1,206 research outputs found
Supramolecular Chemistry and photophysical Properties of a New Gold (I) Cyclic Trinuclear Complex, [Au(μ-C2,N3-1-vinylimidazole)]3
No full textSupramolecular Chemistry and photophysical Properties of a New Gold (I) Cyclic Trinuclear Complex, [Au(μ-C2,N3-1-vinylimidazole)]3
R. Galassia, A. Burinia, C. S. Oumaroua, V. N. Nesterov b, M. A. Omary b.
a Dipartimento di Scienze Chimica, Università di Camerino, Via Sant Agostino, 1, 62032 Camerino, Italia
b Department of Chemistry, University of North Texas, Denton, TX 76203, USA
email: [email protected]
In the past years several cyclic trinuclear complexes (CTC’s) have been synthetized and characterized on the basis of the capacity of d10 transition metal ions to give bicoordinated linear compounds. This intriguing class of compounds display pi-acid/ pi-base properties that can be finely tuned by: the nature of the metal, the substituents on the ligand or the ligand itself. [1] These complexes are attractive building blocks to obtain supramolecular compounds showing interesting photopysical properties [2] or heterobimetallic cyclic trinuclear complexes with potential use in mixed-metal catalysis [3]. Here we report the synthesis of a novel gold (I) CTC, [Au(μ-C2,N3-1-vinylimidazole)]3, and the study of some photophysical properties of its supramolecular derivatives obtained by the intercalation of metal ions in between the metallocycles.
[1] S.M. Terkali, T.R. Cundari, M.A. Omary, J. Am. Chem. Soc. 2008, 130, 1669
[2] a) A. Burini, R. Bravi, J. P. Fackler Jr, Galassi R., T. A. Grant, M. A. Omary, B. R. Pietroni, R. J. Staples . Inorg. Chem. 2000, 39; 3158.b) Burini A, Fackler J. P, JR, Galassi R., Grant T. A, Omary M. A, Rawashdeh-Omary M. A, Pietroni B. R, Staples R.J. J. Am. Chem. Soc. 2000, 122; 11264.
[3] A. Mohamed, R. Galassi, F. Papa, A. Burini, J.P. Fackler , Jr. Inorg. Chem. 2006, 45, 7770-7776
[5] R. Galassi, S. Ricci, A. Burini, A. Macchioni, L. Rocchiagiani, F. Marmottini, S.M. Terkali, V.N. Nesterov, M.A. Omary, Inorg. Chem. 2013, 52, 14124-1413
Coinage metals trinuclear metallocycles: old and new aspects of this class of compounds
No full textCoinage metals trinuclear metallocycles: old and new aspects of this class of compounds
Galassi R. a, Oumarou C. S. a, Omary A. M. b, Nesterov V. b, Burini A.a
aSchool of Science and Technology, Chemistry Division, University of Camerino, Via S. Agostino 1, 62032 Camerino; e-mail: [email protected]
b Department of Chemistry, University of North Texas, Denton, 1155 Union Circle, TX 76203, USA; e-mail: [email protected]
Azoles such as imidazoles and pyrazoles are optimal bridging ligands to obtain C,N or N,N trinuclear coinage metals metallocycles. Since past decade till now, few worldwide research groups including us have focused their attention to their synthesis and characterization.[1] Moreover, the photophysical properties[2] the extended network of metallophilic bondings in the supramolecular structure and the pi-acid/pi-base chemistry[3] of these compounds directed the research to theoretical studies bringing to a better interpretation of the experimental behaviors.[4] Here we report the synthesis of new coinage metals metallocycles and their spectroscopic characterizations highlighting points of continuity with the previous analogs and new features for new perspective research lines. As in example, the 1-vinylimidazole resembles the acid-base chemistry of the 1-benzylimidazole gold(I) metallocycle, while substitution in position 4,5 of 1-benzylimidazole with electron-withdrawing group, do not allow the formation of metallocycles with the same synthethic route and mononuclear gold(I) derivatives have been obtained. The nature of the heterocycle and of the substituents, in addition to their position in the azolate ligand defines and tunes the properties of the final products.
References:
1) Galassi, R.; Burini, A.; Omary-Rawanashed, M., Omary, M. A., Comm. Inorg. Chem. 2014, in submission.
