crivello's protocol has been now clarified, which opens novel scenarios in the preparation of functional materials.
    Language English
    Publishing date 2023-04-26
    Publishing country United States
    Document type Journal Article
    ZDB-ID 123490-0
    ISSN 1520-6904 ; 0022-3263
    ISSN (online) 1520-6904
    ISSN 0022-3263
    DOI 10.1021/acs.joc.2c02596
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

    In stock of ZB MED Cologne/Königswinter

    Zs.A 4473: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (2.OG)
    ab Jg. 2022: Lesesaal (EG)

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

  2. Article: Synthesis of phenazines from ortho-bromo azo compounds via sequential Buchwald-Hartwig amination under micellar conditions and acid promoted cyclization

    Yousif, Dawod / Monti, Mauro / Papagni, Antonio / Vaghi, Luca

    Tetrahedron letters. 2020 Nov. 12, v. 61, no. 46

    2020  

    Abstract: Non-symmetric phenazines were synthesized via the Buchwald-Hartwig amination of ortho-bromoazobenzenes with anilines under micellar conditions, using the commercially available surfactant Kolliphor EL in water, followed by an acid-promoted 6π- ... ...

    Abstract Non-symmetric phenazines were synthesized via the Buchwald-Hartwig amination of ortho-bromoazobenzenes with anilines under micellar conditions, using the commercially available surfactant Kolliphor EL in water, followed by an acid-promoted 6π-electrocyclization-aromatization process. Two different synthetic pathways to obtain the ortho-bromo azo intermediates were explored, namely the palladium catalysed selective ortho bromination of azobenzenes and the diazo coupling of ortho-bromo diazonium salts with N,N-dimethylaniline, imidazole, phenol, sodium methanesulfinate and ethyl chloroformate.
    Keywords amination ; azo compounds ; bromination ; diazo compounds ; diazonium compounds ; imidazole ; palladium ; phenazines ; phenol ; salts ; sodium ; surfactants ; synthesis ; water
    Language English
    Dates of publication 2020-1112
    Publishing place Elsevier Ltd
    Document type Article
    Note NAL-light
    ZDB-ID 204287-3
    ISSN 1873-3581 ; 0040-4039
    ISSN (online) 1873-3581
    ISSN 0040-4039
    DOI 10.1016/j.tetlet.2020.152511
    Database NAL-Catalogue (AGRICOLA)

    Full text online

    More links

    Kategorien

    In stock of ZB MED Cologne/Königswinter

    Zs.A 2837: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (2.OG)
    ab Jg. 2022: Lesesaal (EG)

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

  3. Article ; Online: Thermally Activable Bistetrazoles for Elastomers Crosslinking.

    Monti, Mauro / Giannini, Luca / Tadiello, Luciano / Guerra, Silvia / Papagni, Antonio / Vaghi, Luca

    Polymers

    2022  Volume 14, Issue 14

    Abstract: Sulfur vulcanization is the most used method for curing of natural and synthetic rubbers. The crosslinking degree achieved is usually controlled by adding proper quantities of accelerants, activators, co-activators, retardants, and inhibitors, and ... ...

    Abstract Sulfur vulcanization is the most used method for curing of natural and synthetic rubbers. The crosslinking degree achieved is usually controlled by adding proper quantities of accelerants, activators, co-activators, retardants, and inhibitors, and influences the hardness, elasticity, hysteresis of elastomers and, consequently, the properties and behavior of the materials that incorporate them. Despite the fine tuning pursued over the years, sulfur crosslinking is still difficult to control both in terms of degree and homogeneity of cross-link. Addition of thermally activable bifunctional reagents able to crosslink the polymer matrix through covalent bonds could be a strategy to modulate and control finely the reticulation grade of elastomers. Tetrazoles can form highly reactive nitrilimines by thermal treatment at appropriate temperature, which can react with the vinyl double bonds present in the rubber. In this work a set of bis-tetrazoles were synthesized and those with the right activation temperatures were used for the curing of styrene-butadiene rubber, acting both as single crosslinkers and together with classic sulfur-based ones. The addition of bistetrazoles simplified and made more efficient the compounding process, allowing to prolong the mixing until optimum dispersion and homogeneity were obtained. Moreover, they led to an improvement in the hysteretic properties of the compound and to the reduction of the non-linearity of the dynamic behavior (Payne effect).
    Language English
    Publishing date 2022-07-19
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2527146-5
    ISSN 2073-4360 ; 2073-4360
    ISSN (online) 2073-4360
    ISSN 2073-4360
    DOI 10.3390/polym14142919
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

  4. Article ; Online: Photoinduced Porcine Gelatin Cross-Linking by Homobi- and Homotrifunctional Tetrazoles.

    Vaghi, Luca / Monti, Mauro / Marelli, Marcello / Motto, Elisa / Papagni, Antonio / Cipolla, Laura

    Gels (Basel, Switzerland)

    2021  Volume 7, Issue 3

    Abstract: Gelatin is a costless polypeptide material of natural origin, able to form hydrogels that are potentially useful in biomaterial scaffold design for drug delivery, cell cultures, and tissue engineering. However, gelatin hydrogels are unstable at ... ...