2) Rawashdeh-Omary, M. A.; Omary, M. A.; Fackler Jr, J. P, Galassi R., Pietroni, B. R.; Burini, A. J. Am. Chem. Soc 2001, 123; 9689-9691.
3) Burini, A.;. Fackler Jr, J. P; Galassi R., Grant, T. A.. Omary, M. A; Rawashdeh-Omary, M. A.; Pietroni, B. R.; Staples R. J. J. Am. Chem. Soc., 2000; 11264-11265.
4) Galassi, R.; Ricci, S.; Burini, A.; Macchioni, A; Marmottini, F.; Tekarli, S. M.; Nesterov, N.V.; Omary, M. A. Inorg. Chem. 2013, 52, 14124-14137
Solventless VOC chemisorption by silver metallocycles
No full textSolventless VOC chemisorption by silver metallocycles
Oumarou C. S.a, Tekarli S.,b Nesterov V.,b Omary M. A.,b Burini A.,a Galassi R.,a
aSchool of Science and Technology, Chemistry Division, University of Camerino, Via S. Agostino 1, 62032 Camerino; e-mail: [email protected]
b Department of Chemistry, University of North Texas, Denton, TX 76203, USA
Prior work has focused on detection/sensing aspects of VOCs,[1] this work proposes a method for their simultaneous filtration and removal through their strong chemisorption to a silver(I) metallocyclic trimer.[2] A solid cyclotrimer can quantitatively remove entire molar integers of VOCs (1-3 equivalents of VOCs per mole of the nitrated trimer) from the vapor phase in a solventless “green” chemical process, which is unprecedented for this class of cyclic d10 complexes.
Figure 1. Illustration of quadrupole-dipole interactions involving the [Ag(μ-Pz-2CF3)]3 or [Ag(3,5-(NO2)2pz)]3 trimers and acetonitrile using M06/CEP-31G(d). MEP surfaces are plotted in two manners, either mapped on electron density surfaces (rainbow plots with the color scale shown; isodensity = 0.0004) or positive (blue) and negative (red) regions in space (range = ± 2.2 a. u.; isodensity = 0.02)
[1] Yaghi et al., PNAS 2008, 105, 11623
[2] R. Galassi, S. Ricci, A. Burini, A. Macchioni, L. Rocchigiani, F. Marmottini, S. Tekarli, V. Nesterov, M. A. Omary, J. Am. Chem. Soc., 2013, submitted
Fonti per i materiali e le tecniche del disegno genovese a lapis, in (a cura di) M. C. Galassi e M. Priarone, L’underdrawing del disegno genovese. Dentro la genesi dell’opera grafica attraverso l’esame nell’infrarosso, Genova University Press, 2014, pp. 13-16
No full textPZT film on silicon by electrophoretic deposition
No full textIn recent times direct integration of ferroelectrics on silicon wafer has been attracting interest [1]. Electrophoretic deposition (EPD) was investigated in this laboratory [2] as an alternative mean to produce lead zirconate titanate (PZT) film on silicon wafers followed by sintering at 850-950°C. EPD is an easily implemented deposition technique that requires only basic laboratory gear and a sufficiently stable colloidal suspension to produce ceramic and electroceramic films with thickness in the 100 nm - 10 mm range3 . It has been found that the EPD of niobium-doped lead zirconate titanate (PZTN), performed in ethanol-based suspensions of PZT on bare silicon wafers on which Al/Si alloyed ohmic contacts were made, produced smooth green films that strongly pinned to the silicon substrate after sintering. Thick and well-adhered sintered PZT films on silicon having thickness about 50 µm were thus obtained. Such structures could be the core of novel on-chip sensors/actuators. The results of the production of thick PZT films by EPD and sintering and some characterizations of the same are reported. [1] M. Y. Gureev, A. K. Tangatsev, N. Setter; IEEE T Ultrason Ferr, 58, 1959 (2011) [2] C. Baldisserri, D. Gardini, C. Galassi; Sensor Actuat A-Phys, 174, 123 (2012) [3] P. Sarkar, P.S. Nicholson; J Am Ceram Soc, 79, 1987 (1996
Thick composite magnetoelectric films by electrophoretic deposition