    Abstract Gelatin is a costless polypeptide material of natural origin, able to form hydrogels that are potentially useful in biomaterial scaffold design for drug delivery, cell cultures, and tissue engineering. However, gelatin hydrogels are unstable at physiological conditions, losing their features only after a few minutes at 37 °C. Accordingly, treatments to address this issue are of great interest. In the present work, we propose for the first time the use of bi- and trifunctional tetrazoles, most of them unknown to date, for photoinduced gelatin cross-linking towards the production of physiologically stable hydrogels. Indeed, after UV-B irradiation, aryl tetrazoles generate a nitrilimine intermediate that is reactive towards different functionalities, some of them constitutively present in the amino acid side chains of gelatin. The efficacy of the treatment strictly depends on the structure of the cross-linking agent used, and substantial improved stability was observed by switching from bifunctional to trifunctional cross-linkers.
    Language English
    Publishing date 2021-08-20
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2813982-3
    ISSN 2310-2861 ; 2310-2861
    ISSN (online) 2310-2861
    ISSN 2310-2861
    DOI 10.3390/gels7030124
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

  5. Article ; Online: Pushing Down the Limit of NH

    Freddi, Sonia / Perilli, Daniele / Vaghi, Luca / Monti, Mauro / Papagni, Antonio / Di Valentin, Cristiana / Sangaletti, Luigi

    ACS nano

    2022  Volume 16, Issue 7, Page(s) 10456–10469

    Abstract: An easy and cost-effective method is presented to functionalize graphene through thermally activated dimerization of 2,5-diaryltetrazoles. Consistently with the experimental spectroscopic results, theoretical calculations demonstrate that during the ... ...

    Abstract An easy and cost-effective method is presented to functionalize graphene through thermally activated dimerization of 2,5-diaryltetrazoles. Consistently with the experimental spectroscopic results, theoretical calculations demonstrate that during the thermal treatment a dimerization process to tetrazine is energetically more favorable than covalent grafting. Since both the functionalization method by thermal activation and the use of tetrazoles have never been considered before to prepare graphene-based chemiresistors, this represents a promising approach to develop graphene-related sensing platforms. Five different 2,5-diaryltetrazoles have been tested here for the effective functionalization of low-defect graphene layers on silicon nitride. Based on these layers, an array of sensors has been prepared for testing upon ammonia exposure. The tests on the sensing performances clearly show sensitivity to ammonia, extending the current range of ammonia detection with a graphene-based chemiresistor down to the sub-ppm range, as results from a benchmarking with data available in the literature. Furthermore, all sensors perform better than bare graphene. Density functional theory (DFT) calculations, carried out on a model of the best performing layer of the array, provided the theoretical framework to rationalize the sensing mechanism and disclose a dual role played by the tetrazine molecules, (i) acting as ammonia concentrators and (ii) mediating the electron transfer between ammonia and graphene.
    Language English
    Publishing date 2022-06-22
    Publishing country United States
    Document type Journal Article
    ISSN 1936-086X
    ISSN (online) 1936-086X
    DOI 10.1021/acsnano.2c01095
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  6. Article ; Online: Modular Synthetic Routes to Fluorine-Containing Halogenated Phenazine and Acridine Agents That Induce Rapid Iron Starvation in Methicillin-Resistant

    Liu, Ke / Brivio, Massimiliano / Xiao, Tao / Norwood, Verrill M / Kim, Young S / Jin, Shouguang / Papagni, Antonio / Vaghi, Luca / Huigens, Robert W

    ACS infectious diseases

    2022  Volume 8, Issue 2, Page(s) 280–295

    Abstract: During infection, bacteria use an arsenal of resistance mechanisms to negate antibiotic therapies. In addition, pathogenic bacteria form surface-attached biofilms bearing enriched populations of metabolically dormant persister cells. Bacteria develop ... ...