No full textElectrophoretic deposition (EPD) from colloidal suspensions was utilized for the preparation of composite magneto-dielectric films on a conductive substrate. The present process is developed as a convenient forming process for the development of devices based on thick magneto-dielectric films [1]. The deposition parameters - using EPD - such as colloidal parameters, deposition voltage and deposition time and the post process parameters, such as drying velocity and sintering will be controlled. This work aims to control the fillers/matrix ratio during the deposition and obtain a good adhesion, compaction and functionality of the composite film after the heat treatment. Measurements results for the current transients during constant-voltage deposition and the correlated deposited mass are presented [2, 3].1] A.O. Karilainen, P.M.T. Ikonen, C.R. Simovski, S.A. Tretyakov, A.N. Lagarkov, S.A. Maklakov, K.N. Rozanov, and S.N. Starostenko, Experimental studies on antenna miniaturisation using magneto-dielectric and dielectric materials, IET Microw. Antennas Propag., vol. 5, no. 4, pp. 495-502, 2011. 2] C. Baldisserri, D. Gardini and C. Galassi, An analysis of current transients during electrophoretic deposition (EPD) from colloidal TiO2 suspensions, Journal of Colloid and Interface Science 347 (2010) 102-111 3] H. Farnoush, J.A. Mohandesi, D. H. Fatmehsari and F. Moztarzadeh, A kinetic study on the electrophoretic deposition of hydroxyapatite-titania nanocomposite based on a statistical approach, Ceramics International 38 (2012), 6753-676
Il viaggio e il ritorno
No full textSi tratta dell'introduzione ai temi del volume Andalusia (curato dall'autrice) , che verranno trattati più diffusamente nelle pagine seguenti dal testo di Josè Seguì (tradotto in italiano dall'autrice), che descrive i temi del dibattito urbanistico recente in Spagna e in particolare in Andalusia.This is the introduction to the themes of Andalusia volume (edited by the author), that will be covered more fully in the following pages from the text by Jose Seguì (translated into Italian by the author), which describes the themes of the recent urban debate in Spain and especially in Andalusia
Due expò per trasformare la città di Siviglia
No full textSi tratta del contributo al 3° capitolo del libro (Andalusia), curato dall'autrice, riguardante il tema specifico della "forza progettuale dei grandi eventi".This is the contribution to the 3rd chapter of the book (Andalusia), edited by the author on the specific issue of " the design strenght of major events
Dihydrofolate reductase: a new molecular target for gold(I) drugs?
No full textDehydrofolate reductasi : a new molecular target for gold(I) drugs?
R. Galassi,a A. Burini,a D. Micozzi,a A. Dolmella,b S. Pucciarellic
a School of Science and Technology, Chemistry Division, University of Camerino, 62032 Camerino (Italy);
b Department of Pharmaceutical Sciences, University of Padova, 35131 Padova (Italy);
c School of Biosciences and Biotechnology, University of Camerino, 62032 Camerino (Italy).
[email protected]
DHFR is an important enzyme mainly involved in the synthesis of pyrimidine and thymine basilar for the DNA replication and hence the cell proliferation. To perform its functions the DHFR enzyme needs the presence of a substrate and a cofactor such as NADPH and H2F.[1] Despite its fundamental importance in the cell’s metabolism this enzyme has never been tested as molecular target for gold(I) compounds which anti-proliferative action was ascertained. In fact, it is generally accepted that gold compounds act as multi-target drug and the proposed mechanisms mainly involve enzymes. Moreover, their action is function of their overall structure and of the nature of the ligands around the central metal atom.
Some pyrazolyl and imidazolyl gold(I) phosphane complexes synthesized by us have shown anticancer properties and they successfully inhibit some seleno-dependent enzymes such as thioredoxina reductase and glutathione peroxidase.[2] To investigate in depth their action on the regards of enzyme, inhibitory studies on DHFR have been carried out. Moreover, appropriate modifications in their structure have been performed in order to get information about the structure/properties relationship.
DTNB assays, stability studies in solution and affinity constant determinations have been performed too. Some conclusions about the possible mechanism of action may be taken accordingly.
Acknowledgements
Authors are grateful to CIRCSMB for Daniela Micozzi fellowship.
References
[1] M. Brandsch, I. Knütter, E. Bosse-Doenecke, J. Pharm. Pharmacol. 2008, 60, 543.
[2] R. Galassi, A. Burini, S. Ricci, M. Pellei, M. P. Rigobello, A. Citta, A. Dolmella, V. Gandin, C Marzano. Dalton Trans., 2012, 41, 530
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