    Abstract During infection, bacteria use an arsenal of resistance mechanisms to negate antibiotic therapies. In addition, pathogenic bacteria form surface-attached biofilms bearing enriched populations of metabolically dormant persister cells. Bacteria develop resistance in response to antibiotic insults; however, nonreplicating biofilms are innately tolerant to all classes of antibiotics. As such, molecules that can eradicate antibiotic-resistant and antibiotic-tolerant bacteria are of importance. Here, we report modular synthetic routes to fluorine-containing halogenated phenazine (HP) and halogenated acridine (HA) agents with potent antibacterial and biofilm-killing activities. Nine fluorinated phenazines were rapidly accessed through a synthetic strategy involving (1) oxidation of fluorinated anilines to azobenzene intermediates, (2) S
    MeSH term(s) Acridines/pharmacology ; Anti-Bacterial Agents/pharmacology ; Biofilms ; Fluorine ; Iron ; Methicillin-Resistant Staphylococcus aureus ; Phenazines/pharmacology
    Chemical Substances Acridines ; Anti-Bacterial Agents ; Phenazines ; phenazine ; Fluorine (284SYP0193) ; Iron (E1UOL152H7)
    Language English
    Publishing date 2022-01-28
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ISSN 2373-8227
    ISSN (online) 2373-8227
    DOI 10.1021/acsinfecdis.1c00402
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  7. Article ; Online: Bypassing the statistical limit of singlet generation in sensitized upconversion using fluorinated conjugated systems.

    Vaghi, Luca / Rizzo, Fabio / Pedrini, Jacopo / Mauri, Anna / Meinardi, Francesco / Cosentino, Ugo / Greco, Claudio / Monguzzi, Angelo / Papagni, Antonio

    Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology

    2022  Volume 21, Issue 5, Page(s) 913–921

    Abstract: The photon upconversion based on triplet-triplet annihilation (TTA) is a mechanism that converts the absorbed low-energy electromagnetic radiation into higher energy photons also at extremely low excitation intensities, but its use in actual technologies ...

    Abstract The photon upconversion based on triplet-triplet annihilation (TTA) is a mechanism that converts the absorbed low-energy electromagnetic radiation into higher energy photons also at extremely low excitation intensities, but its use in actual technologies is still hindered by the limited availability of efficient annihilator moieties. We present here the results obtained by the synthesis and application of two new fluorinated chromophores based on phenazine and acridine structures, respectively. Both compounds show upconverted emission demonstrating their ability as TTA annihilator. More interesting, the acridine-based chromophore shows an excellent TTA yield that overcomes the one of some of best model systems. By correlating the experimental data and the quantum mechanical modeling of the investigated compound, we propose an alternative efficient pathway for the generation of the upconverted emissive states involving the peculiar high-energy triplet levels of the dye, thus suggesting a new development strategy for TTA annihilators based on the fine tuning of their high-energy excited states properties.
    MeSH term(s) Acridines ; Light ; Photons
    Chemical Substances Acridines
    Language English
    Publishing date 2022-04-30
    Publishing country England
    Document type Journal Article
    ZDB-ID 2072584-X
    ISSN 1474-9092 ; 1474-905X
    ISSN (online) 1474-9092
    ISSN 1474-905X
    DOI 10.1007/s43630-022-00225-z
    Database MEDical Literature Analysis and Retrieval System OnLINE

    Full text online

    More links

    Kategorien

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

  8. Article ; Online: Gelatin-Based Hydrogels through Homobifunctional Triazolinediones Targeting Tyrosine Residues.

    Guizzardi, Roberto / Vaghi, Luca / Marelli, Marcello / Natalello, Antonino / Andreosso, Ivan / Papagni, Antonio / Cipolla, Laura

    Molecules (Basel, Switzerland)

    2019  Volume 24, Issue 3

    Abstract: Gelatin is a biopolymer with interesting properties that can be useful for biomaterial design for different applications such as drug delivery systems, or 3D scaffolds for tissue engineering. However, gelatin suffers from poor mechanical stability at ... ...

    Abstract Gelatin is a biopolymer with interesting properties that can be useful for biomaterial design for different applications such as drug delivery systems, or 3D scaffolds for tissue engineering. However, gelatin suffers from poor mechanical stability at physiological temperature, hence methods for improving its properties are highly desirable. In the present work, a new chemical cross-linking strategy based on triazolinedione ene-type chemistry towards stable hydrogel is proposed. Two different homobifunctional 1,2,4-triazoline-3,5(4
    MeSH term(s) Biocompatible Materials/chemistry ; Drug Stability ; Gelatin/chemistry ; Hydrogels/chemistry ; Materials Testing ; Molecular Structure ; Spectroscopy, Fourier Transform Infrared ; Temperature ; Triazoles/chemistry ; Tyrosine/chemistry
    Chemical Substances Biocompatible Materials ; Hydrogels ; Triazoles ; Tyrosine (42HK56048U) ; Gelatin (9000-70-8)
    Language English
    Publishing date 2019-02-07
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 1413402-0
    ISSN 1420-3049 ; 1431-5165 ; 1420-3049
    ISSN (online) 1420-3049
    ISSN 1431-5165 ; 1420-3049
    DOI 10.3390/molecules24030589
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

    In stock of ZB MED Cologne/Königswinter

    Zs.MO 81: Show issues

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

  9. Article ; Online: Morphological characterization and electronic properties of pristine and oxygen-exposed graphene nanoribbons on Ag(110).

    Barcelon, Jose Eduardo / Smerieri, Marco / Carraro, Giovanni / Wojciechowski, Pawel / Vattuone, Luca / Rocca, Mario / Nappini, Silvia / Píš, Igor / Magnano, Elena / Bondino, Federica / Vaghi, Luca / Papagni, Antonio / Savio, Letizia

    Physical chemistry chemical physics : PCCP

    2021  Volume 23, Issue 13, Page(s) 7926–7937

    Abstract: Graphene nanoribbons (GNRs) are at the frontier of research on graphene materials since the 1D quantum confinement of electrons allows for the opening of an energy gap. GNRs of uniform and well-defined size and shape can be grown using the bottom-up ... ...

    Abstract Graphene nanoribbons (GNRs) are at the frontier of research on graphene materials since the 1D quantum confinement of electrons allows for the opening of an energy gap. GNRs of uniform and well-defined size and shape can be grown using the bottom-up approach, i.e. by surface assisted polymerization of aromatic hydrocarbons. Since the electronic properties of the nanostructures depend on their width and on their edge states, by careful choice of the precursor molecule it is possible to design GNRs with tailored properties. A key issue for their application in nanoelectronics is their stability under operative conditions. Here, we characterize pristine and oxygen-exposed 1.0 nm wide GNRs with a well-defined mixed edge-site sequence (two zig-zag and one armchair) synthesized on Ag(110) from 1,6-dibromo-pyrene precursors. The energy gap and the presence of quantum confined states are investigated by scanning tunneling spectroscopy. The effect of oxygen exposure under ultra-high vacuum conditions is inferred from scanning tunneling microscopy images and photoemission spectra. Our results demonstrate that oxygen exposure deeply affects the overall system by interacting both with the nanoribbons and with the substrate; this factor must be considered for supported GNRs under operative conditions.
    Language English
    Publishing date 2021-01-06
    Publishing country England
    Document type Journal Article
    ZDB-ID 1476244-4
    ISSN 1463-9084 ; 1463-9076
    ISSN (online) 1463-9084
    ISSN 1463-9076
    DOI 10.1039/d0cp04051g
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

  10. Article: Synthesis of Fluorinated Acridines via Sequential Micellar Buchwald–Hartwig Amination/Cyclization of Aryl Bromides

    Vaghi, Luca / Sanzone, Alessandro / Sassi, Mauro / Pagani, Simone / Papagni, Antonio / Beverina, Luca

    Synthesis

    2018  Volume 50, Issue 08, Page(s) 1621–1628

    Abstract: Fluorinated unsymmetrical acridines are efficiently prepared by means of a tandem micellar Buchwald–Hartwig amination followed by an acid-promoted cyclization. The overall process is advantageous with respect to previously described protocols both in ... ...

    Abstract Fluorinated unsymmetrical acridines are efficiently prepared by means of a tandem micellar Buchwald–Hartwig amination followed by an acid-promoted cyclization. The overall process is advantageous with respect to previously described protocols both in terms of efficiency and sustainability. The role of the cosolvent in the amination step is highlighted, demonstrating that rather than resorting to highly expensive catalysts, Buchwald–Hartwig aminations can be straightforwardly carried out by tuning the reaction site polarity.
    Keywords micellar synthesis ; Buchwald–Hartwig amination ; fluorinated acridines ; cosolvent
    Language English
    Publishing date 2018-02-26
    Publisher © Georg Thieme Verlag
    Publishing place Stuttgart ; New York
    Document type Article
    ZDB-ID 2033062-5
    ISSN 1437-210X ; 0039-7881
    ISSN (online) 1437-210X
    ISSN 0039-7881
    DOI 10.1055/s-0036-1591937
    Database Thieme publisher's database

    More links

    Kategorien

    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

To top